Optical clearing of articular cartilage: a comparison of clearing agents

NASA Astrophysics Data System (ADS)

Bykov, Alexander; Hautala, Tapio; Kinnunen, Matti; Popov, Alexey; Karhula, Sakari; Saarakkala, Simo; Nieminen, Miika T.; Tuchin, Valery

2015-07-01

Optical clearing technique was applied to the problem of OCT imaging of articular cartilage and subchondral bone. We show that optical clearing significantly enhances visualization of articular cartilage and cartilage-bone interface. The effect of different clearing agents was analyzed. For the clearing, iohexol solution and propylene glycol (PG) were used. Clearing was performed in vitro at room temperature by immersion method. Cylindrical osteochondral samples (d=4.8mm) were drilled from bovine lateral femur and stored in phosphate-buffered saline at -20°C until clearing. Monitoring of clearing process was performed using high-speed spectral-domain OCT system providing axial resolution of 5.8μm at 930nm. Total duration of experiment was 90-100min to ensure saturation of clearing. We have shown that iohexol solution and PG are capable to optically clear articular cartilage enabling reliable characterization of cartilagebone interface with OCT. Being a low osmolarity agent, iohexol provides minimal changes to the thickness of cartilage sample. Clearing saturation time for the cartilage sample with the thickness of 0.9 mm measured with OCT is of 50 min. However, less than 15 min is enough to reliably detect the rear cartilage boundary. Alternatively, PG significantly (60%) reduces the cartilage thickness enabling better visualization of subchondral bone. It was observed that PG has higher clearing rate. The clearing saturation time is of 30 min, however less than 5 min is enough to detect cartilage-bone interface. We conclude that iohexol solution is superior for OCT imaging of cartilage and cartilage-bone interface, while PG suits better for subhondral bone visualization.

Decalcification using ethylenediaminetetraacetic acid for clear microstructure imaging of cochlea through optical coherence tomography

NASA Astrophysics Data System (ADS)

Lee, Jaeyul; Kim, Kanghae; Wijesinghe, Ruchire Eranga; Jeon, Doekmin; Lee, Sang Heun; Jeon, Mansik; Jang, Jeong Hun

2016-08-01

The aim of this study was to analyze the effectiveness of decalcification using ethylenediaminetetraacetic acid (EDTA) as an optical clearing method to enhance the depth visibility of internal soft tissues of cochlea. Ex vivo mouse and guinea pig cochlea samples were soaked in EDTA solutions for decalcification, and swept source optical coherence tomography (OCT) was used as imaging modality to monitor the decalcified samples consecutively. The monitored noninvasive cross-sectional images showed that the mouse and guinea pig cochlea samples had to be decalcified for subsequent 7 and 14 days, respectively, to obtain the optimal optical clearing results. Using this method, difficulties in imaging of internal cochlea microstructures of mice could be evaded. The obtained results verified that the depth visibility of the decalcified ex vivo samples was enhanced.

Recent progress in tissue optical clearing

PubMed Central

Zhu, Dan; Larin, Kirill V; Luo, Qingming; Tuchin, Valery V

2013-01-01

Tissue optical clearing technique provides a prospective solution for the application of advanced optical methods in life sciences. This paper gives a review of recent developments in tissue optical clearing techniques. The physical, molecular and physiological mechanisms of tissue optical clearing are overviewed and discussed. Various methods for enhancing penetration of optical-clearing agents into tissue, such as physical methods, chemical-penetration enhancers and combination of physical and chemical methods are introduced. Combining the tissue optical clearing technique with advanced microscopy image or labeling technique, applications for 3D microstructure of whole tissues such as brain and central nervous system with unprecedented resolution are demonstrated. Moreover, the difference in diffusion and/or clearing ability of selected agents in healthy versus pathological tissues can provide a highly sensitive indicator of the tissue health/pathology condition. Finally, recent advances in optical clearing of soft or hard tissue for in vivo imaging and phototherapy are introduced. PMID:24348874

Assessment of the Atmospheric Channel for Short (Ka-Band and Optical) Wavelengths

NASA Technical Reports Server (NTRS)

Piazzolla, Sabino

2007-01-01

Atmospheric turbulence under clear sky conditions is an impairment of the atmospheric channel that greatly affects propagation of optical signal in the troposphere. The turbulence manifests itself in a number of forms within the optical domain, from the twinkling of a star in a clear night, to resolution degradation in a large aperture telescope. Therefore, a body of analytical, numerical, and experimental tools has been developed in optics to study, simulate, and control effects of atmospheric turbulence on an optical signal. Incidentally, there has been an increasing demand for high data rate returns from NASA missions which has led to envision utilizing a carrier signal in the Ka-Band range. The impact of atmospheric turbulence effects must be evaluated and considered for this frequency domain. The purpose of this work is to show that when the turbulence strength from the optical case to the KaBand ease is properly scaled, one can apply the same mathematical simulation developed for optical to predict turbulence effects within the Ka-Band domain. As a demonstration of this principle, we present how the scintillations of a Ka-Band downlink return of a deep space signal was successfully reproduced through wave-optics simulation.

Skin optical clearing potential of disaccharides

NASA Astrophysics Data System (ADS)

Feng, Wei; Shi, Rui; Ma, Ning; Tuchina, Daria K.; Tuchin, Valery V.; Zhu, Dan

2016-08-01

Skin optical clearing can significantly enhance the ability of biomedical optical imaging. Some alcohols and sugars have been selected to be optical clearing agents (OCAs). In this work, we paid attention to the optical clearing potential of disaccharides. Sucrose and maltose were chosen as typical disaccharides to compare with fructose, an excellent monosaccharide-OCA, by using molecular dynamics simulation and an ex vivo experiment. The experimental results indicated that the optical clearing efficacy of skin increases linearly with the concentration for each OCA. Both the theoretical predication and experimental results revealed that the two disaccharides exerted a better optical clearing potential than fructose at the same concentration, and sucrose is optimal. Since maltose has an extremely low saturation concentration, the other two OCAs with saturation concentrations were treated topically on rat skin in vivo, and optical coherence tomography imaging was applied to monitor the optical clearing process. The results demonstrated that sucrose could cause a more significant increase in imaging depth and signal intensity than fructose.

Optical clearing of the dura mater using glycerol: a reversible process to aid the post-mortem investigation of infant head injury.

PubMed

Cheshire, Emma C; Malcomson, Roger D G; Joseph, Shiju; Biggs, Mike J B; Adlam, David; Rutty, Guy N

2015-09-01

In cases of suspected abusive head trauma, a thorough and systematic study of the cranium and its contents is essential, preferably using the best available methods for observing the brain and its coverings. Building upon recent developments in skull bone removal techniques in infant autopsies, we have assessed the use of two optical clearing agents (OCAs), glycerol and mannitol, on pediatric dura mater in an attempt to increase the transparency of this tissue and thereby enhance the post-mortem assessment of infant head injuries, particularly subdural hematomas. Extracorporeal testing revealed glycerol to be the more effective OCA. Therefore, in situ investigations were commenced using glycerol during 33 pediatric post-mortem examinations. An increase in the transparency of the dura was observed in 32 of the 33 cases, within 1 min of application of the OCA. In a 2 year old with cerebral palsy, only partial optical clearance of the dura was seen, most likely due to a significantly atrophic brain, prominent gelatinous leptomeninges, and abnormally thickened dura. This technique allowed for detection of minimal amounts of subdural bleeding over the convexities, before dissection of the dura, avoiding post-mortem blood spillage from artifactually disrupted bridging veins. Optical clearing of the dura aided in the evaluation of patterns of subdural hemorrhage in three cases of non-accidental head injury, three cases of peri-natal head injury and one case of overlaying, apparently resulting in minor crush injury to the head. We have demonstrated that glycerol is an effective and easy-to-use OCA to effect the readily reversible optical clearing of human infant calvarial dura at autopsy.

A large, switchable optical clearing skull window for cerebrovascular imaging

PubMed Central

Zhang, Chao; Feng, Wei; Zhao, Yanjie; Yu, Tingting; Li, Pengcheng; Xu, Tonghui; Luo, Qingming; Zhu, Dan

2018-01-01

Rationale: Intravital optical imaging is a significant method for investigating cerebrovascular structure and function. However, its imaging contrast and depth are limited by the turbid skull. Tissue optical clearing has a great potential for solving this problem. Our goal was to develop a transparent skull window, without performing a craniotomy, for use in assessing cerebrovascular structure and function. Methods: Skull optical clearing agents were topically applied to the skulls of mice to create a transparent window within 15 min. The clearing efficacy, repeatability, and safety of the skull window were then investigated. Results: Imaging through the optical clearing skull window enhanced both the contrast and the depth of intravital imaging. The skull window could be used on 2-8-month-old mice and could be expanded from regional to bi-hemispheric. In addition, the window could be repeatedly established without inducing observable inflammation and metabolic toxicity. Conclusion: We successfully developed an easy-to-handle, large, switchable, and safe optical clearing skull window. Combined with various optical imaging techniques, cerebrovascular structure and function can be observed through this optical clearing skull window. Thus, it has the potential for use in basic research on the physiopathologic processes of cortical vessels. PMID:29774069

TH-C-19A-05: Evaluation of a New Reusable 3D Dosimeter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Juang, T; Adamovics, J; Oldham, M

Purpose: PRESAGE is a radiochromic plastic which has demonstrated strong potential for high resolution single-use 3D dosimetry. This study evaluates a new PRESAGE formulation (Presage-RU) in which the radiochromic response is reversible (the dosimeter optically clears after irradiation), enabling the potential for reusability. Methods: Presage-RU dose response and optical-clearing rates were evaluated in both small volume dosimeters (1×1×4.5cm) and a larger cylindrical dosimeter (8cm diameter, 4.5cm length). All dosimeters were allowed to fully optically clear in dark, room temperature conditions between irradiations. Dose response was determined by irradiating small volume samples from 0–8.0Gy and measuring change in optical density. Themore » cylindrical dosimeter was irradiated with a simple 4-field box plan (parallel opposed pairs of 4cm×4cm AP-PA beams and 2cm×4cm lateral beams) to 20Gy. High resolution 3D dosimetry was achieved utilizing optical-CT readout. Readings were tracked up to 14 days to characterize optical clearing. Results: Initial irradiation yielded a response of 0.0119△OD/(Gy*cm) while two subsequent reirradiations yielded a lower but consistent response of 0.0087△OD/(Gy*cm). Strong linearity of dose response was observed for all irradiations. In the large cylindrical dosimeter, the integral dose within the high dose region exhibited an exponential decay in signal over time (halflife= 23.9 hours), with the dosimeter effectively cleared (0.04% of the initial signal) after 10 days. Subsequent irradiation resulted in 19.5% lower initial signal but demonstrated that the exponential clearing rate remained consistent. Results of additional subsequent irradiations will also be presented. Conclusion: This work introduces a new re-usable radiochromic dosimeter (Presage-RU) compatible with high resolution (sub-millimeter) 3D dosimetry. Sensitivity of the initial radiation was observed to be slightly higher than subsequent irradiations, but the clearing time remained constant, indicating the dosimeter can be re-used after 10 days. Presage-RU has potential to dramatically improve cost-effectiveness and thereby lower the barrier for implementing comprehensive, high resolution 3D dosimetry. John Adamovics is the president of Heuris Inc., which commercializes PRESAGE.« less

Influence of the relative optical air mass on ultraviolet erythemal irradiance

NASA Astrophysics Data System (ADS)

Antón, M.; Serrano, A.; Cancillo, M. L.; García, J. A.

2009-12-01

The main objective of this article is to analyze the relationship between the transmissivity for ultraviolet erythemal irradiance (UVER) and the relative optical air mass at Badajoz (Southwestern Spain). Thus, a power expression between both variables is developed, which analyses in detail how atmospheric transmission is influenced by the total ozone column (TOC) and the atmospheric clearness. The period of analysis extends from 2001 to 2005. The experimental results indicate that clearness conditions play an important role in the relationship between UVER transmissivity and the relative optical air mass, while the effect of TOC is much smaller for this data set. In addition, the results show that UVER transmissivity is more sensitive to changes in atmospheric clearness than to TOC variability. Changes in TOC values higher than 15% cause UVER trasnmissivity to vary between 14% and 22%, while changes between cloud-free and overcast conditions produce variations in UVER transmissivity between 68% and 74% depending on the relative optical air mass.

Seeing through Musculoskeletal Tissues: Improving In Situ Imaging of Bone and the Lacunar Canalicular System through Optical Clearing

PubMed Central

Berke, Ian M.; Miola, Joseph P.; David, Michael A.; Smith, Melanie K.; Price, Christopher

2016-01-01

In situ, cells of the musculoskeletal system reside within complex and often interconnected 3-D environments. Key to better understanding how 3-D tissue and cellular environments regulate musculoskeletal physiology, homeostasis, and health is the use of robust methodologies for directly visualizing cell-cell and cell-matrix architecture in situ. However, the use of standard optical imaging techniques is often of limited utility in deep imaging of intact musculoskeletal tissues due to the highly scattering nature of biological tissues. Drawing inspiration from recent developments in the deep-tissue imaging field, we describe the application of immersion based optical clearing techniques, which utilize the principle of refractive index (RI) matching between the clearing/mounting media and tissue under observation, to improve the deep, in situ imaging of musculoskeletal tissues. To date, few optical clearing techniques have been applied specifically to musculoskeletal tissues, and a systematic comparison of the clearing ability of optical clearing agents in musculoskeletal tissues has yet to be fully demonstrated. In this study we tested the ability of eight different aqueous and non-aqueous clearing agents, with RIs ranging from 1.45 to 1.56, to optically clear murine knee joints and cortical bone. We demonstrated and quantified the ability of these optical clearing agents to clear musculoskeletal tissues and improve both macro- and micro-scale imaging of musculoskeletal tissue across several imaging modalities (stereomicroscopy, spectroscopy, and one-, and two-photon confocal microscopy) and investigational techniques (dynamic bone labeling and en bloc tissue staining). Based upon these findings we believe that optical clearing, in combination with advanced imaging techniques, has the potential to complement classical musculoskeletal analysis techniques; opening the door for improved in situ investigation and quantification of musculoskeletal tissues. PMID:26930293

Seeing through Musculoskeletal Tissues: Improving In Situ Imaging of Bone and the Lacunar Canalicular System through Optical Clearing.

PubMed

Berke, Ian M; Miola, Joseph P; David, Michael A; Smith, Melanie K; Price, Christopher

2016-01-01

In situ, cells of the musculoskeletal system reside within complex and often interconnected 3-D environments. Key to better understanding how 3-D tissue and cellular environments regulate musculoskeletal physiology, homeostasis, and health is the use of robust methodologies for directly visualizing cell-cell and cell-matrix architecture in situ. However, the use of standard optical imaging techniques is often of limited utility in deep imaging of intact musculoskeletal tissues due to the highly scattering nature of biological tissues. Drawing inspiration from recent developments in the deep-tissue imaging field, we describe the application of immersion based optical clearing techniques, which utilize the principle of refractive index (RI) matching between the clearing/mounting media and tissue under observation, to improve the deep, in situ imaging of musculoskeletal tissues. To date, few optical clearing techniques have been applied specifically to musculoskeletal tissues, and a systematic comparison of the clearing ability of optical clearing agents in musculoskeletal tissues has yet to be fully demonstrated. In this study we tested the ability of eight different aqueous and non-aqueous clearing agents, with RIs ranging from 1.45 to 1.56, to optically clear murine knee joints and cortical bone. We demonstrated and quantified the ability of these optical clearing agents to clear musculoskeletal tissues and improve both macro- and micro-scale imaging of musculoskeletal tissue across several imaging modalities (stereomicroscopy, spectroscopy, and one-, and two-photon confocal microscopy) and investigational techniques (dynamic bone labeling and en bloc tissue staining). Based upon these findings we believe that optical clearing, in combination with advanced imaging techniques, has the potential to complement classical musculoskeletal analysis techniques; opening the door for improved in situ investigation and quantification of musculoskeletal tissues.

Stiffness of RBC optical confinement affected by optical clearing

NASA Astrophysics Data System (ADS)

Grishin, Oleg V.; Fedosov, Ivan V.; Tuchin, Valery V.

2017-03-01

In vivo optical trapping is a novel applied direction of an optical manipulation, which enables one to noninvasive measurement of mechanical properties of cells and tissues in living animals directly. But an application area of this direction is limited because strong scattering of many biological tissues. An optical clearing enables one to decrease the scattering and therefore increase a depth of light penetration, decrease a distortion of light beam, improve a resolution in imaging applications. Now novel methods had appeared for a measurement an optical clearing degree at a cellular level. But these methods aren't applicable in vivo. In this paper we present novel measurement method of estimate of the optical clearing, which are based on a measurement of optical trap stiffness. Our method may be applicable in vivo.

3D Cloud Radiative Effects on Aerosol Optical Thickness Retrievals in Cumulus Cloud Fields in the Biomass Burning Region in Brazil

NASA Technical Reports Server (NTRS)

Wen, Guo-Yong; Marshak, Alexander; Cahalan, Robert F.

2004-01-01

Aerosol amount in clear regions of a cloudy atmosphere is a critical parameter in studying the interaction between aerosols and clouds. Since the global cloud cover is about 50%, cloudy scenes are often encountered in any satellite images. Aerosols are more or less transparent, while clouds are extremely reflective in the visible spectrum of solar radiation. The radiative transfer in clear-cloudy condition is highly three- dimensional (3D). This paper focuses on estimating the 3D effects on aerosol optical thickness retrievals using Monte Carlo simulations. An ASTER image of cumulus cloud fields in the biomass burning region in Brazil is simulated in this study. The MODIS products (i-e., cloud optical thickness, particle effective radius, cloud top pressure, surface reflectance, etc.) are used to construct the cloud property and surface reflectance fields. To estimate the cloud 3-D effects, we assume a plane-parallel stratification of aerosol properties in the 60 km x 60 km ASTER image. The simulated solar radiation at the top of the atmosphere is compared with plane-parallel calculations. Furthermore, the 3D cloud radiative effects on aerosol optical thickness retrieval are estimated.

The Role of Optical Radiations in Skin Cancer

PubMed Central

Palla, Marco; Di Trolio, Rossella; Mozzillo, Nicola; Ascierto, Paolo A.

2013-01-01

Purpose. Electromagnetic radiation with wavelength in the range 100 nm to 1 mm is known as optical radiation and includes ultraviolet radiation, the visible spectrum, and infrared radiation. The deleterious short- and long-term biological effects of ultraviolet radiation, including melanoma and other skin cancers, are well recognized. Infrared radiation may also have damaging biological effects. Methods. The objective of this review was to assess the literature over the last 15 years and to summarize correlations between exposure to optical radiation and the risk of melanoma and other cancers. Results. There is a clear correlation between exposure to UV radiation and the development of skin cancer. Most importantly, a strong association between artificial UV radiation exposure, for example, tanning devices, and the risk of melanoma and squamous cell carcinoma has been clearly demonstrated. There is no clear evidence that exposure to IR and laser radiation may increase the risk of skin cancer, although negative health effects have been observed. Conclusions. Preventative strategies that involve provision of public information highlighting the risks associated with exposure to sunlight remain important. In addition, precautionary measures that discourage exposure to tanning appliances are required, as is legislation to prevent their use during childhood. PMID:23710365

Remote atmospheric probing by ground to ground line of sight optical methods

NASA Technical Reports Server (NTRS)

Lawrence, R. S.

1969-01-01

The optical effects arising from refractive-index variations in the clear air are qualitatively described, and the possibilities are discussed of using those effects for remotely sensing the physical properties of the atmosphere. The effects include scintillations, path length fluctuations, spreading of a laser beam, deflection of the beam, and depolarization. The physical properties that may be measured include the average temperature along the path, the vertical temperature gradient, and the distribution along the path of the strength of turbulence and the transverse wind velocity. Line-of-sight laser beam methods are clearly effective in measuring the average properties, but less effective in measuring distributions along the path. Fundamental limitations to the resolution are pointed out and experiments are recommended to investigate the practicality of the methods.

Non-destructive optical clearing technique enhances optical coherence tomography (OCT) for real-time, 3D histomorphometry of brain tissue (Conference Presentation)

NASA Astrophysics Data System (ADS)

Paul, Akshay; Chang, Theodore H.; Chou, Li-Dek; Ramalingam, Tirunelveli S.

2016-03-01

Evaluation of neurodegenerative disease often requires examination of brain morphology. Volumetric analysis of brain regions and structures can be used to track developmental changes, progression of disease, and the presence of transgenic phenotypes. Current standards for microscopic investigation of brain morphology are limited to detection of superficial structures at a maximum depth of 300μm. While histological techniques can provide detailed cross-sections of brain structures, they require complicated tissue preparation and the ultimate destruction of the sample. A non-invasive, label-free imaging modality known as Optical Coherence Tomography (OCT) can produce 3-dimensional reconstructions through high-speed, cross-sectional scans of biological tissue. Although OCT allows for the preservation of intact samples, the highly scattering and absorbing properties of biological tissue limit imaging depth to 1-2mm. Optical clearing agents have been utilized to increase imaging depth by index matching and lipid digestion, however, these contemporary techniques are expensive and harsh on tissues, often irreversibly denaturing proteins. Here we present an ideal optical clearing agent that offers ease-of-use and reversibility. Similar to how SeeDB has been effective for microscopy, our fructose-based, reversible optical clearing technique provides improved OCT imaging and functional immunohistochemical mapping of disease. Fructose is a natural, non-toxic sugar with excellent water solubility, capable of increasing tissue transparency and reducing light scattering. We will demonstrate the improved depth-resolving performance of OCT for enhanced whole-brain imaging of normal and diseased murine brains following a fructose clearing treatment. This technique potentially enables rapid, 3-dimensional evaluation of biological tissues at axial and lateral resolutions comparable to histopathology.

Liquid-crystal-based switchable polarizers for sensor protection.

PubMed

Wu, C S; Wu, S T

1995-11-01

Linear polarizers are generally employed in conjunction with advanced liquid-crystal filters for the protection of human eyes and optical sensors. For detection sensitivity under a no-threat condition to be maximized, the polarizer should remain in a clear state with a minimum insertion loss. When threats are present, it should be quickly switched to function as a linear polarizer with a high extinction ratio. Two types of switchable polarizer for sensor protection are demonstrated. The polarization conversion type exhibits a high optical efficiency in its clear state, a high extinction ratio in the linear polarizer state, and a fast switching speed, except that its field of view is limited to approximately ±10°. In contrast, an improved switchable dichroic polarizer functions effectively over a much wider field of view. However, its extinction ratio and optical efficiency in its clear state are lower than those of the polarization conversion type.

Liquid-crystal-based switchable polarizers for sensor protection

NASA Astrophysics Data System (ADS)

Wu, Chiung-Sheng; Wu, Shin-Tson

1995-11-01

Linear polarizers are generally employed in conjunction with advanced liquid-crystal filters for the protection of human eyes and optical sensors. For detection sensitivity under a no-threat condition to be maximized, the polarizer should remain in a clear state with a minimum insertion loss. When threats are present, it should be quickly switched to function as a linear polarizer with a high extinction ratio. Two types of switchable polarizer for sensor protection are demonstrated. The polarization conversion type exhibits a high optical efficiency in its clear state, a high extinction ratio in the linear polarizer state, and a fast switching speed, except that its field of view is limited to approximately +/-10 deg In contrast, an improved switchable dichroic polarizer functions effectively over a much wider field of view. However, its extinction ratio and optical efficiency in its clear state are lower than those of the polarization conversion type.

Optical clearing of skin enhanced with hyaluronic acid for increased contrast of optoacoustic imaging

NASA Astrophysics Data System (ADS)

Liopo, Anton; Su, Richard; Tsyboulski, Dmitri A.; Oraevsky, Alexander A.

2016-08-01

Enhanced delivery of optical clearing agents (OCA) through skin may improve sensitivity of optical and optoacoustic (OA) methods of imaging, sensing, and monitoring. This report describes a two-step method for enhancement of light penetration through skin. Here, we demonstrate that topical application of hyaluronic acid (HA) improves skin penetration of hydrophilic and lipophilic OCA and thus enhances their performance. We examined the OC effect of 100% polyethylene and polypropylene glycols (PPGs) and their mixture after pretreatment by HA, and demonstrated significant increase in efficiency of light penetration through skin. Increased light transmission resulted in a significant increase of OA image contrast in vitro. Topical pretreatment of skin for about 30 min with 0.5% HA in aqueous solution offers effective delivery of low molecular weight OCA such as a mixture of PPG-425 and polyethylene glycol (PEG)-400. The developed approach of pretreatment by HA prior to application of clearing agents (PEG and PPG) resulted in a ˜47-fold increase in transmission of red and near-infrared light and significantly enhanced contrast of OA images.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Characterisation of optically cleared paper by optical coherence tomography

NASA Astrophysics Data System (ADS)

Fabritius, T.; Alarousu, E.; Prykäri, T.; Hast, J.; Myllylä, Risto

2006-02-01

Due to the highly light scattering nature of paper, the imaging depth of optical methods such as optical coherence tomography (OCT) is limited. In this work, we study the effect of refractive index matching on improving the imaging depth of OCT in paper. To this end, four different refractive index matching liquids (ethanol, 1-pentanol, glycerol and benzyl alcohol) with a refraction index between 1.359 and 1.538 were used in experiments. Low coherent light transmission was studied in commercial copy paper sheets, and the results indicate that benzyl alcohol offers the best improvement in imaging depth, while also being sufficiently stable for the intended purpose. Constructed cross-sectional images demonstrate visually that the imaging depth of OCT is considerably improved by optical clearing. Both surfaces of paper sheets can be detected along with information about the sheet's inner structure.

SW radiative effect of aerosol in GRAPES_GFS

NASA Astrophysics Data System (ADS)

Chen, Qiying

2017-04-01

The aerosol particles can scatter and absorb solar radiation, and so change the shortwave radiation absorbed by the atmosphere, reached the surface and that reflected back to outer space at TOA. Since this process doesn't interact with other processes, it is called direct radiation effect. The clear sky downward SW and net SW fluxes at the surface in GRAPES_GFS of China Meteorological Administration are overestimated in Northern multitudes and Tropics. The main source of these errors is the absence of aerosol SW effect in GRAPES_GFS. The climatic aerosol mass concentration data, which include 13 kinds of aerosol and their 14 SW bands optical properties are considered in GRAPES_GFS. The calculated total optical depth, single scatter albedo and asymmetry factor are used as the input to radiation scheme. Compared with the satellite observation from MISER, the calculated total optical depth is in good consistent. The seasonal experiments show that, the summer averaged clear sky radiation fluxes at the surface are improved after including the SW effect of aerosol. The biases in the clear sky downward SW and net SW fluxes at the surface in Northern multitudes and Tropic reduced obviously. Furthermore, the weather forecast experiments also show that the skill scores in Northern hemisphere and East Asia also become better.

Photoacoustic effect generated by moving optical sources: Motion in one dimension

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bai, Wenyu; Diebold, Gerald J.

2016-03-28

Although the photoacoustic effect is typically generated by pulsed or amplitude modulated optical beams, it is clear from examination of the wave equation for pressure that motion of an optical source in space will result in the production of sound as well. Here, the properties of the photoacoustic effect generated by moving sources in one dimension are investigated. The cases of a moving Gaussian beam, an oscillating delta function source, and an accelerating Gaussian optical sources are reported. The salient feature of one-dimensional sources in the linear acoustic limit is that the amplitude of the beam increases in time withoutmore » bound.« less

Ultrasound sensing using the acousto-optic effect in polymer dispersed liquid crystals

NASA Astrophysics Data System (ADS)

Trushkevych, O.; Eriksson, T. J. R.; Ramadas, S. N.; Dixon, S.; Edwards, R. S.

2015-08-01

Acousto-optic effects are demonstrated in polymer dispersed liquid crystal (PDLC) films, showing promise for applications in ultrasound sensing. The PDLC films are used to image two displacement profiles of air-coupled flexural transducers' resonant modes at 295 kHz and 730 kHz. Results are confirmed using laser vibrometry. The regions on the transducers with the largest displacements are clearly imaged by the PDLC films, with the resolution agreeing well with laser vibrometry scanning. Imaging takes significantly less time than a scanning system (switching time of a few seconds, as compared to 8 h for laser vibrometry). Heating effects are carefully monitored using thermal imaging and are found not to be the main cause of PDLC clearing.

Enhanced optical clearing of skin in vivo and optical coherence tomography in-depth imaging

NASA Astrophysics Data System (ADS)

Wen, Xiang; Jacques, Steven L.; Tuchin, Valery V.; Zhu, Dan

2012-06-01

The strong optical scattering of skin tissue makes it very difficult for optical coherence tomography (OCT) to achieve deep imaging in skin. Significant optical clearing of in vivo rat skin sites was achieved within 15 min by topical application of an optical clearing agent PEG-400, a chemical enhancer (thiazone or propanediol), and physical massage. Only when all three components were applied together could a 15 min treatment achieve a three fold increase in the OCT reflectance from a 300 μm depth and 31% enhancement in image depth Zthreshold.

Quantitative assessment of hyaline cartilage elasticity during optical clearing using optical coherence elastography

NASA Astrophysics Data System (ADS)

Liu, Chih-Hao; Singh, Manmohan; Li, Jiasong; Han, Zhaolong; Wu, Chen; Wang, Shang; Idugboe, Rita; Raghunathan, Raksha; Zakharov, Valery P.; Sobol, Emil N.; Tuchin, Valery V.; Twa, Michael; Larin, Kirill V.

2015-03-01

We report the first study on using optical coherence elastography (OCE) to quantitatively monitor the elasticity change of the hyaline cartilage during the optical clearing administrated by glucose solution. The measurement of the elasticity is verified using uniaxial compression test, demonstrating the feasibility of using OCE to quantify the Young's modulus of the cartilage tissue. As the results, we found that the stiffness of the hyaline cartilage increases during the optical clearing of the tissue. This study might be potentially useful for the early detection of osteoarthritis disease.

Development of Extinction Imagers for the Determination of Atmospheric Optical Extinction

DTIC Science & Technology

2014-08-01

system resulting from the effects of both the optics and the camera system (including the electronics). The MSI sensor includes a fiber optic taper...small dots in Fig. 7-1 are due to the fiber optic taper in the system. The brighter region near the center is due to the lens optics. To apply the...a black target wliich was a hollow black box. Clearly it would be a major advantage if we could use "targets of opportunity" from a ship, and in

Observation of the spectrally invariant properties of clouds in cloudy-to-clear transition zones during the MAGIC field campaign

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Weidong; Marshak, Alexander; McBride, Patrick J.

2016-12-01

We use the spectrally invariant method to study the variability of cloud optical thickness τ and droplet effective radius reff in transition zones (between the cloudy and clear sky columns) observed from Solar Spectral Flux Radiometer (SSFR) and Shortwave Array Spectroradiometer-Zenith (SASZe) during the Marine ARM GPCI Investigation of Clouds (MAGIC) field campaign. The measurements from the SSFR and the SASZe are different, however inter-instrument differences of self-normalized measurements (divided by their own spectra at a fixed time) are small. The spectrally invariant method approximates the spectra in the cloud transition zone as a linear combination of definitely clear andmore » cloudy spectra, where the coefficients, slope and intercept, character-ize the spectrally invariant properties of the transition zone. Simulation results from the SBDART (Santa Barbara DISORT Atmospheric Radiative Transfer) model demonstrate that (1) the slope of the visible band is positively correlated with the cloud optical thickness τ while the intercept of the near-infrared band has high negative cor-relation with the cloud drop effective radius reff even without the exact knowledge of τ; (2) the above relations hold for all Solar Zenith Angle (SZA) and for cloud-contaminated skies. In observations using redundant measure-ments from SSFR and SASZe, we find that during cloudy-to-clear transitions, (a) the slopes of the visible band de-crease, and (b) the intercepts of the near-infrared band remain almost constant near cloud edges. The findings in simulations and observations suggest that, while the optical thickness decreases during the cloudy-to-clear transition, the cloud drop effective radius does not change when cloud edges are approached. These results sup-port the hypothesis that inhomogeneous mixing dominates near cloud edges in the studied cases.« less

Observation of the Spectrally Invariant Properties of Clouds in Cloudy-to-Clear Transition Zones During the MAGIC Field Campaign

NASA Technical Reports Server (NTRS)

Yang, Weidong; Marshak, Alexander; McBride, Patrick; Chiu, J. Christine; Knyazikhin, Yuri; Schmidt, K. Sebastian; Flynn, Connor; Lewis, Ernie R.; Eloranta, Edwin W.

2016-01-01

We use the spectrally invariant method to study the variability of cloud optical thickness tau and droplet effective radius r(sub eff) in transition zones (between the cloudy and clear sky columns) observed from Solar Spectral Flux Radiometer (SSFR) and Shortwave Array Spectroradiometer-Zenith (SASZe) during the Marine ARM GPCI Investigation of Clouds (MAGIC) field campaign. The measurements from the SSFR and the SASZe are different, however inter-instrument differences of self-normalized measurements (divided by their own spectra at a fixed time) are small. The spectrally invariant method approximates the spectra in the cloud transition zone as a linear combination of definitely clear and cloudy spectra, where the coefficients, slope and intercept, characterize the spectrally invariant properties of the transition zone. Simulation results from the SBDART (Santa Barbara DISORT Atmospheric Radiative Transfer) model demonstrate that (1) the slope of the visible band is positively correlated with the cloud optical thickness t while the intercept of the near-infrared band has high negative correlation with the cloud drop effective radius r(sub eff)even without the exact knowledge of tau; (2) the above relations hold for all Solar Zenith Angle (SZA) and for cloud-contaminated skies. In observations using redundant measurements from SSFR and SASZe, we find that during cloudy-to-clear transitions, (a) the slopes of the visible band decrease, and (b) the intercepts of the near-infrared band remain almost constant near cloud edges. The findings in simulations and observations suggest that, while the optical thickness decreases during the cloudy-to-clear transition, the cloud drop effective radius does not change when cloud edges are approached. These results support the hypothesis that inhomogeneous mixing dominates near cloud edges in the studied cases.

Atmospheric Propagation Effects Relevant to Optical Communications

NASA Technical Reports Server (NTRS)

Shaik, K. S.

1988-01-01

A number of atmospheric phenomena affect the propagation of light. This article reviews the effects of clear-air turbulence as well as atmospheric turbidity on optical communications. Among the phenomena considered are astronomical and random refraction, scintillation, beam broadening, spatial coherence, angle of arrival, aperture averaging, absorption and scattering, and the effect of opaque clouds. An extensive reference list is also provided for further study, Useful information on the atmospheric propagation of light in resolution to optical deep-space communications to an earth-based receiving station is available, however, further data must be generated before such a link can be designed with committed performance.

Atmospheric propagation effects relevant to optical communications

NASA Technical Reports Server (NTRS)

Shaik, K. S.

1988-01-01

A number of atmospheric phenomena affect the propagation of light. The effects of clear air turbulence are reviewed as well as atmospheric turbidity on optical communications. Among the phenomena considered are astronomical and random refraction, scintillation, beam broadening, spatial coherence, angle of arrival, aperture averaging, absorption and scattering, and the effect of opaque clouds. An extensive reference list is also provided for further study. Useful information on the atmospheric propagation of light in relation to optical deep space communications to an earth based receiving station is available, however, further data must be generated before such a link can be designed with committed performance.

Penetration kinetics of dimethyl sulphoxide and glycerol in dynamic optical clearing of porcine skin tissue in vitro studied by Fourier transform infrared spectroscopic imaging.

PubMed

Jiang, Jingying; Boese, Matthias; Turner, Paul; Wang, Ruikang K

2008-01-01

By use of a Fourier transform infrared (FTIR) spectroscopic imaging technique, we examine the dynamic optical clearing processes occurring in hyperosmotically biocompatible agents penetrating into skin tissue in vitro. The sequential collection of images in a time series provides an opportunity to assess penetration kinetics of dimethyl sulphoxide (DMSO) and glycerol beneath the surface of skin tissue over time. From 2-D IR spectroscopic images and 3-D false color diagrams, we show that glycerol takes at least 30 min to finally penetrate the layer of epidermis, while DMSO can be detected in epidermis after only 4 min of being topically applied over stratum corneum sides of porcine skin. The results demonstrate the potential of a FTIR spectroscopic imaging technique as an analytical tool for the study of dynamic optical clearing effects when the bio-tissue is impregnated by hyperosmotically biocompatible agents such as glycerol and DMSO.

3D imaging of cleared human skin biopsies using light-sheet microscopy: A new way to visualize in-depth skin structure.

PubMed

Abadie, S; Jardet, C; Colombelli, J; Chaput, B; David, A; Grolleau, J-L; Bedos, P; Lobjois, V; Descargues, P; Rouquette, J

2018-05-01

Human skin is composed of the superimposition of tissue layers of various thicknesses and components. Histological staining of skin sections is the benchmark approach to analyse the organization and integrity of human skin biopsies; however, this approach does not allow 3D tissue visualization. Alternatively, confocal or two-photon microscopy is an effective approach to perform fluorescent-based 3D imaging. However, owing to light scattering, these methods display limited light penetration in depth. The objectives of this study were therefore to combine optical clearing and light-sheet fluorescence microscopy (LSFM) to perform in-depth optical sectioning of 5 mm-thick human skin biopsies and generate 3D images of entire human skin biopsies. A benzyl alcohol and benzyl benzoate solution was used to successfully optically clear entire formalin fixed human skin biopsies, making them transparent. In-depth optical sectioning was performed with LSFM on the basis of tissue-autofluorescence observations. 3D image analysis of optical sections generated with LSFM was performed by using the Amira ® software. This new approach allowed us to observe in situ the different layers and compartments of human skin, such as the stratum corneum, the dermis and epidermal appendages. With this approach, we easily performed 3D reconstruction to visualise an entire human skin biopsy. Finally, we demonstrated that this method is useful to visualise and quantify histological anomalies, such as epidermal hyperplasia. The combination of optical clearing and LSFM has new applications in dermatology and dermatological research by allowing 3D visualization and analysis of whole human skin biopsies. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Recent progress in tissue optical clearing for spectroscopic application

NASA Astrophysics Data System (ADS)

Sdobnov, A. Yu.; Darvin, M. E.; Genina, E. A.; Bashkatov, A. N.; Lademann, J.; Tuchin, V. V.

2018-05-01

This paper aims to review recent progress in optical clearing of the skin and over naturally turbid biological tissues and blood using this technique in vivo and in vitro with multiphoton microscopy, confocal Raman microscopy, confocal microscopy, NIR spectroscopy, optical coherence tomography, and laser speckle contrast imaging. Basic principles of the technique, its safety, advantages and limitations are discussed. The application of optical clearing agent on a tissue allows for controlling the optical properties of tissue. Optical clearing-induced reduction of tissue scattering significantly facilitates the observation of deep-located tissue regions, at the same time improving the resolution and image contrast for a variety of optical imaging methods suitable for clinical applications, such as diagnostics and laser treatment of skin diseases, mucosal tumor imaging, laser disruption of pathological abnormalities, etc. Structural images of different skin layers obtained ex vivo for porcine ear skin samples at application of Omnipaque™ and glycerol solutions during 60 min. Red color corresponds to TPEAF signal channel. Green color corresponds to SHG signal channel.

Second harmonic generation imaging of skeletal muscle tissue and myofibrils

NASA Astrophysics Data System (ADS)

Campagnola, Paul J.; Mohler, William H.; Plotnikov, Sergey; Millard, Andrew C.

2006-02-01

Second Harmonic Generation (SHG) imaging microscopy is used to examine the morphology and structural properties of intact muscle tissue. Using biochemical and optical analysis, we characterize the molecular structure underlying SHG from the complex muscle sarcomere. We find that SHG from isolated myofibrils is abolished by extraction of myosin, but is unaffected by removal or addition of actin filaments. We thus determined that the SHG emission arises from domains of the sarcomere containing thick filaments. By fitting the SHG polarization anisotropy to theoretical response curves, we find an orientation for the harmonophore that corresponds well to the pitch angle of the myosin rod α-helix with respect to the thick filament axis. Taken together, these data indicate that myosin rod domains are the key structures giving rise to SHG from striated muscle. Using SHG imaging microscopy, we have also examined the effect of optical clearing with glycerol to achieve greater penetration into specimens of skeletal muscle tissue. We find that treatment with 50% glycerol results in a 2.5 fold increase in achievable SHG imaging depth. Fast Fourier Transform (FFT) analysis shows quantitatively that the periodicity of the sarcomere structure is unaltered by the clearing process. Also, comparison of the SHG angular polarization dependence shows no change in the supramolecular organization of acto-myosin complexes. We suggest that the primary mechanism of optical clearing in muscle with glycerol treatment results from the reduction of cytoplasmic protein concentration and concomitant decrease in the secondary inner filter effect on the SHG signal. The pronounced lack of dependence of glycerol concentration on the imaging depth indicates that refractive index matching plays only a minor role in the optical clearing of muscle.

Using low-frequency ultrasound to improve the optical clearing of porcine skin

NASA Astrophysics Data System (ADS)

Zhong, Huiqing; Guo, Zhouyi; Wei, Huajiang; Zhang, Zude; Zeng, Changchun; Zhai, Juan; He, Yonghong

2008-12-01

The glycerol used as an enhancer for tissue optical clearing technique has been researched. However, using it and a physical way of ultrasound enhance optical clearing of tissue reported a few. We researched that the ultrasound whether can improve the optical clearing of dealt with 80% glycerol tissue. The fresh porcine skins divided into four groups. The first group was not dealt with by ultrasound and 80% glycerol, the second group was dealt with by only ultrasound, the third group was dealt with by 80% glycerol and no by ultrasound, and the fourth group was dealt with by both 80% glycerol and ultrasound. And we measured changes in optical scattering of the porcine skins under treatment with OCT. From the OCT images show that the fourth group changed very faster than the other's during the 0~15 min. And it can be clearly seen that there is a significant improvement in the light penetration depth and imaging contrast in a shorter time. It is possible that the low-frequency ultrasound can make disordering of the stratum corneum lipids of the porcine skin (because the cavitation has happened), and improve the speed of 80% glycerol through the stratum corneum of skin. These results proved that using 80% glycerol with the ultrasound can better improve the optical clearing of tissue.

Virtual experiment of optical spatial filtering in Matlab environment

NASA Astrophysics Data System (ADS)

Ji, Yunjing; Wang, Chunyong; Song, Yang; Lai, Jiancheng; Wang, Qinghua; Qi, Jing; Shen, Zhonghua

2017-08-01

The principle of spatial filtering experiment has been introduced, and the computer simulation platform with graphical user interface (GUI) has been made out in Matlab environment. Using it various filtering processes for different input image or different filtering purpose will be completed accurately, and filtering effect can be observed clearly with adjusting experimental parameters. The physical nature of the optical spatial filtering can be showed vividly, and so experimental teaching effect will be promoted.

Comparison of seven optical clearing methods for mouse brain

NASA Astrophysics Data System (ADS)

Wan, Peng; Zhu, Jingtan; Yu, Tingting; Zhu, Dan

2018-02-01

Recently, a variety of tissue optical clearing techniques have been developed to reduce light scattering for imaging deeper and three-dimensional reconstruction of tissue structures. Combined with optical imaging techniques and diverse labeling methods, these clearing methods have significantly promoted the development of neuroscience. However, most of the protocols were proposed aiming for specific tissue type. Though there are some comparison results, the clearing methods covered are limited and the evaluation indices are lack of uniformity, which made it difficult to select a best-fit protocol for clearing in practical applications. Hence, it is necessary to systematically assess and compare these clearing methods. In this work, we evaluated the performance of seven typical clearing methods, including 3DISCO, uDISCO, SeeDB, ScaleS, ClearT2, CUBIC and PACT, on mouse brain samples. First, we compared the clearing capability on both brain slices and whole-brains by observing brain transparency. Further, we evaluated the fluorescence preservation and the increase of imaging depth. The results showed that 3DISCO, uDISCO and PACT posed excellent clearing capability on mouse brains, ScaleS and SeeDB rendered moderate transparency, while ClearT2 was the worst. Among those methods, ScaleS was the best on fluorescence preservation, and PACT achieved the highest increase of imaging depth. This study is expected to provide important reference for users in choosing most suitable brain optical clearing method.

Evaluation of optical up- and downlinks from high altitude platforms using IM/DD

NASA Astrophysics Data System (ADS)

Henniger, Hennes; Giggenbach, Dirk; Horwath, Joachim; Rapp, Christoph

2005-04-01

The advantages of optical links like small, light and power efficient terminals are practical for high data rate services over high altitude platforms (HAPs). However, atmospheric effects can disturb the optical links and must be considered in link design. In this paper we evaluate clear sky and non clear sky attenuation effects and their impact on the link-quality of up- and downlinks from HAPs. As vertical links could be restricted by very large cloud and fog attenuation, investigations of the scattering effects in cloud media has been done. The Mie-theory shows that cloud transmittance is not depending on the wavelength, whereas the attenuation of fog and dust is smaller for longer wavelengths. Satellite cloud data has been used to predict the link availability for a ground station in Germany. A ground station diversity concept is introduced to achieve higher link availability. As high receiver sensitivity helps to reduce terminal mass, power and size, evaluation of receiver sensitivity is shown. Also, a receiver model is developed which enables to calculate for the background light loss in direct detection systems.

Optical clearing of human skin for the enhancement of optical imaging of proximal interphalangeal joints

NASA Astrophysics Data System (ADS)

Kolesnikova, Ekaterina A.; Kolesnikov, Aleksandr S.; Zabarylo, Urszula; Minet, Olaf; Genina, Elina A.; Bashkatov, Alexey N.; Tuchin, Valery V.

2014-01-01

We are proposing a new method for enhancement of optical imaging of proximal interphalangeal (PIP) joints in humans at skin using optical clearing technique. A set of illuminating laser diodes with the wavelengths 670, 820, and 904 nm were used as a light source. The laser diodes, monochromatic digital CCD camera and specific software allowed for detection of the finger joint image in a transillumination mode. The experiments were carried out in vivo with human fingers. Dehydrated glycerol and hand cream with urea (5%) were used as optical clearing agents (OCAs). The contrast of the obtained images was analyzed to determine the effect of the OCA. It was found that glycerol application to the human skin during 60 min caused the decrease of contrast in 1.4 folds for 670 nm and the increase of contrast in 1.5 and 1.7 folds for 820 nm and 904 nm, respectively. At the same time, the hand cream application to the human skin during 60 min caused the decrease of contrast in 1.1 folds for 670 nm and the increase of contrast in 1.3 and 1.1 folds for 820 nm and 904 nm, respectively. The results have shown that glycerol and the hand cream with 5% urea allow for obtaining of more distinct image of finger joint in the NIR. Obtained data can be used for development of optical diagnostic methods of rheumatoid arthritis.

Traveling wave electro-optic phase modulators based on intrinsically polar self-assembled chromophoric superlattices

NASA Astrophysics Data System (ADS)

Zhao, Y.-G.; Wu, A.; Lu, H.-L.; Chang, S.; Lu, W.-K.; Ho, S. T.; van der Boom, M. E.; Marks, T. J.

2001-07-01

Traveling-wave electro-optic modulators based on chromophoric self-assembled superlattices (SASs) possessing intrinsically polar microstructures have been designed and fabricated. Although the thickness of the SAS layer is only ˜150 nm, a π-phase shift is clearly observed. From the measured Vπ value, the effective electro-optic coefficient of the SAS film is determined to be ˜21.8 pm/V at an input wavelength of 1064 nm.

Mobile Bay turbidity plume study

NASA Technical Reports Server (NTRS)

Crozier, G. F.

1976-01-01

Laboratory and field transmissometer studies on the effect of suspended particulate material upon the appearance of water are reported. Quantitative correlations were developed between remotely sensed image density, optical sea truth data, and actual sediment load. Evaluation of satellite image sea truth data for an offshore plume projects contours of transmissivity for two different tidal phases. Data clearly demonstrate the speed of change and movement of the optical plume for water patterns associated with the mouth of Mobile bay in which relatively clear Gulf of Mexico water enters the bay on the eastern side. Data show that wind stress in excess of 15 knots has a marked impact in producing suspended sediment loads.

Switchable skin window induced by optical clearing method for dermal blood flow imaging

NASA Astrophysics Data System (ADS)

Wang, Jing; Shi, Rui; Zhu, Dan

2013-06-01

Optical imaging techniques have shown tremendous potential for assessing cutaneous microcirculation, but the imaging depth and contrast is limited by the strong scattering of skin. Current skin windows have to be fulfilled by surgical operation and suffer from some side effects. In this study, a switchable skin window was developed by topical application of an optical clearing agent (OCA) and saline on rat skin in vivo. The validity of the skin window was evaluated by the laser speckle contrast imaging technique, and the safety of OCA to the body was tested through histologic examinations. The results indicated that administration of OCA or saline on rat skin in vivo can open or close the window of skin repeatedly for three days. With the repair effect of hyaluronic acid and Vaseline, it is able to repeatedly visualize the dermal blood vessels and flow distribution. Long-term observation shows that there is no abnormal reflection in micro-structure, body weight, organ coefficients, histopathologic lesions, or toxic reactions compared with a control group. This switchable window will provide an effective tool not only for cutaneous microcirculation with laser speckle contrast imaging, but also for diagnosis and treatment of peripheral vascular diseases, including tumor research with various optical imaging techniques.

Optical coherence tomography angiography offers comprehensive evaluation of skin optical clearing in vivo by quantifying optical properties and blood flow imaging simultaneously

NASA Astrophysics Data System (ADS)

Guo, Li; Shi, Rui; Zhang, Chao; Zhu, Dan; Ding, Zhihua; Li, Peng

2016-08-01

Tissue optical clearing (TOC) is helpful for reducing scattering and enhancing the penetration depth of light, and shows promising potential in optimizing optical imaging performances. A mixture of fructose with PEG-400 and thiazone (FPT) is used as an optical clearing agent in mouse dorsal skin and evaluated with OCT angiography (Angio-OCT) by quantifying optical properties and blood flow imaging simultaneously. It is observed that FPT leads to an improved imaging performance for the deeper tissues. The imaging performance improvement is most likely caused by the FPT-induced dehydration of skin, and the reduction of scattering coefficient (more than ˜40.5%) and refractive-index mismatching (more than ˜25.3%) in the superficial (epidermal, dermal, and hypodermal) layers. A high correlation (up to ˜90%) between the relative changes in refractive-index mismatching and Angio-OCT signal strength is measured. The optical clearing rate is ˜5.83×10-5 cm/s. In addition, Angio-OCT demonstrates enhanced performance in imaging cutaneous hemodynamics with satisfactory spatiotemporal resolution and contrast when combined with TOC, which exhibits a powerful practical application in studying microcirculation.

How Well Can Infrared Sounders Observe the Atmosphere and Surface Through Clouds?

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Larar, Allen M.; Liu, Xu; Smith, William L.; Strow, L. Larrabee; Yang, Ping

2010-01-01

Infrared sounders, such as the Atmospheric Infrared Sounder (AIRS), the Infrared Atmospheric Sounding Interferometer (IASI), and the Cross-track Infrared sounder (CrIS), have a cloud-impenetrable disadvantage in observing the atmosphere and surface under opaque cloudy conditions. However, recent studies indicate that hyperspectral, infrared sounders have the ability to detect cloud effective-optical and microphysical properties and to penetrate optically thin clouds in observing the atmosphere and surface to a certain degree. We have developed a retrieval scheme dealing with atmospheric conditions with cloud presence. This scheme can be used to analyze the retrieval accuracy of atmospheric and surface parameters under clear and cloudy conditions. In this paper, we present the surface emissivity results derived from IASI global measurements under both clear and cloudy conditions. The accuracy of surface emissivity derived under cloudy conditions is statistically estimated in comparison with those derived under clear sky conditions. The retrieval error caused by the clouds is shown as a function of cloud optical depth, which helps us to understand how well infrared sounders can observe the atmosphere and surface through clouds.

Atmospheric optical depth effects on angular anisotropy of plant canopy reflectance

NASA Technical Reports Server (NTRS)

Deering, Donald W.; Eck, Thomas F.

1987-01-01

The effects of varying atmospheric aerosol optical depth on the bidirectional reflectance distribution of vegetation canopies is investigated. The reflectance distributions of two pasture grass canopies and one soya bean canopy under different sky irradiance distributions were measured, and the data were analyzed in the visible and IR spectral bands. It is observed that, for the pasture grass canopies, the change in reflectance is due to the percentage of shadowed area viewed by the sensor, and for the soya bean, the specular reflection effect and increased diffuse irradiance penetration into the canopy cause reflectance changes. It is detected that the reflectivity for the soya bean canopy on a hazy day is lower than on a clear day; however, the opposite change is observed for the pasture grass. It is also detected that the normalized difference vegetation index values differ under clear and hazy conditions for the same vegetation canopy conditions.

Rapid and prodium iodide-compatible optical clearing method for brain tissue based on sugar/sugar-alcohol

NASA Astrophysics Data System (ADS)

Yu, Tingting; Qi, Yisong; Wang, Jianru; Feng, Wei; Xu, Jianyi; Zhu, Jingtan; Yao, Yingtao; Gong, Hui; Luo, Qingming; Zhu, Dan

2016-08-01

The developed optical clearing methods show great potential for imaging of large-volume tissues, but these methods present some nonnegligible limitations such as complexity of implementation and long incubation times. In this study, we tried to screen out rapid optical clearing agents by means of molecular dynamical simulation and experimental demonstration. According to the optical clearing potential of sugar and sugar-alcohol, we further evaluated the improvement in the optical clearing efficacy of mouse brain samples, imaging depth, fluorescence preservation, and linear deformation. The results showed that drops of sorbitol, sucrose, and fructose could quickly make the mouse brain sample transparent within 1 to 2 min, and induce about threefold enhancement in imaging depth. The former two could evidently enhance the fluorescence intensity of green fluorescent protein (GFP) and prodium iodide (PI) nuclear dye. Fructose could significantly increase the fluorescence intensity of PI, but slightly decrease the fluorescence intensity of GFP. Even though the three agents caused some shrinkage in samples, the contraction in horizontal and longitudinal directions are almost the same.

Intracanalicular Optic Nerve Swelling and Signal Change in Fulminant Untreated Idiopathic Intracranial Hypertension.

PubMed

Moodley, Anand A; Dlwati, Mahlubonke S; Durand, Miranda

2017-04-01

The role of the optic canal in the pathogenesis of papilloedema has been under scrutiny recently. Whether a larger canal precedes more severe papilloedema or is the result of bone remodelling from chronically raised pressure across a pressure gradient is not clear. The authors present the magnetic resonance imaging findings of a 29-year-old female with fulminant and untreated idiopathic intracranial hypertension. Imaging showed focal expansion and intrinsic signal changes of the intracanalicular optic nerve. The authors discuss the possibility of either fluid accumulation within the optic nerves from a water hammer effect across blocked optic canals resulting from the steep pressure gradient or opticomalacia (optic nerve softening) from chronic ischaemia.

Observation of the spectrally invariant properties of clouds in cloudy-to-clear transition zones during the MAGIC field campaign

DOE PAGES

Yang, Weidong; Marshak, Alexander; McBride, Patrick J.; ...

2016-08-11

We use the spectrally invariant method to study the variability of cloud optical thickness τ and droplet effective radius r eff in transition zones (between the cloudy and clear sky columns) observed from Solar Spectral Flux Radiometer (SSFR) and Shortwave Array Spectroradiometer-Zenith (SASZe) during the Marine ARM GPCI Investigation of Clouds (MAGIC) field campaign. The measurements from the SSFR and the SASZe are different, however inter-instrument differences of self-normalized measurements (divided by their own spectra at a fixed time) are small. The spectrally invariant method approximates the spectra in the cloud transition zone as a linear combination of definitely clearmore » and cloudy spectra, where the coefficients, slope and intercept, characterize the spectrally invariant properties of the transition zone. Simulation results from the SBDART (Santa Barbara DISORT Atmospheric Radiative Transfer) model demonstrate that (1) the slope of the visible band is positively correlated with the cloud optical thickness τ while the intercept of the near-infrared band has high negative correlation with the cloud drop effective radius r eff even without the exact knowledge of τ; (2) the above relations hold for all Solar Zenith Angle (SZA) and for cloud-contaminated skies. In observations using redundant measurements from SSFR and SASZe, we find that during cloudy-to-clear transitions, (a) the slopes of the visible band decrease, and (b) the intercepts of the near-infrared band remain almost constant near cloud edges. The findings in simulations and observations suggest that, while the optical thickness decreases during the cloudy-to-clear transition, the cloud drop effective radius does not change when cloud edges are approached. Furthermore, these results support the hypothesis that inhomogeneous mixing dominates near cloud edges in the studied cases.« less

Whole blood clot optical clearing for nondestructive 3D imaging and quantitative analysis

PubMed Central

Höök, Peter; Brito-Robinson, Teresa; Kim, Oleg; Narciso, Cody; Goodson, Holly V.; Weisel, John W.; Alber, Mark S.; Zartman, Jeremiah J.

2017-01-01

A technological revolution in both light and electron microscopy imaging now allows unprecedented views of clotting, especially in animal models of hemostasis and thrombosis. However, our understanding of three-dimensional high-resolution clot structure remains incomplete since most of our recent knowledge has come from studies of relatively small clots or thrombi, due to the optical impenetrability of clots beyond a few cell layers in depth. Here, we developed an optimized optical clearing method termed cCLOT that renders large whole blood clots transparent and allows confocal imaging as deep as one millimeter inside the clot. We have tested this method by investigating the 3D structure of clots made from reconstituted pre-labeled blood components yielding new information about the effects of clot contraction on erythrocytes. Although it has been shown recently that erythrocytes are compressed to form polyhedrocytes during clot contraction, observations of this phenomenon have been impeded by the inability to easily image inside clots. As an efficient and non-destructive method, cCLOT represents a powerful research tool in studying blood clot structure and mechanisms controlling clot morphology. Additionally, cCLOT optical clearing has the potential to facilitate imaging of ex vivo clots and thrombi derived from healthy or pathological conditions. PMID:28856043

The Effect on Vision of Light Scatter From HMD Visors and Aircraft Windscreens

DTIC Science & Technology

1999-01-01

This paper was cleared by ASC99-0447 on 5 Mar 1999 The Effect on Vision of Light Scatter from HMD Visors and Aircraft Windscreens Peter L. Marasco ...Medical Research Laboratory, Wright-Patterson AFB, Ohio. BIOGRAPHIES This paper was cleared by ASC99-0447 on 5 Mar 1999 Peter Marasco came to the U.S. Air...and improving optical test methods. Mr. Marasco received a BS degree from the University of Rochester in 1991 and an MS degree from the University of

Automatic and adaptive heterogeneous refractive index compensation for light-sheet microscopy.

PubMed

Ryan, Duncan P; Gould, Elizabeth A; Seedorf, Gregory J; Masihzadeh, Omid; Abman, Steven H; Vijayaraghavan, Sukumar; Macklin, Wendy B; Restrepo, Diego; Shepherd, Douglas P

2017-09-20

Optical tissue clearing has revolutionized researchers' ability to perform fluorescent measurements of molecules, cells, and structures within intact tissue. One common complication to all optically cleared tissue is a spatially heterogeneous refractive index, leading to light scattering and first-order defocus. We designed C-DSLM (cleared tissue digital scanned light-sheet microscopy) as a low-cost method intended to automatically generate in-focus images of cleared tissue. We demonstrate the flexibility and power of C-DSLM by quantifying fluorescent features in tissue from multiple animal models using refractive index matched and mismatched microscope objectives. This includes a unique measurement of myelin tracks within intact tissue using an endogenous fluorescent reporter where typical clearing approaches render such structures difficult to image. For all measurements, we provide independent verification using standard serial tissue sectioning and quantification methods. Paired with advancements in volumetric image processing, C-DSLM provides a robust methodology to quantify sub-micron features within large tissue sections.Optical clearing of tissue has enabled optical imaging deeper into tissue due to significantly reduced light scattering. Here, Ryan et al. tackle first-order defocus, an artefact of a non-uniform refractive index, extending light-sheet microscopy to partially cleared samples.

[Macular thickness measured by optical coherence tomography in pseudoaphakic eyes with clear vs yellow implant].

PubMed

Chamorro, E; Bonnin-Arias, C; Pérez-Carrasco, M J; Alvarez-Rementería, L; Villa-Collar, C; Armadá-Maresca, F; Sánchez-Ramos, C

2014-04-01

To study the use of optical coherence tomography (OCT), for measuring the macular thickness variations produced over time in elderly pseudophakic subjects implanted with a clear intraocular lens (IOL) in one eye, and a yellow IOL in the other eye. Macular thickness measurements were obtained in the 36 eyes of 18 subjects over 65 years, with cataracts surgically removed from both eyes and implanted with different absorbance (clear and yellow) IOLs in 2 separate surgeries. Stratus-OCT was used to determine the macular thickness in 2 sessions with 5 years of difference. After 5 years of follow-up, the eyes implanted with clear IOLs revealed a significant decrease in macular thickness. However, in eyes implanted with yellow IOLs the macular thickness remained stable. The mean overall decrease in macular thickness in eyes implanted with clear IOLs was 5 ± 8 μm (P=.02), and foveal thickness reduction was 10 ± 17 μm (P=.02). The macular thickness changes produced in eyes implanted with a yellow IOL differ from those with a clear IOL. These observation point to a possible protective effect of yellow IOL against the harmful effects of light in elderly pseudophakic subjects. However, studies with a longer follow-up are still needed to confirm that the protection provided by this IOL model is clinically significant. Copyright © 2010 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

Quantum entangled dark solitons formed by ultracold atoms in optical lattices.

PubMed

Mishmash, R V; Carr, L D

2009-10-02

Inspired by experiments on Bose-Einstein condensates in optical lattices, we study the quantum evolution of dark soliton initial conditions in the context of the Bose-Hubbard Hamiltonian. An extensive set of quantum measures is utilized in our analysis, including von Neumann and generalized quantum entropies, quantum depletion, and the pair correlation function. We find that quantum effects cause the soliton to fill in. Moreover, soliton-soliton collisions become inelastic, in strong contrast to the predictions of mean-field theory. These features show that the lifetime and collision properties of dark solitons in optical lattices provide clear signals of quantum effects.

A Semianalytical Ocean Color Inversion Algorithm with Explicit Water Column Depth and Substrate Reflectance Parameterization

NASA Technical Reports Server (NTRS)

Mckinna, Lachlan I. W.; Werdell, P. Jeremy; Fearns, Peter R. C.; Weeks, Scarla J.; Reichstetter, Martina; Franz, Bryan A.; Shea, Donald M.; Feldman, Gene C.

2015-01-01

A semianalytical ocean color inversion algorithm was developed for improving retrievals of inherent optical properties (IOPs) in optically shallow waters. In clear, geometrically shallow waters, light reflected off the seafloor can contribute to the water-leaving radiance signal. This can have a confounding effect on ocean color algorithms developed for optically deep waters, leading to an overestimation of IOPs. The algorithm described here, the Shallow Water Inversion Model (SWIM), uses pre-existing knowledge of bathymetry and benthic substrate brightness to account for optically shallow effects. SWIM was incorporated into the NASA Ocean Biology Processing Group's L2GEN code and tested in waters of the Great Barrier Reef, Australia, using the Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua time series (2002-2013). SWIM-derived values of the total non-water absorption coefficient at 443 nm, at(443), the particulate backscattering coefficient at 443 nm, bbp(443), and the diffuse attenuation coefficient at 488 nm, Kd(488), were compared with values derived using the Generalized Inherent Optical Properties algorithm (GIOP) and the Quasi-Analytical Algorithm (QAA). The results indicated that in clear, optically shallow waters SWIM-derived values of at(443), bbp(443), and Kd(443) were realistically lower than values derived using GIOP and QAA, in agreement with radiative transfer modeling. This signified that the benthic reflectance correction was performing as expected. However, in more optically complex waters, SWIM had difficulty converging to a solution, a likely consequence of internal IOP parameterizations. Whilst a comprehensive study of the SWIM algorithm's behavior was conducted, further work is needed to validate the algorithm using in situ data.

Study of the inhibition effect of thiazone on muscle optical clearing

NASA Astrophysics Data System (ADS)

Jin, Xiaowei; Deng, Zhichao; Wang, Jin; Ye, Qing; Mei, Jianchun; Zhou, Wenyuan; Zhang, Chunping; Tian, Jianguo

2016-10-01

We investigated the effect of thiazone, a widely used penetration enhancer, on in vitro porcine skin and muscle tissue by single-integrating sphere technique during optical clearing (OC) treatment. The results showed that thiazone induced an increase on the total transmittance of skin which led to a reduction in that of muscle in the spectral range from 400 to 800 nm. Small particles crystalized out from the thiazone-treated muscle were observed by microscopy imaging. With the help of x-ray diffraction measurement, we ascertained that the crystal was a single-crystal of thiazone, which mainly induced an increase of the scattering. Contrast transmittance measurements carried on the mixture of water, thizaone-propylene glycol solution showed that the free water in muscle could be the main reason for the thiazone crystallization. Therefore, during OC treatment of thiazone, the remarkable effect on skin and the noticeable inhibition effect on subcutaneous muscle tissue after penetrating into the skin should be considered. The experimental results provide such a reference for the choice of penetration enhancer.

Intracanalicular Optic Nerve Swelling and Signal Change in Fulminant Untreated Idiopathic Intracranial Hypertension

PubMed Central

Moodley, Anand A.; Dlwati, Mahlubonke S.; Durand, Miranda

2017-01-01

ABSTRACT The role of the optic canal in the pathogenesis of papilloedema has been under scrutiny recently. Whether a larger canal precedes more severe papilloedema or is the result of bone remodelling from chronically raised pressure across a pressure gradient is not clear. The authors present the magnetic resonance imaging findings of a 29-year-old female with fulminant and untreated idiopathic intracranial hypertension. Imaging showed focal expansion and intrinsic signal changes of the intracanalicular optic nerve. The authors discuss the possibility of either fluid accumulation within the optic nerves from a water hammer effect across blocked optic canals resulting from the steep pressure gradient or opticomalacia (optic nerve softening) from chronic ischaemia. PMID:28348630

Viscous optical clearing agent for in vivo optical imaging

NASA Astrophysics Data System (ADS)

Deng, Zijian; Jing, Lijia; Wu, Ning; lv, Pengyu; Jiang, Xiaoyun; Ren, Qiushi; Li, Changhui

2014-07-01

By allowing more photons to reach deeper tissue, the optical clearing agent (OCA) has gained increasing attention in various optical imaging modalities. However, commonly used OCAs have high fluidity, limiting their applications in in vivo studies with oblique, uneven, or moving surfaces. In this work, we reported an OCA with high viscosity. We measured the properties of this viscous OCA, and tested its successful performances in the imaging of a living animal's skin with two optical imaging modalities: photoacoustic microscopy and optical coherence tomography. Our results demonstrated that the viscous OCA has a great potential in the study of different turbid tissues using various optical imaging modalities.

Internally Consistent MODIS Estimate of Aerosol Clear-Sky Radiative Effect Over the Global Oceans

NASA Technical Reports Server (NTRS)

Remer, Lorraine A.; Kaufman, Yoram J.

2004-01-01

Modern satellite remote sensing, and in particular the MODerate resolution Imaging Spectroradiometer (MODIS), offers a measurement-based pathway to estimate global aerosol radiative effects and aerosol radiative forcing. Over the Oceans, MODIS retrieves the total aerosol optical thickness, but also reports which combination of the 9 different aerosol models was used to obtain the retrieval. Each of the 9 models is characterized by a size distribution and complex refractive index, which through Mie calculations correspond to a unique set of single scattering albedo, assymetry parameter and spectral extinction for each model. The combination of these sets of optical parameters weighted by the optical thickness attributed to each model in the retrieval produces the best fit to the observed radiances at the top of the atmosphere. Thus the MODIS Ocean aerosol retrieval provides us with (1) An observed distribution of global aerosol loading, and (2) An internally-consistent, observed, distribution of aerosol optical models that when used in combination will best represent the radiances at the top of the atmosphere. We use these two observed global distributions to initialize the column climate model by Chou and Suarez to calculate the aerosol radiative effect at top of the atmosphere and the radiative efficiency of the aerosols over the global oceans. We apply the analysis to 3 years of MODIS retrievals from the Terra satellite and produce global and regional, seasonally varying, estimates of aerosol radiative effect over the clear-sky oceans.

Cloud and aerosol optical depths

NASA Technical Reports Server (NTRS)

Pueschel, R. F.; Russell, P. B.; Ackerman, Thomas P.; Colburn, D. C.; Wrigley, R. C.; Spanner, M. A.; Livingston, J. M.

1988-01-01

An airborne Sun photometer was used to measure optical depths in clear atmospheres between the appearances of broken stratus clouds, and the optical depths in the vicinity of smokes. Results show that (human) activities can alter the chemical and optical properties of background atmospheres to affect their spectral optical depths. Effects of water vapor adsorption on aerosol optical depths are apparent, based on data of the water vapor absorption band centered around 940 nm. Smoke optical depths show increases above the background atmosphere by up to two orders of magnitude. When the total optical depths measured through clouds were corrected for molecular scattering and gaseous absorption by subtracting the total optical depths measured through the background atmosphere, the resultant values are lower than those of the background aerosol at short wavelengths. The spectral dependence of these cloud optical depths is neutral, however, in contrast to that of the background aerosol or the molecular atmosphere.

Optical Dating of Holocene Dune Sands in the Ferris Dune Field, Wyoming

NASA Astrophysics Data System (ADS)

Stokes, Stephen; Gaylord, David R.

1993-05-01

Optical dating of late Quaternary quartz dune sands from the Clear Creek portion of Ferris dune field, Wyoming, demonstrates the considerable potential of the technique as a chronostratigraphic tool. A sequence of radiocarbon-dated Holocene interdune strata permit optical dating of the intercalated dune sand to be tested; the concordance is good. The optical dates for the aeolian deposits not datable by radiocarbon suggest that aeolian sedimentation at Clear Creek peaked during two relatively short phases at ca. 8500 and 4000 yr B.P. The dates indicate that aeolian accumulation maxima (at least in the Clear Creek area) may not be synchronous with previously defined phases of marked aridity.

The Moire Effect in Physics Teaching.

ERIC Educational Resources Information Center

Bernero, Bruce

1989-01-01

The Moire pattern is the shimmering pattern which looks like an odd interference pattern in window screens or folds of nylon shower curtain. Illustrates some of the ways the effect may be used, including demonstration of wave interference, detection of small displacement, persistence of vision, contour measurement, beats, and optical clearness.…

Dynamic evolution of light-induced orientation of dye-doped liquid crystals in liquid phase studied by time-resolved optically heterodyned optical Kerr effect technique.

PubMed

Yang, Pei; Liu, Liying; Xu, Lei

2008-02-28

Transient evolution of light-induced molecular reorientation both in 1-amino-anthraquinone (1AAQ) dye and azobenzene doped isotropic liquid crystals (LCs) were studied by time-resolved optically heterodyned optical Kerr effect method. The results give clear direct experimental proof that under short pulse (30 ps) excitation, LC molecules orientate toward the excitation light polarization direction in the 1AAQ/LC system. However, LC molecular orientation becomes orthogonal to the light polarization in azobenzene/LC system. Time-resolved excited-state absorption of 1AAQ and wavelength dependent excited-state absorption of azobenzene were also observed and their contributions to the early dynamics of the third order optical responses of the two systems were confirmed. A simplified two-level mean-field theory was derived to reveal the intensity dependence of orientation enhancement factor in azobenzene/LC system considering the photoisomerization process.

Preliminary analyses of WL experiment No. 701, space environment effects on operating fiber optic systems

NASA Technical Reports Server (NTRS)

Taylor, E. W.; Berry, J. N.; Sanchez, A. D.; Padden, R. J.; Chapman, S. P.

1992-01-01

A brief overview of the analyses performed to date on WL Experiment-701 is presented. Four active digital fiber optic links were directly exposed to the space environment for a period of 2114 days. The links were situated aboard the Long Duration Exposure Facility (LDEF) with the cabled, single fiber windings atop an experimental tray containing instrumentation for exercising the experiment in orbit. Despite the unplanned and prolonged exposure to trapped and galactic radiation, wide temperature extremes, atomic oxygen interactions, and micro-meteorite and debris impacts, in most instances the optical data links performed well within the experimental limits. Analysis of the recorded orbital data clearly indicates that fiber optic applications in space will meet with success. Ongoing tests and analysis of the experiment at the Phillips Laboratory's Optoelectronics Laboratory will expand this premise, and establish the first known and extensive database of active fiber optic link performance during prolonged space exposure. WL Exp-701 was designed as a feasibility demonstration for fiber optic technology in space applications, and to study the performance of operating fiber systems exposed to space environmental factors such as galactic radiation, and wide temperature cycling. WL Exp-701 is widely acknowledged as a benchmark accomplishment that clearly demonstrates, for the first time, that fiber optic technology can be successfully used in a variety of space applications.

Nonadiabatic quantum path analysis of high-order harmonic generation: Role of the carrier-envelope phase on short and long paths

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sansone, G.; Stagira, S.; Nisoli, M.

2004-07-01

High-order harmonic generation process in the few- and multiple-optical-cycle regime is theoretically investigated, using the saddle-point method generalized to account for nonadiabatic effects. The influence of the carrier-envelope phase of the driving pulses on the various electron quantum paths is analyzed. We demonstrate that the short and long quantum paths are influenced in different ways by the carrier-envelope phase. In particular, we show that clear phase effects are visible on the long quantum paths even in the multiple-optical-cycle regime, while the short quantum paths are significantly influenced by the carrier-envelope phase only in the few-optical-cycle regime.

Optical and electrical properties of heavily indium-doped CdS around the semiconductor-metal phase transition

NASA Astrophysics Data System (ADS)

Broser, I.; Broser, R.; Birkicht, E.

1990-04-01

Heavily indium-doped CdS crystals are studied by comparing their optical and electrical properties. It is shown that in the near infrared spectral region for highly conducting crystals the correlation of electrical conductivity and optical effects can still be understood in the frame of the classical Drude-Lorentz model. Even for high doping the relaxation time τ and the effective mass m ∗ of the electrons are not markedly different from the room temperature values of "pure" crystals. At photon energies near the band gap, however, optical spectra in transmission, reflectivity, and emission show clearly the existence of band-tails and screening effects. A different situation holds for a highly compensated specimen: They are in a wide temperature region highly isolating, show activated photoconductivity and special structures in the optical spectra near the band gap. Their properties can be explained by assuming a meandering bandbending due to the combined action of donors and acceptors and the assumption of spatially isolated electron and hole droplets [6].

Optical character recognition with feature extraction and associative memory matrix

NASA Astrophysics Data System (ADS)

Sasaki, Osami; Shibahara, Akihito; Suzuki, Takamasa

1998-06-01

A method is proposed in which handwritten characters are recognized using feature extraction and an associative memory matrix. In feature extraction, simple processes such as shifting and superimposing patterns are executed. A memory matrix is generated with singular value decomposition and by modifying small singular values. The method is optically implemented with two liquid crystal displays. Experimental results for the recognition of 25 handwritten alphabet characters clearly shows the effectiveness of the method.

Functionality of bismuth sulfide quantum dots/wires-glass nanocomposite as an optical current sensor with enhanced Verdet constant

NASA Astrophysics Data System (ADS)

Panmand, Rajendra P.; Kumar, Ganapathy; Mahajan, Satish M.; Kulkarni, Milind V.; Amalnerkar, D. P.; Kale, Bharat B.; Gosavi, Suresh. W.

2011-02-01

We report optical studies with magneto-optic properties of Bi2S3 quantum dot/wires-glass nanocomposite. The size of the Q-dot was observed to be in the range 3-15 nm along with 11 nm Q-wires. Optical study clearly demonstrated the size quantization effect with drastic band gap variation with size. Faraday rotation tests on the glass nanocomposites show variation in Verdet constant with Q-dot size. Bi2S3 Q-dot/wires glass nanocomposite demonstrated 190 times enhanced Verdet constant compared to the host glass. Prima facie observations exemplify the significant enhancement in Verdet constant of Q-dot glass nanocomposites and will have potential application in magneto-optical devices.

Optical clearing of skin using flash lamp-induced enhancement of epidermal permeability.

PubMed

Tuchin, V V; Altshuler, G B; Gavrilova, A A; Pravdin, A B; Tabatadze, D; Childs, J; Yaroslavsky, I V

2006-10-01

Strong light scattering in skin prevents precise targeting of optical energy in therapeutic and diagnostic applications. Optical immersion based on matching refractive index of scattering centers with that of surrounding matter through introduction of an exogenous index-matching agent can alleviate the problem. However, slow diffusion of the index-matching agent through skin barrier makes practical implementation of this approach difficult. We propose a method of accelerating penetration of the index-matching compounds by enhancing skin permeability through creating a lattice of micro-zones (islets) of limited thermal damage in the stratum corneum (SC). A flash lamp (intense pulsed light) system and an island mask with a pattern of absorbing centers (center size approximately 75-120 microm, lattice pitch approximately 450-500 microm) were used to create the lattice of islets of damage (LID). Index-matching agents, such as glucose solution, propylene glycol solution, and glycerol solution, were applied. Experimental results of optical clearing ex vivo rat and pig skin, and ex vivo and in vivo human skin are presented. Optical transmission spectra of the skin samples with LID were measured during some 2 hours after application of index-matching chemical agents. In order to assess and compare the clearing rate under different treatment and clearing agents we calculated the quantity that we call "relative transmittance": T(rel) = I(t)(lambda)/I(0)(lambda), were I(t)(lambda) is the intensity measured at elapsed time t. The dynamics of relative transmittance of skin samples at 470 and 650 nm shows that the implementation of limited thermal damage technique leads to a 3-10-fold increase of optical clearing (rise of transmittance) rate compared to the results obtained when the samples were treated with high-intensity light pulses but without the use of island damage mask (IDM). It was observed from the plotted spectra of relative transmittance that the maximum increase of transmitted light intensity has been obtained with glucose solution as a clearing agent. Noteworthy is the difference in the trend of spectral curves: relative transmittance spectrum for glycerol reveals, on the whole, a greater slope which may be indicative of higher extent of index matching between the scattering centers and base material for this index-matching agent. Under the transillumination of the skin sample by the wide flat beam the more effective clearing (the increase of transmitted intensity) is attained within the hemoglobin absorption bands; with the narrow quasi-collimated beam the higher relative transmittance was observed over the intervals of minimum absorption. The use of specially designed island mask combined with non-laser intensive pulse irradiation produces a lattice of islands of limited thermal damage in SC that substantially enhances the penetration rate of topically applied index-matching agents. The suggested technique gave comparable magnitudes of clearing dynamics enhancement for glucose solution, glycerol solution, and propylene glycol solution applied to mammalian skin.

Structural and optical properties of nanostructured CdSe thin films prepared by electrochemical deposition

NASA Astrophysics Data System (ADS)

Bai, Rekha; Chaudhary, Sujeet; Pandya, Dinesh K.

2018-05-01

Cadmium selenide (CdSe) nanostructured thin films have been grown on fluorine doped tin oxide (FTO) coated glass substrates by potentiostatic electrochemical deposition (ECD) technique for use in solar energy conversion devices. The effect of bath temperature on the structural, morphological and optical properties of prepared CdSe films has been explored. X-ray diffraction (XRD) and Raman spectroscopy clearly show that the CdSe films are polycrystalline and exhibit phase transformation from wurtzite to zincblende structure with increase in bath temperature. Optical spectra reveal that the nanostructured CdSe films have high absorbance in visible region and the films show a red shift in direct optical energy band gap from 1.90 to 1.65 eV with increase in bath temperature due to change in phase and bandgap tuning related to quantum confinement effect.

Nonthermal ultrafast optical control of the magnetization in garnet films

NASA Astrophysics Data System (ADS)

Hansteen, Fredrik; Kimel, Alexey; Kirilyuk, Andrei; Rasing, Theo

2006-01-01

We demonstrate coherent optical control of the magnetization in ferrimagnetic garnet films on the femtosecond time scale through a combination of two different ultrafast and nonthermal photomagnetic effects and by employing multiple pump pulses. Linearly polarized laser pulses are shown to create a long-lived modification of the magnetocrystalline anisotropy via optically induced electron transfer between nonequivalent ion sites while circularly polarized pulses additionally act as strong transient magnetic field pulses originating from the nonabsorptive inverse Faraday effect. Due to the slow phonon-magnon interaction in these dielectrics, thermal effects of the laser excitation are clearly distinguished from the ultrafast nonthermal effects and can be seen only on the time scale of nanoseconds for sample temperatures near the Curie point. The reported effects open exciting possibilities for ultrafast manipulation of spins by light, and provide insight into the physics of magnetism on ultrafast time scales.

Molecular modeling of the process of reversible dissolution of the collagen protein under the action of tissue-clearing agents

NASA Astrophysics Data System (ADS)

Dvoretsky, K. N.; Berezin, K. V.; Chernavina, M. L.; Likhter, A. M.; Shagautdinova, I. T.; Antonova, E. M.; Rybakov, A. V.; Grechukhina, O. N.; Tuchin, V. V.

2018-04-01

The interaction of glycerol immersion agent with collagen mimetic peptide ((GPH)9)3 and a fragment of the microfibril 5((GPH)12)3 was studied by the classical molecular dynamics method using the GROMACS software. The change in geometric parameters of collagen α-chains at various concentrations of an aqueous solution of glycerol is analyzed. It is shown that these changes nonlinearly depend on the concentration and are limited to a certain level, which correlates with the experimental data on optical clearing efficiency of human skin. A hypothesis on the cause of the decreased efficiency of optical skin clearing at high immersion agent concentrations is put forward. The molecular mechanism of immersion optical clearing of biological tissues is discussed.

AFM imaging of natural optical structures

NASA Astrophysics Data System (ADS)

Dallaeva, Dinara; Tománek, Pavel; Prokopyeva, Elena; Kaspar, Pavel; Grmela, Lubomír.; Škarvada, Pavel

2015-01-01

The colors of some living organisms assosiated with the surface structure. Irridesence butterfly wings is an example of such coloration. Optical effects such as interference, diffraction, polarization are responsible for physical colors appearance. Alongside with amazing beauty this structure represent interest for design of optical devices. Here we report the results of morphology investigation by atomic force microscopy. The difference in surface structure of black and blue wings areas is clearly observed. It explains the angle dependence of the wing blue color, since these micrometer and sub-micrometer quasiperiodical structures could control the light propagation, absorption and reflection.

Magnetic microparticle-polydimethylsiloxane composite for reversible microchannel bonding

PubMed Central

Tsao, Chia-Wen; Lee, Yueh-Pu

2016-01-01

Abstract In this study, an iron oxide magnetic microparticles and poly(dimethylsiloxane) (MMPs-PDMS) composite material was employed to demonstrate a simple high-strength reversible magnetic bonding method. This paper presents the casting of opaque-view (where optical inspection through the microchannels was impossible) and clear-view (where optical inspection through the microchannel was possible) MMPs-PDMS. The influence of the microchannel geometries on the casting of the opaque-view casting was limited, which is similar to standard PDMS casting. Clear-view casting performance was highly associated with the microchannel geometries. The effects of the microchannel layout and the gap between the PDMS cover layer and the micromold substrate were thoroughly investigated. Compared with the native PDMS bonding strength of 31 kPa, the MMPs-PDMS magnetic bonding experiments showed that the thin PDMS film with an MMPs-PDMS layer effectively reduced the surface roughness and enhanced MMPs-PDMS reversible magnetic bonding strength. A thin PDMS film-coated opaque-view MMPs-PDMS device exhibited the greatest bonding strength of 110 kPa, and a clear-view MMPs-PDMS device with a thin PDMS film attained a magnetic bonding strength of 81 kPa. PMID:27877852

Study of image reconstruction for terahertz indirect holography with quasi-optics receiver.

PubMed

Gao, Xiang; Li, Chao; Fang, Guangyou

2013-06-01

In this paper, an indirect holographic image reconstruction algorithm was studied for terahertz imaging with a quasi-optics receiver. Based on the combination of the reciprocity principle and modified quasi-optics theory, analytical expressions of the received spatial power distribution and its spectrum are obtained for the interference pattern of target wave and reference wave. These results clearly give the quantitative relationship between imaging quality and the parameters of a Gaussian beam, which provides a good criterion for terahertz quasi-optics transceivers design in terahertz off-axis holographic imagers. To validate the effectiveness of the proposed analysis method, some imaging results with a 0.3 THz prototype system are shown based on electromagnetic simulation.

Optical probe of Heisenberg-Kitaev magnetism in α -RuCl3

NASA Astrophysics Data System (ADS)

Sandilands, Luke J.; Sohn, C. H.; Park, H. J.; Kim, So Yeun; Kim, K. W.; Sears, Jennifer A.; Kim, Young-June; Noh, Tae Won

2016-11-01

We report a temperature-dependent optical spectroscopic study of the Heisenberg-Kitaev magnet α -RuCl3 . Our measurements reveal anomalies in the optical response near the magnetic ordering temperature. At higher temperatures, we observe a redistribution of spectral weight over a broad energy range that is associated with nearest-neighbor spin-spin correlations. This finding is consistent with highly frustrated magnetic interactions and in agreement with theoretical expectations for this class of material. The optical data also reveal significant electron-hole interaction effects, including a bound excitonic state. These results demonstrate a clear coupling between charge and spin degrees of freedom and provide insight into the properties of thermally disordered Heisenberg-Kitaev magnets.

Farris-Tang retractor in optic nerve sheath decompression surgery.

PubMed

Spiegel, Jennifer A; Sokol, Jason A; Whittaker, Thomas J; Bernard, Benjamin; Farris, Bradley K

2016-01-01

Our purpose is to introduce the use of the Farris-Tang retractor in optic nerve sheath decompression surgery. The procedure of optic nerve sheath fenestration was reviewed at our tertiary care teaching hospital, including the use of the Farris-Tang retractor. Pseudotumor cerebri is a syndrome of increased intracranial pressure without a clear cause. Surgical treatment can be effective in cases in which medical therapy has failed and disc swelling with visual field loss progresses. Optic nerve sheath decompression surgery (ONDS) involves cutting slits or windows in the optic nerve sheath to allow cerebrospinal fluid to escape, reducing the pressure around the optic nerve. We introduce the Farris-Tang retractor, a retractor that allows for excellent visualization of the optic nerve sheath during this surgery, facilitating the fenestration of the sheath and visualization of the subsequent cerebrospinal fluid egress. Utilizing a medial conjunctival approach, the Farris-Tang retractor allows for easy retraction of the medial orbital tissue and reduces the incidence of orbital fat protrusion through Tenon's capsule. The Farris-Tang retractor allows safe, easy, and effective access to the optic nerve with good visualization in optic nerve sheath decompression surgery. This, in turn, allows for greater surgical efficiency and positive patient outcomes.

Optimized optical clearing method for imaging central nervous system

NASA Astrophysics Data System (ADS)

Yu, Tingting; Qi, Yisong; Gong, Hui; Luo, Qingming; Zhu, Dan

2015-03-01

The development of various optical clearing methods provides a great potential for imaging entire central nervous system by combining with multiple-labelling and microscopic imaging techniques. These methods had made certain clearing contributions with respective weaknesses, including tissue deformation, fluorescence quenching, execution complexity and antibody penetration limitation that makes immunostaining of tissue blocks difficult. The passive clarity technique (PACT) bypasses those problems and clears the samples with simple implementation, excellent transparency with fine fluorescence retention, but the passive tissue clearing method needs too long time. In this study, we not only accelerate the clearing speed of brain blocks but also preserve GFP fluorescence well by screening an optimal clearing temperature. The selection of proper temperature will make PACT more applicable, which evidently broaden the application range of this method.

In vitro and clinical evaluation of optical coherence tomography for the detection of subgingival calculus and root cementum.

PubMed

Tsubokawa, Masaki; Aoki, Akira; Kakizaki, Sho; Taniguchi, Yoichi; Ejiri, Kenichiro; Mizutani, Koji; Koshy, Geena; Akizuki, Tatsuya; Oda, Shigeru; Sumi, Yasunori; Izumi, Yuichi

2018-05-24

This study evaluated the effectiveness of swept-source optical coherence tomography (ss-OCT) for detecting calculus and root cementum during periodontal therapy. Optical coherence tomography (OCT) images were taken before and after removal of subgingival calculus from extracted teeth and compared with non-decalcified histological sections. Porcine gingival sheets of various thicknesses were applied to the root surfaces of extracted teeth with calculus and OCT images were taken. OCT images were also taken before and after scaling and root planing (SRP) in human patients. In vitro, calculus was clearly detected as a white-gray amorphous structure on the root surface, which disappeared after removal. Cementum was identified as a thin, dark-gray layer. The calculus could not be clearly observed when soft tissues were present on the root surface. Clinically, supragingival calculus and cementum could be detected clearly with OCT, and subgingival calculus in the buccal cervical area of the anterior and premolar teeth was identified, which disappeared after SRP. Digital processing of the original OCT images was useful for clarifying the calculus. In conclusion, ss-OCT showed potential as a periodontal diagnostic tool for detecting cementum and subgingival calculus, although the practical applications of subgingival imaging remain limited.

Importance of molecular Rayleigh scattering in the enhancement of clear sky reflectance in the vicinity of boundary layer cumulus clouds

NASA Astrophysics Data System (ADS)

Wen, Guoyong; Marshak, Alexander; Cahalan, Robert F.

2008-12-01

Clouds increase the complexity of atmospheric radiative transfer processes, particularly for aerosol retrievals in clear regions in the vicinity of clouds. This study focuses on identifying mechanisms responsible for the enhancement of nadir reflectance in clear regions in the vicinity of cumulus clouds and quantifies the relative importance of each mechanism. Using cloud optical properties and surface albedo derived from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Moderate Resolution Imaging Spectroradiometer (MODIS), we performed extensive Monte Carlo simulations of radiative transfer in two cumulus scenes in a biomass burning region in Brazil. The results show that the scattering of radiation by clouds, followed by upward Rayleigh scattering by molecules above cloud top over clear gaps, is the dominant mechanism for the enhancement of visible reflectance in clear regions in boundary layer cumulus field over dark surfaces with aerosols trapped in the boundary layer. The Rayleigh scattering contributes ˜80% and ˜50% to the total enhancement for wavelengths 0.47 μm (with aerosol optical thickness 0.2) and 0.66 μm (with aerosol optical thickness 0.1), respectively. Out of the total contribution of molecular scattering, ˜90% arises from the clear atmosphere above cloud top height. The mechanism is valid for a large range of aerosol optical thicknesses (up to 1 in this study) for 0.47 μm, and for aerosol optical thickness up to 0.2 for 0.66 μm. Our results provide a basis to develop simplifications for future aerosol remote sensing from satellite.

Second-order optical effects in several pyrazolo-quinoline derivatives

NASA Astrophysics Data System (ADS)

Makowska-Janusik, M.; Gondek, E.; Kityk, I. V.; Wisła, J.; Sanetra, J.; Danel, A.

2004-11-01

Using optical poling of several pyazolo-quinoline (PAQ) derivatives we have found an existence of sufficiently high second order optical susceptibility at wavelength 1.76 μm varying in the range 0.9-2.8 pm/V. The performed quantum chemical simulations of the UV-absorption for isolated, solvated and incorporated into the polymethacrylate (PMMA) polymer films have shown that the PM3 method is the best among the semi-empirical ones to simulate the optical properties. The calculations of the hyperpolarizabilites have shown a good correlation with experimentally measured susceptibilities obtained from the optical poling. We have found that experimental susceptibility depends on linear molecular polarizability and photoinducing changes of the molecular dipole moment. It is clearly seen for the PAQ4-PAQ6 molecules possessing halogen atoms with relatively large polarizabilities.

Experimental evidence of zone-center optical phonon softening by accumulating holes in thin Ge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kabuyanagi, Shoichi; Nishimura, Tomonori; Yajima, Takeaki

2016-01-15

We discuss the impact of free carriers on the zone-center optical phonon frequency in germanium (Ge). By taking advantage of the Ge-on-insulator structure, we measured the Raman spectroscopy by applying back-gate bias. Phonon softening by accumulating holes in Ge film was clearly observed. This fact strongly suggests that the phonon softening in heavily-doped Ge is mainly attributed to the free carrier effect rather than the dopant atom counterpart. Furthermore, we propose that the free carrier effect on phonon softening is simply understandable from the viewpoint of covalent bonding modification by free carriers.

ReagentTF: a rapid and versatile optical clearing method for biological imaging(Conference Presentation)

NASA Astrophysics Data System (ADS)

Yu, Tingting; Zhu, Jingtan; Li, Yusha; Qi, Yisong; Xu, Jianyi; Gong, Hui; Luo, Qingming; Zhu, Dan

2017-02-01

The emergence of various optical clearing methods provides a great potential for imaging deep inside tissues by combining with multiple-labelling and microscopic imaging techniques. They were generally developed for specific imaging demand thus presented some non-negligible limitations such as long incubation time, tissue deformation, fluorescence quenching, incompatibility with immunostaining or lipophilic tracers. In this study, we developed a rapid and versatile clearing method, termed ReagentTF, for deep imaging of various fluorescent samples. This method can not only efficiently clear embryos, neonatal whole-brains and adult thick brain sections by simple immersion in aqueous mixtures with minimal volume change, but also can preserve fluorescence of various fluorescent proteins and simultaneously be compatible with immunostaining and lipophilic neuronal dyes. We demonstrate the effectiveness of this method in reconstructing the cell distributions of mouse hippocampus, visualizing the neural projection from CA1 (Cornu Ammonis 1) to HDB (nucleus of the horizontal limb of the diagonal band), and observing the growth of forelimb plexus in whole-mount embryos. These results suggest that ReagentTF is useful for large-volume imaging and will be an option for the deep imaging of biological tissues.

Long-term variability of aerosol optical properties and radiative effects in Northern Finland

NASA Astrophysics Data System (ADS)

Lihavainen, Heikki; Hyvärinen, Antti; Asmi, Eija; Hatakka, Juha; Viisanen, Yrjö

2017-04-01

We introduce long term dataset of aerosol scattering and absorption properties and combined aerosol optical properties measured in Pallas Atmosphere-Ecosystem Supersite in Norhern Finland. The station is located 170 km north of the Arctic Circle. The station is affected by both pristine Arctic air masses as well as long transported air pollution from northern Europe. We studied the optical properties of aerosols and their radiative effects in continental and marine air masses, including seasonal cycles and long-term trends. The average (median) scattering coefficient, backscattering fraction, absorption coefficient and single scattering albedo at the wavelength of 550 nm were 7.9 (4.4) 1/Mm, 0.13 (0.12), 0.74 (0.35) 1/Mm and 0.92 (0.93), respectively. We observed clear seasonal cycles in these variables, the scattering coefficient having high values during summer and low in fall, and absorption coefficient having high values during winter and low in fall. We found that the high values of the absorption coefficient and low values of the single scattering albedo were related to continental air masses from lower latitudes. These aerosols can induce an additional effect on the surface albedo and melting of snow. We observed the signal of the Arctic haze in marine (northern) air masses during March and April. The haze increased the value of the absorption coefficient by almost 80% and that of the scattering coefficient by about 50% compared with the annual-average values. We did not observe any long-term trend in the scattering coefficient, while our analysis showed a clear decreasing trend in the backscattering fraction and scattering Ångström exponent during winter. We also observed clear relationship with temperature and aerosol scattering coefficient. We will present also how these different features affects to aerosol direct radiative forcing.

Bidirectional optical subassembly-shaped 20-Gbit/s compact single-mode four-channel wavelength-division multiplexing optical modules for optical multimedia interfaces

NASA Astrophysics Data System (ADS)

Lim, Kwon-Seob; Yu, Hong-Yeon; Park, Hyoung-Jun; Kang, Hyun Seo; Jang, Jae-Hyung

2016-06-01

Low-cost single-mode four-channel optical transmitter and receiver modules using the wavelength-division multiplexing (WDM) method have been developed for long-reach fiber optic applications. The single-mode four-channel WDM optical transmitter and receiver modules consist of two dual-wavelength optical transmitter and receiver submodules, respectively. The integration of two channels in a glass-sealed transistor outline-can package is an effective way to reduce cost and size and to extend the number of channels. The clear eye diagrams with more than about 6 dB of the extinction ratio and the minimum receiver sensitivity of lower than -16 dBm at a bit error rate of 10-12 have been obtained for the transmitter and receiver modules, respectively, at 5 Gbps/channel. The 4K ultrahigh definition contents have been transmitted over a 1-km-long single-mode fiber using a pair of proposed four-channel transmitter optical subassembly and receiver optical subassembly.

Effects of optical clearing agents on noninvasive blood glucose monitoring with optical coherence tomography: a pilot study

NASA Astrophysics Data System (ADS)

He, Ruoyu; Wei, Huajiang; Gu, Huimin; Zhu, Zhengguo; Zhang, Yuqing; Guo, Xiao; Cai, Tiantian

2012-10-01

Recently, the capability of optical coherence tomography (OCT) has been demonstrated for noninvasive blood glucose monitoring. In this work, we investigate the administration of chemical agents onto human skin tissue to increase the transparency of the surface of the skin, as a means of improving the capability of OCT imaging for clinically relevant applications. Eight groups of experiments were proposed, in which different optical clearing agents (OCA) were used. The results indicate that, when properly used, some OCAs perform well in promoting the capability of OCT for noninvasive blood glucose monitoring. Among the four kinds of OCA we used, 50% v/v glycerol solute turns out to be the best enhancer. Compared with the results of the experiments in which no OCA was used, when 50% glycerol was applied onto the human skin topically, the correlation coefficient between the OCT signal slope (OCTSS) and blood glucose concentration (BGC) was improved by 7.1% on average, and the lag time between changes in the OCTSS and BGC was cut by 8 min on average. The results of 10 w/v mannitol were also good, but not as pronounced.

Quantification of optical turbulence in the ocean and its effects on beam propagation.

PubMed

Nootz, Gero; Jarosz, Ewa; Dalgleish, Fraser R; Hou, Weilin

2016-11-01

The influence of optically active turbulence on the propagation of laser beams is investigated in clear ocean water over a path length of 8.75 m. The measurement apparatus is described and the effects of optical turbulence on the laser beam are presented. The index of refraction structure constant is extracted from the beam deflection and the results are compared to independently made measures of the turbulence strength (Cn2) by a vertical microstructure profiler. Here we present values of Cn2 taken from aboard the R/V Walton Smith during the Bahamas optical turbulence exercise (BOTEX) in the Tongue of the Ocean between June 30 and July 12, 2011, spanning a range from 10^-14 to 10^-10  m^-2/3. To the best of our knowledge, this is the first time such measurements are reported for the ocean.

Use of an optical clearing agent to enhance the visibility of subsurface structures and lesions from tooth occlusal surfaces

NASA Astrophysics Data System (ADS)

Kang, Hobin; Darling, Cynthia L.; Fried, Daniel

2016-08-01

The purpose of this study is to show that optical clearing agents can be used to increase the visibility of deeply penetrating occlusal lesions that have reached the underlying dentin and spread laterally under the enamel. Previous studies have shown that high refractive index fluids can increase the contrast of caries lesions. Extracted teeth with natural occlusal lesions were imaged with optical coherence tomography (OCT) with and without the addition of a transparent vinyl polysiloxane impression material (VPS) currently used in vivo. The relative intensity of the reflectivity from the underlying lesion area for each sample was measured before and after application of the VPS. Lesion presence was confirmed with polarized light microscopy and microradiography. Application of VPS significantly increased (P<0.0001) the integrated reflectivity of subsurface dentinal lesions. This study shows that optical clearing agents can be used to increase the optical penetration and the visibility of subsurface lesions and the dentinal-enamel junction under sound and demineralized enamel in OCT images.

Monolithically integrated quantum dot optical modulator with semiconductor optical amplifier for thousand and original band optical communication

NASA Astrophysics Data System (ADS)

Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Matsumoto, Atsushi; Kawanishi, Tetsuya

2016-04-01

A monolithically integrated quantum dot (QD) optical gain modulator (OGM) with a QD semiconductor optical amplifier (SOA) was successfully developed with T-band (1.0 µm waveband) and O-band (1.3 µm waveband) QD optical gain materials for Gbps-order, high-speed optical data generation. The insertion loss due to coupling between the device and the optical fiber was effectively compensated for by the SOA section. It was also confirmed that the monolithic QD-OGM/SOA device enabled >4.8 Gbps optical data generation with a clear eye opening in the T-band. Furthermore, we successfully demonstrated error-free 4.8 Gbps optical data transmissions in each of the six wavelength channels over a 10-km-long photonic crystal fiber using the monolithic QD-OGM/SOA device in multiple O-band wavelength channels, which were generated by the single QD gain chip. These results suggest that the monolithic QD-OGM/SOA device will be advantageous in ultra-broadband optical frequency systems that utilize the T+O-band for short- and medium-range optical communications.

Parameterization of clear-sky surface irradiance and its implications for estimation of aerosol direct radiative effect and aerosol optical depth

PubMed Central

Xia, Xiangao

2015-01-01

Aerosols impact clear-sky surface irradiance () through the effects of scattering and absorption. Linear or nonlinear relationships between aerosol optical depth (τa) and have been established to describe the aerosol direct radiative effect on (ADRE). However, considerable uncertainties remain associated with ADRE due to the incorrect estimation of (τa in the absence of aerosols). Based on data from the Aerosol Robotic Network, the effects of τa, water vapor content (w) and the cosine of the solar zenith angle (μ) on are thoroughly considered, leading to an effective parameterization of as a nonlinear function of these three quantities. The parameterization is proven able to estimate with a mean bias error of 0.32 W m−2, which is one order of magnitude smaller than that derived using earlier linear or nonlinear functions. Applications of this new parameterization to estimate τa from , or vice versa, show that the root-mean-square errors were 0.08 and 10.0 Wm−2, respectively. Therefore, this study establishes a straightforward method to derive from τa or estimate τa from measurements if water vapor measurements are available. PMID:26395310

Glycerol dehydration of native and diabetic animal tissues studied by THz-TDS and NMR methods

PubMed Central

Smolyanskaya, O. A.; Schelkanova, I. J.; Kulya, M. S.; Odlyanitskiy, E. L.; Goryachev, I. S.; Tcypkin, A. N.; Grachev, Ya. V.; Toropova, Ya. G.; Tuchin, V. V.

2018-01-01

The optical clearing method has been widely used for different spectral ranges where it provides tissue transparency. In this work, we observed the enhanced penetration of the terahertz waves inside biological samples (skin, kidney, and cornea) treated with glycerol solutions inducing changes of optical and dielectric properties. It was supported by the observed trend of free-to-bound water ratio measured by the nuclear magnetic resonance (NMR) method. The terahertz clearing efficiency was found to be less for diabetic samples than for normal ones. Results of the numerical simulation proved that pulse deformation is due to bigger penetration depth caused by the reduction of absorption and refraction at optical clearing. PMID:29541513

Polarization Considerations for the Laser Interferometer Space Antenna

NASA Technical Reports Server (NTRS)

Waluschka, Eugene; Pedersen, Tracy R.; McNamara, Paul

2005-01-01

A polarization ray trace model of the Laser Interferometer Space Antenna s (LISA) optical path is being created. The model will be able to assess the effects of various polarizing elements and the optical coatings on the required, very long path length, picometer level dynamic interferometry. The computational steps are described. This should eliminate any ambiguities associated with polarization ray tracing of interferometers and provide a basis for determining the computer model s limitations and serve as a clearly defined starting point for future work.

Study of the effect of ZnO film on some properties of clear and color window glass

NASA Astrophysics Data System (ADS)

Hamead, Alaa A. Abdul; Ahmed, Sura S.; Khdheer, Mena F.

2018-05-01

In the current research, a samples of transparent color and colorless window glass were prepared, (includes metal transition oxides) for construction applications. A nano-film layer of zinc oxide ZnO was deposited by spray pyrolysis technique for use in sustainability applications prepared. Structural properties (x-ray diffraction XRD, scanning electron microscopy SEM and atomic force microscopy AFM), and thermal properties, as well as optical properties and the effect of weathering conditions on applied film on clear and colored glass were examined. The results showed that the deposition film had a thickness of less than 90nm and that it was crystallized with high optical transparently, that was not significantly affected after deposited the ZnO nano film. While thermal insulation decreased significantly after deposition, and the effect of the weather conditions was very low as the ZnO coating was not affected, as the thermal insulation did not change after exposure to accelerated air conditions. Make it suitable in glass applications for buildings in vertical construction.

Ultrafast optical excitation of magnetic skyrmions

NASA Astrophysics Data System (ADS)

Ogawa, N.; Seki, S.; Tokura, Y.

2015-04-01

Magnetic skyrmions in an insulating chiral magnet Cu2OSeO3 were studied by all-optical spin wave spectroscopy. The spins in the conical and skyrmion phases were excited by the impulsive magnetic field from the inverse-Faraday effect, and resultant spin dynamics were detected by using time-resolved magneto-optics. Clear dispersions of the helimagnon were observed, which is accompanied by a distinct transition into the skyrmion phase, by sweeping temperature and magnetic field. In addition to the collective excitations of skyrmions, i.e., rotation and breathing modes, several spin precession modes were identified, which would be specific to optical excitation. The ultrafast, nonthermal, and local excitation of the spin systems by photons would lead to the efficient manipulation of nano-magnetic structures.

Adaptive optical imaging through complex living plant cells

NASA Astrophysics Data System (ADS)

Tamada, Yosuke; Hayano, Yutaka; Murata, Takashi; Oya, Shin; Honma, Yusuke; Kanazawa, Minoru; Miura, Noriaki; Hasebe, Mitsuyasu; Kamei, Yasuhiro; Hattori, Masayuki

2017-04-01

Live-cell imaging using fluorescent molecules is now essential for biological researches. However, images of living cells are accompanied with blur, which becomes stronger according to the depth inside the cells and tissues. This image blur is caused by the disturbance on light that goes through optically inhomogeneous living cells and tissues. Here, we show adaptive optics (AO) imaging of living plant cells. AO has been developed in astronomy to correct the disturbance on light caused by atmospheric turbulence. We developed AO microscope effective for the observation of living plant cells with strong disturbance by chloroplasts, and successfully obtained clear images inside plant cells.

Effect of CTAB on structural and optical properties of CuO nanoparticles prepared by coprecipitation route

NASA Astrophysics Data System (ADS)

Varghese, Donna; Tom, Catherine; Krishna Chandar, N.

2017-11-01

CuO (Copper Oxide) nanoparticles were synthesized by a simple coprecipitation route by using copper acetate, sodium hydroxide as precursors and cetyltrimethyl ammonium bromide (CTAB) as surfactant. For the purpose of the study, the surfactant-CTAB treated and non-treated samples were synthesized separately. Both the synthesized samples were studied to understand their structural and optical properties. The formation of CuO and its crystallinity was confirmed by XRD. Further, the optical studies showed a defined blue shift in CTAB treated sample which is clear evidence that the particles undergo confinement when they are nano-regime.

Comparing optical test methods for a lightweight primary mirror of a space-borne Cassegrain telescope

NASA Astrophysics Data System (ADS)

Lin, Wei-Cheng; Chang, Shenq-Tsong; Yu, Zong-Ru; Lin, Yu-Chuan; Ho, Cheng-Fong; Huang, Ting-Ming; Chen, Cheng-Huan

2014-09-01

A Cassegrain telescope with a 450 mm clear aperture was developed for use in a spaceborne optical remote-sensing instrument. Self-weight deformation and thermal distortion were considered: to this end, Zerodur was used to manufacture the primary mirror. The lightweight scheme adopted a hexagonal cell structure yielding a lightweight ratio of 50%. In general, optical testing on a lightweight mirror is a critical technique during both the manufacturing and assembly processes. To prevent unexpected measurement errors that cause erroneous judgment, this paper proposes a novel and reliable analytical method for optical testing, called the bench test. The proposed algorithm was used to distinguish the manufacturing form error from surface deformation caused by the mounting, supporter and gravity effects for the optical testing. The performance of the proposed bench test was compared with a conventional vertical setup for optical testing during the manufacturing process of the lightweight mirror.

Verification of antiferromagnetic exchange coupling at room temperature using polar magneto-optic Kerr effect in thin EuS/Co multilayers with perpendicular magnetic anisotropy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goschew, A., E-mail: alexander.goschew@fu-berlin.de; Scott, M.; Fumagalli, P.

2016-08-08

We report on magneto-optic Kerr measurements in polar geometry carried out on a series of thin Co/EuS multilayers on suitable Co/Pd-multilayer substrates. Thin Co/EuS multilayers of a few nanometers individual layer thickness usually have their magnetization in plane. Co/Pd multilayers introduce a perpendicular magnetic anisotropy in the Co/EuS layers deposited on top, thus making it possible to measure magneto-optic signals in the polar geometry in remanence in order to study exchange coupling. Magneto-optic Kerr-effect spectra and hysteresis loops were recorded in the visible and ultraviolet photon-energy range at room temperature. The EuS contribution to the magneto-optic signal is extracted atmore » 4.1 eV by combining hysteresis loops measured at different photon energies with polar magneto-optic Kerr-effect spectra recorded in remanence and in an applied magnetic field of 2.2 T. The extracted EuS signal shows clear signs of antiferromagnetic coupling of the Eu magnetic moments to the Co layers. This implies that the ordering temperature of at least a fraction of the EuS layers is above room temperature proving that magneto-optic Kerr-effect spectroscopy can be used here as a quasi-element-specific method.« less

Education kits for fiber optics, optoelectronics, and optical communications

NASA Astrophysics Data System (ADS)

Hájek, Martin; Švrček, Miroslav

2007-04-01

Our company MIKROKOM, s.r.o. is engaged for many years in development of education equipment and kits for fiber optics, optoelectronics and optical communications. We would like to inform competitors of conference about results of this long-time development. Requirements on education kits and equipment in a modern and dynamic area as is optical communications and fiber optics are quite difficult. The education kits should to clearly introduce students to given issue - the most important physical principles and technical approaches, but it should to introduce also to new and modern technologies, which are quickly changing and developing. On the other hand should be these tools and kits reasonable for the schools. In our paper we would like to describe possible ways of development of this education kits and equipment and present our results of long-time work, which covers very wide range. On the one hand we developed equipment and kits for clear demonstration of physical effects using plastic optical fibers POF, next we prepare kits with a glass fibers, which are the most used fibers in practice and after as much as the kits, which covers broad range of passive and active elements of the optical networks and systems and which makes possible to create complex optical transmission connection. This kind of systems with using corresponding tools and equipment introduce the students to properties, manipulation, measurement and usage of optical fibers, traces and many active and passive components. Furthermore, with using different sorts of optical sources, photodetectors, fiber optics couplers etc., students can get acquainted with all optoelectronics transmission system, which uses different sorts of signals. Special part will be devoted also to effort mentioned before - to implement modern technologies such as e.g. Wavelength Division Multiplex (WDM) into the education kits. Our presentation will inform auditors about development of mentioned education kits and equipment and about their potentials and practical utility at school education.

3D morphological analysis of the mouse cerebral vasculature: Comparison of in vivo and ex vivo methods

PubMed Central

Steinman, Joe; Koletar, Margaret M.; Stefanovic, Bojana; Sled, John G.

2017-01-01

Ex vivo 2-photon fluorescence microscopy (2PFM) with optical clearing enables vascular imaging deep into tissue. However, optical clearing may also produce spherical aberrations if the objective lens is not index-matched to the clearing material, while the perfusion, clearing, and fixation procedure may alter vascular morphology. We compared in vivo and ex vivo 2PFM in mice, focusing on apparent differences in microvascular signal and morphology. Following in vivo imaging, the mice (four total) were perfused with a fluorescent gel and their brains fructose-cleared. The brain regions imaged in vivo were imaged ex vivo. Vessels were segmented in both images using an automated tracing algorithm that accounts for the spatially varying PSF in the ex vivo images. This spatial variance is induced by spherical aberrations caused by imaging fructose-cleared tissue with a water-immersion objective. Alignment of the ex vivo image to the in vivo image through a non-linear warping algorithm enabled comparison of apparent vessel diameter, as well as differences in signal. Shrinkage varied as a function of diameter, with capillaries rendered smaller ex vivo by 13%, while penetrating vessels shrunk by 34%. The pial vasculature attenuated in vivo microvascular signal by 40% 300 μm below the tissue surface, but this effect was absent ex vivo. On the whole, ex vivo imaging was found to be valuable for studying deep cortical vasculature. PMID:29053753

A versatile new technique to clear mouse and human brain

NASA Astrophysics Data System (ADS)

Costantini, Irene; Di Giovanna, Antonino Paolo; Allegra Mascaro, Anna Letizia; Silvestri, Ludovico; Müllenbroich, Marie Caroline; Sacconi, Leonardo; Pavone, Francesco S.

2015-07-01

Large volumes imaging with microscopic resolution is limited by light scattering. In the last few years based on refractive index matching, different clearing approaches have been developed. Organic solvents and water-based optical clearing agents have been used for optical clearing of entire mouse brain. Although these methods guarantee high transparency and preservation of the fluorescence, though present other non-negligible limitations. Tissue transformation by CLARITY allows high transparency, whole brain immunolabelling and structural and molecular preservation. This method however requires a highly expensive refractive index matching solution limiting practical applicability. In this work we investigate the effectiveness of a water-soluble clearing agent, the 2,2'-thiodiethanol (TDE) to clear mouse and human brain. TDE does not quench the fluorescence signal, is compatible with immunostaining and does not introduce any deformation at sub-cellular level. The not viscous nature of the TDE make it a suitable agent to perform brain slicing during serial two-photon (STP) tomography. In fact, by improving penetration depth it reduces tissue slicing, decreasing the acquisition time and cutting artefacts. TDE can also be used as a refractive index medium for CLARITY. The potential of this method has been explored by imaging a whole transgenic mouse brain with the light sheet microscope. Moreover we apply this technique also on blocks of dysplastic human brain tissue transformed with CLARITY and labeled with different antibody. This clearing approach significantly expands the application of single and two-photon imaging, providing a new useful method for quantitative morphological analysis of structure in mouse and human brain.

Impact of Cumulus Cloud Spacing on Landsat Atmospheric Correction and Aerosol Retrieval

NASA Technical Reports Server (NTRS)

Wen, Guoyong; Cahalan, Robert F.; Tsay, Si-Chee; Oreopoulos, Lazaros

2001-01-01

A Landsat-7 ETM+ image acquired over the Southern Great Plains DoE/ARM site during the ARESE II experiment is used to study the effect of clouds on reflected radiation in clear patches of a cumulus cloud field. The result shows that the apparent path radiance in the clear patches is enhanced by nearby clouds in both band 1 (blue) and band 3 (red) of ETM+. More importantly, the magnitude of the enhancement depends on the mean cloud-free distance in the clear patches. For cloud-free distance less than 0.5 km, the enhancement of apparent path radiance is more than 0.025 and 0.015 (reflectance units) in band 1 and band 3 respectively, which corresponds to an enhancement of apparent aerosol optical thickness of approximately 0.25 and approximately 0.15. Neglecting of the 3-D cloud effect would lead to underestimates of surface reflectance of approximately 0.025 and approximately 0.015 in the blue and red band respectively, if the true aerosol optical thickness is 0.2 and the surface reflectance is 0.05. The enhancement decreases exponentially with mean cloud-free distance, reaching asymptotic values of 0.09 for band 1 and 0.027 for band 3 at a mean cloud-free distance about 2 km. The asymptotic values are slightly larger than the mean path radiances retrieved from a completely clear region -- 0.086 and 0.024 for the blue and red band respectively.

Femtosecond dynamics in hydrogen-bonded solvents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castner, E.W. Jr.; Chang, Y.J.

1993-09-01

We present results on the ultrafast dynamics of pure hydrogen-bonding solvents, obtained using femtosecond Fourier-transform optical-heterodyne-detected, Raman-induced Kerr effect spectroscopy. Solvent systems we have studied include the formamides, water, ethylene glycol, and acetic acid. Inertial and diffusive motions are clearly resolved. We comment on the effect that such ultrafast solvent motions have on chemical reactions in solution.

Fast fission neutron detection using the Cherenkov effect

NASA Astrophysics Data System (ADS)

Millard, Matthew James

The Cherenkov effect in optically clear media of varying indices of refraction and composition was investigated for quantification of fast neutrons. The ultimate application of the proposed detection system is criticality monitoring. The optically clear medium, composed of select target nuclei, was coupled to a photomultiplier tube. Neutron reaction products of the target nuclei contained within the optical medium emit beta particles and gamma rays that produce Cherenkov photons within the medium which can be detected. Assessed media include quartz (SiO2), sapphire (Al2O3), spinel (MgAl2O4), and zinc sulfide (ZnS), which were irradiated with un-moderated 252Cf. Monte Carlo N-Particle (MCNP) code simulations were conducted to quantify the neutron flux incident on the media. High resolution gamma-ray spectroscopic measurements of the samples were conducted to verify the MCNP estimate. The threshold reactions of interest were 28Si (n, p) 28Al, 27 Al (n, p) 27Mg, 24Mg(n, p)24 Na, and 64Zn(n, p)64Cu which have neutron reaction cross sections in the 1 to 10 MeV range on the order of 0.1 barn. The detection system offers a unique way to measure a criticality event; it can count in place, making retrieval by emergency personnel unnecessary.

Center for Adaptive Optics | Software

Science.gov Websites

Center for Adaptive Optics A University of California Science and Technology Center home Adaptive Optics Software The Center for Adaptive Optics acts as a clearing house for distributing Software to Institutes it gives specialists in Adaptive Optics a place to distribute their software. All software is

Biogenic Aerosols – Effects on Climate and Clouds. Cloud Optical Depth (COD) Sensor Three-Waveband Spectrally-Agile Technique (TWST) Field Campaign Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niple, E. R.; Scott, H. E.

2016-04-01

This report describes the data collected by the Three-Waveband Spectrally-agile Technique (TWST) sensor deployed at Hyytiälä, Finland from 16 July to 31 August 2014 as a guest on the Biogenic Aerosols Effects on Climate and Clouds (BAECC) campaign. These data are currently available from the Atmospheric Radiation Measurement (ARM) Data Archive website and consists of Cloud Optical Depth (COD) measurements for the clouds directly overhead approximately every second (with some dropouts described below) during the daylight periods. A good range of cloud conditions were observed from clear sky to heavy rainfall.

Sensitivity of Marine Warm Cloud Retrieval Statistics to Algorithm Choices: Examples from MODIS Collection 6

NASA Astrophysics Data System (ADS)

Platnick, S.; Wind, G.; Zhang, Z.; Ackerman, S. A.; Maddux, B. C.

2012-12-01

The optical and microphysical structure of warm boundary layer marine clouds is of fundamental importance for understanding a variety of cloud radiation and precipitation processes. With the advent of MODIS (Moderate Resolution Imaging Spectroradiometer) on the NASA EOS Terra and Aqua platforms, simultaneous global/daily 1km retrievals of cloud optical thickness and effective particle size are provided, as well as the derived water path. In addition, the cloud product (MOD06/MYD06 for MODIS Terra and Aqua, respectively) provides separate effective radii results using the 1.6, 2.1, and 3.7 μm spectral channels. Cloud retrieval statistics are highly sensitive to how a pixel identified as being "not-clear" by a cloud mask (e.g., the MOD35/MYD35 product) is determined to be useful for an optical retrieval based on a 1-D cloud model. The Collection 5 MODIS retrieval algorithm removed pixels associated with cloud edges (defined by immediate adjacency to "clear" MOD/MYD35 pixels) as well as ocean pixels with partly cloudy elements in the 250m MODIS cloud mask - part of the so-called Clear Sky Restoral (CSR) algorithm. Collection 6 attempts retrievals for those two pixel populations, but allows a user to isolate or filter out the populations via CSR pixel-level Quality Assessment (QA) assignments. In this paper, using the preliminary Collection 6 MOD06 product, we present global and regional statistical results of marine warm cloud retrieval sensitivities to the cloud edge and 250m partly cloudy pixel populations. As expected, retrievals for these pixels are generally consistent with a breakdown of the 1D cloud model. While optical thickness for these suspect pixel populations may have some utility for radiative studies, the retrievals should be used with extreme caution for process and microphysical studies.

Use of an optical clearing agent to enhance the visibility of subsurface structures and lesions from tooth occlusal surfaces

PubMed Central

Kang, Hobin; Darling, Cynthia L.; Fried, Daniel

2016-01-01

Abstract. The purpose of this study is to show that optical clearing agents can be used to increase the visibility of deeply penetrating occlusal lesions that have reached the underlying dentin and spread laterally under the enamel. Previous studies have shown that high refractive index fluids can increase the contrast of caries lesions. Extracted teeth with natural occlusal lesions were imaged with optical coherence tomography (OCT) with and without the addition of a transparent vinyl polysiloxane impression material (VPS) currently used in vivo. The relative intensity of the reflectivity from the underlying lesion area for each sample was measured before and after application of the VPS. Lesion presence was confirmed with polarized light microscopy and microradiography. Application of VPS significantly increased (P<0.0001) the integrated reflectivity of subsurface dentinal lesions. This study shows that optical clearing agents can be used to increase the optical penetration and the visibility of subsurface lesions and the dentinal–enamel junction under sound and demineralized enamel in OCT images. PMID:27071709

Co-doping as a tool for tuning the optical properties of singlewalled carbon nanotubes: A first principles study

NASA Astrophysics Data System (ADS)

Sharma, Deepa; Jaggi, Neena

2017-07-01

This paper presents a first principles study on the effect of co-doping on various optical spectra of a zigzag single-walled carbon nanotube (SWCNT). Optical spectra of a pristine SWCNT, SWCNT co-doped with Aluminum (Al) & Phosphorus (P) and another one co-doped with Al, P and Nitrogen (N) have been calculated using density functional theory (DFT).The theory has been implemented using the Cambridge sequential total energy package (CASTEP) code available as a userfriendly module with the software 'Material Studio'. Polarized and unpolarized light as well as light through polycrystalline media have been considered. The dependence of various spectra on the status of incident light presents a clear evidence of anisotropicity in the optical properties. Analysis of the simulated spectra involves calculation and comparison of different optical properties like dielectric function, reflectivity, refractive index, conductivity and loss function for the pristine and co-doped SWCNTs. Noticeable variations are observed in the optical properties on simultaneously doping the SWCNT with Al and P and then further introducing N atom into the structure so that it can be concluded that co-doping (simultaneous doping with different combinations of dopants) can be evolved as a novel and effective tool for tailoring the optical properties of SWCNTs as per the requirements while designing an optical device. It will prove to be highly significant for effective designing of SWCNT based sensitive optical devices for a variety of technological applications.

Chip-to-chip optical link by using optical wiring method

NASA Astrophysics Data System (ADS)

Cho, In-Kui; Ahn, Seoung Ho; Jeong, Myung-Yung; Rho, Byung Sup; Park, Hyo Hoon

2008-01-01

A practical optical link system was prepared with a transmitter (Tx) and receiver (Rx). The optical TRx module consisted of a metal optical bench, a module printed circuit board (PCB), a driver/receiver IC, a VCSEL/PD array, and an optical link block composed of plastic optical fiber (POF). For the optical interconnection between the light-sources and detectors, an optical wiring method has been proposed to enable easy assembly. This paper provides a method for optical interconnection between an optical Tx and an optical Rx, comprising the following steps: (a) forming a light source device, an optical detection device, and an optical transmission unit on a substrate (metal optical bench (MOB)); (b) preparing a flexible optical transmission-connection medium (optical wiring link) to optically connect the light source device formed on the substrate with the optical detection device; and (c) directly connecting one end of the surface-finished optical transmission connection medium with the light source device and the other end with the optical detection device. A chip-to-chip optical link system constructed with TRx modules was fabricated and the optical characteristics were measured. The results clearly demonstrate that the use of an optical wiring method can provide robust and cost-effective assembly for vertical-cavity surface-emitting lasers (VCSELs) and photodiodes (PDs). We successfully achieved a 5 Gb/s data transmission rate with this optical link.

EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Transient clearing of a water aerosol in the case of thermal blooming of an optical beam

NASA Astrophysics Data System (ADS)

Kucherov, Arkadii N.

1995-03-01

The moisture approximation is used in a study of transient clearing of a water aerosol when droplets are evaporated by an intense laser beam in the presence of a cross wind. Coordinate distributions of the beam intensity and moisture are obtained between the moment at which the beam begins to act and the attainment of a steady state. The dependences of the intensity of the beam transmitted by an aerosol medium on the scaling parameters (representing aerosol evaporation or clearing, beam attenuation, and thermal blooming) are derived. A comparison is made with experimental and theoretical results obtained by other authors.

Noninvasively Imaging Subcutaneous Tumor Xenograft by a Handheld Raman Detector, with the Assistance of an Optical Clearing Agent.

PubMed

Zhang, Yunfei; Liu, Haoran; Tang, Jiali; Li, Zhuoyun; Zhou, Xingyu; Zhang, Ren; Chen, Liang; Mao, Ying; Li, Cong

2017-05-31

A handheld Raman detector with operational convenience, high portability, and rapid acquisition rate has been applied in clinics for diagnostic purposes. However, the inherent weakness of Raman scattering and strong scattering of the turbid tissue restricts its utilization to superficial locations. To extend the applications of a handheld Raman detector to deep tissues, a gold nanostar-based surface-enhanced Raman scattering (SERS) nanoprobe with robust colloidal stability, a fingerprint-like spectrum, and extremely high sensitivity (5.0 fM) was developed. With the assistance of FPT, a multicomponent optical clearing agent (OCA) efficiently suppressing light scattering from the turbid dermal tissues, the handheld Raman detector noninvasively visualized the subcutaneous tumor xenograft with a high target-to-background ratio after intravenous injection of the gold nanostar-based SERS nanoprobe. To the best of our knowledge, this work is the first example to introduce the optical clearing technique in assisting SERS imaging in vivo. The combination of optical clearing technology and SERS is a promising strategy for the extension of the clinical applications of the handheld Raman detector from superficial tissues to subcutaneous or even deeper lesions that are usually "concealed" by the turbid dermal tissue.

Laser identification system based on acousto-optical barcode scanner principles

NASA Astrophysics Data System (ADS)

Khansuvarov, Ruslan A.; Korol, Georgy I.; Preslenev, Leonid N.; Bestugin, Aleksandr R.; Paraskun, Arthur S.

2016-09-01

The main purpose of the bar code in the modern world is the unique identification of the product, service, or any of their features, so personal and stationary barcode scanners so widely used. One of the important parameters of bar code scanners is their reliability, accuracy of the barcode recognition, response time and performance. Nowadays, the most popular personal barcode scanners contain a mechanical part, which extremely impairs the reliability indices. Group of SUAI engineers has proposed bar code scanner based on laser beam acoustic deflection effect in crystals [RU patent No 156009 issued 4/16/2015] Through the use of an acousto-optic deflector element in barcode scanner described by a group of engineers SUAI, it can be implemented in the manual form factor, and the stationary form factor of a barcode scanner. Being a wave electronic device, an acousto-optic element in the composition of the acousto-optic barcode scanner allows you to clearly establish a mathematical link between the encoded function of the bar code with the accepted input photodetector intensities function that allows you to speak about the great probability of a bar code clear definition. This paper provides a description of the issued patent, the description of the principles of operation based on the mathematical analysis, a description of the layout of the implemented scanner.

Pore size and concentration effect of mesoporous silica nanoparticles on the coefficient of thermal expansion and optical transparency of poly(ether sulfone) films.

PubMed

Vo, Nhat Tri; Patra, Astam K; Kim, Dukjoon

2017-01-18

Mesoporous silica nanoparticles (MSNs) with uniform size (<50 nm) yet with different pore diameters were synthesized, and used as fillers in poly(ether sulfone) (PES) films in order to decrease their coefficient of thermal expansion (CTE) without sacrificing optical transparency. Here, both CTE and optical transparency of the MSN/PES nanocomposite films gradually decreased with increasing MSN concentration. The PES films containing MSNs with larger pores showed the best performance in CTE and optical transparency. While the CTE decreased by 32.3% with increasing MSN content up to 0.5 wt%, the optical transparency decreased by only less than 6.9% because of the small and uniform particle size of less than 50 nm, which minimizes light scattering. This pore size effect is more clearly observed via an annealing process, which enables the polymer chains to slowly move and fill in the free volume in the pores of the MSN, and thus restricts the thermal motion. The effect of the silica nanoparticles was investigated not only on the thermal stability but also on the mechanical stability. We expect the MSNs synthesized in this study to be used as a promising filler to enhance the thermal and mechanical stability of the PES substrate without sacrificing its optical transparency.

Pre-clinical longitudinal monitoring of hemodynamic response to anti-vascular chemotherapy by hybrid diffuse optics.

PubMed

Farzam, Parisa; Johansson, Johannes; Mireles, Miguel; Jiménez-Valerio, Gabriela; Martínez-Lozano, Mar; Choe, Regine; Casanovas, Oriol; Durduran, Turgut

2017-05-01

The longitudinal effect of an anti-vascular endothelial growth factor receptor 2 (VEGFR-2) antibody (DC 101) therapy on a xenografted renal cell carcinoma (RCC) mouse model was monitored using hybrid diffuse optics. Two groups of immunosuppressed male nude mice (seven treated, seven controls) were measured. Tumor microvascular blood flow, total hemoglobin concentration and blood oxygenation were investigated as potential biomarkers for the monitoring of the therapy effect twice a week and were related to the final treatment outcome. These hemodynamic biomarkers have shown a clear differentiation between two groups by day four. Moreover, we have observed that pre-treatment values and early changes in hemodynamics are highly correlated with the therapeutic outcome demonstrating the potential of diffuse optics to predict the therapy response at an early time point.

Ocean water color assessment from ERTS-1 RBV and MSS imagery

NASA Technical Reports Server (NTRS)

Ross, D. S. (Principal Investigator)

1973-01-01

The author has identified the following significant results. Photo-optical and electronic density slicing were applied to ERTS-1 E 1007-151651-4, 30 July 1972, an area in the Caribbean showing deep ocean water, and shallow areas on the Great Baham Bank ranging from 0.5 meter or less to 18 meters. The density slicing processes were adjusted to correlate water radiance to bathmetric contours shown on C and GS Chart 1112. A number of large areas corresponding to water depths of 2 meters or less, 5 to 10 meters, and 10 to about 20 meters were isolated by both processes. Where clear water and uniformly reflective bottom was found, clear of marine growths, the photo-optical and electronic image density slicing processes proved effective in delineating areas where the depth was in the order of 5 meters, plus or minus 1 meter.

Features of optical surfaces of multifocal diffractive-refractive eye lenses

NASA Astrophysics Data System (ADS)

Lenkova, G. A.

2017-09-01

This paper considers shape features of the surface structures of multifocal intraocular lenses (IOLs), which, unlike bifocal IOLs, generate additional foci or extends the depth of focus, which not only corrects near and far vision but also provides good vision at intermediate distances. Expansion of the field of clear vision is achieved due to the effects of diffraction, interference, and refraction (change in the radius of curvature of the lens surface). The optical characteristics of the most famous multifocal IOLs (trifocal and quadrafocal lenses and lenses with extended focal area) are given.

High-Density Near-Field Readout over 50 GB Capacity Using Solid Immersion Lens with High Refractive Index

NASA Astrophysics Data System (ADS)

Shinoda, Masataka; Saito, Kimihiro; Kondo, Takao; Ishimoto, Tsutomu; Nakaoki, Ariyoshi

2003-02-01

We have investigated high-density near-field readout using a solid immersion lens with a high refractive index. By using a glass material with a high refractive index of 2.08, we developed an optical pick-up with the effective numerical aperture of 1.8. We could observe a clear eye pattern for a 50 GB capacity disc in 120 mm diameter. We confirmed that the near-field readout system is promising method of realizing a high-density optical disc system.

Propagation of a general-type beam through a truncated fractional Fourier transform optical system.

PubMed

Zhao, Chengliang; Cai, Yangjian

2010-03-01

Paraxial propagation of a general-type beam through a truncated fractional Fourier transform (FRT) optical system is investigated. Analytical formulas for the electric field and effective beam width of a general-type beam in the FRT plane are derived based on the Collins formula. Our formulas can be used to study the propagation of a variety of laser beams--such as Gaussian, cos-Gaussian, cosh-Gaussian, sine-Gaussian, sinh-Gaussian, flat-topped, Hermite-cosh-Gaussian, Hermite-sine-Gaussian, higher-order annular Gaussian, Hermite-sinh-Gaussian and Hermite-cos-Gaussian beams--through a FRT optical system with or without truncation. The propagation properties of a Hermite-cos-Gaussian beam passing through a rectangularly truncated FRT optical system are studied as a numerical example. Our results clearly show that the truncated FRT optical system provides a convenient way for laser beam shaping.

Distributed optical fibre sensing for early detection of shallow landslides triggering.

PubMed

Schenato, Luca; Palmieri, Luca; Camporese, Matteo; Bersan, Silvia; Cola, Simonetta; Pasuto, Alessandro; Galtarossa, Andrea; Salandin, Paolo; Simonini, Paolo

2017-10-31

A distributed optical fibre sensing system is used to measure landslide-induced strains on an optical fibre buried in a large scale physical model of a slope. The fibre sensing cable is deployed at the predefined failure surface and interrogated by means of optical frequency domain reflectometry. The strain evolution is measured with centimetre spatial resolution until the occurrence of the slope failure. Standard legacy sensors measuring soil moisture and pore water pressure are installed at different depths and positions along the slope for comparison and validation. The evolution of the strain field is related to landslide dynamics with unprecedented resolution and insight. In fact, the results of the experiment clearly identify several phases within the evolution of the landslide and show that optical fibres can detect precursory signs of failure well before the collapse, paving the way for the development of more effective early warning systems.

Intraocular application of gold nanodisks optically tuned for optical coherence tomography: inhibitory effect on retinal neovascularization without unbearable toxicity.

PubMed

Song, Hyun Beom; Wi, Jung-Sub; Jo, Dong Hyun; Kim, Jin Hyoung; Lee, Sang-Won; Lee, Tae Geol; Kim, Jeong Hun

2017-08-01

Bare gold nanospheres have been shown to have anti-angiogenic effects but are optically unfavorable because their resonant wavelength lies in the visible spectrum. Here, we design gold nanodisks with a higher scattering capability than gold nanorods and with a resonant wavelength at near-infrared region - the area where the source of light utilized by optical coherence tomography (OCT) lies. With a physical synthesis system, we then fabricate 160-nm-sized gold nanodisks exhibiting resonant wavelength at 830 nm. The synthesized nanoparticles were successfully visualized in in vivo OCT at concentrations as low as 1 pM. After demonstrating their binding ability to vascular endothelial growth factor (VEGF), we show that they suppress VEGF-induced migration of endothelial cells. Finally, we demonstrate that intravitreally injected gold nanodisks attenuate neovascularization of oxygen-induced retinopathy in mice, in a dose dependent manner, such that they are cleared from the vitreous within 2 weeks without histologic or electrophysiologic toxicity. Copyright © 2017 Elsevier Inc. All rights reserved.

High-power laser radiation in atmospheric aerosols: Nonlinear optics of aerodispersed media

NASA Astrophysics Data System (ADS)

Zuev, V. E.; Zemlianov, A. A.; Kopytin, Iu. D.; Kuzikovskii, A. V.

The bulk of this book contains the results of investigations carried out at the Institute of Atmospheric Optics, Siberian Branch, USSR Academy of Science with the participation of the authors. The microphysical and optical characteristics of atmospheric aerosols are considered, taking into account light scattering by a single aerosol particle, light scattering by a system of particles, the scattering phase matrix, light scattering by clouds and fogs, light scattering by hazes, and scattering phase functions of polydispersed aerosols. Other topics studies are related to low-energy (subexplosive) effects of radiation on individual particles, the formation of clear zones in clouds and fogs due to the vaporization of droplets under regular regimes, self-action of a wave beam in a water aerosol under conditions of regular droplet vaporization, laser beam propagation through an explosively evaporating water-droplet aerosol, the propagation of high-power laser radiation through hazes, the ionization and optical breakdown in aerosol media, and laser monitoring of a turbid atmosphere using nonlinear effects.

Characterizing the Optical Variability of Bright Blazars: Variability-Based Selection of Fermi Active Galactic Nuclei

DTIC Science & Technology

2012-11-20

10′. We do not apply cosmological redshift corrections here for blazar selection. Similar to the conclusions drawn from Figure 4, there is clear...effects. For example, the observed blazar characteristic damping timescale τblz,obs (after correcting for cosmological redshift) should be shortened in

Can a coupled meteorology–chemistry model reproduce the historical trend in aerosol direct radiative effects over the Northern Hemisphere?

EPA Science Inventory

The ability of a coupled meteorology–chemistry model, i.e., Weather Research and Forecast and Community Multiscale Air Quality (WRF-CMAQ), to reproduce the historical trend in aerosol optical depth (AOD) and clear-sky shortwave radiation (SWR) over the Northern Hemisphere h...

Study on the refractive index matching effect of ultrasound on optical clearing of bio-tissues based on the derivative total reflection method.

PubMed

Zeng, Huanhuan; Wang, Jin; Ye, Qing; Deng, Zhichao; Mei, Jianchun; Zhou, Wenyuan; Zhang, Chunping; Tian, Jianguo

2014-10-01

In recent years, the tissue optical clearing (OC) technique in the biomedicine field has drawn lots of attention. Various physical and chemical methods have been introduced to improve the efficacy of OC. In this study, the effect of the combination of glycerol and ultrasound treatment on OC of in vitro porcine muscle tissues has been investigated. The refractive index (RI) matching mechanism of OC was directly observed based on the derivative total reflection method. A theoretical model was used to simulate the proportion of tissue fluid in the illuminated area. Moreover, the total transmittance spectra have been obtained by a spectrometer over the range from 450 nm to 700 nm. The administration of glycerol and ultrasound has led to an increase of the RI of background medium and a more RI matching environment was achieved. The experimental results support the validity of the ultrasound treatment for OC. The RI matching mechanism has been firstly quantitatively analyzed based on the derivative total reflection method.

Effective cloud optical depth and enhancement effects for broken liquid water clouds in Valencia (Spain)

NASA Astrophysics Data System (ADS)

Marín, M. J.; Serrano, D.; Utrillas, M. P.; Núñez, M.; Martínez-Lozano, J. A.

2017-10-01

Partly cloudy skies with liquid water clouds have been analysed, founding that it is essential to distinguish data if the Sun is obstructed or not by clouds. Both cases can be separated considering simultaneously the Cloud Modification Factor (CMF) and the clearness index (kt). For partly cloudy skies and the Sun obstructed the effective cloud optical depth (τ) has been obtained by the minimization method for overcast skies. This method was previously developed by the authors but, in this case, taking into account partial cloud cover. This study has been conducted for the years 2011-2015 with the multiple scattering model SBDART and irradiance measurements for the UV Erythemal Radiation (UVER) and the broadband ranges. Afterwards a statistical analysis of τ has shown that the maximum value is much lower than for overcast skies and there is more discrepancy between the two spectral ranges regarding the results for overcast skies. In order to validate these results the effective cloud optical depth has been correlated with several transmission factors, giving similar fit parameters to those obtained for overcast skies except for the clearness index in the UVER range. As our method is not applicable for partly cloudy skies with the visible Sun, the enhancement of radiation caused by clouds when the Sun is visible has been studied. Results show that the average enhancement CMF values are the same for both ranges although enhancement is more frequent for low cloud cover in the UVER and medium-high cloud cover in the broadband range and it does not depend on the solar zenith angle.

3D imaging of optically cleared tissue using a simplified CLARITY method and on-chip microscopy

PubMed Central

Zhang, Yibo; Shin, Yoonjung; Sung, Kevin; Yang, Sam; Chen, Harrison; Wang, Hongda; Teng, Da; Rivenson, Yair; Kulkarni, Rajan P.; Ozcan, Aydogan

2017-01-01

High-throughput sectioning and optical imaging of tissue samples using traditional immunohistochemical techniques can be costly and inaccessible in resource-limited areas. We demonstrate three-dimensional (3D) imaging and phenotyping in optically transparent tissue using lens-free holographic on-chip microscopy as a low-cost, simple, and high-throughput alternative to conventional approaches. The tissue sample is passively cleared using a simplified CLARITY method and stained using 3,3′-diaminobenzidine to target cells of interest, enabling bright-field optical imaging and 3D sectioning of thick samples. The lens-free computational microscope uses pixel super-resolution and multi-height phase recovery algorithms to digitally refocus throughout the cleared tissue and obtain a 3D stack of complex-valued images of the sample, containing both phase and amplitude information. We optimized the tissue-clearing and imaging system by finding the optimal illumination wavelength, tissue thickness, sample preparation parameters, and the number of heights of the lens-free image acquisition and implemented a sparsity-based denoising algorithm to maximize the imaging volume and minimize the amount of the acquired data while also preserving the contrast-to-noise ratio of the reconstructed images. As a proof of concept, we achieved 3D imaging of neurons in a 200-μm-thick cleared mouse brain tissue over a wide field of view of 20.5 mm2. The lens-free microscope also achieved more than an order-of-magnitude reduction in raw data compared to a conventional scanning optical microscope imaging the same sample volume. Being low cost, simple, high-throughput, and data-efficient, we believe that this CLARITY-enabled computational tissue imaging technique could find numerous applications in biomedical diagnosis and research in low-resource settings. PMID:28819645

Tropospheric haze and colors of the clear twilight sky.

PubMed

Lee, Raymond L; Mollner, Duncan C

2017-07-01

At the earth's surface, clear-sky colors during civil twilights depend on the combined spectral effects of molecular scattering, extinction by tropospheric aerosols, and absorption by ozone. Molecular scattering alone cannot produce the most vivid twilight colors near the solar horizon, for which aerosol scattering and absorption are also required. However, less well known are haze aerosols' effects on twilight sky colors at larger scattering angles, including near the antisolar horizon. To analyze this range of colors, we compare 3D Monte Carlo simulations of skylight spectra with hyperspectral measurements of clear twilight skies over a wide range of aerosol optical depths. Our combined measurements and simulations indicate that (a) the purest antisolar twilight colors would occur in a purely molecular, multiple-scattering atmosphere, whereas (b) the most vivid solar-sky colors require at least some turbidity. Taken together, these results suggest that multiple scattering plays an important role in determining the redness of the antitwilight arch.

Novel optical switch with a reconfigurable dielectric liquid droplet.

PubMed

Ren, Hongwen; Xu, Su; Ren, Daqiu; Wu, Shin-Tson

2011-01-31

We demonstrated a novel optical switch with a reconfigurable dielectric liquid droplet. The device consists of a clear liquid droplet (glycerol) surrounded by a black liquid (dye-doped liquid crystal). In the voltage-off state, the incident light passing through the clear liquid droplet is absorbed by the black liquid, resulting in a dark state. In the voltage-on state, the dome of the clear liquid droplet is uplifted by the dielectric force to form a light pipe which in turn transmits the incident light. Upon removing the voltage, the droplet recovers to its original shape and the switch is closed. We also demonstrated a red color light switch with ~10:1 contrast ratio and ~300 ms response time. Devices based on such an operation mechanism will find attractive applications in light shutter, tunable iris, variable optical attenuators, and displays.

Protective shield for an instrument probe

DOEpatents

Johnsen, Howard A.; Ross, James R.; Birtola, Sal R.

2004-10-26

A shield is disclosed that is particularly useful for protecting exposed optical elements at the end of optical probes used in the analysis of hazardous emissions in and around an industrial environment from the contaminating effects of those emissions. The instant invention provides a hood or cowl in the shape of a right circular cylinder that can be fitted over the end of such optical probes. The hood provides a clear aperture through which the probe can perform unobstructed analysis. The probe optical elements are protected from the external environment by passing a dry gas through the interior of the hood and out through the hood aperture in sufficient quantity and velocity to prevent any significant mixing between the internal and external environments. Additionally, the hood is provided with a cooling jacket to lessen the potential for damaging the probe due to temperature excursions.

Monitoring of interaction of low-frequency electric field with biological tissues upon optical clearing with optical coherence tomography.

PubMed

Peña, Adrián F; Doronin, Alexander; Tuchin, Valery V; Meglinski, Igor

2014-08-01

The influence of a low-frequency electric field applied to soft biological tissues ex vivo at normal conditions and upon the topical application of optical clearing agents has been studied by optical coherence tomography (OCT). The electro-kinetic response of tissues has been observed and quantitatively evaluated by the double correlation OCT approach, utilizing consistent application of an adaptive Wiener filtering and Fourier domain correlation algorithm. The results show that fluctuations, induced by the electric field within the biological tissues are exponentially increased in time. We demonstrate that in comparison to impedance measurements and the mapping of the temperature profile at the surface of the tissue samples, the double correlation OCT approach is much more sensitive to the changes associated with the tissues' electro-kinetic response. We also found that topical application of the optical clearing agent reduces the tissues' electro-kinetic response and is cooling the tissue, thus reducing the temperature induced by the electric current by a few degrees. We anticipate that dcOCT approach can find a new application in bioelectrical impedance analysis and monitoring of the electric properties of biological tissues, including the resistivity of high water content tissues and its variations.

Quantitative analysis of dehydration in porcine skin for assessing mechanism of optical clearing

NASA Astrophysics Data System (ADS)

Yu, Tingting; Wen, Xiang; Tuchin, Valery V.; Luo, Qingming; Zhu, Dan

2011-09-01

Dehydration induced by optical clearing agents (OCAs) can improve tissue optical transmittance; however, current studies merely gave some qualitative descriptions. We develop a model to quantitatively evaluate water content with partial least-squares method based on the measurements of near-infrared reflectance spectroscopy and weight of porcine skin. Furthermore, a commercial spectrometer with an integrating sphere is used to measure the transmittance and reflectance of skin after treatment with different OCAs, and then the water content and optical properties of sample are calculated, respectively. The results show that both the reduced scattering coefficient and dehydration of skin decrease with prolongation of action of OCAs, but the relative change in former is larger than that in latter after a 60-min treatment. The absorption coefficient at 1450 nm decreases completely coincident with dehydration of skin. Further analysis illustrates that the correlation coefficient between the relative changes in the reduced scattering coefficient and dehydration is ~1 during the 60-min treatment of agents, but there is an extremely significant difference between the two parameters for some OCAs with more hydroxyl groups, especially, glycerol or D-sorbitol, which means that the dehydration is a main mechanism of skin optical clearing, but not the only mechanism.

The lymphatic mechanisms of brain cleaning: application of optical coherence tomography and fluorescence microscopy

NASA Astrophysics Data System (ADS)

Glushkovskaya-Semyachkina, O.; Abdurashitov, A.; Fedosov, I.; Namykin, A.; Pavlov, A.; Shirokov, A.; Shushunova, N.; Sindeeva, O.; Khorovodov, A.; Ulanova, M.; Sagatova, V.; Agranovich, I.; Bodrova, A.; Kurths, J.

2018-04-01

Here we studied the role of cerebral lymphatic system in the brain clearing using intraparenchymal injection of Evans Blue and gold nanorods assessed by optical coherent tomography and fluorescence microscopy. Our data clearly show that the cerebral lymphatic system plays an important role in the brain cleaning via meningeal lymphatic vessels but not cerebral veins. Meningeal lymphatic vessels transport fluid from the brain into the deep cervical node, which is the first anatomical "station" for lymph outflow from the brain. The lymphatic processes underlying brain clearing are more slowly vs. peripheral lymphatics. These results shed light on the lymphatic mechanisms responsible for brain clearing as well as interaction between the intra- and extracranial lymphatic compartment.

Optical characterization of poly(methyl methacrylate) implanted with low energy ions

NASA Astrophysics Data System (ADS)

Gupta, Renu; Kumar, Vijay; Goyal, Parveen Kumar; Kumar, Shyam

2012-12-01

The samples of poly(methyl methacrylate) (PMMA) were subjected to 100 keV N+ and Ar+ ion implantation up to a maximum fluence of 2 × 1016 ions/cm2. The effect of ion implantation on the optical energy gap and the refractive index has been studied through UV-visible spectroscopy. The results clearly indicate a decrease in the values of optical energy gap and an increase in the values of refractive index as an effect of ion implantation corresponding to both of the ions. It has also been observed that the changes induced by the implanted ions are more pronounced for N+ ions in comparison to Ar+ ions. This variation has been correlated with the calculated ranges of these ions in PMMA polymer using Stopping and Range of Ions in Matter (SRIM) code. Finally, an attempt has been made to correlate all the observed changes with the induced structural changes as revealed through Raman spectroscopy.

A cost-effective 25-Gb/s EML TOSA using all-in-one FPCB wiring and metal optical bench.

PubMed

Han, Young-Tak; Kwon, Oh-Kee; Lee, Dong-Hun; Lee, Chul-Wook; Leem, Young-Ahn; Shin, Jang-Uk; Park, Sang-Ho; Baek, Yongsoon

2013-11-04

We present a cost-effective 25-Gb/s electro-absorption modulator integrated laser (EML) transmitter optical sub-assembly (TOSA) using all-in-one flexible printed circuit board (FPCB) wiring and a metal optical bench (MOB). For a low cost and high bandwidth TOSA, internal and external wirings and feed-through of the TOSA to transmit radio-frequency (RF) signal are configured all-in-one using the FPCB. The FPCB is extended from an exterior of the TOSA package up to an EML chip inside the package through the slit formed on a rear sidewall of the package and die-bonded on the MOB. The EML TOSA shows a modulated output power of more than 3.5 dBm and a clear eye pattern with a dynamic extinction ratio of ~8.4 dB at a data rate of 25.78 Gb/s.

Angle-of-arrival variance of waves and rays in strong atmospheric scattering: split-step simulation results

NASA Astrophysics Data System (ADS)

Voelz, David; Wijerathna, Erandi; Xiao, Xifeng; Muschinski, Andreas

2017-09-01

The analysis of optical propagation through both deterministic and stochastic refractive-index fields may be substantially simplified if diffraction effects can be neglected. With regard to simplification, it is known that certain geometricaloptics predictions often agree well with field observations but it is not always clear why this is so. Here, a new investigation of this issue is presented involving wave optics and geometrical (ray) optics computer simulations of a beam of visible light propagating through fully turbulent, homogeneous and isotropic refractive-index fields. We compare the computationally simulated, aperture-averaged angle-of-arrival variances (for aperture diameters ranging from 0.5 to 13 Fresnel lengths) with theoretical predictions based on the Rytov theory.

Effect of phosphorus on the electronic and optical properties of naphthoxaphospholes: theoretical investigation

NASA Astrophysics Data System (ADS)

Moon, Jiwon; Kim, Minbi; Lim, Jeong Sik; Kim, Joonghan

2018-06-01

Density functional theory (DFT) and time-dependent DFT calculations were performed to elucidate the electronic and optical properties of 2-R-naphthol[2,3-d]oxaphospholes (R-NOPs). On the basis of the calculated results, the poor π overlap between the 3pz orbital of P atom and the 2pz orbitals of other atoms and increasing polarity of P atom result in a reduced energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital. When these two effects are considered simultaneously, the absorption energies obtained for the S1 state can be below 3.00 eV according to replace the P atom of oxaphosphole ring by As atom (increasing the poor π overlap) and change the functional groups (increasing polarity). The origin of these two effects is the inherent size of the 3p orbital of P atom. The role of P atom in the control of the electronic and optical properties of R-NOPs is clearly elucidated.

Assessment of the effect of air pollution controls on trends in shortwave radiation over the United States from 1995 through 2010 from multiple observation networks

EPA Science Inventory

Long-term data sets of all-sky and clear-sky downwelling shortwave (SW) radiation, cloud cover fraction, and aerosol optical depth (AOD) were analyzed together with surface concentrations from several networks (e.g., Surface Radiation Budget Network (SURFRAD), Clean Air Status an...

Optical feedback in dfb quantum cascade laser for mid-infrared cavity ring-down spectroscopy

NASA Astrophysics Data System (ADS)

Terabayashi, Ryohei; Sonnenschein, Volker; Tomita, Hideki; Hayashi, Noriyoshi; Kato, Shusuke; Jin, Lei; Yamanaka, Masahito; Nishizawa, Norihiko; Sato, Atsushi; Nozawa, Kohei; Hashizume, Kenta; Oh-hara, Toshinari; Iguchi, Tetsuo

2017-11-01

A simple external optical feedback system has been applied to a distributed feedback quantum cascade laser (DFB QCL) for cavity ring-down spectroscopy (CRDS) and a clear effect of feedback was observed. A long external feedback path length of up to 4m can decrease the QCL linewidth to around 50kHz, which is of the order of the transmission linewidth of our high finesse ring-down cavity. The power spectral density of the transmission signal from high finesse cavity reveals that the noise at frequencies above 20kHz is reduced dramatically.

Early opacification and subsequent in vivo clearing of a silicone intraocular lens.

PubMed

Nikrooyan, Idean; Anderson, Justin E

2011-09-01

To report a case of early opacification and spontaneous in vivo clearing of a silicone intraocular lens (IOL). A 79-year-old women underwent uncomplicated cataract extraction and subsequent implantation of a +21.5 D AMO Z9002 (Abbott Medical Optics, Santa Ana, CA) silicone lens. On postoperative day 1, the patient presented with a translucent, milky white appearing, diffuse IOL opacification. On postoperative day 8, the IOL periphery had cleared, but a full thickness haze persisted in the central portion of the optic. By postoperative day 14, the IOL had cleared. To date, the lens has remained clear. One possible mechanism might be exposure to industrial chemicals; however, the manufacturer reports no other similar lens opacities from this manufacturing batch of IOLs. We recommend that surgeons who implant or have implanted an AMO Z9002 silicone IOL and observe similar findings follow the patient closely for resolution of the haze.

Changes in morphology and optical properties of sclera and choroidal layers due to hyperosmotic agent.

PubMed

Zaman, Raiyan T; Rajaram, Narasimhan; Nichols, Brandon S; Rylander, Henry G; Wang, Tianyi; Tunnell, James W; Welch, Ashley J

2011-07-01

Light scattering in the normally white sclera prevents diagnostic imaging or delivery of a focused laser beam to a target in the underlying choroid layer. In this study, we examine optical clearing of the sclera and changes in blood flow resulting from the application of glycerol to the sclera of rabbits. Recovery dynamics are monitored after the application of saline. The speed of clearing for injection delivery is compared to the direct application of glycerol through an incision in the conjunctiva. Although, the same volume of glycerol was applied, the sclera cleared much faster (5 to 10 s) with the topical application of glycerol compared to the injection method (3 min). In addition, the direct topical application of glycerol spreads over a larger area in the sclera than the latter method. A diffuse optical spectroscopy system provided spectral analysis of the remitted light every two minutes during clearing and rehydration. Comparison of measurements to those obtained from phantoms with various absorption and scattering properties provided estimates of the absorption coefficient and reduced scattering coefficient of rabbit eye tissue.

Atmospheric Visibility Monitoring for planetary optical communications

NASA Technical Reports Server (NTRS)

Cowles, Kelly

1991-01-01

The Atmospheric Visibility Monitoring project endeavors to improve current atmospheric models and generate visibility statistics relevant to prospective earth-satellite optical communications systems. Three autonomous observatories are being used to measure atmospheric conditions on the basis of observed starlight; these data will yield clear-sky and transmission statistics for three sites with high clear-sky probabilities. Ground-based data will be compared with satellite imagery to determine the correlation between satellite data and ground-based observations.

Optical design of the National Ignition Facility main laser and switchyard/target area beam transport systems

NASA Astrophysics Data System (ADS)

Miller, John L.; English, R. Edward, Jr.; Korniski, Ronald J.; Rodgers, J. Michael

1999-07-01

The optical design of the main laser and transport mirror sections of the National Ignition Facility are described. For the main laser the configuration, layout constraints, multiple beam arrangement, pinhole layout and beam paths, clear aperture budget, ray trace models, alignment constraints, lens designs, wavefront performance, and pupil aberrations are discussed. For the transport mirror system the layout, alignment controls and clear aperture budget are described.

Light propagation in tissues with controlled optical properties

NASA Astrophysics Data System (ADS)

Tuchin, Valery V.; Maksimova, Irina L.; Zimnyakov, Dmitry A.; Kon, Irina L.; Mavlyutov, Albert H.; Mishin, Alexey A.

1997-10-01

Theoretical and computer modeling approaches, such as Mie theory, radiative transfer theory, diffusion wave correlation spectroscopy, and Monte Carlo simulation were used to analyze tissue optics during a process of optical clearing due to refractive index matching. Continuous wave transmittance and forward scattering measurement as well as intensity correlation experiments were used to monitor tissue structural and optical properties. As a control, tissue samples of the human sclera were taken. Osmotically active solutions, such as Trazograph, glucose, and polyethylene glycol, were used as chemicals. A characteristic time response of human scleral optical clearing the range 3 to 10 min was determined. The diffusion coefficients describing the permeability of the scleral samples to Trazograph were experimentally estimated; the average value was DT approximately equals (0.9 +/- 0.5) X 10-5 cm2/s. The results are general and can be used to describe many other fibrous tissues.

Ten Years of Cloud Optical and Microphysical Retrievals from MODIS

NASA Technical Reports Server (NTRS)

Platnick, Steven; King, Michael D.; Wind, Galina; Hubanks, Paul; Arnold, G. Thomas; Amarasinghe, Nandana

2010-01-01

The MODIS cloud optical properties algorithm (MOD06/MYD06 for Terra and Aqua MODIS, respectively) has undergone extensive improvements and enhancements since the launch of Terra. These changes have included: improvements in the cloud thermodynamic phase algorithm; substantial changes in the ice cloud light scattering look up tables (LUTs); a clear-sky restoral algorithm for flagging heavy aerosol and sunglint; greatly improved spectral surface albedo maps, including the spectral albedo of snow by ecosystem; inclusion of pixel-level uncertainty estimates for cloud optical thickness, effective radius, and water path derived for three error sources that includes the sensitivity of the retrievals to solar and viewing geometries. To improve overall retrieval quality, we have also implemented cloud edge removal and partly cloudy detection (using MOD35 cloud mask 250m tests), added a supplementary cloud optical thickness and effective radius algorithm over snow and sea ice surfaces and over the ocean, which enables comparison with the "standard" 2.1 11m effective radius retrieval, and added a multi-layer cloud detection algorithm. We will discuss the status of the MOD06 algorithm and show examples of pixellevel (Level-2) cloud retrievals for selected data granules, as well as gridded (Level-3) statistics, notably monthly means and histograms (lD and 2D, with the latter giving correlations between cloud optical thickness and effective radius, and other cloud product pairs).

Optically pumped lasing and electroluminescence of formamidinium perovskite semiconductors prepared by the cast-capping method

NASA Astrophysics Data System (ADS)

Sasaki, Fumio; Nguyen, Van-Cao; Yanagi, Hisao

2018-03-01

Optically pumped lasing and electroluminescence (EL) have been observed in solution-processed perovskite semiconducting materials of formamidinium lead bromide, CH(NH2)2PbBr3. Microcavities with flat surfaces and sharp edges have been easily obtained by the simple solution process called the “cast-capping method”. The crystals show clear multimode lasing of Fabry-Pérot cavities. The mode intervals are well explained by the optical constants with large dispersions of the materials. We have also fabricated EL devices and obtained clear EL in a single layer of the materials, but the EL intensity has been quenched rapidly.

Neonatal Hypoglycaemia and Visual Development: A Review.

PubMed

Paudel, Nabin; Chakraborty, Arijit; Anstice, Nicola; Jacobs, Robert J; Hegarty, Jo E; Harding, Jane E; Thompson, Benjamin

2017-01-01

Many newborn babies experience low blood glucose concentrations, a condition referred to as neonatal hypoglycaemia (NH). The effect of NH on visual development in infancy and childhood is of interest because the occipital lobes, which include the primary visual cortex and a number of extrastriate visual areas, may be particularly susceptible to NH-induced injury. In addition, a number of case series have suggested that NH can affect eye and optic nerve development. To review the existing literature concerning the effect of NH on the visual system. A PubMed, Embase, Medline, and Google Scholar literature search was conducted using prespecified MeSH terms. The literature reviewed revealed no clear evidence for an effect of NH on the development of the eye and optic nerve. Furthermore, occipital and occipital-parietal lobe injuries following NH often occurred in conjunction with comorbid conditions and were not clearly linked to subsequent visual dysfunction, possibly due to difficulties in measuring vision in young children and a lack of studies at older ages. A recent, large-scale, prospective study of NH outcomes at 2 years of age found no effect of mild-to-moderate NH on visual development. The effect of NH on visual development is unclear. It is currently unknown whether NH affects visual function in mid-to-late childhood when many visual functions reach adult levels. © 2017 S. Karger AG, Basel.

Neonatal hypoglycaemia and visual development: a review

PubMed Central

Paudel, Nabin; Chakraborty, Arijit; Anstice, Nicola; Jacobs, Robert J; Hegarty, Jo E; Harding, Jane E; Thompson, Benjamin

2017-01-01

Background Many newborn babies experience low blood glucose concentrations, a condition referred to as neonatal hypoglycaemia (NH). The effect of NH on visual development in infancy and childhood is of interest because the occipital lobes, which include the primary visual cortex and a number of extra-striate visual areas, may be particularly susceptible to NH induced injury. In addition, a number of case series have suggested that NH can affect eye and optic nerve development. Objective To review the existing literature concerning the effect of NH on the visual system. Methods A PubMed, Embase, Medline and Google Scholar literature search was conducted using pre-specified MeSH terms. Results The literature reviewed revealed no clear evidence for an effect of NH on the development of the eye and optic nerve. Furthermore, occipital and occipital-parietal lobe injuries following NH often occurred in conjunction with co-morbid conditions and were not clearly linked to subsequent visual dysfunction, possibly due to difficulties in measuring vision in young children and a lack of studies at older ages. A recent, large scale, prospective study of NH outcomes at 2 years of age found no effect of mild to moderate NH on visual development. Conclusion The effect of NH on visual development is unclear. It is currently unknown whether NH affects visual function in mid to late childhood when many visual functions reach adult levels. PMID:28253512

AIRBORNE INVESTIGATIONS OF CLEAR AIR TURBULENCE WITH OPTICAL RADAR.

DTIC Science & Technology

relevant meteorlogical data. The design of this equipment and the development of the flight programs was predicated on theoretical considerations of optical scattering from particulate matter. (Author)

Thermoacoustic and photoacoustic characterizations of few-layer graphene by pulsed excitations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Xiong; Department of Medical Imaging, The University of Arizona, Tucson, Arizona 85724; School of Information Science and Technology, ShanghaiTech University, Shanghai 200031

2016-04-04

We characterized the thermoacoustic and photoacoustic properties of large-area, few-layer graphene by pulsed microwave and optical excitations. Due to its high electric conductivity and low heat capacity per unit area, graphene lends itself to excellent microwave and optical energy absorption and acoustic signal emanation due to the thermoacoustic effect. When exposed to pulsed microwave or optical radiation, distinct thermoacoustic and photoacoustic signals generated by the few-layer graphene are obtained due to microwave and laser absorption of the graphene, respectively. Clear thermoacoustic and photoacoustic images of large-area graphene sample are achieved. A numerical model is developed and the simulated results aremore » in good accordance with the measured ones. This characterization work may find applications in ultrasound generator and detectors for microwave and optical radiation. It may also become an alternative characterization approach for graphene and other types of two-dimensional materials.« less

Computational analysis of the effectiveness of blood flushing with saline injection from an intravascular diagnostic catheter

PubMed Central

Ghata, Narugopal; Aldredge, Ralph C.; Bec, Julien; Marcu, Laura

2015-01-01

SUMMARY Optical techniques including fluorescence lifetime spectroscopy have demonstrated potential as a tool for study and diagnosis of arterial vessel pathologies. However, their application in the intravascular diagnostic procedures has been hampered by the presence of blood hemoglobin that affects the light delivery to and the collection from the vessel wall. We report a computational fluid dynamics model that allows for the optimization of blood flushing parameters in a manner that minimizes the amount of saline needed to clear the optical field of view and reduces any adverse effects caused by the external saline jet. A 3D turbulence (k−ω) model was employed for Eulerian–Eulerian two-phase flow to simulate the flow inside and around a side-viewing fiber-optic catheter. Current analysis demonstrates the effects of various parameters including infusion and blood flow rates, vessel diameters, and pulsatile nature of blood flow on the flow structure around the catheter tip. The results from this study can be utilized in determining the optimal flushing rate for given vessel diameter, blood flow rate, and maximum wall shear stress that the vessel wall can sustain and subsequently in optimizing the design parameters of optical-based intravascular catheters. PMID:24953876

Optical effects in artificial opals infiltrated with gold nanoparticles

NASA Astrophysics Data System (ADS)

Comoretto, Davide; Morandi, Valentina; Marabelli, Franco; Amendola, Vincenzo; Meneghetti, Moreno

2006-04-01

Polystyrene artificial opals are directly grown with embedded gold nanoparticles (NpAu) in their interstices. Reflectance spectra of samples having different sphere diameters and nanoparticles load clearly show a red shift of the photonic band gap as well as a reduction of its width without showing direct evidence of NpAu absorption. The case of transmission spectra is instead more complicated: here, overlapped to a broad NpAu absorption, a structure having unusual lineshape is detected. The infiltration of opal with NpAu removes the polarization dependence of the photonic band structure observed in bare opals. The lineshape of the absorption spectra suggest a spatial localization of the electromagnetic field in the volume where NpAu are confined thus enhancing its local intensity. This effect seems to be effective to stimulate optical nonlinearities of NpAu. Nanosecond transient absorption measurements on NpAu infiltrated opals indicate that a variation of transmission of about 10% is observed. Since this effect takes place within the pump pulse and since NpAu photoluminescence has been subtracted to the signal, we attribute it to an optical switching process.

Optically Clear and Resilient Free-Form µ-Optics 3D-Printed via Ultrafast Laser Lithography.

PubMed

Jonušauskas, Linas; Gailevičius, Darius; Mikoliūnaitė, Lina; Sakalauskas, Danas; Šakirzanovas, Simas; Juodkazis, Saulius; Malinauskas, Mangirdas

2017-01-02

We introduce optically clear and resilient free-form micro-optical components of pure (non-photosensitized) organic-inorganic SZ2080 material made by femtosecond 3D laser lithography (3DLL). This is advantageous for rapid printing of 3D micro-/nano-optics, including their integration directly onto optical fibers. A systematic study of the fabrication peculiarities and quality of resultant structures is performed. Comparison of microlens resiliency to continuous wave (CW) and femtosecond pulsed exposure is determined. Experimental results prove that pure SZ2080 is ∼20 fold more resistant to high irradiance as compared with standard lithographic material (SU8) and can sustain up to 1.91 GW/cm² intensity. 3DLL is a promising manufacturing approach for high-intensity micro-optics for emerging fields in astro-photonics and atto-second pulse generation. Additionally, pyrolysis is employed to homogeneously shrink structures up to 40% by removing organic SZ2080 constituents. This opens a promising route towards downscaling photonic lattices and the creation of mechanically robust glass-ceramic microstructures.

Optically Clear and Resilient Free-Form μ-Optics 3D-Printed via Ultrafast Laser Lithography

PubMed Central

Jonušauskas, Linas; Gailevičius, Darius; Mikoliūnaitė, Lina; Sakalauskas, Danas; Šakirzanovas, Simas; Juodkazis, Saulius; Malinauskas, Mangirdas

2017-01-01

We introduce optically clear and resilient free-form micro-optical components of pure (non-photosensitized) organic-inorganic SZ2080 material made by femtosecond 3D laser lithography (3DLL). This is advantageous for rapid printing of 3D micro-/nano-optics, including their integration directly onto optical fibers. A systematic study of the fabrication peculiarities and quality of resultant structures is performed. Comparison of microlens resiliency to continuous wave (CW) and femtosecond pulsed exposure is determined. Experimental results prove that pure SZ2080 is ∼20 fold more resistant to high irradiance as compared with standard lithographic material (SU8) and can sustain up to 1.91 GW/cm2 intensity. 3DLL is a promising manufacturing approach for high-intensity micro-optics for emerging fields in astro-photonics and atto-second pulse generation. Additionally, pyrolysis is employed to homogeneously shrink structures up to 40% by removing organic SZ2080 constituents. This opens a promising route towards downscaling photonic lattices and the creation of mechanically robust glass-ceramic microstructures. PMID:28772389

Theoretical and experimental investigation of near-infrared light propagation in a model of the adult head.

PubMed

Okada, E; Firbank, M; Schweiger, M; Arridge, S R; Cope, M; Delpy, D T

1997-01-01

Near-infrared light propagation in various models of the adult head is analyzed by both time-of-flight measurements and mathematical prediction. The models consist of three- or four-layered slabs, the latter incorporating a clear cerebrospinal fluid (CSF) layer. The most sophisticated model also incorporates slots that imitate sulci on the brain surface. For each model, the experimentally measured mean optical path length as a function of source-detector spacing agrees well with predictions from either a Monte Carlo model or a finite-element method based on diffusion theory or a hybrid radiosity-diffusion theory. Light propagation in the adult head is shown to be highly affected by the presence of the clear CSF layer, and both the optical path length and the spatial sensitivity profile of the models with a CSF layer are quite different from those without the CSF layer. However, the geometry of the sulci and the boundary between the gray and the white matter have little effect on the detected light distribution.

The Optics Institute of Southern California: organizing and implementing outreach effort

NASA Astrophysics Data System (ADS)

Silberman, Donn M.

2003-10-01

The Optics Institute of Southern California is organizing the local educational outreach effort. Working with local optics businesses, society chapters, science discovery centers, K-12, community college and university educators, and others from the global optics education and training community, the OISC is becoming a one-stop clearing house for a wide range of educational outreach activities.

Ultrafast all-optical control of the magnetization in magnetic dielectrics

NASA Astrophysics Data System (ADS)

Kirilyuk, Andrei; Kimel, Alexey; Hansteen, Fredrik; Rasing, Theo; Pisarev, Roman V.

2006-08-01

The purpose of this review is to summarize the recent progress on laser-induced magnetization dynamics in magnetic dielectrics. Due to the slow phonon-magnon interaction in these materials, direct thermal effects of the laser excitation can only be seen on the time scale of almost a nanosecond and thus are clearly distinguished from the ultrafast nonthermal effects. However, laser pulses are shown to indirectly modify the magnetic anisotropy in rare-earth orthoferrites via the crystal field, and to bring about spin reorientation within a few picoseconds. More interesting, however, are the direct nonthermal effects of light on spin systems. We demonstrate coherent optical control of the magnetization in ferrimagnetic garnet films on a femtosecond time scale through a combination of two different ultrafast and nonthermal photomagnetic effects and by employing multiple pump pulses. Linearly polarized laser pulses are shown to create a long-lived modification of the magnetocrystalline anisotropy via optically induced electron transfer between nonequivalent ion sites. In addition, circularly polarized pulses are shown to act as strong transient magnetic field pulses originating from the nonabsorptive inverse Faraday effect. An all-optical scheme of excitation and detection of different antiferromagnetic resonance modes with frequencies of up to 500GHz will be discussed as well. The reported effects open new and exciting possibilities for ultrafast manipulation of spins by light and provide new insight into the physics of magnetism on ultrafast time scales.

Use of an UROV to develop 3-D optical models of submarine environments

NASA Astrophysics Data System (ADS)

Null, W. D.; Landry, B. J.

2017-12-01

The ability to rapidly obtain high-fidelity bathymetry is crucial for a broad range of engineering, scientific, and defense applications ranging from bridge scour, bedform morphodynamics, and coral reef health to unexploded ordnance detection and monitoring. The present work introduces the use of an Underwater Remotely Operated Vehicle (UROV) to develop 3-D optical models of submarine environments. The UROV used a Raspberry Pi camera mounted to a small servo which allowed for pitch control. Prior to video data collection, in situ camera calibration was conducted with the system. Multiple image frames were extracted from the underwater video for 3D reconstruction using Structure from Motion (SFM). This system provides a simple and cost effective solution to obtaining detailed bathymetry in optically clear submarine environments.

Introducing Optical Concepts in Electrical Engineering.

ERIC Educational Resources Information Center

Daneshvar, K.; Coleman, R.

The expansion in the fields of optical engineering and optoelectronics has made it essential to introduce optical engineering concepts into undergraduate courses and curricula. Because of limits on the number of course requirements for the BS degree, it is not clear how these topics should be introduced without replacing some of the traditional…

Deformation of phospholipid vesicles in an optical stretcher.

PubMed

Delabre, Ulysse; Feld, Kasper; Crespo, Eleonore; Whyte, Graeme; Sykes, Cecile; Seifert, Udo; Guck, Jochen

2015-08-14

Phospholipid vesicles are common model systems for cell membranes. Important aspects of the membrane function relate to its mechanical properties. Here we have investigated the deformation behaviour of phospholipid vesicles in a dual-beam laser trap, also called an optical stretcher. This study explicitly makes use of the inherent heating present in such traps to investigate the dependence of vesicle deformation on temperature. By using lasers with different wavelengths, optically induced mechanical stresses and temperature increase can be tuned fairly independently with a single setup. The phase transition temperature of vesicles can be clearly identified by an increase in deformation. In the case of no heating effects, a minimal model for drop deformation in an optical stretcher and a more specific model for vesicle deformation that takes explicitly into account the angular dependence of the optical stress are presented to account for the experimental results. Elastic constants are extracted from the fitting procedures, which agree with literature data. This study demonstrates the utility of optical stretching, which is easily combined with microfluidic delivery, for the future serial, high-throughput study of the mechanical and thermodynamic properties of phospholipid vesicles.

A continuum from clear to cloudy hot-Jupiter exoplanets without primordial water depletion

NASA Astrophysics Data System (ADS)

Sing, David K.; Fortney, Jonathan J.; Nikolov, Nikolay; Wakeford, Hannah R.; Kataria, Tiffany; Evans, Thomas M.; Aigrain, Suzanne; Ballester, Gilda E.; Burrows, Adam S.; Deming, Drake; Désert, Jean-Michel; Gibson, Neale P.; Henry, Gregory W.; Huitson, Catherine M.; Knutson, Heather A.; Lecavelier Des Etangs, Alain; Pont, Frederic; Showman, Adam P.; Vidal-Madjar, Alfred; Williamson, Michael H.; Wilson, Paul A.

2016-01-01

Thousands of transiting exoplanets have been discovered, but spectral analysis of their atmospheres has so far been dominated by a small number of exoplanets and data spanning relatively narrow wavelength ranges (such as 1.1-1.7 micrometres). Recent studies show that some hot-Jupiter exoplanets have much weaker water absorption features in their near-infrared spectra than predicted. The low amplitude of water signatures could be explained by very low water abundances, which may be a sign that water was depleted in the protoplanetary disk at the planet’s formation location, but it is unclear whether this level of depletion can actually occur. Alternatively, these weak signals could be the result of obscuration by clouds or hazes, as found in some optical spectra. Here we report results from a comparative study of ten hot Jupiters covering the wavelength range 0.3-5 micrometres, which allows us to resolve both the optical scattering and infrared molecular absorption spectroscopically. Our results reveal a diverse group of hot Jupiters that exhibit a continuum from clear to cloudy atmospheres. We find that the difference between the planetary radius measured at optical and infrared wavelengths is an effective metric for distinguishing different atmosphere types. The difference correlates with the spectral strength of water, so that strong water absorption lines are seen in clear-atmosphere planets and the weakest features are associated with clouds and hazes. This result strongly suggests that primordial water depletion during formation is unlikely and that clouds and hazes are the cause of weaker spectral signatures.

A continuum from clear to cloudy hot-Jupiter exoplanets without primordial water depletion.

PubMed

Sing, David K; Fortney, Jonathan J; Nikolov, Nikolay; Wakeford, Hannah R; Kataria, Tiffany; Evans, Thomas M; Aigrain, Suzanne; Ballester, Gilda E; Burrows, Adam S; Deming, Drake; Désert, Jean-Michel; Gibson, Neale P; Henry, Gregory W; Huitson, Catherine M; Knutson, Heather A; des Etangs, Alain Lecavelier; Pont, Frederic; Showman, Adam P; Vidal-Madjar, Alfred; Williamson, Michael H; Wilson, Paul A

2016-01-07

Thousands of transiting exoplanets have been discovered, but spectral analysis of their atmospheres has so far been dominated by a small number of exoplanets and data spanning relatively narrow wavelength ranges (such as 1.1-1.7 micrometres). Recent studies show that some hot-Jupiter exoplanets have much weaker water absorption features in their near-infrared spectra than predicted. The low amplitude of water signatures could be explained by very low water abundances, which may be a sign that water was depleted in the protoplanetary disk at the planet's formation location, but it is unclear whether this level of depletion can actually occur. Alternatively, these weak signals could be the result of obscuration by clouds or hazes, as found in some optical spectra. Here we report results from a comparative study of ten hot Jupiters covering the wavelength range 0.3-5 micrometres, which allows us to resolve both the optical scattering and infrared molecular absorption spectroscopically. Our results reveal a diverse group of hot Jupiters that exhibit a continuum from clear to cloudy atmospheres. We find that the difference between the planetary radius measured at optical and infrared wavelengths is an effective metric for distinguishing different atmosphere types. The difference correlates with the spectral strength of water, so that strong water absorption lines are seen in clear-atmosphere planets and the weakest features are associated with clouds and hazes. This result strongly suggests that primordial water depletion during formation is unlikely and that clouds and hazes are the cause of weaker spectral signatures.

Effects of optical dopants and laser wavelength on atom probe tomography analyses of borosilicate glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Xiaonan; Schreiber, Daniel K.; Neeway, James J.

Atom probe tomography (APT) is a novel analytical microscopy method that provides three dimensional elemental mapping with sub-nanometer spatial resolution and has only recently been applied to insulating glass and ceramic samples. In this paper, we have studied the influence of the optical absorption in glass samples on APT characterization by introducing different transition metal optical dopants to a model borosilicate nuclear waste glass (international simple glass). A systematic comparison is presented of the glass optical properties and the resulting APT data quality in terms of compositional accuracy and the mass spectra quality for two APT systems: one with amore » green laser (532 nm, LEAP 3000X HR) and one with a UV laser (355 nm, LEAP 4000X HR). These data were also compared to the study of a more complex borosilicate glass (SON68). The results show that the analysis data quality such as compositional accuracy and total ions collected, was clearly linked to optical absorption when using a green laser, while for the UV laser optical doping aided in improving data yield but did not have a significant effect on compositional accuracy. Comparisons of data between the LEAP systems suggest that the smaller laser spot size of the LEAP 4000X HR played a more critical role for optimum performance than the optical dopants themselves. The smaller spot size resulted in more accurate composition measurements due to a reduced background level independent of the material’s optical properties.« less

SYSTEMATIC EFFECTS IN POLARIZING FOURIER TRANSFORM SPECTROMETERS FOR COSMIC MICROWAVE BACKGROUND OBSERVATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nagler, Peter C.; Tucker, Gregory S.; Fixsen, Dale J.

The detection of the primordial B-mode polarization signal of the cosmic microwave background (CMB) would provide evidence for inflation. Yet as has become increasingly clear, the detection of a such a faint signal requires an instrument with both wide frequency coverage to reject foregrounds and excellent control over instrumental systematic effects. Using a polarizing Fourier transform spectrometer (FTS) for CMB observations meets both of these requirements. In this work, we present an analysis of instrumental systematic effects in polarizing FTSs, using the Primordial Inflation Explorer (PIXIE) as a worked example. We analytically solve for the most important systematic effects inherentmore » to the FTS—emissive optical components, misaligned optical components, sampling and phase errors, and spin synchronous effects—and demonstrate that residual systematic error terms after corrections will all be at the sub-nK level, well below the predicted 100 nK B-mode signal.« less

Optical link by using optical wiring method for reducing EMI

NASA Astrophysics Data System (ADS)

Cho, In-Kui; Kwon, Jong-Hwa; Choi, Sung-Woong; Bondarik, Alexander; Yun, Je-Hoon; Kim, Chang-Joo; Ahn, Seung-Beom; Jeong, Myung-Yung; Park, Hyo Hoon

2008-12-01

A practical optical link system was prepared with a transmitter (Tx) and receiver (Rx) for reducing EMI (electromagnetic interference). The optical TRx module consisted of a metal optical bench, a module printed circuit board (PCB), a driver/receiver IC, a VCSEL/PD array, and an optical link block composed of plastic optical fiber (POF). For the optical interconnection between the light-sources and detectors, an optical wiring method has been proposed to enable easy assembly. The key benefit of fiber optic link is the absence of electromagnetic interference (EMI) noise creation and susceptibility. This paper provides a method for optical interconnection between an optical Tx and an optical Rx, comprising the following steps: (i) forming a light source device, an optical detection device, and an optical transmission unit on a substrate (metal optical bench (MOB)); (ii) preparing a flexible optical transmission-connection medium (optical wiring link) to optically connect the light source device formed on the substrate with the optical detection device; and (iii) directly connecting one end of the surface-finished optical transmission connection medium with the light source device and the other end with the optical detection device. Electronic interconnections have uniquely electronic problems such as EMI, shorting, and ground loops. Since these problems only arise during transduction (electronics-to-optics or opticsto- electronics), the purely optical part and optical link(interconnection) is free of these problems. 1 An optical link system constructed with TRx modules was fabricated and the optical characteristics about data links and EMI levels were measured. The results clearly demonstrate that the use of an optical wiring method can provide robust and cost-effective assembly for reducing EMI of inter-chip interconnect. We successfully achieved a 4.5 Gb/s data transmission rate without EMI problems.

Optical clearing of vaginal tissues in cadavers

NASA Astrophysics Data System (ADS)

Chang, Chun-Hung; Hardy, Luke A.; Peters, Michael G.; Bastawros, Dina A.; Myers, Erinn M.; Kennelly, Michael J.; Fried, Nathaniel M.

2018-02-01

A nonsurgical laser procedure is being developed for treatment of female stress urinary incontinence (SUI). Previous studies in porcine vaginal tissues, ex vivo, as well as computer simulations, showed the feasibility of using near-infrared laser energy delivered through a transvaginal contact cooling probe to thermally remodel endopelvic fascia, while preserving the vaginal wall from thermal damage. This study explores optical properties of vaginal tissue in cadavers as an intermediate step towards future pre-clinical and clinical studies. Optical clearing of tissue using glycerol resulted in a 15-17% increase in optical transmission after 11 min at room temperature (and a calculated 32.5% increase at body temperature). Subsurface thermal lesions were created using power of 4.6 - 6.4 W, 5.2-mm spot, and 30 s irradiation time, resulting in partial preservation of vaginal wall to 0.8 - 1.1 mm depth.

The effect of optically active turbulence on Gaussian laser beams in the ocean

NASA Astrophysics Data System (ADS)

Nootz, G.; Matt, S.; Jarosz, E.; Hou, W.

2016-02-01

Motivated by the high resolution and data transfer potential, optical imaging and communication methods are intensely investigated for marine applications. The majority of research focuses on overcoming the strong scattering of light by particles present in the ocean. However when operating in very clear water the limiting factor for such applications can be the strongly forward biased scattering from optically active turbulent layers. For this presentation the effect of optically active turbulence on focused Gaussian beams has been studied in the field, in a controlled laboratory test tank, and by numerical simulations. For the field experiments a telescoping rigid underwater sensor structure (TRUSS) was deployed in the Bahamas equipped with a diffractive optics element projecting a matrix of beams towards a fast beam profiler. Image processing techniques are used to extract the beam wander and beam breathing. The results are compared to theoretical values for the optical turbulence strength derived from the measured temperature microstructure at the test side. Laboratory and simulated experiments are carried out in a physical and numerical Rayleigh-Benard convection turbulence tank of the same geometry. A focused Gaussian laser beam is propagated through the test tank and recorded with a camera from the back side of a diffuser. Similarly, a focused Gaussian beam is propagated numerically by means of split-step Fourier method through the simulated turbulence environment. Results will be presented for weak to moderate turbulence as they are most typical for oceanic conditions. Conclusions about the effect on optical imaging and communication applications will be discussed.

Light comfort zones of mesopelagic acoustic scattering layers in two contrasting optical environments

NASA Astrophysics Data System (ADS)

Røstad, Anders; Kaartvedt, Stein; Aksnes, Dag L.

2016-07-01

We make a comparison of the mesopelagic sound scattering layers (SLs) in two contrasting optical environments; the clear Red Sea and in murkier coastal waters of Norway (Masfjorden). The depth distributions of the SL in Masfjorden are shallower and narrower than those of the Red Sea. This difference in depth distribution is consistent with the hypothesis that the organisms of the SL distribute according to similar light comfort zones (LCZ) in the two environments. Our study suggest that surface and underwater light measurements ranging more than 10 orders of magnitude is required to assess the controlling effects of light on SL structure and dynamics.

Optical coherence tomography based imaging of dental demineralisation and cavity restoration in 840 nm and 1310 nm wavelength regions

NASA Astrophysics Data System (ADS)

Damodaran, Vani; Rao, Suresh Ranga; Vasa, Nilesh J.

2016-08-01

In this paper, a study of in-house built optical coherence tomography (OCT) system with a wavelength of 840 nm for imaging of dental caries, progress in demineralisation and cavity restoration is presented. The caries when imaged with the 840 nm OCT system showed minute demineralisation in the order of 5 μm. The OCT system was also proposed to study the growth of lesion and this was demonstrated by artificially inducing caries with a demineralisation solution of pH 4.8. The progress of carious lesion to a depth of about 50-60 μm after 60 hours of demineralisation was clearly observed with the 840 nm OCT system. The tooth samples were subjected to accelerated demineralisation condition at pH of approximately 2.3 to study the adverse effects and the onset of cavity formation was clearly observed. The restoration of cavity was also studied by employing different restorative materials (filled and unfilled). In the case of restoration without filler material (unfilled), the restoration boundaries were clearly observed. Overall, results were comparable with that of the widely used 1310 nm OCT system. In the case of restoration with filler material, the 1310 nm OCT imaging displayed better imaging capacity due to lower scattering than 840 nm imaging.

Development Of Fiber Optics For Passenger Car Applications

NASA Astrophysics Data System (ADS)

Steele, R. E.; Schmitt, H. J.

1987-12-01

The benefits of fiber optics for telecommunications and Local Area Networks (LANs) are well documented. The benefits to passenger car applications are not as clearly defined. This paper examines the differences between Telecommunications, LAN, and automotive point to point and network applications. Current production automotive applications of optics and fiber optics, automotive data communications trends, and both functional and non-functional requirements and constraints will be described.

Base-Level Management of Laser Radiation Protection Program

DTIC Science & Technology

1992-02-01

safety eyewear . special considerations for medical lasers and optical fibers, and summary evaluations of common Air Force laser systems... optical density of 2. Laser safety eyewear should have the optical density clearly marked for ail wavelengths for which the eyewear provides protection. c...density of protective eyewear . The optical density required for laser safety eyewear is dependent on the irradiance or radiant exposure-of the

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dodson-Robinson, Sarah E.; Salyk, Colette, E-mail: sdr@astro.as.utexas.edu

Although there has yet been no undisputed discovery of a still-forming planet embedded in a gaseous protoplanetary disk, the cleared inner holes of transitional disks may be signposts of young planets. Here, we show that the subset of accreting transitional disks with wide, optically thin inner holes of 15 AU or more can only be sculpted by multiple planets orbiting inside each hole. Multiplanet systems provide two key ingredients for explaining the origins of transitional disks. First, multiple planets can clear wide inner holes where single planets open only narrow gaps. Second, the confined, non-axisymmetric accretion flows produced by multiplemore » planets provide a way for an arbitrary amount of mass transfer to occur through an apparently optically thin hole without overproducing infrared excess flux. Rather than assuming that the gas and dust in the hole are evenly and axisymmetrically distributed, one can construct an inner hole with apparently optically thin infrared fluxes by covering a macroscopic fraction of the hole's surface area with locally optically thick tidal tails. We also establish that other clearing mechanisms, such as photoevaporation, cannot explain our subset of accreting transitional disks with wide holes. Transitional disks are therefore high-value targets for observational searches for young planetary systems.« less

Reverse process of usual optical analysis of boson-exchange superconductors: impurity effects on s- and d-wave superconductors.

PubMed

Hwang, Jungseek

2015-03-04

We performed a reverse process of the usual optical data analysis of boson-exchange superconductors. We calculated the optical self-energy from two (MMP and MMP+peak) input model electron-boson spectral density functions using Allen's formula for one normal and two (s- and d-wave) superconducting cases. We obtained the optical constants including the optical conductivity and the dynamic dielectric function from the optical self-energy using an extended Drude model, and finally calculated the reflectance spectrum. Furthermore, to investigate impurity effects on optical quantities we added various levels of impurities (from the clean to the dirty limit) in the optical self-energy and performed the same reverse process to obtain the optical conductivity, the dielectric function, and reflectance. From these optical constants obtained from the reverse process we extracted the impurity-dependent superfluid densities for two superconducting cases using two independent methods (the Ferrel-Glover-Tinkham sum rule and the extrapolation to zero frequency of -ϵ1(ω)ω(2)); we found that a certain level of impurities is necessary to get a good agreement on results obtained by the two methods. We observed that impurities give similar effects on various optical constants of s- and d-wave superconductors; the greater the impurities the more distinct the gap feature and the lower the superfluid density. However, the s-wave superconductor gives the superconducting gap feature more clearly than the d-wave superconductor because in the d-wave superconductors the optical quantities are averaged over the anisotropic Fermi surface. Our results supply helpful information to see how characteristic features of the electron-boson spectral function and the s- and d-wave superconducting gaps appear in various optical constants including raw reflectance spectrum. Our study may help with a thorough understanding of the usual optical analysis process. Further systematic study of experimental data collected at various conditions using the optical analysis process will help to reveal the origin of the mediated boson in the boson-exchange superconductors.

Label-free volumetric optical imaging of intact murine brains

NASA Astrophysics Data System (ADS)

Ren, Jian; Choi, Heejin; Chung, Kwanghun; Bouma, Brett E.

2017-04-01

A central effort of today’s neuroscience is to study the brain’s ’wiring diagram’. The nervous system is believed to be a network of neurons interacting with each other through synaptic connection between axons and dendrites, therefore the neuronal connectivity map not only depicts the underlying anatomy, but also has important behavioral implications. Different approaches have been utilized to decipher neuronal circuits, including electron microscopy (EM) and light microscopy (LM). However, these approaches typically demand extensive sectioning and reconstruction for a brain sample. Recently, tissue clearing methods have enabled the investigation of a fully assembled biological system with greatly improved light penetration. Yet, most of these implementations, still require either genetic or exogenous contrast labeling for light microscopy. Here we demonstrate a high-speed approach, termed as Clearing Assisted Scattering Tomography (CAST), where intact brains can be imaged at optical resolution without labeling by leveraging tissue clearing and the scattering contrast of optical frequency domain imaging (OFDI).

Enhanced in vivo visualization of the microcirculation by topical application of fructose solution confirmed with correlation mapping optical coherence tomography

NASA Astrophysics Data System (ADS)

Enfield, Joey; McGrath, James; Daly, Susan M.; Leahy, Martin

2016-08-01

Changes within the microcirculation can provide an early indication of the onset of a plethora of ailments. Various techniques have thus been developed that enable the study of microcirculatory irregularities. Correlation mapping optical coherence tomography (cmOCT) is a recently proposed technique, which enables mapping of vasculature networks at the capillary level in a noninvasive and noncontact manner. This technique is an extension of conventional optical coherence tomography (OCT) and is therefore likewise limited in the penetration depth of ballistic photons in biological media. Optical clearing has previously been demonstrated to enhance the penetration depth and the imaging capabilities of OCT. In order to enhance the achievable maximum imaging depth, we propose the use of optical clearing in conjunction with the cmOCT technique. We demonstrate in vivo a 13% increase in OCT penetration depth by topical application of a high-concentration fructose solution, thereby enabling the visualization of vessel features at deeper depths within the tissue.

The effect of carbon chain length of starting materials on the formation of carbon dots and their optical properties

NASA Astrophysics Data System (ADS)

Pan, Xiaohua; Zhang, Yan; Sun, Xiaobo; Pan, Wei; Yu, Guifeng; Si, Shuxin; Wang, Jinping

2018-04-01

Carbon dots (CDs) have attracted increasing attention due to their high performances and potential applications in wide range of areas. However, their emission mechanism is not clear so far. In order to reveal more factors contributing to the emission of CDs, the effect of carbon chain length of starting materials on the formation of CDs and their optical properties was experimentally investigated in this work. In order to focus on the effect of carbon chain length, the starting materials with C, O, N in fully identical forms and only carbon chain lengths being different were selected for synthesizing CDs, including citric acid (CA) and adipic acid (AA) as carbon sources, and diamines with different carbon chain lengths (H2N(CH2)nNH2, n = 2, 4, 6) as nitrogen sources, as well as ethylenediamine (EDA) as nitrogen source and diacids with different carbon chain lengths (HOOC(CH2)nCOOH, n = 0, 2, 4, 6) as carbon sources. Therefore, the effect of carbon chain length of starting materials on the formation and optical properties of CDs can be systematically investigated by characterizing and comparing the structures and optical properties of as-prepared nine types of CDs. Moreover, the density of –NH2 on the surface of the CDs was quantitatively detected by a spectrophotometry so as to elucidate the relationship between the –NH2 related surface state and the optical properties.

New Treatments for Nonarteritic Anterior Ischemic Optic Neuropathy.

PubMed

Foroozan, Rod

2017-02-01

Despite increasing knowledge about the risk factors and clinical findings of nonarteritic anterior ischemic optic neuropathy (NAION), the treatment of this optic neuropathy has remained limited and without clear evidence-based benefit. Historical treatments of NAION are reviewed, beginning with the Ischemic Optic Neuropathy Decompression Trial. More recent treatments are placed within the historical context and illustrate the need for evidence-based therapy for ischemic optic neuropathy. Copyright © 2016 Elsevier Inc. All rights reserved.

The development of skin immersion clearing method for increasing of laser exposure efficiency on subcutaneous objects

NASA Astrophysics Data System (ADS)

Kozina, Alexandra M.; Genina, Elina A.; Terentyuk, Georgy S.; Terentyuk, Artem G.; Bashkatov, Alexey N.; Tuchin, Valery V.; Khlebtsov, Boris N.

2012-06-01

In this paper we have studied effect of a hyperosmotic optical clearing agent (OCA), such as polyethylene glycol, on the fluorescence intensity from a target located in subcutaneous area in the model experiments. As a fluorescence agent the nanocomposite including gold nanorods with hematophorphyrin was used. The remitted fluorescent signal traveling to the tissue surface was monitored over time as the tissue was treated with the OCA. The detected fluorescent signal increased as the scattering in tissue samples was substantially reduced. The study has shown how OCA can be used to improve the detected signal at localization of subcutaneous target tissue at the photothermal or photodynamic therapy. Immersion clearing of skin can be also useful for improvement of laser exposure efficiency due to the increasing of light penetration depth.

SU-E-T-353: Effects of Time and Temperature On a Potential Reusable 3D Dosimeter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Juang, T; Miles, D; Crockett, E

Purpose: Preliminary studies of a novel, optically-clearing PRESAGE 3D dosimeter formulation (Presage-RU) demonstrated potential reusability. This study investigates the effects of time and temperature on the accuracy and reusability of Presage-RU, and reports on progress toward developing a reusable 3D dosimeter. Methods: Presage-RU was cast as small volume samples (1×1×4.5cm). The effect of dose response sensitivity with reirradiation and time was evaluated by irradiating samples from 0–10Gy, measuring change in optical density (ΔOD), clearing at room temperature (RT) (5–7 days to fully clear), and then repeating for a total of 5 irradiations. Effects of heating on clearing rate were investigatedmore » by irradiating samples to 8Gy, then tracking measurements with samples held at RT, 35°C, and 45°C. Two cylindrical dosimeters (11cm diameter, 9.5cm length) were evaluated for dosimetric accuracy when stored at RT and −3°C prior to irradiation. Plans delivered were 2 overlapping AP fields (RT) and VMAT (-3°C). Results: Heating the dosimeters reduced the clearing half-life from 16.3h at RT to 5.8h (35°C) and 5.1h (45°C), but also increased background ΔOD by 1.7x (35°C) and 2.3x (45°C). Reductions in dose response were more closely linked to age than reirradiation, and storage at RT showed pronounced desensitization from dosimeter edges. These results suggest desensitization from oxygen diffusion. It should be noted that atmospheric diffusion into the dosimeter is not seen in standard, single-use PRESAGE, and is likely caused by differences in the Presage-RU polyurethane matrix. The dosimeter kept in cold storage, however, showed no evidence of desensitization and exhibited accuracy on par with standard PRESAGE with a 3%/3mm 3D gamma passing rate of 98.1%. Conclusions: Presage-RU is sensitive to storage temperatures and time, both of which affect oxygen diffusion and subsequent desensitization. Development shows promising progress with further formulation optimization as the next step toward achieving a successful reusable 3D dosimeter. This work was supported by NIH R01CA100835. John Adamovics is the president of Heuris Inc., which commercializes PRESAGE.« less

Visual performance assessment through clear and sunscreen-treated windows.

DOT National Transportation Integrated Search

1978-09-01

Reflective sunscreen filters are frequently bonded to vehicle windows to reduce interior heat and brightness. The present study was conducted to investigate the optical properties of and visual preformance through clear and sunscreen-treated glass pa...

Effect of Liquid-Crystalline Epoxy Backbone Structure on Thermal Conductivity of Epoxy-Alumina Composites

NASA Astrophysics Data System (ADS)

Giang, Thanhkieu; Kim, Jinhwan

2017-01-01

In a series of papers published recently, we clearly demonstrated that the most important factor governing the thermal conductivity of epoxy-Al2O3 composites is the backbone structure of the epoxy. In this study, three more epoxies based on diglycidyl ester-terminated liquid-crystalline epoxy (LCE) have been synthesized to draw conclusions regarding the effect of the epoxy backbone structure on the thermal conductivity of epoxy-alumina composites. The synthesized structures were characterized by proton nuclear magnetic resonance (1H-NMR) and Fourier-transform infrared (FT-IR) spectroscopy. Differential scanning calorimetry, thermogravimetric analysis, and optical microscopy were also employed to examine the thermal and optical properties of the synthesized LCEs and the cured composites. All three LCE resins exhibited typical liquid-crystalline behaviors: clear solid crystalline state below the melting temperature ( T m), sharp crystalline melting at T m, and transition to nematic phase above T m with consequent isotropic phase above the isotropic temperature ( T i). The LCE resins displayed distinct nematic liquid-crystalline phase over a wide temperature range and retained liquid-crystalline phase after curing, with high thermal conductivity of the resulting composite. The thermal conductivity values ranged from 3.09 W/m-K to 3.89 W/m-K for LCE-Al2O3 composites with 50 vol.% filler loading. The steric effect played a governing role in the difference. The neat epoxy resin thermal conductivity was obtained as 0.35 W/m-K to 0.49 W/m-K based on analysis using the Agari-Uno model. The results clearly support the objective of this study in that the thermal conductivity of the LCE-containing networks strongly depended on the epoxy backbone structure and the degree of ordering in the cured network.

New optical museum at Saint-Petersburg for education and training

NASA Astrophysics Data System (ADS)

Vasil'ev, V. N.; Stafeef, S. K.; Tomilin, M. G.

2009-06-01

Nowadays the educational problem of teaching optics and photonics is to attract the young generation to the wonderful and magic world of light, optical science, technology and systems. The main issue is to explain that in the course of last several hundred years optics has been representing the most clear world view for humanity. In fact, the optics itself is a multidisciplinary complex of independent scientific directions, and, moreover, it has always been a generator of new fields of knowledge. Besides, optics and photonics are the fields within which the most fundamental problems of today's reality are to be resolved. It is absolutely necessary to encourage our scholars in getting optics and photonics education as an alternative physical basis to gaining solely computer knowledge. The main obstacle is the poor connection between program of optical education and the real optical researches, disintegration of different branches of the optical science, the demographic situation, some problems with teaching mathematics and physics at schools, and the collision between traditional educational methods and the mentality of the new generation. In Russia the Saint-Petersburg State University of Information Technologies, Mechanics and Optics offers partial solution to these problems: the organization of a real place for interactive optical science in a form of a new museum of optics, intended for education and training, seems to be the most effective way. This was the main reason for establishing such a museum in Saint-Petersburg at the end of 2008.

SWIM: A Semi-Analytical Ocean Color Inversion Algorithm for Optically Shallow Waters

NASA Technical Reports Server (NTRS)

McKinna, Lachlan I. W.; Werdell, P. Jeremy; Fearns, Peter R. C. S.; Weeks, Scarla J.; Reichstetter, Martina; Franz, Bryan A.; Shea, Donald M.; Feldman, Gene C.

2014-01-01

Ocean color remote sensing provides synoptic-scale, near-daily observations of marine inherent optical properties (IOPs). Whilst contemporary ocean color algorithms are known to perform well in deep oceanic waters, they have difficulty operating in optically clear, shallow marine environments where light reflected from the seafloor contributes to the water-leaving radiance. The effect of benthic reflectance in optically shallow waters is known to adversely affect algorithms developed for optically deep waters [1, 2]. Whilst adapted versions of optically deep ocean color algorithms have been applied to optically shallow regions with reasonable success [3], there is presently no approach that directly corrects for bottom reflectance using existing knowledge of bathymetry and benthic albedo.To address the issue of optically shallow waters, we have developed a semi-analytical ocean color inversion algorithm: the Shallow Water Inversion Model (SWIM). SWIM uses existing bathymetry and a derived benthic albedo map to correct for bottom reflectance using the semi-analytical model of Lee et al [4]. The algorithm was incorporated into the NASA Ocean Biology Processing Groups L2GEN program and tested in optically shallow waters of the Great Barrier Reef, Australia. In-lieu of readily available in situ matchup data, we present a comparison between SWIM and two contemporary ocean color algorithms, the Generalized Inherent Optical Property Algorithm (GIOP) and the Quasi-Analytical Algorithm (QAA).

Effect of topography-dependent light coupling through a near-field aperture on the local photocurrent of a solar cell.

PubMed

Cao, Zhao; Ermes, Markus; Lehnen, Stephan; Carius, Reinhard; Bittkau, Karsten

2018-01-03

An aperture-type scanning near-field optical microscope (a-SNOM) is readily used for the optical and optoelectronic characterizations of a wide variety of chemical, biological and optoelectronic samples with sub-wavelength optical resolution. These samples mostly exhibit nanoscale topographic variations, which are related to local material inhomogeneity probed either by an optical contrast or by secondary effects such as photoconductivity or photoluminescence. To date, in the interpretation and evaluation of the measurement results from a-SNOM or derived methods, often only the local material inhomogeneity is taken into account. A possible influence of the optical interaction between the scanning probe and the surface topography is rarely discussed. In this paper, we present experimental and theoretical investigation of the effects of nanoscale topographic features on a-SNOM measurement results. We conduct local photocurrent measurements on a thin-film solar cell with an a-SNOM as the illumination source. A clear correlation between the photocurrent response and local topography is observed in all measurements with a signal contrast of up to ∼30%, although the sample features homogeneous permittivity and electrical properties. With the help of finite-difference time-domain (FDTD) simulations, this correlation is reproduced and local light coupling is identified as the mechanism which determines the local photocurrent response. Our results suggest that a-SNOM-based measurements of any sample with material inhomogeneity will be superimposed by the local light-coupling effect if surface topography variation exists. This effect should always be taken into consideration for an accurate interpretation of the measurement results.

SWIM: A Semi-Analytical Ocean Color Inversion Algorithm for Optically Shallow Waters

NASA Technical Reports Server (NTRS)

McKinna, Lachlan I. W.; Werdell, P. Jeremy; Fearns, Peter R. C. S.; Weeks, Scarla J.; Reichstetter, Martina; Franz, Bryan A.; Bailey, Sean W.; Shea, Donald M.; Feldman, Gene C.

2014-01-01

In clear shallow waters, light that is transmitted downward through the water column can reflect off the sea floor and thereby influence the water-leaving radiance signal. This effect can confound contemporary ocean color algorithms designed for deep waters where the seafloor has little or no effect on the water-leaving radiance. Thus, inappropriate use of deep water ocean color algorithms in optically shallow regions can lead to inaccurate retrievals of inherent optical properties (IOPs) and therefore have a detrimental impact on IOP-based estimates of marine parameters, including chlorophyll-a and the diffuse attenuation coefficient. In order to improve IOP retrievals in optically shallow regions, a semi-analytical inversion algorithm, the Shallow Water Inversion Model (SWIM), has been developed. Unlike established ocean color algorithms, SWIM considers both the water column depth and the benthic albedo. A radiative transfer study was conducted that demonstrated how SWIM and two contemporary ocean color algorithms, the Generalized Inherent Optical Properties algorithm (GIOP) and Quasi-Analytical Algorithm (QAA), performed in optically deep and shallow scenarios. The results showed that SWIM performed well, whilst both GIOP and QAA showed distinct positive bias in IOP retrievals in optically shallow waters. The SWIM algorithm was also applied to a test region: the Great Barrier Reef, Australia. Using a single test scene and time series data collected by NASA's MODIS-Aqua sensor (2002-2013), a comparison of IOPs retrieved by SWIM, GIOP and QAA was conducted.

Effect of Mo and Ti doping concentration on the structural and optical properties of ZnS nanoparticles

NASA Astrophysics Data System (ADS)

Naz, Hina; Ali, Rai Nauman; Zhu, Xingqun; Xiang, Bin

2018-06-01

In this paper, we report the effect of single phase Mo and Ti doping concentration on the structural and optical properties of the ZnS nanoparticles. The structural and optical properties of the as-synthesized samples have been examined by x-ray diffraction, transmission electron microscopy (TEM), UV-visible near infrared absorption spectroscopy and x-ray photoelectron spectroscopy. TEM characterizations reveal a variation in the doped ZnS nanoparticle size distribution by utilizing different dopants of Mo and Ti. In absorption spectra, a clear red shift of 14 nm is observed with increasing Mo concentration as compared to pure ZnS nanoparticles, while by increasing Ti doping concentration, blue shift of 14 nm is obtained. Moreover, it demonstrates that the value of energy band gap decreases from 4.03 eV to 3.89 eV in case of Mo doping. However, the value of energy band gap have shown a remarkable increase from 4.11 eV to 4.27 eV with increasing Ti doping concentration. Our results provide a new pathway to understand the effect of Mo and Ti doping concentrations on the structural and optical properties of ZnS nanoparticles as it could be the key to tune the properties for future optoelectronic devices.

Measurement of diffusion coefficient of propylene glycol in skin tissue

NASA Astrophysics Data System (ADS)

Genin, Vadim D.; Bashkatov, Alexey N.; Genina, Elina A.; Tuchin, Valery V.

2015-03-01

Optical clearing of the rat skin under the action of propylene glycol was studied ex vivo. It was found that collimated transmittance of skin samples increased, whereas weight and thickness of the samples decreased during propylene glycol penetration in skin tissue. A mechanism of the optical clearing under the action of propylene glycol is discussed. Diffusion coefficient of propylene glycol in skin tissue ex vivo has been estimated as (1.35±0.95)×10-7 cm2/s with the taking into account of kinetics of both weight and thickness of skin samples. The presented results can be useful for enhancement of many methods of laser therapy and optical diagnostics of skin diseases and localization of subcutaneous neoplasms.

Optical response of bowtie antennas

NASA Astrophysics Data System (ADS)

Guo, Ying-Nan; Pan, Shi; Li, Xu-Feng; Wang, Shuo; Wang, Qiao

2010-10-01

Optical properties of bowtie antennas are investigated using a numerical method of finite-difference time-domain (FDTD). The optical response in the antenna feed gap is simulated as functions of its geometry parameters (flare angle, arm length, apex width, thickness, gap dimension, as well as the index of substrate), which provide a clear guideline to exploit such antenna structures in practice.

Effect of solvents on the optical and morphological properties of MEH-PPV: PC70BM nanocomposites

NASA Astrophysics Data System (ADS)

Mhamdi, Asya; Ltaief, Adnen; Bouazizi, Abdelaziz

2017-10-01

Focused on phase separation and morphologies of polymer poly [2-methoxy-5-(2'-ethyl) hexoxy-1,4-phenylenevinylene] (MEH-PPV) and [6,6]-phenylC71-butyric acid methyl ester (PC70BM) nanocomposite, we studied the effect of organic solvent on the optical and morphological properties of these blends. The MEH-PPV: PC70BM films was prepared using three different solvent; Tetrahydrofuran (THF), Chlorobenzene (CB) and Toluene. On the other hand, the effect of 1-8 octanedithiol additives is also studied with the same different solvents. These blend films are characterized by photoluminescence spectroscopy, UV-Vis absorption spectroscopy and atomic force microscopy (AFM). The photoluminescence results show that the THF solvent provide the better charge transfer. In a morphological view point, the phase segregation was clearly appearing by the addition of the additive on the surface of the blend films.

Optical effects of shadow masks on short circuit current of organic photovoltaic devices.

PubMed

Lin, Chi-Feng; Lin, Bing-Hong; Liu, Shun-Wei; Hsu, Wei-Feng; Zhang, Mi; Chiu, Tien-Lung; Wei, Mau-Kuo; Lee, Jiun-Haw

2012-03-21

In this paper, we have employed different shadow masks attached on top of organic photovoltaic (OPV) devices to study the optical effects of the former on the short circuit current (J(SC)). To rule out possible lateral electrical conduction and simplify the optical effects inside the device, a small-molecular heterojunction OPV device with a clear donor/acceptor interface was employed with a hole extraction layer exhibiting high resistance intentionally. Careful calibration with a shadow mask was employed. By attaching two layers of opaque masks in combination with a suitable holder design to shield the light from the edges and backside, the value of J(SC) approached that of the dark current, even under 1-sun radiation. With different illumination areas, we found that the photons illuminating the non-active region of the device contributed to 40% of the J(SC) by optical effect within the width of about 1 mm around the active region. When illuminating the non-active area with 12 mm to the active area, a 5.6 times improvement in the J(SC) was observed when the incident angle was 75°. With the introduction of a microstructured film onto the OPV device and an increase in the reflection from the non-active region, a 15% enhancement of the J(SC) compared to the control device was achieved.

Nanopore arrays in a silicon membrane for parallel single-molecule detection: DNA translocation

NASA Astrophysics Data System (ADS)

Zhang, Miao; Schmidt, Torsten; Jemt, Anders; Sahlén, Pelin; Sychugov, Ilya; Lundeberg, Joakim; Linnros, Jan

2015-08-01

Optical nanopore sensing offers great potential in single-molecule detection, genotyping, or DNA sequencing for high-throughput applications. However, one of the bottle-necks for fluorophore-based biomolecule sensing is the lack of an optically optimized membrane with a large array of nanopores, which has large pore-to-pore distance, small variation in pore size and low background photoluminescence (PL). Here, we demonstrate parallel detection of single-fluorophore-labeled DNA strands (450 bps) translocating through an array of silicon nanopores that fulfills the above-mentioned requirements for optical sensing. The nanopore array was fabricated using electron beam lithography and anisotropic etching followed by electrochemical etching resulting in pore diameters down to ∼7 nm. The DNA translocation measurements were performed in a conventional wide-field microscope tailored for effective background PL control. The individual nanopore diameter was found to have a substantial effect on the translocation velocity, where smaller openings slow the translocation enough for the event to be clearly detectable in the fluorescence. Our results demonstrate that a uniform silicon nanopore array combined with wide-field optical detection is a promising alternative with which to realize massively-parallel single-molecule detection.

Effect of Co doping concentration on structural properties and optical parameters of Co-doped ZnO thin films by sol-gel dip-coating method.

PubMed

Nam, Giwoong; Yoon, Hyunsik; Kim, Byunggu; Lee, Dong-Yul; Kim, Jong Su; Leem, Jae-Young

2014-11-01

The structural and optical properties of Co-doped ZnO thin films prepared by a sol-gel dip-coating method were investigated. X-ray diffraction analysis showed that the thin films were grown with a c-axis preferred orientation. The position of the (002) peak was almost the same in all samples, irrespective of the Co concentration. It is thus clear that Co doping had little effect on the position of the (002) peak. To confirm that Co2+ was substituted for Zn2+ in the wurtzite structure, optical measurements were conducted at room temperature by a UV-visible spectrometer. Three absorption peaks are apparent in the Co-doped ZnO thin films that do not appear for the undoped ZnO thin film. As the Co concentration was increased, absorption related to characteristic Co2+ transitions increased because three absorption band intensities and the area underneath the absorption wells between 500 and 700 nm increased with increasing Co concentration. The optical band gap and static dielectric constant decreased and the Urbach energy and extinction coefficient increased with increasing Co concentration.

Use Of Adaptive Optics Element For Wavefront Error Correction In The Gemini CO2 Laser Fusion System

NASA Astrophysics Data System (ADS)

Viswanathan, V. K.; Parker, J. V.; Nussmier, T. A.; Swigert, C. J.; King, W.; Lau, A. S.; Price, K.

1980-11-01

The Gemini two beam CO2 laser fusion system incorporates a complex optical system with nearly 100 surfaces per beam, associated with the generation, transport and focusing of CO2 laser beams for irradiating laser fusion targets. Even though the system is nominally diffraction limited, in practice the departure from the ideal situation drops the Strehl ratio to 0.24. This departure is caused mostly by the imperfections in the large (34 cm optical clear aperture diameter) state-of-the-art components like the sodium chloride windows and micromachined mirrors. While the smaller optical components also contribute to this degradation, the various possible misalignments and nonlinear effects are considered to contribute very little to it. Analysis indicates that removing the static or quasi-static errors can dramatically improve the Strehl ratio. A deformable mirror which can comfortably achieve the design goal Strehl ratio of >= 0.7 is described, along with the various system trade-offs in the design of the mirror and the control system.

Optical registration of spaceborne low light remote sensing camera

NASA Astrophysics Data System (ADS)

Li, Chong-yang; Hao, Yan-hui; Xu, Peng-mei; Wang, Dong-jie; Ma, Li-na; Zhao, Ying-long

2018-02-01

For the high precision requirement of spaceborne low light remote sensing camera optical registration, optical registration of dual channel for CCD and EMCCD is achieved by the high magnification optical registration system. System integration optical registration and accuracy of optical registration scheme for spaceborne low light remote sensing camera with short focal depth and wide field of view is proposed in this paper. It also includes analysis of parallel misalignment of CCD and accuracy of optical registration. Actual registration results show that imaging clearly, MTF and accuracy of optical registration meet requirements, it provide important guarantee to get high quality image data in orbit.

Evaluation of copper ion of antibacterial effect on Pseudomonas aeruginosa, Salmonella typhimurium and Helicobacter pylori and optical, mechanical properties

NASA Astrophysics Data System (ADS)

Kim, Young-Hwan; Choi, Yu-ri; Kim, Kwang-Mahn; Choi, Se-Young

2012-02-01

Antibacterial effect on Pseudomonas aeruginosa, Salmonella typhimurium and Helicobacter pylori of copper ion was researched. Also, additional effects of copper ion coating on optical and mechanical properties were researched as well. Copper ion was coated on glass substrate as a thin film to prevent bacteria from growing. Cupric nitrate was used as precursors for copper ion. The copper ion contained sol was deposited by spin coating process on glass substrate. Then, the deposited substrates were heat treated at the temperature range between 200 °C and 250 °C. The thickness of deposited copper layer on the surface was 63 nm. The antibacterial effect of copper ion coated glass on P. aeruginosa, S. typhimurium and H. pylori demonstrated excellent effect compared with parent glass. Copper ion contained layer on glass showed a similar value of transmittance compared with value of parent glass. The 3-point bending strength and Vickers hardness were 209.2 MPa, 540.9 kg/mm2 which were about 1.5% and 1.3% higher than the value of parent glass. From these findings, it is clear that copper ion coating on glass substrate showed outstanding effect not only in antibacterial activity but also in optical and mechanical properties as well.

The neuron net method for processing the clear pixels and method of the analytical formulas for processing the cloudy pixels of POLDER instrument images

NASA Astrophysics Data System (ADS)

Melnikova, I.; Mukai, S.; Vasilyev, A.

Data of remote measurements of reflected radiance with the POLDER instrument on board of ADEOS satellite are used for retrieval of the optical thickness, single scattering albedo and phase function parameter of cloudy and clear atmosphere. The method of perceptron neural network that from input values of multiangle radiance and Solar incident angle allows to obtain surface albedo, the optical thickness, single scattering albedo and phase function parameter in case of clear sky. Two last parameters are determined as optical average for atmospheric column. The calculation of solar radiance with using the MODTRAN-3 code with taking into account multiple scattering is accomplished for neural network learning. All mentioned parameters were randomly varied on the base of statistical models of possible measured parameters variation. Results of processing one frame of remote observation that consists from 150,000 pixels are presented. The methodology elaborated allows operative determining optical characteristics as cloudy as clear atmosphere. Further interpretation of these results gives the possibility to extract the information about total contents of atmospheric aerosols and absorbing gases in the atmosphere and create models of the real cloudiness An analytical method of interpretation that based on asymptotic formulas of multiple scattering theory is applied to remote observations of reflected radiance in case of cloudy pixel. Details of the methodology and error analysis were published and discussed earlier. Here we present results of data processing of pixel size 6x6 km In many studies the optical thickness is evaluated earlier in the assumption of the conservative scattering. But in case of true absorption in clouds the large errors in parameter obtained are possible. The simultaneous retrieval of two parameters at every wavelength independently is the advantage comparing with earlier studies. The analytical methodology is based on the transfer theory asymptotic formula inversion for optically thick stratus clouds. The model of horizontally infinite layer is considered. The slight horizontal heterogeneity is approximately taken into account. Formulas containing only the measured values of two-direction radiance and functions of solar and view angles were derived earlier. The 6 azimuth harmonics of reflection function are taken into account. The simple approximation of the cloud top boarder heterogeneity is used. The clouds, projecting upper the cloud top plane causes the increase of diffuse radiation in the incident flux. It is essential for calculation of radiative characteristics, which depends on lighting conditions. Escape and reflection functions describe this dependence for reflected radiance and local albedo of semi-infinite medium - for irradiance. Thus the functions depending on solar incident angle is to replace by their modifications. Firstly optical thickness of every pixel is obtained with simple formula assuming conservative scattering for all available view directions. Deviations between obtained values may be taken as a measure of the cloud top deviation from the plane. The special parameter is obtained, which takes into account the shadowing effect. Then single scattering albedo and optical thickness (with the true absorption assuming) are obtained for pairs of view directions with equal optical thickness. After that the averaging of values obtained and relative error evaluation is accomplished for all viewing directions of every pixel. The procedure is repeated for all wavelengths and pixels independently.

Optical coherence tomography of the effects of stromal hydration on clear corneal incision architecture.

PubMed

Calladine, Daniel; Tanner, Vaughan

2009-08-01

To evaluate the effects of stromal hydration on clear corneal incision (CCI) architecture immediately after surgery using anterior segment optical coherence tomography (AS-OCT). Department of Ophthalmology, Royal Berkshire Hospital, Reading, United Kingdom. Clear corneal incisions in adult eyes were examined using a Visante AS-OCT imaging system within 1 hour of surgery. Half the CCIs had stromal hydration with a balanced salt solution and half did not. Incisions were made with a 2.75 mm steel keratome. Intraocular pressure (IOP) was measured within 90 minutes after surgery. The CCI length and corneal thickness at the CCI site were measured using software built into the AS-OCT system. Thirty CCIs were evaluated. Stromal hydration significantly increased the measured CCI length (P<.05, t test); this was the result of a trend toward increased corneal thickness at the CCI site with hydration (P<.1, t test). The mean CCI length was 1.69 mm +/- 0.27 (SD) (range 1.31 to 2.32 mm) with hydration and 1.51 +/- 0.23 mm (range 1.30 to 1.95 mm) without hydration. The mean IOP was 20.9 +/- 8.18 mm Hg and 15.8 +/- 8.20 mm Hg, respectively. The IOP tended to be higher with hydration (P<.1, t test). Local detachment of Descemet membrane was more likely with stromal hydration (63%) than without (25%). Stromal hydration significantly increased CCI length and tended to leave the eye with a higher early postoperative IOP, showing the importance of taking stromal hydration into account when designing similar OCT studies of CCI architecture.

RF/optical shared aperture for high availability wideband communication RF/FSO links

DOEpatents

Ruggiero, Anthony J; Pao, Hsueh-yuan; Sargis, Paul

2014-04-29

An RF/Optical shared aperture is capable of transmitting and receiving optical signals and RF signals simultaneously. This technology enables compact wide bandwidth communications systems with 100% availability in clear air turbulence, rain and fog. The functions of an optical telescope and an RF reflector antenna are combined into a single compact package by installing an RF feed at either of the focal points of a modified Gregorian telescope.

RF/optical shared aperture for high availability wideband communication RF/FSO links

DOEpatents

Ruggiero, Anthony J; Pao, Hsueh-yuan; Sargis, Paul

2015-03-24

An RF/Optical shared aperture is capable of transmitting and receiving optical signals and RF signals simultaneously. This technology enables compact wide bandwidth communications systems with 100% availability in clear air turbulence, rain and fog. The functions of an optical telescope and an RF reflector antenna are combined into a single compact package by installing an RF feed at either of the focal points of a modified Gregorian telescope.

Correlation Between the "seeing FWHM" of Satellite Optical Observations and Meteorological Data at the OWL-Net Station, Mongolia

NASA Astrophysics Data System (ADS)

Bae, Young-Ho; Jo, Jung Hyun; Yim, Hong-Suh; Park, Young-Sik; Park, Sun-Youp; Moon, Hong Kyu; Choi, Young-Jun; Jang, Hyun-Jung; Roh, Dong-Goo; Choi, Jin; Park, Maru; Cho, Sungki; Kim, Myung-Jin; Choi, Eun-Jung; Park, Jang-Hyun

2016-06-01

The correlation between meteorological data collected at the optical wide-field patrol network (OWL-Net) Station No. 1 and the seeing of satellite optical observation data was analyzed. Meteorological data and satellite optical observation data from June 2014 to November 2015 were analyzed. The analyzed meteorological data were the outdoor air temperature, relative humidity, wind speed, and cloud index data, and the analyzed satellite optical observation data were the seeing full-width at half-maximum (FWHM) data. The annual meteorological pattern for Mongolia was analyzed by collecting meteorological data over four seasons, with data collection beginning after the installation and initial set-up of the OWL-Net Station No. 1 in Mongolia. A comparison of the meteorological data and the seeing of the satellite optical observation data showed that the seeing degrades as the wind strength increases and as the cloud cover decreases. This finding is explained by the bias effect, which is caused by the fact that the number of images taken on the less cloudy days was relatively small. The seeing FWHM showed no clear correlation with either temperature or relative humidity.

Multicolor Photometric Observation of Lightning from Space: Comparison with Radio Measurements

NASA Technical Reports Server (NTRS)

Adachi, Toru; Cohen, Morris; Said, Ryan; Blakeslee, Richard J.; Cummer, Steven A.; Li, Jingbo; Lu, Geopeng; Hsu, Rue-Ron; Su, Han-Tzong; Chen, Alfred Bing-Chih;

Influence of aerosols on surface reaching spectral irradiance and introduction to a new technique of estimating aerosol radiative forcing from high resolution spectral flux measurements

NASA Astrophysics Data System (ADS)

Rao, Roshan

2016-04-01

Aerosol radiative forcing estimates with high certainty are required in climate change studies. The approach in estimating the aerosol radiative forcing by using the chemical composition of aerosols is not effective as the chemical composition data with radiative properties are not widely available. We look into the approach where ground based spectral radiation flux measurement is made and along with an Radtiative transfer (RT) model, radiative forcing is estimated. Measurements of spectral flux were made using an ASD spectroradiometer with 350 - 1050 nm wavelength range and a 3nm resolution during around 54 clear-sky days during which AOD range was around 0.01 to 0.7. Simultaneous measurements of black carbon were also made using Aethalometer (Magee Scientific) which ranged from around 1.5 ug/m3 to 8 ug/m3. The primary study involved in understanding the sensitivity of spectral flux due to change in individual aerosol species (Optical properties of Aerosols and Clouds (OPAC) classified aerosol species) using the SBDART RT model. This made us clearly distinguish the influence of different aerosol species on the spectral flux. Following this, a new technique has been introduced to estimate an optically equivalent mixture of aerosol species for the given location. The new method involves matching different combinations of aerosol species in OPAC model and RT model as long as the combination which gives the minimum root mean squared deviation from measured spectral flux is obtained. Using the optically equivalent aerosol mixture and RT model, aerosol radiative forcing is estimated. Also an alternate method to estimate the spectral SSA is discussed. Here, the RT model, the observed spectral flux and spectral AOD is used. Spectral AOD is input to RT model and SSA is varied till the minimum root mean squared difference between observed and simulated spectral flux from RT model is obtained. The methods discussed are limited to clear sky scenes and its accuracy to derive an optically equivalent aerosol mixture reduces when diffuse component of flux increases. In our analysis, RT model clearly shows that direct component of spectral flux is more sensitive to different aerosol species than total spectral flux which is also supported by our observed data.

Feedback control for manipulating magnetization in spin-exchange optical pumping system

NASA Astrophysics Data System (ADS)

Zhang, Ke; Li, Jun; Jiang, Min; Zhao, Nan; Peng, XinHua

2018-08-01

Control of magnetization plays an important role in the scientific and technological field of manipulating spin systems. In this work, we study the problem of manipulating nuclear magnetization in the spin-exchange optical pumping system, including accelerating the recovery of nuclear polarization and fixing it on a specific desired state. A real-time feedback control strategy is exploited here. We have also done some numerical simulations, with the results clearly demonstrating the effectiveness of our method, that the nuclear magnetization is able to be driven towards the equilibrium state at a much faster speed and also can be stabilized to a target state. We expect that our feedback control method can find applications in gyro experiments.

The magic of 4X mask reduction

NASA Astrophysics Data System (ADS)

Lercel, Michael

2006-06-01

Although changing the mask reduction factor from 4X to a larger value offers several technical advantages, previous attempts to enact this change have not identified enough clear technical advantages to overcome the impact to productivity. Improvements in mask manufacturing, mask polarization effects, and optics cost have not been thought to be sufficient reason to accept a reduced throughput and field size. This paper summarizes the latest workshop and discussion revisiting the mask reduction factor for 32nm half-pitch lithography with hyper-numerical aperture (NA) optical or extreme ultraviolet lithography (EUVL). The workshop consensus was strongly in favor of maintaining the current magnification ratio and field size as long as mask costs can be contained.

Optical coherence tomography to evaluate the effects of oxidative hair dye on the fiber.

PubMed

Velasco, Maria Valéria Robles; de Abreu, Simone Rachid Pfannemüller; de Freitas, Anderson Zanardi; Bedin, Valcinir; Baby, André Rolim; da Gama, Robson Miranda

2016-11-01

Oxidative hair dyes can damage the hair, since these chemical procedures are involved to change the fiber structure and therefore changes in their mechanical and surface properties. Evaluate and compare the effect of the two colors of oxidative hair dye emulsions on Caucasian hair. This research analyzed the Dark brown hair untreated (I); Dark brown hair treated with light brown dye (II); Dark brown hair treated with light blond dye (III); Light blond hair untreated (IV); Light blond hair treated with light brown dye (V); Light blond hair treated with light blond dye (VI) on Caucasian hair. The hair samples were submitted to breaking strength, color, and optical coherence tomography (OCT) analysis. For the breaking strength assay no presented statistically significant differences between treatments. The parameters of color and brightness can differ in some hair dye formulations, but also the hair type can respond differently. The OCT images of the sample I and IV was possible observed, clearly Medulla and Cortex, which was not observed clearly after treatment with both oxidative hair dye colors. Based on the results, the oxidative hair dyes increased alteration in color and ultrastructure of hair. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Aerosol radiative effects and their trends under clear-sky situations over Europe

NASA Astrophysics Data System (ADS)

Bartok, Blanka

2017-04-01

In the literature great uncertainties ca be found regarding radiative effects of aerosols on the energy budget of the atmosphere (IPCC, 2013). In the study the aerosols radiative effects on clear-sky solar radiation are quantified over Europe using empirical and physical modelling approaches. The values of aerosol radiation effect are determined by the MAGIC radiation code. In the first run clear-sky radiation is calculated integrating KINEE/MPI/Aerocom aerosol climatology and ERA-INTERIM water vapour multiannual monthly means. In the next run the clear-sky radiation are also calculated ignoring aerosol data (adjusted to 0) from the algorithm. Both runs were carried out for each months of the year, taking into account the varying astrological factors. The difference between the aerosol-included and aerosol-free clear-sky radiation is equal to the absolute aerosol radiative effect in W/m2. The annual mean of the surface aerosol radiative effects in clear-sky situations over Europe is -7.1 ± 2.9 W/m2, high values are representing the central part of the continent and the Mediterranean Basin. Furthermore the trends of the aerosol radiative effects are also determined for the period of 2001-2012. First a linear fitting is elaborated between the aerosol optical depth (AOT) built in the MAGIC code and its aerosol radiative effect calculated by the code. Next, based on these linear functions a radiative effect values are assigned to each monthly AOT500 value available from the Moderate Resolution Imaging Spectroradiometer (MODIS) Terra Level-3 experiment. In this way a new dataset of aerosol radiative effect for the period of 2001-2012 has been created. Beside of this approach the changes in aerosol radiative effects are also calculated based on ground-based clear-sky radiation trends. This approach is used as a validation of the method applied in earlier stage, mainly for the linear fitting. The starting point of this approach is to elaborate the trends of clear-sky radiation controlled by the effects of aerosols and water vapour. If we subtract the water vapour effects also calculated by MAGIC radiation code from this trend, the magnitude of the trends in aerosol radiative effects can be estimated. In this case it is assumed that the two effects do not amplify and do not cancel each other, and their arithmetic sum gives the change in clear-sky radiation trend. The two approaches give good fit, based on the direct (modelled) approach the annual trend of the aerosol radiative effects on clear-sky solar surface radiation is -4.41 W/m2 per decade for the period of 2001-2013, while in the case of the indirect approach (based on clear-sky trends) this trend is found to be -4.46 W/m2 per decade.

Use of fractional laser microablation of skin for improvement of its immersion clearing

NASA Astrophysics Data System (ADS)

Kolesnikova, Ekaterina A.; Kolesnikov, Aleksandr S.; Genina, Elina A.; Dolotov, Leonid E.; Tuchina, Darya K.; Bashkatov, Alexey N.; Tuchin, Valery V.

2013-02-01

We are proposing a new method for enhancement of optical clearing agent delivery into the skin using fractional laser microablation of the skin surface. The Palomar Lux2940 erbium laser with the wavelength 2940 nm and pulse duration of 5 ms was used as a light source. Two regimes of laser action were used in the experiments: the first one realized microablation of skin upper layer and the second one created microchannels in skin. As optical clearing agents mineral oil and PEG-300 were used. In vivo studies were carried out with white outbred rats. Both parameters: the permeability coefficient of the agents in the tissue and the optical probing depth were measured using the OCT system at a wavelength of 930 nm. The following values of the permeability coefficient of the skin with microablation were obtained: (3.41+/-0.46)×10-5 cm/s and (2.35+/-0.30)×10-5 cm/s for mineral oil and PEG-300, respectively, at the use of the surface microablation and (3.32+/-0.09)×10-5 cm/s and (3.61+/-0.34)×10-5 cm/s for mineral oil and PEG-300, respectively, at the use of the microporation. The results have shown that the joint application of mineral oil with microablation in the first regime promotes maximal (nearly 2-folds) increasing of optical probing depth in 30 min. Obtained data can be used for development of optical diagnostic methods of skin diseases.

The improvement of laser induced damage resistance of optical workpiece surface by hydrodynamic effect polishing

NASA Astrophysics Data System (ADS)

Peng, Wenqiang; Guan, Chaoliang; Li, Shengyi; Wang, Zhuo

2016-10-01

Surface and subsurface damage in optical element will greatly decrease the laser induced damage threshold (LIDT) in the intense laser optical system. Processing damage on the workpiece surface can be inevitably caused when the material is removed in brittle or plastic mode. As a non-contact polishing technology, hydrodynamic effect polishing (HEP) shows very good performance on generating an ultra-smooth surface without damage. The material is removed by chemisorption between nanoparticle and workpiece surface in the elastic mode in HEP. The subsurface damage and surface scratches can be effectively removed after the polishing process. Meanwhile ultra-smooth surface with atomic level surface roughness can be achieved. To investigate the improvement of LIDT of optical workpiece, polishing experiment was conducted on a magnetorheological finishing (MRF) silica glass sample. AFM measurement results show that all the MRF directional plastic marks have been removed clearly and the root-mean-square (rms) surface roughness has decreased from 0.673nm to 0.177nm after HEP process. Laser induced damage experiment was conducted with laser pulse of 1064nm wavelength and 10ns time width. Compared with the original state, the LEDT of the silica glass sample polished by HEP has increased from 29.78J/cm2 to 45.47J/cm2. It demonstrates that LIDT of optical element treated by HEP can be greatly improved for ultra low surface roughness and nearly defect-free surface/subsurface.

An optical clearing technique for plant tissues allowing deep imaging and compatible with fluorescence microscopy.

PubMed

Warner, Cherish A; Biedrzycki, Meredith L; Jacobs, Samuel S; Wisser, Randall J; Caplan, Jeffrey L; Sherrier, D Janine

2014-12-01

We report on a nondestructive clearing technique that enhances transmission of light through specimens from diverse plant species, opening unique opportunities for microscope-enabled plant research. After clearing, plant organs and thick tissue sections are amenable to deep imaging. The clearing method is compatible with immunocytochemistry techniques and can be used in concert with common fluorescent probes, including widely adopted protein tags such as GFP, which has fluorescence that is preserved during the clearing process. © 2014 American Society of Plant Biologists. All Rights Reserved.

Silver nanoparticles as optical clearing agent enhancers to improve caries diagnostic by optical coherence tomography

NASA Astrophysics Data System (ADS)

Carneiro, Vanda S. M.; Mota, Cláudia C. B. O.; Souza, Alex F.; da Silva, Evair J.; da Silva, Andrea F.; Gerbi, Marleny E. M. M.; Gomes, Anderson S. L.

2018-02-01

The use of silver nanoparticles as optical clearing agent (OCA) enhancers to improve caries diagnostic by optical coherence tomography (OCT) is demonstrated here. Five molars with no evident cavitation were selected. The OCAs were based on aqueous solution of silver nanoparticles (AgNP, 1.18x 1014 particles/mL, ø ≈ 10nm) and its dilution at 10% in glycerol. Teeth were placed on a platform with a micrometric screw, and after applying the OCAs, they were scanned with a Callisto SD-OCT system operating ate 930nm central wavelength. The occlusal surfaces were scanned by OCT, capturing crosssectional images with 8 mm transversal scanning, generating numerical matrices (2000x512). The OCT images had their transverse dimension preserved. AgNP-OCAs promoted image stretching due to the modification in the light optical path caused by AgNP-OCAs refractive indices close to that of the enamel. AgNP-OCAs evidenced the enamel birefringence and highlighted initial demineralization areas, that presented defined margins with higher contrast between sound and demineralized regions, with higher OCT signal intensity in those areas.

Optical Design of the LSST Camera

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olivier, S S; Seppala, L; Gilmore, K

2008-07-16

The Large Synoptic Survey Telescope (LSST) uses a novel, three-mirror, modified Paul-Baker design, with an 8.4-meter primary mirror, a 3.4-m secondary, and a 5.0-m tertiary feeding a camera system that includes a set of broad-band filters and refractive corrector lenses to produce a flat focal plane with a field of view of 9.6 square degrees. Optical design of the camera lenses and filters is integrated with optical design of telescope mirrors to optimize performance, resulting in excellent image quality over the entire field from ultra-violet to near infra-red wavelengths. The LSST camera optics design consists of three refractive lenses withmore » clear aperture diameters of 1.55 m, 1.10 m and 0.69 m and six interchangeable, broad-band, filters with clear aperture diameters of 0.75 m. We describe the methodology for fabricating, coating, mounting and testing these lenses and filters, and we present the results of detailed tolerance analyses, demonstrating that the camera optics will perform to the specifications required to meet their performance goals.« less

Comparison of optical projection tomography and optical coherence tomography for assessment of murine embryonic development

NASA Astrophysics Data System (ADS)

Singh, Manmohan; Nair, Achuth; Vadakkan, Tegy; Piazza, Victor; Udan, Ryan; Frazier, Michael V.; Janecek, Trevor; Dickinson, Mary E.; Larin, Kirill V.

2015-03-01

The murine model is a common model for studying developmental diseases. In this study, we compare the performance of the relatively new method of Optical Projection Tomography (OPT) to the well-established technique of Optical Coherence Tomography (OCT) to assess murine embryonic development at three stages, 9.5, 11.5, and 13.5 days post conception. While both methods can provide spatial resolution at the micrometer scale, OPT can provide superior imaging depth compared to OCT. However, OPT requires samples to be fixed, placed in an immobilization media such as agar, and cleared before imaging. Because OCT does not require fixing, it can be used to image embryos in vivo and in utero. In this study, we compare the efficacy of OPT and OCT for imaging murine embryonic development. The data demonstrate the superior capability of OPT for imaging fine structures with high resolution in optically-cleared embryos while only OCT can provide structural and functional imaging of live embryos ex vivo and in utero with micrometer scale resolution.

MACv2-SP: a parameterization of anthropogenic aerosol optical properties and an associated Twomey effect for use in CMIP6

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stevens, Bjorn; Fiedler, Stephanie; Kinne, Stefan

A simple plume implementation of the second version (v2) of the Max Planck Institute Aerosol Climatology, MACv2-SP, is described. MACv2-SP provides a prescription of anthropogenic aerosol optical properties and an associated Twomey effect. It was created to provide a harmonized description of post-1850 anthropogenic aerosol radiative forcing for climate modeling studies. MACv2-SP has been designed to be easy to implement, change and use, and thereby enable studies exploring the climatic effects of different patterns of aerosol radiative forcing, including a Twomey effect. MACv2-SP is formulated in terms of nine spatial plumes associated with different major anthropogenic source regions. The shapemore » of the plumes is fit to the Max Planck Institute Aerosol Climatology, version 2, whose present-day (2005) distribution is anchored by surface-based observations. Two types of plumes are considered: one predominantly associated with biomass burning, the other with industrial emissions. These differ in the prescription of their annual cycle and in their optical properties, thereby implicitly accounting for different contributions of absorbing aerosol to the different plumes. A Twomey effect for each plume is prescribed as a change in the host model's background cloud-droplet population density using relationships derived from satellite data. Year-to-year variations in the amplitude of the plumes over the historical period (1850–2016) are derived by scaling the plumes with associated national emission sources of SO 2 and NH 3. Experiments using MACv2-SP are performed with the Max Planck Institute Earth System Model. The globally and annually averaged instantaneous and effective aerosol radiative forcings are estimated to be -0.6 and -0.5 W m -2, respectively. Forcing from aerosol–cloud interactions (the Twomey effect) offsets the reduction of clear-sky forcing by clouds, so that the net effect of clouds on the aerosol forcing is small; hence, the clear-sky forcing, which is more readily measurable, provides a good estimate of the total aerosol forcing.« less

MACv2-SP: a parameterization of anthropogenic aerosol optical properties and an associated Twomey effect for use in CMIP6

NASA Astrophysics Data System (ADS)

Stevens, Bjorn; Fiedler, Stephanie; Kinne, Stefan; Peters, Karsten; Rast, Sebastian; Müsse, Jobst; Smith, Steven J.; Mauritsen, Thorsten

2017-02-01

A simple plume implementation of the second version (v2) of the Max Planck Institute Aerosol Climatology, MACv2-SP, is described. MACv2-SP provides a prescription of anthropogenic aerosol optical properties and an associated Twomey effect. It was created to provide a harmonized description of post-1850 anthropogenic aerosol radiative forcing for climate modeling studies. MACv2-SP has been designed to be easy to implement, change and use, and thereby enable studies exploring the climatic effects of different patterns of aerosol radiative forcing, including a Twomey effect. MACv2-SP is formulated in terms of nine spatial plumes associated with different major anthropogenic source regions. The shape of the plumes is fit to the Max Planck Institute Aerosol Climatology, version 2, whose present-day (2005) distribution is anchored by surface-based observations. Two types of plumes are considered: one predominantly associated with biomass burning, the other with industrial emissions. These differ in the prescription of their annual cycle and in their optical properties, thereby implicitly accounting for different contributions of absorbing aerosol to the different plumes. A Twomey effect for each plume is prescribed as a change in the host model's background cloud-droplet population density using relationships derived from satellite data. Year-to-year variations in the amplitude of the plumes over the historical period (1850-2016) are derived by scaling the plumes with associated national emission sources of SO2 and NH3. Experiments using MACv2-SP are performed with the Max Planck Institute Earth System Model. The globally and annually averaged instantaneous and effective aerosol radiative forcings are estimated to be -0.6 and -0.5 W m-2, respectively. Forcing from aerosol-cloud interactions (the Twomey effect) offsets the reduction of clear-sky forcing by clouds, so that the net effect of clouds on the aerosol forcing is small; hence, the clear-sky forcing, which is more readily measurable, provides a good estimate of the total aerosol forcing.

Large core plastic planar optical splitter fabricated by 3D printing technology

NASA Astrophysics Data System (ADS)

Prajzler, Václav; Kulha, Pavel; Knietel, Marian; Enser, Herbert

2017-10-01

We report on the design, fabrication and optical properties of large core multimode optical polymer splitter fabricated using fill up core polymer in substrate that was made by 3D printing technology. The splitter was designed by the beam propagation method intended for assembling large core waveguide fibers with 735 μm diameter. Waveguide core layers were made of optically clear liquid adhesive, and Veroclear polymer was used as substrate and cover layers. Measurement of optical losses proved that the insertion optical loss was lower than 6.8 dB in the visible spectrum.

Optical Brain Imaging: A Powerful Tool for Neuroscience.

PubMed

Zhu, Xinpei; Xia, Yanfang; Wang, Xuecen; Si, Ke; Gong, Wei

2017-02-01

As the control center of organisms, the brain remains little understood due to its complexity. Taking advantage of imaging methods, scientists have found an accessible approach to unraveling the mystery of neuroscience. Among these methods, optical imaging techniques are widely used due to their high molecular specificity and single-molecule sensitivity. Here, we overview several optical imaging techniques in neuroscience of recent years, including brain clearing, the micro-optical sectioning tomography system, and deep tissue imaging.

High quality adaptive optics zoom with adaptive lenses

NASA Astrophysics Data System (ADS)

Quintavalla, M.; Santiago, F.; Bonora, S.; Restaino, S.

2018-02-01

We present the combined use of large aperture adaptive lens with large optical power modulation with a multi actuator adaptive lens. The Multi-actuator Adaptive Lens (M-AL) can correct up to the 4th radial order of Zernike polynomials, without any obstructions (electrodes and actuators) placed inside its clear aperture. We demonstrated that the use of both lenses together can lead to better image quality and to the correction of aberrations of adaptive optics optical systems.

Expanded all-optical programmable logic array based on multi-input/output canonical logic units.

PubMed

Lei, Lei; Dong, Jianji; Zou, Bingrong; Wu, Zhao; Dong, Wenchan; Zhang, Xinliang

2014-04-21

We present an expanded all-optical programmable logic array (O-PLA) using multi-input and multi-output canonical logic units (CLUs) generation. Based on four-wave mixing (FWM) in highly nonlinear fiber (HNLF), two-input and three-input CLUs are simultaneously achieved in five different channels with an operation speed of 40 Gb/s. Clear temporal waveforms and wide open eye diagrams are successfully observed. The effectiveness of the scheme is validated by extinction ratio and optical signal-to-noise ratio measurements. The computing capacity, defined as the total amount of logic functions achieved by the O-PLA, is discussed in detail. For a three-input O-PLA, the computing capacity of the expanded CLUs-PLA is more than two times as large as that of the standard CLUs-PLA, and this multiple will increase to more than three and a half as the idlers are individually independent.

System Engineering of Photonic Systems for Space Application

NASA Technical Reports Server (NTRS)

Watson, Michael D.; Pryor, Jonathan E.

2014-01-01

The application of photonics in space systems requires tight integration with the spacecraft systems to ensure accurate operation. This requires some detailed and specific system engineering to properly incorporate the photonics into the spacecraft architecture and to guide the spacecraft architecture in supporting the photonics devices. Recent research in product focused, elegant system engineering has led to a system approach which provides a robust approach to this integration. Focusing on the mission application and the integration of the spacecraft system physics incorporation of the photonics can be efficiently and effectively accomplished. This requires a clear understanding of the driving physics properties of the photonics device to ensure proper integration with no unintended consequences. The driving physics considerations in terms of optical performance will be identified for their use in system integration. Keywords: System Engineering, Optical Transfer Function, Optical Physics, Photonics, Image Jitter, Launch Vehicle, System Integration, Organizational Interaction

Planck intermediate results: XXXVI. Optical identification and redshifts of Planck SZ sources with telescopes at the Canary Islands observatories

DOE PAGES

Ade, P. A. R.; Aghanim, N.; Arnaud, M.; ...

2016-02-09

In this paper, we present the results of approximately three years of observations of Planck Sunyaev-Zeldovich (SZ) sources with telescopes at the Canary Islands observatories as part of the general optical follow-up programme undertaken by the Planck Collaboration. In total, 78 SZ sources are discussed. Deep-imaging observations were obtained for most of these sources; spectroscopic observations in either in long-slit or multi-object modes were obtained for many. We effectively used 37.5 clear nights. We found optical counterparts for 73 of the 78 candidates. This sample includes 53 spectroscopic redshift determinations, 20 of them obtained with a multi-object spectroscopic mode. Finally,more » the sample contains new redshifts for 27 Planck clusters that were not included in the first Planck SZ source catalogue (PSZ1).« less

Energy gaps, valence and conduction charge densities and optical properties of GaAs1‑xPx

NASA Astrophysics Data System (ADS)

Al-Hagan, O. A.; Algarni, H.; Bouarissa, N.; Alhuwaymel, T. F.; Ajmal Khan, M.

2018-04-01

The electronic structure and its derived valence and conduction charge distributions along with the optical properties of zinc-blende GaAs1‑xPx ternary alloys have been studied. The calculations are performed using a pseudopotential approach under the virtual crystal approximation (VCA) which takes into account the compositional disorder effect. Our findings are found to be generally in good accord with experiment. The composition dependence of direct and indirect bandgaps showed a clear bandgap bowing. The nature of the gap is found to depend on phosphorous content. The bonding and ionicity of the material of interest have been examined in terms of the anti-symmetric gap and charge densities. The variation in the optical constants versus phosphorous concentration has been discussed. The present investigation may give a useful applications in infrared and visible spectrum light emitters.

Second harmonic generation spectroscopy in the Reststrahl band of SiC using an infrared free-electron laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paarmann, Alexander, E-mail: alexander.paarmann@fhi-berlin.mpg.de; Razdolski, Ilya; Melnikov, Alexey

2015-08-24

The Reststrahl spectral region of silicon carbide has recently attracted much attention owing to its potential for mid-infrared nanophotonic applications based on surface phonon polaritons (SPhPs). Studies of optical phonon resonances responsible for surface polariton formation, however, have so far been limited to linear optics. In this Letter, we report the first nonlinear optical investigation of the Reststrahl region of SiC, employing an infrared free-electron laser to perform second harmonic generation (SHG) spectroscopy. We observe two distinct resonance features in the SHG spectra, one attributed to resonant enhancement of the nonlinear susceptibility χ{sup (2)} and the other due to amore » resonance in the Fresnel transmission. Our work clearly demonstrates high sensitivity of mid-infrared SHG to phonon-driven phenomena and opens a route to studying nonlinear effects in nanophotonic structures based on SPhPs.« less

Room temperature three-photon pumped CH3NH3PbBr3 perovskite microlasers.

PubMed

Gao, Yisheng; Wang, Shuai; Huang, Can; Yi, Ningbo; Wang, Kaiyang; Xiao, Shumin; Song, Qinghai

2017-03-28

Hybrid lead halide perovskites have made great strides in next-generation light-harvesting and light emitting devices. Recently, they have also shown great potentials in nonlinear optical materials. Two-photon absorption and two-photon light emission have been thoroughly studied in past two years. However, the three-photon processes are rarely explored, especially for the laser emissions. Here we synthesized high quality CH 3 NH 3 PbBr 3 perovskite microstructures with solution processed precipitation method and studied their optical properties. When the microstructures are pumped with intense 1240 nm lasers, we have observed clear optical limit effect and the band-to-band photoluminescence at 540 nm. By increasing the pumping density, whispering-gallery-mode based microlasers have been achieved from CH 3 NH 3 PbBr 3 perovskite microplate and microrod for the first time. This work demonstrates the potentials of hybrid lead halide perovskites in nonlinear photonic devices.

Room temperature three-photon pumped CH3NH3PbBr3 perovskite microlasers

NASA Astrophysics Data System (ADS)

Gao, Yisheng; Wang, Shuai; Huang, Can; Yi, Ningbo; Wang, Kaiyang; Xiao, Shumin; Song, Qinghai

2017-03-01

Hybrid lead halide perovskites have made great strides in next-generation light-harvesting and light emitting devices. Recently, they have also shown great potentials in nonlinear optical materials. Two-photon absorption and two-photon light emission have been thoroughly studied in past two years. However, the three-photon processes are rarely explored, especially for the laser emissions. Here we synthesized high quality CH3NH3PbBr3 perovskite microstructures with solution processed precipitation method and studied their optical properties. When the microstructures are pumped with intense 1240 nm lasers, we have observed clear optical limit effect and the band-to-band photoluminescence at 540 nm. By increasing the pumping density, whispering-gallery-mode based microlasers have been achieved from CH3NH3PbBr3 perovskite microplate and microrod for the first time. This work demonstrates the potentials of hybrid lead halide perovskites in nonlinear photonic devices.

Oblique incidence reflectometry: optical models and measurements using a side-viewing gradient index lens-based endoscopic imaging system

NASA Astrophysics Data System (ADS)

Wall, R. Andrew; Barton, Jennifer K.

2014-06-01

A side-viewing, 2.3-mm diameter oblique incidence reflectometry endoscope has been designed to obtain optical property measurements of turbid samples. Light from a single-mode fiber is relayed obliquely onto the tissue with a gradient index lens-based distal optics assembly and the resulting diffuse reflectance profile is imaged and collected with a 30,000 element, 0.72 mm clear aperture fiber bundle. Sampling the diffuse reflectance in two-dimensions allows for fitting of the reflected intensity profile to a well-known theoretical model, permitting the extraction of both absorption and reduced scattering coefficients of the tissue sample. Models and measurements of the endoscopic imaging system are presented in tissue phantoms and in vivo mouse colon, verifying the endoscope's capabilities to accurately measure effective attenuation coefficient and differentiate diseased from normal colon.

Room temperature synthesis and optical properties of small diameter (5 nm) ZnO nanorod arrays.

PubMed

Cho, Seungho; Jang, Ji-Wook; Lee, Jae Sung; Lee, Kun-Hong

2010-10-01

We report a simple wet-chemical synthesis of ∼5 nm diameter ZnO nanorod arrays at room temperature (20 °C) and normal atmospheric pressure (1 atm) and their optical properties. They were single crystalline in nature, and grew in the [001] direction. These small diameter ZnO nanorod arrays can also be synthesized at 0 °C. Control experiments were also conducted. On the basis of the results, we propose a mechanism for the spontaneous growth of the small diameter ZnO structures. The optical properties of the 5 nm diameter ZnO nanorod arrays synthesized using this method were probed by UV-Visible diffuse reflectance spectroscopy. A clear blue-shift, relative to the absorption band from 50 nm diameter ZnO nanorod arrays, was attributed to the quantum confinement effects caused by the small nanocrystal size in the 5 nm diameter ZnO nanorods.

Transition from two-dimensional photonic crystals to dielectric metasurfaces in the optical diffraction with a fine structure

PubMed Central

Rybin, Mikhail V.; Samusev, Kirill B.; Lukashenko, Stanislav Yu.; Kivshar, Yuri S.; Limonov, Mikhail F.

2016-01-01

We study experimentally a fine structure of the optical Laue diffraction from two-dimensional periodic photonic lattices. The periodic photonic lattices with the C4v square symmetry, orthogonal C2v symmetry, and hexagonal C6v symmetry are composed of submicron dielectric elements fabricated by the direct laser writing technique. We observe surprisingly strong optical diffraction from a finite number of elements that provides an excellent tool to determine not only the symmetry but also exact number of particles in the finite-length structure and the sample shape. Using different samples with orthogonal C2v symmetry and varying the lattice spacing, we observe experimentally a transition between the regime of multi-order diffraction, being typical for photonic crystals to the regime where only the zero-order diffraction can be observed, being is a clear fingerprint of dielectric metasurfaces characterized by effective parameters. PMID:27491952

Optical single sideband millimeter-wave signal generation and transmission using 120° hybrid coupler

NASA Astrophysics Data System (ADS)

Zheng, Zhiwei; Peng, Miao; Zhou, Hui; Chen, Ming; Jiang, Leyong; Tan, Li; Dai, Xiaoyu; Xiang, Yuanjiang

2018-03-01

We propose a novel 60 GHz optical single sideband (OSSB) millimeter-wave (mm-wave) signal generation scheme using 120° hybrid coupler based on external integrated Mach-Zehnder modulator (MZM). The proposed scheme shows that the bit error ratio (BER) performance is improved by suppressing the +2nd-order sideband. Meanwhile, the transmission distance is extended as only the optical +1st-order sideband is modulated by using 5 Gbit/s baseband signal while the carrier is blank, owing to the elimination of walk-off effect suffered from fiber dispersion. The simulation results demonstrated that the eye diagrams of the generated 60 GHz OSSB signal keep open and clear after 100 km standard single-mode fiber (SSMF). In addition, the proposed scheme can achieve 2 dB receiver sensitivity improvements than the conventional 90° hybrid coupler when transmitted over 100 km SSMF at a BER of 10-9.

A new method for the assessment of the surface topography of NiTi rotary instruments.

PubMed

Ferreira, F; Barbosa, I; Scelza, P; Russano, D; Neff, J; Montagnana, M; Zaccaro Scelza, M

2017-09-01

To describe a new method for the assessment of nanoscale alterations in the surface topography of nickel-titanium endodontic instruments using a high-resolution optical method and to verify the accuracy of the technique. Noncontact three-dimensional optical profilometry was used to evaluate defects on a size 25, .08 taper reciprocating instrument (WaveOne ® ), which was subjected to a cyclic fatigue test in a simulated root canal in a clear resin block. For the investigation, an original procedure was established for the analysis of similar areas located 3 mm from the tip of the instrument before and after canal preparation to enable the repeatability and reproducibility of the measurements with precision. All observations and analysis were taken in areas measuring 210 × 210 μm provided by the software of the equipment. The three-dimensional high-resolution image analysis showed clear alterations in the surface topography of the examined cutting blade and flute of the instrument, before and after use, with the presence of surface irregularities such as deformations, debris, grooves, cracks, steps and microcavities. Optical profilometry provided accurate qualitative nanoscale evaluation of similar surfaces before and after the fatigue test. The stability and repeatability of the technique enables a more comprehensive understanding of the effects of wear on the surface of endodontic instruments. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Systematic investigation of the optical coatings damages induced in harsh space environment

NASA Astrophysics Data System (ADS)

Corso, Alain Jody; Tessarolo, Enrico; Martucci, Alessandro; Pelizzo, Maria Guglielmina

2017-09-01

The scientific goals required to the next-generation space missions lead the development of innovative instrumentation, conceived to operate in increasingly harsh environments. Optical coatings are among the sub-systems which can highly suffer the agents in such environments. In particular, as recently demonstrated, the accelerated ions and particles can potentially jeopardize the coatings optical performances, with a consequent degradation of the overall functionality of an instrument. Despite its importance, this issue is still poorly investigated. In fact, the fragmentary knowledge of the space environments and the low number of previous ground testing experiments complicates the definition of clear procedures to investigate the behavior of the optical coatings in space. A systematic approach devoted to identify a methodology for the validation of optical coatings under ions irradiation is presented. Monte Carlo simulations are used to evaluate the effects induced by different ion species and energies on both layers and multilayers of different materials, getting an accurate overview of the main criticalities. Such results are then used to plan representative irradiation experiments and the subsequent analysis procedures needed for a proper characterization of the exposed samples. In this paper, a summary of the experiments performed so far is presented. Thanks to these studies we have identified three main damage mechanisms which can be used to explain most of the degradation effects observed when an optical coating is irradiated with low energy particles. A brief discussion of such mechanisms is reported.

Measuring optical properties of a blood vessel model using optical coherence tomography

NASA Astrophysics Data System (ADS)

Levitz, David; Hinds, Monica T.; Tran, Noi; Vartanian, Keri; Hanson, Stephen R.; Jacques, Steven L.

2006-02-01

In this paper we develop the concept of a tissue-engineered optical phantom that uses engineered tissue as a phantom for calibration and optimization of biomedical optics instrumentation. With this method, the effects of biological processes on measured signals can be studied in a well controlled manner. To demonstrate this concept, we attempted to investigate how the cellular remodeling of a collagen matrix affected the optical properties extracted from optical coherence tomography (OCT) images of the samples. Tissue-engineered optical phantoms of the vascular system were created by seeding smooth muscle cells in a collagen matrix. Four different optical properties were evaluated by fitting the OCT signal to 2 different models: the sample reflectivity ρ and attenuation parameter μ were extracted from the single scattering model, and the scattering coefficient μ s and root-mean-square scattering angle θ rms were extracted from the extended Huygens-Fresnel model. We found that while contraction of the smooth muscle cells was clearly evident macroscopically, on the microscopic scale very few cells were actually embedded in the collagen. Consequently, no significant difference between the cellular and acellular samples in either set of measured optical properties was observed. We believe that further optimization of our tissue-engineering methods is needed in order to make the histology and biochemistry of the cellular samples sufficiently different from the acellular samples on the microscopic level. Once these methods are optimized, we can better verify whether the optical properties of the cellular and acellular collagen samples differ.

Optics vs copper: from the perspective of "Thunderbolt" interconnect technology

NASA Astrophysics Data System (ADS)

Cheng, Hengju; Krause, Christine; Ko, Jamyuen; Gao, Miaobin; Liu, Guobin; Wu, Huichin; Qi, Mike; Lam, Chun-Chit

2013-02-01

Interconnect technology has been progressed at a very fast pace for the past decade. The signaling rates have steadily increased from 100:Mb/s to 25Gb/s. In every generation of interconnect technology evolution, optics always seems to take over at first, however, at the end, the cost advantage of copper wins over. Because of this, optical interconnects are limited to longer distance links where the attenuation in copper cable is too large for the integrated circuits to compensate. Optical interconnect has long been viewed as the premier solution in compared with copper interconnect. With the release of Thunderbolt technology, we are entering a new era in consumer electronics that runs at 10Gb/s line rate (20Gb/s throughput per connector interface). Thunderbolt interconnect technology includes both active copper cables and active optical cables as the transmission media which have very different physical characteristics. In order for optics to succeed in consumer electronics, several technology hurdles need to be cleared. For example, the optical cable needs to handle the consumer abuses such as pinch and bend. Also, the optical engine used in the active optical cable needs to be physically very small so that we don't change the looks and feels of the cable/connector. Most importantly, the cost of optics needs to come down significantly to effectively compete with the copper solution. Two interconnect technologies are compared and discussed on the relative cost, power consumption, form factor, density, and future scalability.

The Effect of Eye Patching on Clear Corneal Incision Architecture in Phacoemulsification: A Randomized Controlled Trial.

PubMed

Ho, Fui Li; Salowi, Mohamad Aziz; Bastion, Mae-Lynn Catherine

2017-01-01

To investigate the effects of postoperative eye patching on clear corneal incision architecture in phacoemulsification. A single-center, randomized controlled trial. A total of 132 patients with uncomplicated phacoemulsification were randomly allocated to the intervention or control group. The intervention group received postoperative eye patching for approximately 18 hours, whereas the control group received eye shield. The clear corneal incision architecture was examined postoperatively at 2 hours, 1 day, and 7 days after surgery using optical coherence tomography. Epithelial gaping was significantly reduced on postoperative day 1 in the intervention group (52.4%) compared with control (74.2%) (P = 0.01). No differences were found for other architectural defects. Descemet membrane detachment was associated with lower intraocular pressure on postoperative day 7 (P = 0.02). Presence of underlying diabetes mellitus did not seem to influence architectural defects. Postoperative eye patching facilitated epithelial healing and reduced the occurrence of epithelial gaping on postoperative day 1. It may play a role in protecting and improving corneal wounds during the critical immediate postoperative period. Copyright 2017 Asia-Pacific Academy of Ophthalmology.

Longterm and spatial variability of Aerosol optical properties measured by sky radiometer in Japan sites

NASA Astrophysics Data System (ADS)

Aoki, K.

2016-12-01

Aerosols and cloud play an important role in the climate change. We started the long-term monitoring of aerosol and cloud optical properties since 1990's by using sky radiometer (POM-01, 02; Prede Co. Ltd., Japan). We provide the information, in this presentation, on the aerosol optical properties with respect to their temporal and spatial variability in Japan site (ex. Sapporo, Toyama, Kasuga and etc). The global distributions of aerosols have been derived from earth observation satellite and have been simulated in numerical models, which assume optical parameters. However, these distributions are difficult to derive because of variability in time and space. Therefore, Aerosol optical properties were investigated using the measurements from ground-based and ship-borne sky radiometer. The sky radiometer is an automatic instrument that takes observations only in daytime under the clear sky conditions. Observation of diffuse solar intensity interval was made every ten or five minutes by once. The aerosol optical properties were computed using the SKYRAD.pack version 4.2. The obtained Aerosol optical properties (Aerosol optical thickness, Ångström exponent, Single scattering albedo, and etc.) and size distribution volume clearly showed spatial and temporal variability in Japan area. In this study, we present the temporal and spatial variability of Aerosol optical properties at several Japan sites, applied to validation of satellite and numerical models. This project is validation satellite of GCOM-C, JAXA. The GCOM-C satellite scheduled to be launched in early 2017.

Modeling optical and UV polarization of AGNs. IV. Polarization timing

NASA Astrophysics Data System (ADS)

Rojas Lobos, P. A.; Goosmann, R. W.; Marin, F.; Savić, D.

2018-03-01

Context. Optical observations cannot resolve the structure of active galactic nuclei (AGN), and a unified model for AGN was inferred mostly from indirect methods, such as spectroscopy and variability studies. Optical reverberation mapping allowed us to constrain the spatial dimension of the broad emission line region and thereby to measure the mass of supermassive black holes. Recently, reverberation was also applied to the polarized signal emerging from different AGN components. In principle, this should allow us to measure the spatial dimensions of the sub-parsec reprocessing media. Aim. We conduct numerical modeling of polarization reverberation and provide theoretical predictions for the polarization time lag induced by different AGN components. The model parameters are adjusted to the observational appearance of the Seyfert 1 galaxy NGC 4151. Methods: We modeled scattering-induced polarization and tested different geometries for the circumnuclear dust component. Our tests included the effects of clumpiness and different dust prescriptions. To further extend the model, we also explored the effects of additional ionized winds stretched along the polar direction, and of an equatorial scattering ring that is responsible for the polarization angle observed in pole-on AGN. The simulations were run using a time-dependent version of the STOKES code. Results: Our modeling confirms the previously found polarization characteristics as a function of the observer`s viewing angle. When the dust adopts a flared-disk geometry, the lags reveal a clear difference between type 1 and type 2 AGN. This distinction is less clear for a torus geometry where the time lag is more sensitive to the geometry and optical depth of the inner surface layers of the funnel. The presence of a scattering equatorial ring and ionized outflows increased the recorded polarization time lags, and the polar outflows smooths out dependence on viewing angle, especially for the higher optical depth of the wind (τ = 0.3). Conclusions: Together with other AGN observables, the polarization time lag places new, independent "seismological" constraints on the inner geometry of AGN. If we conduct time-dependent spectropolarimetric observing campaigns of AGN, this method has a high potential for a census of supermassive black holes.

Optical vortices with starlight

NASA Astrophysics Data System (ADS)

Anzolin, G.; Tamburini, F.; Bianchini, A.; Umbriaco, G.; Barbieri, C.

2008-09-01

Aims: In this paper we present our first observations at the Asiago 122 cm telescope of ℓ = 1 optical vortices generated with starlight beams. Methods: We used a fork-hologram blazed at the first diffraction order as a phase modifying device. The multiple system Rasalgethi (α Herculis) in white light and the single star Arcturus (α Bootis) through a 300 Å bandpass were observed using a fast CCD camera. In the first case we could adopt the Lucky Imaging approach to partially correct for seeing effects. Results: For both stars, the optical vortices could be clearly detected above the smearing caused by the mediocre seeing conditions. The profiles of the optical vortices produced by the beams of the two main components of the α Her system are consistent with numerically simulated on-axis and off-axis optical vortices. The optical vortices produced by α Boo can also be reproduced by numerical simulations. Our experiments confirm that the ratio between the intensity peaks of an optical vortex can be extremely sensitive to off-axis displacements of the beam. Conclusions: Our results give insights for future astronomical applications of optical vortices both for space telescopes and ground-based telescopes with good seeing conditions and adaptive optics devices. The properties of optical vortices can be used to perform high precision astrometry and tip/tilt correction of the isoplanatic field. We are now designing a ℓ = 2 optical vortex coronagraph around a continuous spiral phase plate. We also point out that optical vortices could find extremely interesting applications also in the infrared and radio wavelengths.

Biphoton optics

NASA Astrophysics Data System (ADS)

Strekalov, Dmitry Vladimirovich

1997-10-01

The subject of this dissertation is the study of the two- photon entanglement. This phenomenon has been paid a great deal of attention since 1935, when A. Einstein, B. Podolsky and N. Rosen asked their famous question, 'Can quantum-mechanical description of physical reality be considered complete?' An entangled system behavior is inconsistent with many classical concepts. Therefore, the understanding of two-photon entanglement is important for the foundations of quantum theory. A two-photon entangled sate represents a two-photon, or a biphoton, rather than two photons. The concept of biphoton as a single nonlocal quantum object is fundamentally different from the concept of a photon pair, as has been experimentally demonstrated in the present dissertation. Two-photon entanglement gives rise to unusual 'ghost' interference and diffraction, nonlocal geometrical phase, and other quantum phenomena originally studied in the present dissertation. The variety of available results calls for bringing them into a general system which we call Biphoton Optics. This is the main goal of this dissertation. Biphoton optics operate with two-photon wave packets, or with an equivalent concept of advanced wave. We show that in the framework of the advanced wave concept two-photon phenomena can be effectively described in terms of classical optics. Therefore the biphoton optics has the same structure as the classical optics. It includes two- photon geometrical optics, dispersion and frequency beating, polarization effects, interference, diffraction, and geometrical phase. All these two-photon effects are represented by experiments included in this dissertation. Our approach does not make two-photon quantum effects 'classical', however. It should be understood that the advanced wave model operates with counter-propagation in time which does not correspond to any real physical process. Therefore it is just a model, but it is clearly a great advantage to have such a model that is both simple and powerful, in terms of its ability to describe the known results and accurately predict the new ones. Therefore an important step is made in understanding and describing of the quantum phenomena of two-photon entanglement.

Graphene-based carbon-layered electrode array technology for neural imaging and optogenetic applications

PubMed Central

Park, Dong-Wook; Schendel, Amelia A.; Mikael, Solomon; Brodnick, Sarah K.; Richner, Thomas J.; Ness, Jared P.; Hayat, Mohammed R.; Atry, Farid; Frye, Seth T.; Pashaie, Ramin; Thongpang, Sanitta; Ma, Zhenqiang; Williams, Justin C.

2014-01-01

Neural micro-electrode arrays that are transparent over a broad wavelength spectrum from ultraviolet to infrared could allow for simultaneous electrophysiology and optical imaging, as well as optogenetic modulation of the underlying brain tissue. The long-term biocompatibility and reliability of neural micro-electrodes also require their mechanical flexibility and compliance with soft tissues. Here we present a graphene-based, carbon-layered electrode array (CLEAR) device, which can be implanted on the brain surface in rodents for high-resolution neurophysiological recording. We characterize optical transparency of the device at >90% transmission over the ultraviolet to infrared spectrum and demonstrate its utility through optical interface experiments that use this broad spectrum transparency. These include optogenetic activation of focal cortical areas directly beneath electrodes, in vivo imaging of the cortical vasculature via fluorescence microscopy and 3D optical coherence tomography. This study demonstrates an array of interfacing abilities of the CLEAR device and its utility for neural applications. PMID:25327513

Particle image velocimetry measurements in an anatomical vascular model fabricated using inkjet 3D printing

NASA Astrophysics Data System (ADS)

Aycock, Kenneth I.; Hariharan, Prasanna; Craven, Brent A.

2017-11-01

For decades, the study of biomedical fluid dynamics using optical flow visualization and measurement techniques has been limited by the inability to fabricate transparent physical models that realistically replicate the complex morphology of biological lumens. In this study, we present an approach for producing optically transparent anatomical models that are suitable for particle image velocimetry (PIV) using a common 3D inkjet printing process (PolyJet) and stock resin (VeroClear). By matching the index of refraction of the VeroClear material using a room-temperature mixture of water, sodium iodide, and glycerol, and by printing the part in an orientation such that the flat, optical surfaces are at an approximately 45° angle to the build plane, we overcome the challenges associated with using this 3D printing technique for PIV. Here, we summarize our methodology and demonstrate the process and the resultant PIV measurements of flow in an optically transparent anatomical model of the human inferior vena cava.

Mechanical and optical characterization of tungsten oxynitride (W-O-N) nano-coatings

NASA Astrophysics Data System (ADS)

Nunez, Oscar Roberto

Aation and cation doping of transition metal oxides has recently gained attention as a viable option to design materials for application in solar energy conversion, photo-catalysis, transparent electrodes, photo-electrochemical cells, electrochromics and flat panel displays in optoelectronics. Specifically, nitrogen doped tungsten oxide (WO3) has gained much attention for its ability to facilitate optical property tuning while also demonstrating enhanced photo-catalytic and photochemical properties. The effect of nitrogen chemistry and mechanics on the optical and mechanical properties of tungsten oxynitride (W-O-N) nano-coatings is studied in detail in this work. The W-O-N coatings were deposited by direct current (DC) sputtering to a thickness of ˜100 nm and the structural, compositional, optical and mechanical properties were characterized in order to gain a deeper understanding of the effects of nitrogen incorporation and chemical composition. All the W-O-N coatings fabricated under variable nitrogen gas flow rate were amorphous. X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectrometry (RBS) measurements revealed that nitrogen incorporation is effective only for a nitrogen gas flow rates ?9 sccm. Optical characterization using ultraviolet-visible-near infrared (UV-VIS-NIR) spectroscopy and spectroscopic ellipsometry (SE) indicate that the nitrogen incorporation induced effects on the optical parameters is significant. The band gap (Eg) values decreased from ˜2.99 eV to ˜1.89 eV indicating a transition from insulating WO3 to metallic-like W-N phase. Nano-mechanical characterization using indentation revealed a corresponding change in mechanical properties; maximum values of 4.46 GPa and 98.5 GPa were noted for hardness and Young?s modulus, respectively. The results demonstrate a clear relationship between the mechanical, physical and optical properties of amorphous W-O-N nano-coatings. The correlation presented in this thesis could provide a road-map to optimize and produce W-O-N nano-coatings with desired optical and mechanical properties for a given technological application in the field where structure, mechanical and optical properties are important.

Backscattering from a Gaussian distributed, perfectly conducting, rough surface

NASA Technical Reports Server (NTRS)

Brown, G. S.

1977-01-01

The problem of scattering by random surfaces possessing many scales of roughness is analyzed. The approach is applicable to bistatic scattering from dielectric surfaces, however, this specific analysis is restricted to backscattering from a perfectly conducting surface in order to more clearly illustrate the method. The surface is assumed to be Gaussian distributed so that the surface height can be split into large and small scale components, relative to the electromagnetic wavelength. A first order perturbation approach is employed wherein the scattering solution for the large scale structure is perturbed by the small scale diffraction effects. The scattering from the large scale structure is treated via geometrical optics techniques. The effect of the large scale surface structure is shown to be equivalent to a convolution in k-space of the height spectrum with the following: the shadowing function, a polarization and surface slope dependent function, and a Gaussian factor resulting from the unperturbed geometrical optics solution. This solution provides a continuous transition between the near normal incidence geometrical optics and wide angle Bragg scattering results.

Example MODIS Global Cloud Optical and Microphysical Properties: Comparisons between Terra and Aqua

NASA Technical Reports Server (NTRS)

Hubanks, P. A.; Platnick, S.; King, M. D.; Ackerman, S. A.; Frey, R. A.

2003-01-01

MODIS observations from the NASA EOS Terra spacecraft (launched in December 1999, 1030 local time equatorial crossing) have provided a unique data set of Earth observations. With the launch of the NASA Aqua spacecraft in May 2002 (1330 local time), two MODIS daytime (sunlit) and nighttime observations are now available in a 24 hour period, allowing for some measure of diurnal variability. We report on an initial analysis of several operational global (Level-3) cloud products from the two platforms. The MODIS atmosphere Level-3 products, which include clear-sky and aerosol products in addition to cloud products, are available as three separate files providing daily, eight-day, and monthly aggregations; each temporal aggregation is spatially aggregated to a 1 degree grid. The files contain approximately 600 statisitical datasets (from simple means and standard deviations to 1 - and 2-dimensional histograms). Operational cloud products include detection (cloud fraction), cloud-top properties, and daytimeonly cloud optical thickness and particle effective radius for both water and ice clouds. We will compare example global Terra and Aqua cloud fraction, optical thickness, and effective radius aggregations.

Derivation of an applied nonlinear Schroedinger equation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pitts, Todd Alan; Laine, Mark Richard; Schwarz, Jens

We derive from first principles a mathematical physics model useful for understanding nonlinear optical propagation (including filamentation). All assumptions necessary for the development are clearly explained. We include the Kerr effect, Raman scattering, and ionization (as well as linear and nonlinear shock, diffraction and dispersion). We explain the phenomenological sub-models and each assumption required to arrive at a complete and consistent theoretical description. The development includes the relationship between shock and ionization and demonstrates why inclusion of Drude model impedance effects alters the nature of the shock operator. Unclassified Unlimited Release

On Solar Cycle Predictions and Reconstructions

DTIC Science & Technology

2008-12-01

the At present it is still not fully clear whether solar activity optical assumptions (Wilson 1994; Beck el al. I995; Hathaway is purely stochastic... Beck et al. 1995). The Waldmeier effect was found to be a result of (or at least consistent with) var- ious dynamo models, starting with non-linear...Geophys. Res. Lett., 35, 1.20109 Beck . R., Hilbrecht, H., Reinsch, K., & Volker, P. 1995. Solar Astronomy Handbook (Richmond: Willmann-Bell) Beer. J

Observation of plasmonic dipolar anti-bonding mode in silver nanoring structures.

PubMed

Ye, Jian; Van Dorpe, Pol; Lagae, Liesbet; Maes, Guido; Borghs, Gustaaf

2009-11-18

We report on a clear experimental observation of the plasmonic dipolar anti-bonding resonance in silver nanorings. The data can be explained effectively by the plasmon hybridization model, which is confirmed by the numerical calculations of the electromagnetic field and surface charge distribution profiles. The experimental demonstration of the plasmon hybridization model indicates its usefulness as a valuable tool to understand, design and predict optical properties of metallic nanostructures.

Observation of plasmonic dipolar anti-bonding mode in silver nanoring structures

NASA Astrophysics Data System (ADS)

Ye, Jian; Van Dorpe, Pol; Lagae, Liesbet; Maes, Guido; Borghs, Gustaaf

2009-11-01

We report on a clear experimental observation of the plasmonic dipolar anti-bonding resonance in silver nanorings. The data can be explained effectively by the plasmon hybridization model, which is confirmed by the numerical calculations of the electromagnetic field and surface charge distribution profiles. The experimental demonstration of the plasmon hybridization model indicates its usefulness as a valuable tool to understand, design and predict optical properties of metallic nanostructures.

High Spectral Resolution Lidar Data

DOE Data Explorer

Eloranta, Ed

2004-12-01

The HSRL provided calibrated vertical profiles of optical depth, backscatter cross section and depoloarization at a wavelength of 532 nm. Profiles were acquired at 2.5 second intervals with 7.5 meter resolution. Profiles extended from an altitude of 100 m to 30 km in clear air. The lidar penetrated to a maximum optical depth of ~ 4 under cloudy conditions. Our data contributed directly to the aims of the M-PACE experiment, providing calibrated optical depth and optical backscatter measurements which were not available from any other instrument.

Pigment-dispersing factor sets the night state of the medulla bilateral neurons in the optic lobe of the cricket, Gryllus bimaculatus.

PubMed

Saifullah, A S M; Tomioka, Kenji

2003-03-01

Pigment-dispersing factor (PDF) is an octadeca-neuropeptide widely distributed in the insect brain and suggested to be involved in the insect circadian systems. We have examined its effects on the neuronal activity of the brain efferents in the optic stalk including medulla bilateral neurons (MBNs) in the cricket, Gryllus bimaculatus. The MBNs are visually responding interneurons connecting the bilateral medulla, which show a clear day/night change in their light responsiveness that is greater during the night. Microinjection of PDF into the optic lobe induced a significant increase in the spontaneous activity of the brain efferents and the photo-responsiveness of the MBNs during the day, while little change was induced during the night. The enhancing effects began to occur about 20 min after the injection and another 10 min was necessary to reach the maximal level. The effects of PDF were dose-dependent. When 22 nl of anti-Gryllus-PDF (1:200) IgG was injected into the medulla, the photo-responsiveness of the MBNs was suppressed in both the day and the night with greater magnitude during the night. No significant suppression was induced by injection of the same amount of IgG from normal rabbit serum. These results suggest that in the cricket optic lobe, PDF is released during the night and enhances MBNs' photo-responsiveness to set their night state.

The effect of dimethyl sulfoxide (DMSO) on dentin bonding and nanoleakage of etch-and-rinse adhesives.

PubMed

Tjäderhane, Leo; Mehtälä, Pekka; Scaffa, Polliana; Vidal, Cristina; Pääkkönen, Virve; Breschi, Lorenzo; Hebling, Josimeri; Tay, Franklin R; Nascimento, Fabio D; Pashley, David H; Carrilho, Marcela R

2013-10-01

The objective was to examine the effect of a solvent dimethyl sulfoxide (DMSO) on resin-dentin bond durability, as well as potential functional mechanisms behind the effect. Microtensile bond strength (μTBS) was evaluated in extracted human teeth in two separate experiments. Dentin specimens were acid-etched and assigned to pre-treatment with 0.5mM (0.004%) DMSO as additional primer for 30s and to controls with water pre-treatment. Two-step etch-and-rinse adhesive (Scotchbond 1XT, 3M ESPE) was applied and resin composite build-ups were created. Specimens were immediately tested for μTBS or stored in artificial saliva for 6 and 12 months prior to testing. Additional immediate and 6-month specimens were examined for interfacial nanoleakage analysis under SEM. Matrix metalloproteinase (MMP) inhibition by DMSO was examined with gelatin zymography. Demineralized dentin disks were incubated in 100% DMSO to observe the optical clearing effect. The use of 0.5mM DMSO had no effect on immediate bond strength or nanoleakage. In controls, μTBS decreased significantly after storage, but increased significantly in DMSO-treated group. The control group had significantly lower μTBS than DMSO-group after 6 and 12 months. DMSO also eliminated the increase in nanoleakage seen in controls. 5% and higher DMSO concentrations significantly inhibited the gelatinases. DMSO induced optical clearing effect demonstrating collagen dissociation. DMSO as a solvent may be useful in improving the preservation of long-term dentin-adhesive bond strength. The effect may relate to dentinal enzyme inhibition or improved wetting of collagen by adhesives. The collagen dissociation required much higher DMSO concentrations than the 0.5mM DMSO used for bonding. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

The Hubble Space Telescope optical systems failure report

NASA Technical Reports Server (NTRS)

1990-01-01

The findings of the Hubble Space Telescope Optical Systems Board of Investigation are reported. The Board was formed to determine the cause of the flaw in the telescope, how it occurred, and why it was not detected before launch. The Board conducted its investigation to include interviews with personnel involved in the fabrication and test of the telescope, review of documentation, and analysis and test of the equipment used in the fabrication of the telescope's mirrors. The investigation proved that the primary mirror was made in the wrong shape (a 0.4-wave rms wavefront error at 632.8 nm). The primary mirror was manufactured by the Perkin-Elmer Corporation (Hughes Danbury Optical Systems, Inc.). The critical optics used as a template in shaping the mirror, the reflective null corrector (RNC), consisted of two small mirrors and a lens. This unit had been preserved by the manufacturer exactly as it was during the manufacture of the mirror. When the Board measured the RNC, the lens was incorrectly spaced from the mirrors. Calculations of the effect of such displacement on the primary mirror show that the measured amount, 1.3 mm, accounts in detail for the amount and character of the observed image blurring. No verification of the reflective null corrector's dimensions was carried out by Perkin-Elmer after the original assembly. There were, however, clear indications of the problem from auxiliary optical tests made at the time. A special optical unit called an inverse null corrector, designed to mimic the reflection from a perfect primary mirror, was built and used to align the apparatus; when so used, it clearly showed the error in the reflective null corrector. A second null corrector was used to measure the vertex radius of the finished primary mirror. It, too, clearly showed the error in the primary mirror. Both indicators of error were discounted at the time as being themselves flawed. The Perkin-Elmer plan for fabricating the primary mirror placed complete reliance on the reflective null corrector as the only test to be used in both manufacturing and verifying the mirror's surface with the required precision. This methodology should have alerted NASA management to the fragility of the process and the possibility of gross error. Such errors had been seen in other telescope programs, yet no independent tests were planned, although some simple tests to protect against major error were considered and rejected. During the critical time period, there was great concern about cost and schedule, which further inhibited consideration of independent tests.

Nanodiamond in Colloidal Suspension: Electrophoresis; Other Observations

NASA Technical Reports Server (NTRS)

Meshik, A. P.; Pravdivtseva, O. V.; Hohenberg, C. M.

2002-01-01

Selective laser extraction has demonstrated that meteoritic diamonds may consist of subpopulations with different optical absorption properties, but it is not clear what makes them optically different. More work is needed to understand the mechanism for selective laser extraction. Additional information is contained in the original extended abstract.

Aerosol optical depth under "clear" sky conditions derived from sea surface reflection of lidar signals.

PubMed

He, Min; Hu, Yongxiang; Huang, Jian Ping; Stamnes, Knut

2016-12-26

There are considerable demands for accurate atmospheric correction of satellite observations of the sea surface or subsurface signal. Surface and sub-surface reflection under "clear" atmospheric conditions can be used to study atmospheric correction for the simplest possible situation. Here "clear" sky means a cloud-free atmosphere with sufficiently small aerosol particles. The "clear" aerosol concept is defined according to the spectral dependence of the scattering cross section on particle size. A 5-year combined CALIPSO and AMSR-E data set was used to derive the aerosol optical depth (AOD) from the lidar signal reflected from the sea surface. Compared with the traditional lidar-retrieved AOD, which relies on lidar backscattering measurements and an assumed lidar ratio, the AOD retrieved through the surface reflectance method depends on both scattering and absorption because it is based on two-way attenuation of the lidar signal transmitted to and then reflected from the surface. The results show that the clear sky AOD derived from the surface signal agrees with the clear sky AOD available in the CALIPSO level 2 database in the westerly wind belt located in the southern hemisphere, but yields significantly higher aerosol loadings in the tropics and in the northern hemisphere.

Fabrication and performance analysis of a high-coupling-efficiency and convenient-integration optical transceiver

NASA Astrophysics Data System (ADS)

He, Hui-min; Liu, Feng-man; Xue, Hai-yun; Wu, Peng; Song, Man-gu; Sun, Yu; Cao, Li-qiang

2017-07-01

An optical transceiver with a novel optical subassembly structure is proposed in this paper, which achieves high coupling efficiency and low assembly difficulty. The proposed optical transceiver consumes 0.9 W power and retains a small size of 28 mm×16 mm×3 mm. The fabrication process of the silicon substrate and the assembly process of the optical transceiver are demonstrated in details. Moreover, the optical transceiver is measured in order to verify its transmission performance. The clear eye diagrams and the low bit error rate ( BER) less than 10-13 at 10 Gbit/s per channel show good transmission characteristics of the designed optical transceiver.

Design and fabrication of plasmonic cavities for magneto-optical sensing

NASA Astrophysics Data System (ADS)

Loughran, T. H. J.; Roth, J.; Keatley, P. S.; Hendry, E.; Barnes, W. L.; Hicken, R. J.; Einsle, J. F.; Amy, A.; Hendren, W.; Bowman, R. M.; Dawson, P.

2018-05-01

The design and fabrication of a novel plasmonic cavity, intended to allow far-field recovery of signals arising from near field magneto-optical interactions, is presented. Finite element modeling is used to describe the interaction between a gold film, containing cross-shaped cavities, with a nearby magnetic under-layer. The modeling revealed strong electric field confinement near the center of the cross structure for certain optical wavelengths, which may be tuned by varying the length of the cross through a range that is compatible with available fabrication techniques. Furthermore, the magneto optical Kerr effect (MOKE) response of the composite structure can be enhanced with respect to that of the bare magnetic film. To confirm these findings, cavities were milled within gold films deposited upon a soluble film, allowing relocation to a ferromagnetic film using a float transfer technique. Cross cavity arrays were fabricated and characterized by optical transmission spectroscopy prior to floating, revealing resonances at optical wavelengths in good agreement with the finite element modeling. Following transfer to the magnetic film, circular test apertures within the gold film yielded clear magneto-optical signals even for diameters within the sub-wavelength regime. However, no magneto-optical signal was observed for the cross cavity arrays, since the FIB milling process was found to produce nanotube structures within the soluble under-layer that adhered to the gold. Further optimization of the fabrication process should allow recovery of magneto-optical signal from cross cavity structures.

OCT analysis of microneedle and Er:YAG surface ablation for enhanced transdermal delivery of hyperosmotic agents for optical skin clearing

NASA Astrophysics Data System (ADS)

Stumpp, Oliver F.; Welch, A. J.; Gill, Harvinder S.; Prausnitz, Mark R.

2004-07-01

The purpose of this study is to investigate the feasibility of using microneedles in comparison to Er:YAG skin surface laser ablation as a means to modify the epidermis of in-vitro hamster skin to facilitate delivery of topically applied hyper-osmotics such as glycerol into the skin to achieve optical skin clearing. This allows to temporarily reduce scattering of light in otherwise turbid tissues with potential applications pertaining to non-invasive optical imaging techniques such as optical coherence tomography (OCT) or therapeutic applications like laser blood vessel coagulation to treat port wine stains in skin. A portable, battery powered Er:YAG laser (Lasette) manufactured by Cell Robotics Inc. was used to produce holes in the stratum corneum and epidermis using individual 400 μs pulses causing localized ablation. Following each laser pulse the tissue was mechanically translated by 1 mm before another pulse was delivered. As an alternative method to the use of an expensive laser source requiring some kind of light scanning mechanism to treat larger skin areas efficiently, microneedles were investigated. They do not require an energy supply, are also pain-free and can be manufactured into arrays allowing treatment of larger skin areas. A single application forms micron scale holes in the stratum corneum through which topically applied skin clearing agents such as glycerol can penetrate into the tissue. In this feasibility study individual microneedles were used to manually induce holes in the skin each spaced approximately 1 mm apart from the other. Upon such epidermal modification by either technique, glycerol was then applied to the tissue surface and amplitude OCT measurements monitored changes of the optical properties of the tissue over time. Due to the geometry of the microneedle used in this study the cross sectional area of each hole in the epidermis was about 68% smaller than the comparable ablation site caused by an individual laser pulse. Results indicate enhanced skin clearing rates due to the induced holes in the stratum corneum in both cases by a factor of 5 to 8. Due to the larger area of laser ablation in comparison to the holes caused by microneedles, overall skin clearing rates are higher with the laser. However, localized data analysis near holes produced by either technique yields comparable results which show an increase in the clearing rate of up to 10 to 13 times over intact skin without any holes.

Cascaded two-photon nonlinearity in a one-dimensional waveguide with multiple two-level emitters

PubMed Central

Roy, Dibyendu

2013-01-01

We propose and theoretically investigate a model to realize cascaded optical nonlinearity with few atoms and photons in one-dimension (1D). The optical nonlinearity in our system is mediated by resonant interactions of photons with two-level emitters, such as atoms or quantum dots in a 1D photonic waveguide. Multi-photon transmission in the waveguide is nonreciprocal when the emitters have different transition energies. Our theory provides a clear physical understanding of the origin of nonreciprocity in the presence of cascaded nonlinearity. We show how various two-photon nonlinear effects including spatial attraction and repulsion between photons, background fluorescence can be tuned by changing the number of emitters and the coupling between emitters (controlled by the separation). PMID:23948782

Optics-based compressibility parameter for pharmaceutical tablets obtained with the aid of the terahertz refractive index.

PubMed

Chakraborty, Mousumi; Ridgway, Cathy; Bawuah, Prince; Markl, Daniel; Gane, Patrick A C; Ketolainen, Jarkko; Zeitler, J Axel; Peiponen, Kai-Erik

2017-06-15

The objective of this study is to propose a novel optical compressibility parameter for porous pharmaceutical tablets. This parameter is defined with the aid of the effective refractive index of a tablet that is obtained from non-destructive and contactless terahertz (THz) time-delay transmission measurement. The optical compressibility parameter of two training sets of pharmaceutical tablets with a priori known porosity and mass fraction of a drug was investigated. Both pharmaceutical sets were compressed with one of the most commonly used excipients, namely microcrystalline cellulose (MCC) and drug Indomethacin. The optical compressibility clearly correlates with the skeletal bulk modulus determined by mercury porosimetry and the recently proposed terahertz lumped structural parameter calculated from terahertz measurements. This lumped structural parameter can be used to analyse the pattern of arrangement of excipient and drug particles in porous pharmaceutical tablets. Therefore, we propose that the optical compressibility can serve as a quality parameter of a pharmaceutical tablet corresponding with the skeletal bulk modulus of the porous tablet, which is related to structural arrangement of the powder particles in the tablet. Copyright © 2017 Elsevier B.V. All rights reserved.

Cost-effective parallel optical interconnection module based on fully passive-alignment process

NASA Astrophysics Data System (ADS)

Son, Dong Hoon; Heo, Young Soon; Park, Hyoung-Jun; Kang, Hyun Seo; Kim, Sung Chang

2017-11-01

In optical interconnection technology, high-speed and large data transitions with low error rate and cost reduction are key issues for the upcoming 8K media era. The researchers present notable types of optical manufacturing structures of a four-channel parallel optical module by fully passive alignment, which are able to reduce manufacturing time and cost. Each of the components, such as vertical-cavity surface laser/positive-intrinsic negative-photodiode array, microlens array, fiber array, and receiver (RX)/transmitter (TX) integrated circuit, is integrated successfully using flip-chip bonding, die bonding, and passive alignment with a microscope. Clear eye diagrams are obtained by 25.78-Gb/s (for TX) and 25.7-Gb/s (for RX) nonreturn-to-zero signals of pseudorandom binary sequence with a pattern length of 231 to 1. The measured responsivity and minimum sensitivity of the RX are about 0.5 A/W and ≤-6.5 dBm at a bit error rate (BER) of 10-12, respectively. The optical power margin at a BER of 10-12 is 7.5 dB, and cross talk by the adjacent channel is ≤1 dB.

Fused-fiber-based 3-dB mode insensitive power splitters for few-mode optical fiber networks

NASA Astrophysics Data System (ADS)

Ren, Fang; Huang, Xiaoshan; Wang, Jianping

2017-11-01

We propose a 3-dB mode insensitive power splitter (MIPS) capable of broadcasting and combining optical signals. It is fabricated with two identical few-mode fibers (FMFs) by a heating and pulling technique. The mode-dependent power transfer characteristic as a function of pulling length is investigated. For exploiting its application, we experimentally demonstrate both FMF-based transmissive and reflective star couplers consisting of multiple 3-dB mode insensitive power splitters, which perform broadcasting and routing signals in few-mode optical fiber networks such as mode-division multiplexing (MDM) local area networks using star topology. For experimental demonstration, optical on-off keying signals at 10 Gb/s carried on three spatial modes are successfully processed with open and clear eye diagrams. Measured bit error ratio results show reasonable power penalties. It is found that a reflective star coupler in MDM networks can reduce half of the total amount of required fibers comparing to that of a transmissive star coupler. This MIPS is more efficient, more reliable, more flexible, and more cost-effective for future expansion and application in few-mode optical fiber networks.

Development of a 0.5m clear aperture Cassegrain type collimator telescope

NASA Astrophysics Data System (ADS)

Ekinci, Mustafa; Selimoǧlu, Özgür

2016-07-01

Collimator is an optical instrument used to evaluate performance of high precision instruments, especially space-born high resolution telescopes. Optical quality of the collimator telescope needs to be better than the instrument to be measured. This requirement leads collimator telescope to be a very precise instrument with high quality mirrors and a stable structure to keep it operational under specified conditions. In order to achieve precision requirements and to ensure repeatability of the mounts for polishing and metrology, opto-mechanical principles are applied to mirror mounts. Finite Element Method is utilized to simulate gravity effects, integration errors and temperature variations. Finite element analyses results of deformed optical surfaces are imported to optical domain by using Zernike polynomials to evaluate the design against specified WFE requirements. Both mirrors are aspheric and made from Zerodur for its stability and near zero CTE, M1 is further light-weighted. Optical quality measurements of the mirrors are achieved by using custom made CGHs on an interferometric test setup. Spider of the Cassegrain collimator telescope has a flexural adjustment mechanism driven by precise micrometers to overcome tilt errors originating from finite stiffness of the structure and integration errors. Collimator telescope is assembled and alignment methods are proposed.

Parabolic Dish Concentrator (PDC-1)

NASA Technical Reports Server (NTRS)

Dennison, E. W.; Argoud, M. J.

1984-01-01

The design, construction, and installation of the Parabolic Dish Concentrator, Type 1 (PDC-1) has been one of the most significant JPL concentrator projects because of the knowledge gained about this type of concentrator and the development of design, testing, and analysis procedures which are applicable to all solar concentrator projects. The need for these procedures was more clearly understood during the testing period which started with the prototype panel evaluation and ended with the performance characterization of the completed concentrator. For each phase of the test program, practical test procedures were required and these procedures defined the mathematical analysis which was essential for successful concentrator development. The concentrator performance appears to be limited only by the distortions resulting from thermal gradients through the reflecting panels. Simple optical testing can be extremely effective, but comprehensive mechanical and optical analysis is essential for cost effective solar concentrator development.

Plasma exchange therapy in steroid-unresponsive relapses in patients with multiple sclerosis.

PubMed

Trebst, Corinna; Reising, Ansgar; Kielstein, Jan T; Hafer, Carsten; Stangel, Martin

2009-01-01

Plasma exchange (PE) is well established for conditions such as rapid progressive vasculitis associated with autoantibodies against neutrophil cytoplasmic antigens (ANCA), anti-glomerular basement membrane (GBM) antibody disease, or thrombotic thrombocytopenic purpura (TTP). Also, several neurological disorders, such as acute worsening in myasthenia gravis, Guillan-Barré syndrome (GBS) and chronic inflammatory demyelinating polyneuropathy (CIDP), can successfully be treated with PE. Only small case series have previously shown that PE is also effective in relapses in patients with multiple sclerosis (MS). We report our experiences of PE therapy in a series of 20 patients with 21 steroid unresponsive MS relapses. A marked-to-moderate clinical response with clear gain of function in 76% of patients with uni- or bilateral optic neuritis and in 87.5% of patients with relapses other than optic neuritis was observed. PE is an effective and well tolerated therapeutic option for steroid-unresponsive MS relapses.

Effect of Carrier Thermalization Dynamics on Light Emission and Amplification in Organometal Halide Perovskites.

PubMed

Chen, Kai; Barker, Alex J; Morgan, Francis L C; Halpert, Jonathan E; Hodgkiss, Justin M

2015-01-02

The remarkable rise of organometal halide perovskites as solar photovoltaic materials has been followed by promising developments in light-emitting devices, including lasers. Here we present unique insights into the processes leading to photon emission in these materials. We employ ultrafast broadband photoluminescence (PL) and transient absorption spectroscopies to directly link density dependent ultrafast charge dynamics to PL. We find that exceptionally strong PL at the band edge is preceded by thermalization of free charge carriers. Short-lived PL above the band gap is clear evidence of nonexcitonic emission from hot carriers, and ultrafast PL depolarization confirms that uncorrelated charge pairs are precursors to photon emission. Carrier thermalization has a profound effect on amplified stimulated emission at high fluence; the delayed onset of optical gain we resolve within the first 10 ps and the unusual oscillatory behavior are both consequences of the kinetic interplay between carrier thermalization and optical gain.

GaSb/AlGaSb VCSEL structures and microcavities in the 1.5 μm wavelength range

NASA Astrophysics Data System (ADS)

Koeth, J.; Dietrich, R.; Reithmaier, J. P.; Forchel, A.

Vertical cavity surface emitting laser structures for 1.5 μm wavelength applications were realized by growing AlSb/AlGaSb Bragg mirrors on GaAs substrates with solid source molecular beam epitaxy. Due to the high refractive index contrast between GaSb and AlSb high quality resonators can be made by only 15 layer pairs for each Bragg mirror. Laser operation could be demonstrated by optical pumping with threshold excitation densities of about 500 W/cm2. In laterally deeply etched microcavities with diameters of 5 μm a clear discretization of the optical modes was observed. The lateral confinement effects are compared with results of AlAs/GaAs microcavities designed for 0.9 μm emission wavelength. Due to the longer wavelength a stronger confinement effect can be achieved in AlSb/AlGaSb microcavities for the same lateral dimensions.

Influence of aerosols on surface reaching spectral irradiance and introduction to a new technique for estimating aerosol radiative forcing from spectral flux measurements

NASA Astrophysics Data System (ADS)

Rao, R. R.

2015-12-01

Aerosol radiative forcing estimates with high certainty are required in climate change studies. The approach in estimating the aerosol radiative forcing by using the chemical composition of aerosols is not effective as the chemical composition data with radiative properties are not widely available. In this study we look into the approach where ground based spectral radiation flux measurements along with an RT model is used to estimate radiative forcing. Measurements of spectral flux were made using an ASD spectroradiometer with 350 - 1050 nm wavelength range and 3nm resolution for around 54 clear-sky days during which AOD range was around 0.1 to 0.7. Simultaneous measurements of black carbon were also made using Aethalometer (Magee Scientific) which ranged from around 1.5 ug/m3 to 8 ug/m3. All the measurements were made in the campus of Indian Institute of Science which is in the heart of Bangalore city. The primary study involved in understanding the sensitivity of spectral flux to change in the mass concentration of individual aerosol species (Optical properties of Aerosols and Clouds -OPAC classified aerosol species) using the SBDART RT model. This made us clearly distinguish the region of influence of different aerosol species on the spectral flux. Following this, a new technique has been introduced to estimate an optically equivalent mixture of aerosol species for the given location. The new method involves an iterative process where the mixture of aerosol species are changed in OPAC model and RT model is run as long as the mixture which mimics the measured spectral flux within 2-3% deviation from measured spectral flux is obtained. Using the optically equivalent aerosol mixture and RT model aerosol radiative forcing is estimated. The new method is limited to clear sky scenes and its accuracy to derive an optically equivalent aerosol mixture reduces when diffuse component of flux increases. Our analysis also showed that direct component of spectral flux is more sensitive to different aerosol species than total spectral flux which was also supported by our observed data.

Clear-Sky Narrowband Albedo Datasets Derived from Modis Data

NASA Astrophysics Data System (ADS)

Chen, Y.; Minnis, P.; Sun-Mack, S.; Arduini, R. F.; Hong, G.

2013-12-01

Satellite remote sensing of clouds requires an accurate estimate of the clear-sky radiances for a given scene to detect clouds and aerosols and to retrieve their microphysical properties. Knowing the spatial and angular variability of clear-sky albedo is essential for predicting the clear-sky radiance at solar wavelengths. The Clouds and the Earth's Radiant Energy System (CERES) Project uses the near-infrared (NIR; 1.24, 1.6 or 2.13 μm) and visible (VIS; 0.63 μm) channels available on the Terra and Aqua Moderate Resolution Imaging Spectroradiometers (MODIS) to help identify clouds and retrieve their properties. Generally, clear-sky albedo for a given surface type is determined for conditions when the vegetation is either thriving or dormant and free of snow. The clear-sky albedos are derived using a radiative transfer parameterization of the impact of the atmosphere, including aerosols, on the observed reflectances. This paper presents the method of generating monthly clear-sky overhead albedo maps for both snow-free and snow-covered surfaces of these channels using one year of MODIS (Moderate Resolution Imaging Spectroradiometer) CERES products. Maps of 1.24 and 1.6 μm are being used as the background to help retrieve cloud properties (e.g., effective particle size, optical depth) in CERES cloud retrievals in both snow-free and snow-covered conditions.

Optical clearing of vaginal tissues

NASA Astrophysics Data System (ADS)

Chang, Chun-Hung; Myers, Erinn M.; Kennelly, Michael J.; Fried, Nathaniel M.

2017-02-01

Near-IR laser energy in conjunction with applied tissue cooling is being investigated for thermal remodeling of endopelvic fascia during minimally invasive treatment of female stress urinary incontinence. Previous simulations of light transport, heat transfer, and tissue thermal damage have shown that a transvaginal approach is more feasible than a transurethral approach. However, undesirable thermal insult to vaginal wall was predicted. This study explores whether an optical clearing agent (OCA) can improve optical penetration depth and completely preserve vaginal wall during subsurface treatment of endopelvic fascia. Several OCA mixtures were tested, and 100% glycerol was found to be optimal. Optical transmission studies, optical coherence tomography, reflection spectroscopy, and computer simulations of thermal damage to tissue using glycerol were performed. The OCA produced a 61% increase in optical transmission through porcine vaginal wall at 37 °C after 30 min. Monte Carlo (MC) light transport, heat transfer, and Arrhenius integral thermal damage simulations were performed. MC model showed improved energy deposition in endopelvic fascia using OCA. Without OCA, 62, 37, and 1% of energy was deposited in vaginal wall, endopelvic fascia, and urethral wall, compared with 50, 49, and 1% with OCA. Use of OCA also yielded 0.5 mm increase in treatment depth, allowing potential thermal tissue remodeling at 3 mm depth.

NuSTAR and Swift Observations of the Dwarf Nova Z Camelpardalis in a Standstill

NASA Astrophysics Data System (ADS)

Mukai, Koji; Sokoloski, Jennifer; Nelson, Thomas; Luna, Gerardo Juan Manuel; Ringwald, Frederick

2018-01-01

Dwarf nova outbursts are dramatic increases in the optical/UV emission from the accretion disks surrounding non-magnetic, or weakly magnetic, white dwarfs, and they are believed to be caused by disk instabilities. During the optical outburst, the optically thin X-rays originating from the boundary layer between the disk and the white dwarf are known to become fainter and softer. However, during an outburst, neither the disk nor the boundary layer has the time to settle into a steady state, exhibiting clear hysteresis effects instead. The Z Cam-type dwarf novae exhibit a rare, third state called standstill, lasting several months to several years, at an optical brightness roughly one magnitude below outburst peak. A standstill is therefore an ideal opportunity to study a high-state disk while minimizing the hysteresis effects. Here we report our NuSTAR and Swift observations of the prototype, Z Cam, in late September, 2017, roughly 6 months into its most recent standstill episode. To the best of our knowledge, this is the first pointed X-ray observation of a Z Cam-type object in a standstill, and our preliminary analysis suggests Z Cam in standstill has X-ray properties broadly similar to those seen during past outbursts. We will describe these results and discuss implications for the disk physics.

Development of carbon dioxide laser doppler instrumentation detection of clear air turbulence

NASA Technical Reports Server (NTRS)

Sonnenschein, C.; Jelalian, A.; Keene, W.

1970-01-01

The analytical, experimental, and developmental aspects of an airborne, pulsed, carbon dioxide laser-optical radar system are described. The laser detects clear air turbulence and performs Doppler measurements of this air-motion phenomenon. Conclusions and recommendations arising from the development of the laser system are presented.

Plant Histology: Clearing and the Optical Section.

ERIC Educational Resources Information Center

Freeman, H. E.

1985-01-01

Clearing is a simple and rapid technique in which 75 percent lactic acid is used to remove pigments and cytoplasmic contents of fresh leaves, enabling microscopic view of various internal leaf layers. Procedures for using the technique (which helps students gain a more thorough understanding of plant anatomy) are given. (DH)

VCSEL-based optical transceiver module for high-speed short-reach interconnect

NASA Astrophysics Data System (ADS)

Yagisawa, Takatoshi; Oku, Hideki; Mori, Tatsuhiro; Tsudome, Rie; Tanaka, Kazuhiro; Daikuhara, Osamu; Komiyama, Takeshi; Ide, Satoshi

2017-02-01

Interconnects have been more important in high-performance computing systems and high-end servers beside its improvements in computing capability. Recently, active optical cables (AOCs) have started being used for this purpose instead of conventionally used copper cables. The AOC enables to extend the transmission distance of the high-speed signals dramatically by its broadband characteristics, however, it tend to increase the cost. In this paper, we report our developed quad small form-factor pluggable (QSFP) AOC utilizing cost-effective optical-module technologies. These are a unique structure using generally used flexible printed circuit (FPC) in combination with an optical waveguide that enables low-cost high-precision assembly with passive alignment, a lens-integrated ferrule that improves productivity by eliminating a polishing process for physical contact of standard PMT connector for the optical waveguide, and an overdrive technology that enables 100 Gb/s (25 Gb/s × 4-channel) operation with low-cost 14 Gb/s vertical-cavity surfaceemitting laser (VCSEL) array. The QSFP AOC demonstrated clear eye opening and error-free operation at 100 Gb/s with high yield rate even though the 14 Gb/s VCSEL was used thanks to the low-coupling loss resulting from the highprecision alignment of optical devices and the over-drive technology.

Black phosphorus quantum dots for femtosecond laser photonics

NASA Astrophysics Data System (ADS)

Liu, Meng; Jiang, Xiao-Fang; Yan, Yu-Rong; Wang, Xu-De; Luo, Ai-Ping; Xu, Wen-Cheng; Luo, Zhi-Chao

2018-01-01

As a rising two-dimensional (2D) nanomaterial, layered black phosphorus (BP) nanosheets have shown promising applications in electronics and photonics. Besides the 2D layered structure, recently black phosphorus quantum dots (BPQDs) exhibiting unique optoelectronic properties had been successfully fabricated. However, the nonlinear optical properties of BPQDs at the telecommunication band have not been investigated. Herein, we synthesized the BPQDs by using a liquid exfoliation method that combined probe sonication and bath sonication. It was found that the evident saturable absorption ability of BPQDs at 1.55 μm waveband could be clearly observed. As for the applications of ultrafast photonics, we fabricated the BPQDs saturable absorber (BPQDs-SA) and applied it to an ultrafast laser. By virtue of the excellent nonlinear optical properties of BPQDs, the fiber laser delivers the stable pulse train with duration as short as 291 fs, whose performance could, to the best of our knowledge, compete with nowadays' commercial optical saturable absorber devices. In addition, due to the highly nonlinear optical effect generated by the fabricated BPQDs-SA, the multi-soliton nonlinear dynamics in the fiber laser were also investigated. The obtained results suggest that the BPQDs could be an attractive nonlinear optical material for applications in the field of nonlinear optics.

Cloud Radiative Forcing at the ARM Climate Research Facility. Part 1; Technique, Validation, and Comparison to Satellite-derived Diagnostic Quantities

NASA Technical Reports Server (NTRS)

Mace, Gerald G.; Benson, Sally; Sonntag, Karen L.; Kato, Seiji; Min, Qilong; Minnis, Patrick; Twohy, Cynthia H.; Poellot, Michael; Dong, Xiquan; Long, Charles;

Polyimide/Carbon Nanotube Composite Films for Electrostatic Charge Mitigation

NASA Technical Reports Server (NTRS)

Smith, Joseph G., Jr.; Delozier, Donavon M.; Connell, John W.; Watson, Kent A.

2004-01-01

Low color, space environmentally durable polymeric films with sufficient electrical conductivity to mitigate electrostatic charge (ESC) build-up have potential applications on large, deployable, ultra-light weight Gossamer spacecraft as thin film membranes on antennas, solar sails, thermal/optical coatings, multi-layer insulation blankets, etc.. The challenge has been to develop a method to impart robust electrical conductivity into these materials without increasing solar absorptivity (alpha ) or decreasing optical transparency or film flexibility. Since these spacecraft will require significant compaction prior to launch, the film portion of the spacecraft will require folding. The state-of-the-art clear, conductive coating (e.g. indium-tin-oxide, ITO) is brittle and cannot tolerate folding. In this report, doping a polymer with single-walled carbon nanotubes (SWNTs) using two different methods afforded materials with good flexibility and surface conductivities in the range sufficient for ESC mitigation. A coating method afforded materials with minimal effects on the mechanical, optical, and thermo-optical properties as compared to dispersal of SWNTs in the matrix. The chemistry and physical properties of these nanocomposites are discussed.

Fluorescence Diffusion in the Presence of Optically Clear Tissues in a Mouse Head Model.

PubMed

Ancora, Daniele; Zacharopoulos, Athanasios; Ripoll, Jorge; Zacharakis, Giannis

2017-05-01

Diffuse Optical Tomography commonly neglects or assumes as insignificant the presence of optically clear regions in biological tissues, estimating their contribution as a small perturbation to light transport. The inaccuracy introduced by this practice is examined in detail in the context of a complete, based on realistic geometry, virtual fluorescence Diffuse Optical Tomography experiment where a mouse head is imaged in the presence of cerebral spinal fluid. Despite the small thickness of such layer, we point out that an error is introduced when neglecting it from the model with possibly reduction in the accuracy of the reconstruction and localization of the fluorescence distribution within the brain. The results obtained in the extensive study presented here suggest that fluorescence diffuse neuroimaging studies can be improved in terms of quantitative and qualitative reconstruction by accurately taking into account optically transparent regions especially in the cases where the reconstruction is aided by the prior knowledge of the structural geometry of the specimen. Thus, this has only recently become an affordable choice, thanks to novel computation paradigms that allow to run Monte Carlo photon propagation on a simple graphic card, hence speeding up the process a thousand folds compared to CPU-based solutions.

Application of focused-beam flat-sample method to synchrotron powder X-ray diffraction with anomalous scattering effect

NASA Astrophysics Data System (ADS)

Tanaka, M.; Katsuya, Y.; Matsushita, Y.

2013-03-01

The focused-beam flat-sample method (FFM), which is a method for high-resolution and rapid synchrotron X-ray powder diffraction measurements by combination of beam focusing optics, a flat shape sample and an area detector, was applied for diffraction experiments with anomalous scattering effect. The advantages of FFM for anomalous diffraction were absorption correction without approximation, rapid data collection by an area detector and good signal-to-noise ratio data by focusing optics. In the X-ray diffraction experiments of CoFe2O4 and Fe3O4 (By FFM) using X-rays near the Fe K absorption edge, the anomalous scattering effect between Fe/Co or Fe2+/Fe3+ can be clearly detected, due to the change of diffraction intensity. The change of observed diffraction intensity as the incident X-ray energy was consistent with the calculation. The FFM is expected to be a method for anomalous powder diffraction.

Comparison of Aperture Averaging and Receiver Diversity Techniques for Free Space Optical Links in Presence of Turbulence and Various Weather Conditions

NASA Astrophysics Data System (ADS)

Kaur, Prabhmandeep; Jain, Virander Kumar; Kar, Subrat

2014-12-01

In this paper, we investigate the performance of a Free Space Optic (FSO) link considering the impairments caused by the presence of various weather conditions such as very clear air, drizzle, haze, fog, etc., and turbulence in the atmosphere. Analytic expression for the outage probability is derived using the gamma-gamma distribution for turbulence and accounting the effect of weather conditions using the Beer-Lambert's law. The effect of receiver diversity schemes using aperture averaging and array receivers on the outage probability is studied and compared. As the aperture diameter is increased, the outage probability decreases irrespective of the turbulence strength (weak, moderate and strong) and weather conditions. Similar effects are observed when the number of direct detection receivers in the array are increased. However, it is seen that as the desired level of performance in terms of the outage probability decreases, array receiver becomes the preferred choice as compared to the receiver with aperture averaging.

Comprehensive validation scheme for in situ fiber optics dissolution method for pharmaceutical drug product testing.

PubMed

Mirza, Tahseen; Liu, Qian Julie; Vivilecchia, Richard; Joshi, Yatindra

2009-03-01

There has been a growing interest during the past decade in the use of fiber optics dissolution testing. Use of this novel technology is mainly confined to research and development laboratories. It has not yet emerged as a tool for end product release testing despite its ability to generate in situ results and efficiency improvement. One potential reason may be the lack of clear validation guidelines that can be applied for the assessment of suitability of fiber optics. This article describes a comprehensive validation scheme and development of a reliable, robust, reproducible and cost-effective dissolution test using fiber optics technology. The test was successfully applied for characterizing the dissolution behavior of a 40-mg immediate-release tablet dosage form that is under development at Novartis Pharmaceuticals, East Hanover, New Jersey. The method was validated for the following parameters: linearity, precision, accuracy, specificity, and robustness. In particular, robustness was evaluated in terms of probe sampling depth and probe orientation. The in situ fiber optic method was found to be comparable to the existing manual sampling dissolution method. Finally, the fiber optic dissolution test was successfully performed by different operators on different days, to further enhance the validity of the method. The results demonstrate that the fiber optics technology can be successfully validated for end product dissolution/release testing. (c) 2008 Wiley-Liss, Inc. and the American Pharmacists Association

A Fast Infrared Radiative Transfer Model for Overlapping Clouds

NASA Technical Reports Server (NTRS)

Niu, Jianguo; Yang, Ping; Huang, Huang-Lung; Davies, James E.; Li, Jun; Baum, Bryan A.; Hu, Yong X.

2006-01-01

A fast infrared radiative transfer model (FIRTM2) appropriate for application to both single-layered and overlapping cloud situations is developed for simulating the outgoing infrared spectral radiance at the top of the atmosphere (TOA). In FIRTM2 a pre-computed library of cloud reflectance and transmittance values is employed to account for one or two cloud layers, whereas the background atmospheric optical thickness due to gaseous absorption can be computed from a clear-sky radiative transfer model. FIRTM2 is applicable to three atmospheric conditions: 1) clear-sky, 2) single-layered ice or water cloud, and 3) two simultaneous cloud layers in a column (e.g., ice cloud overlying water cloud). Moreover, FIRTM2 outputs the derivatives (i.e., Jacobians) of the TOA brightness temperature with respect to cloud optical thickness and effective particle size. Sensitivity analyses have been carried out to assess the performance of FIRTM2 for two spectral regions, namely the longwave (LW) band (587.3 - 1179.5/cm) and the short-to-medium wave (SMW) band (1180.1 - 2228.9/cm). The assessment is carried out in terms of brightness temperature differences (BTD) between FIRTM2 and the well-known discrete ordinates radiative transfer model (DISORT), henceforth referred to as BTD (F-D). The BTD (F-D) values for single-layered clouds are generally less than 0.8 K. For the case of two cloud layers (specifically ice cloud over water cloud), the BTD(F-D) values are also generally less than 0.8 K except for the SMW band for the case of a very high altitude (>15 km) cloud comprised of small ice particles. Note that for clear-sky atmospheres, FIRTM2 reduces to the clear-sky radiative transfer model that is incorporated into FIRTM2, and the errors in this case are essentially those of the clear-sky radiative transfer model.

Cross-correlation photothermal optical coherence tomography with high effective resolution.

PubMed

Tang, Peijun; Liu, Shaojie; Chen, Junbo; Yuan, Zhiling; Xie, Bingkai; Zhou, Jianhua; Tang, Zhilie

2017-12-01

We developed a cross-correlation photothermal optical coherence tomography (CC-PTOCT) system for photothermal imaging with high lateral and axial resolution. The CC-PTOCT system consists of a phase-sensitive OCT system, a modulated pumping laser, and a digital cross-correlator. The pumping laser was used to induce the photothermal effect in the sample, causing a slight phase modulation of the OCT signals. A spatial phase differentiation method was employed to reduce phase accumulation. The noise brought by the phase differentiation method and the strong background noise were suppressed efficiently by the cross-correlator, which was utilized to extract the photothermal signals from the modulated signals. Combining the cross-correlation technique with spatial phase differentiation can improve both lateral and axial resolution of the PTOCT imaging system. Clear photothermal images of blood capillaries of a mouse ear in vivo were successfully obtained with high lateral and axial resolution. The experimental results demonstrated that this system can enhance the effective transverse resolution, effective depth resolution, and contrast of the PTOCT image effectively, aiding the ongoing development of the accurate 3D functional imaging.

The Center for Advanced Systems and Engineering (CASE). Visiting Faculty Research Program 06 March 2007 to 05 March 2009

DTIC Science & Technology

2009-09-01

and could be used to compensate for high frequency distortions to the LOS caused by platform jitter and the effects of the optical turbulence . In...engineer an unknown detector based on few experimental interactions. For watermarking algorithms in particular, we seek to identify specific distortions ...of a watermarked image that clearly identify or rule out one particular class of embedding. These experimental distortions surgical test for rapid

Comparative assessments of the effects of alcohol exposure on fetal brain development using optical coherence tomography and ultrasound imaging

NASA Astrophysics Data System (ADS)

Sudheendran, Narendran; Bake, Shameena; Miranda, Rajesh C.; Larin, Kirill V.

2013-02-01

The developing fetal brain is vulnerable to a variety of environmental agents including maternal ethanol consumption. Preclinical studies on the development and amelioration of fetal teratology would be significantly facilitated by the application of high resolution imaging technologies like optical coherence tomography (OCT) and high-frequency ultrasound (US). This study investigates the ability of these imaging technologies to measure the effects of maternal ethanol exposure on brain development, ex vivo, in fetal mice. Pregnant mice at gestational day 12.5 were administered ethanol (3 g/Kg b.wt.) or water by intragastric gavage, twice daily for three consecutive days. On gestational day 14.5, fetuses were collected and imaged. Three-dimensional images of the mice fetus brains were obtained by OCT and high-resolution US, and the volumes of the left and right ventricles of the brain were measured. Ethanol-exposed fetuses exhibited a statistically significant, 2-fold increase in average left and right ventricular volumes compared with the ventricular volume of control fetuses, with OCT-derived measures of 0.38 and 0.18 mm3, respectively, whereas the boundaries of the fetal mouse lateral ventricles were not clearly definable with US imaging. Our results indicate that OCT is a useful technology for assessing ventriculomegaly accompanying alcohol-induced developmental delay. This study clearly demonstrated advantages of using OCT for quantitative assessment of embryonic development compared with US imaging.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boivin, Jonathan, E-mail: jonathan.boivin.1@ulaval.ca; Beaulieu, Luc; Beddar, Sam

Purpose: The authors’ objective was to systematically assess the performance of seven photodetectors used in plastic scintillation dosimetry. The authors also propose some guidelines for selecting an appropriate detector for a specific application. Methods: The plastic scintillation detector (PSD) consisted of a 1-mm diameter, 10-mm long plastic scintillation fiber (BCF-60), which was optically coupled to a clear 10-m long optical fiber of the same diameter. A light-tight plastic sheath covered both fibers and the scintillator end was sealed. The clear fiber end was connected to one of the following photodetectors: two polychromatic cameras (one with an optical lens and onemore » with a fiber optic taper replacing the lens), a monochromatic camera with an optical lens, a PIN photodiode, an avalanche photodiode (APD), or a photomultiplier tube (PMT). A commercially available W1 PSD was also included in the study, but it relied on its own fiber and scintillator. Each PSD was exposed to both low-energy beams (120, 180, and 220 kVp) from an orthovoltage unit and high-energy beams (6 and 23 MV) from a linear accelerator. Various dose rates were tested to identify the operating range and accuracy of each photodetector. Results: For all photodetectors, the relative uncertainty was less than 5% for dose rates higher than 3 mGy/s. The cameras allowed multiple probes to be used simultaneously, but they are less sensitive to low-light signals. The PIN, APD, and PMT had higher sensitivity, making them more suitable for low dose rate and out-of-field dose monitoring. The relative uncertainty of the PMT was less than 1% at the lowest dose rate achieved (0.10 mGy/s), suggesting that it was optimal for use in live dosimetry. Conclusions: For dose rates higher than 3 mGy/s, the PIN diode is the most effective photodetector in terms of performance/cost ratio. For lower dose rates, such as those seen in interventional radiology or high-gradient radiotherapy, PMTs are the optimal choice.« less

Observation of biexcitonic emission at extremely low power density in tungsten disulfide atomic layers grown on hexagonal boron nitride.

PubMed

Okada, Mitsuhiro; Miyauchi, Yuhei; Matsuda, Kazunari; Taniguchi, Takashi; Watanabe, Kenji; Shinohara, Hisanori; Kitaura, Ryo

2017-03-23

Monolayer transition metal dichalcogenides (TMDCs) including WS 2 , MoS 2 , WSe 2 and WS 2 , are two-dimensional semiconductors with direct bandgap, providing an excellent field for exploration of many-body effects in 2-dimensions (2D) through optical measurements. To fully explore the physics of TMDCs, the prerequisite is preparation of high-quality samples to observe their intrinsic properties. For this purpose, we have focused on high-quality samples, WS 2 grown by chemical vapor deposition method with hexagonal boron nitride as substrates. We observed sharp exciton emissions, whose linewidth is typically 22~23 meV, in photoluminescence spectra at room temperature, which result clearly demonstrates the high-quality of the current samples. We found that biexcitons formed with extremely low-excitation power (240 W/cm 2 ) at 80 K, and this should originate from the minimal amount of localization centers in the present high-quality samples. The results clearly demonstrate that the present samples can provide an excellent field, where one can observe various excitonic states, offering possibility of exploring optical physics in 2D and finding new condensates.

Comparison between optical coherence tomography angiography and fluorescein angiography findings in retinal vasculitis.

PubMed

Abucham-Neto, Julio Zaki; Torricelli, André Augusto Miranda; Lui, Aline Cristina Fioravanti; Guimarães, Sarah Napoli; Nascimento, Heloisa; Regatieri, Caio Vinícius

2018-01-01

To describe optical coherence tomography angiography (OCT-A) findings in patients with retinal vasculitis and to compare them to current fluorescein angiography (FA) findings. This was an observational case series. Nineteen eyes in 10 patients with retinal vasculitis of various etiologies were imaged with FA (TRC-50DX, Topcon) and OCT-A (SD-OCT, Optovue). The images were reviewed and analyzed. The mean age was 36 years (range 24-67 years); there were three males and seven females. The primary vessels involved were veins (89%). Fourteen eyes (74%) had active inflammatory disease during the study period, with signs of vascular sheathing and perivascular leakage on FA. Interestingly, in this group, OCT-A was not able to detect clear signs of active inflammation around the affected vessels. Nevertheless, OCT-A was able to detect secondary lesions in fourteen eyes (74%), including some findings not clearly shown on FA. Most of these were within the macular area. OCT-A was particularly effective in cases of capillary dropout, increased foveal avascular zone, telangiectasias, shunts, and areas of neovascularization. FA remains an essential complementary exam for detection of retinal vasculitis. However, OCT-A extends FA findings and affords better assessment of secondary complications.

Study of atmospheric scattering and absorbing aerosols at 550 nm over nearby western Indian tropical sites of Thar Desert effected region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vyas, B. M., E-mail: bmvyas@yahoo.com; Saxenna, Abhishek; Panwar, Chhagan

The first time experimental results based on spaced satellite observations of different kinds of aerosols properties have been described over two different contrast environmental conditions locations in western tropical Indian region specifically first at Jaisalmer (26.90°N, 69.90°E, 220 m above mean sea level (amsl)) located in central Thar dessert vicinity of western Indian site over Indian Thar Desert region and another at Udaipur (24.6° N, 73.7° E, 560 m amsl) site concerning to semi-urban and semi arid place of hilly areas. The daily values of aerosols optical depth absorption at 500nm (AOD abs 500nm), aerosols optical depth extinction at 500nmmore » (AOD ext 500nm) along with aerosols optical depth at 500nmon (AOD 500nm) of eleven year period from Jan., 2004 to Dec., 2014 are basis of primary database of the present investigation. From the synthesis if the above database and the basis of rigorous statistical approach, following some of interesting facts are noted (i) larger annual monthly AOD variation of 0.93 is noted over JSM when compared to observed annual monthly change in AOD cycle, over UDP, of only 0.50 clearly indicating the more impact of desert influence activities about more than double times over JSM than UDP (ii) The higher abundance of absorbing aerosols occurrences about two time higher are seen in JSM in comparison to UDP. It indicates the clear evidence of strong optical absorption properties of useful solar mid visible wavelength at 550nm as the results of presence of more availability of dust aerosols as mineral natural type in pre-monsoon to post-monsoon over JSM which is also more predominant over JSM than the UDP region located far away from desert activity regime (iii) The greater sharing of extinction solar radiation effect on aerosols are more effective in pre-monsoon in UDP in reference to over JSM, where as in case of UDP, the aerosols effect through the scattering mechanism gradually reduce from monsoon to winter months as compared to observed over JSM. The more detailed analysis other important results are also discussed thoroughly in this paper.« less

Hyperspectrally-Resolved Surface Emissivity Derived Under Optically Thin Clouds

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Larar, Allen M.; Liu, Xu; Smith, William L.; Strow, L. Larrabee; Yang, Ping

2010-01-01

Surface spectral emissivity derived from current and future satellites can and will reveal critical information about the Earth s ecosystem and land surface type properties, which can be utilized as a means of long-term monitoring of global environment and climate change. Hyperspectrally-resolved surface emissivities are derived with an algorithm utilizes a combined fast radiative transfer model (RTM) with a molecular RTM and a cloud RTM accounting for both atmospheric absorption and cloud absorption/scattering. Clouds are automatically detected and cloud microphysical parameters are retrieved; and emissivity is retrieved under clear and optically thin cloud conditions. This technique separates surface emissivity from skin temperature by representing the emissivity spectrum with eigenvectors derived from a laboratory measured emissivity database; in other words, using the constraint as a means for the emissivity to vary smoothly across atmospheric absorption lines. Here we present the emissivity derived under optically thin clouds in comparison with that under clear conditions.

Absorption of Sunlight by Water Vapor in Cloudy Conditions: A Partial Explanation for the Cloud Absorption Anomaly

NASA Technical Reports Server (NTRS)

Crisp, D.

1997-01-01

The atmospheric radiative transfer algorithms used in most global general circulation models underestimate the globally-averaged solar energy absorbed by cloudy atmospheres by up to 25 W/sq m. The origin of this anomalous absorption is not yet known, but it has been attributed to a variety of sources including oversimplified or missing physical processes in these models, uncertainties in the input data, and even measurement errors. Here, a sophisticated atmospheric radiative transfer model was used to provide a more comprehensive description of the physical processes that contribute to the absorption of solar radiation by the Earth's atmosphere. We found that the amount of sunlight absorbed by a cloudy atmosphere is inversely proportional to the solar zenith angle and the cloud top height, and directly proportional to the cloud optical depth and the water vapor concentration within the clouds. Atmospheres with saturated, optically-thick, low clouds absorbed about 12 W/sq m more than clear atmospheres. This accounts for about 1/2 to 1/3 of the anomalous ab- sorption. Atmospheres with optically thick middle and high clouds usually absorb less than clear atmospheres. Because water vapor is concentrated within and below the cloud tops, this absorber is most effective at small solar zenith angles. An additional absorber that is distributed at or above the cloud tops is needed to produce the amplitude and zenith angle dependence of the observed anomalous absorption.

Laser line scan performance prediction

NASA Astrophysics Data System (ADS)

Mahoney, Kevin L.; Schofield, Oscar; Kerfoot, John; Giddings, Tom; Shirron, Joe; Twardowski, Mike

2007-09-01

The effectiveness of sensors that use optical measurements for the laser detection and identification of subsurface mines is directly related to water clarity. The primary objective of the work presented here was to use the optical data collected by UUV (Slocum Glider) surveys of an operational areas to estimate the performance of an electro-optical identification (EOID) Laser Line Scan (LLS) system during RIMPAC 06, an international naval exercise off the coast of Hawaii. Measurements of optical backscattering and beam attenuation were made with a Wet Labs, Inc. Scattering Absorption Meter (SAM), mounted on a Rutgers University/Webb Research Slocum glider. The optical data universally indicated extremely clear water in the operational area, except very close to shore. The beam-c values from the SAM sensor were integrated to three attenuation lengths to provide an estimate of how well the LLS would perform in detecting and identifying mines in the operational areas. Additionally, the processed in situ optical data served as near-real-time input to the Electro-Optic Detection Simulator, ver. 3 (EODES-3; Metron, Inc.) model for EOID performance prediction. Both methods of predicting LLS performance suggested a high probability of detection and probability of identification. These predictions were validated by the actual performance of the LLS as the EOID system yielded imagery from which reliable mine identification could be made. Future plans include repeating this work in more optically challenging water types to demonstrate the utility of pre-mission UUV surveys of operational areas as a tactical decision aid for planning EOID missions.

Application of the Kano-Hamilton multiangle inversion method in clear atmospheres

Treesearch

Mariana Adam; Vladimir A. Kovalev; Cyle Wold; Jenny Newton; Markus Pahlow; Wei M. Hao; Marc B. Parlange

2007-01-01

An improved measurement methodology and a data-processing technique for multiangle data obtained with an elastic scanning lidar in clear atmospheres are introduced. Azimuthal and slope scans are combined to reduce the atmospheric heterogeneity. Vertical profiles of optical depth and intercept (proportional to the logarithm of the backscatter coefficient) are determined...

Developing 3D microscopy with CLARITY on human brain tissue: Towards a tool for informing and validating MRI-based histology.

PubMed

Morawski, Markus; Kirilina, Evgeniya; Scherf, Nico; Jäger, Carsten; Reimann, Katja; Trampel, Robert; Gavriilidis, Filippos; Geyer, Stefan; Biedermann, Bernd; Arendt, Thomas; Weiskopf, Nikolaus

2017-11-28

Recent breakthroughs in magnetic resonance imaging (MRI) enabled quantitative relaxometry and diffusion-weighted imaging with sub-millimeter resolution. Combined with biophysical models of MR contrast the emerging methods promise in vivo mapping of cyto- and myelo-architectonics, i.e., in vivo histology using MRI (hMRI) in humans. The hMRI methods require histological reference data for model building and validation. This is currently provided by MRI on post mortem human brain tissue in combination with classical histology on sections. However, this well established approach is limited to qualitative 2D information, while a systematic validation of hMRI requires quantitative 3D information on macroscopic voxels. We present a promising histological method based on optical 3D imaging combined with a tissue clearing method, Clear Lipid-exchanged Acrylamide-hybridized Rigid Imaging compatible Tissue hYdrogel (CLARITY), adapted for hMRI validation. Adapting CLARITY to the needs of hMRI is challenging due to poor antibody penetration into large sample volumes and high opacity of aged post mortem human brain tissue. In a pilot experiment we achieved transparency of up to 8 mm-thick and immunohistochemical staining of up to 5 mm-thick post mortem brain tissue by a combination of active and passive clearing, prolonged clearing and staining times. We combined 3D optical imaging of the cleared samples with tailored image processing methods. We demonstrated the feasibility for quantification of neuron density, fiber orientation distribution and cell type classification within a volume with size similar to a typical MRI voxel. The presented combination of MRI, 3D optical microscopy and image processing is a promising tool for validation of MRI-based microstructure estimates. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Optical Characterization of Wide Field-of-View Night Vision Devices

DTIC Science & Technology

1999-01-01

This paper has been cleared by ASC 99-2354 Optical Characterization of Wide Field-Of-View Night Vision Devices Peter L. Marasco and H. Lee Task Air...the SAFE SocietyÕs 36th Annual Symposium. Task, H.L., Hartman, R., Marasco , P.L., Zobel, A, (1993) Methods for measuring characteristics of night

Arsenic complexes optical signatures in As-doped HgCdTe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gemain, F.; Robin, I. C.; Brochen, S.

2013-04-08

In this paper, the optical signatures of arsenic complexes in As-doped HgCdTe samples grown by molecular beam epitaxy are clearly identified using comparison between photoluminescence spectra, Extended X-Ray Absorption Fine Structure, and Hall measurements. The ionization energies of the different complexes are measured both by photoluminescence and Hall measurements.

Optical bistability and second-harmonic generation in thin film coupled cavity photonic crystal structures

NASA Astrophysics Data System (ADS)

Diao, Liyong

This thesis deals with design, fabrication and modeling of bistable and multi-stable switching dynamics and second-harmonic generation in two groups of thin film coupled cavity photonic crystal structures. The first component studies optical bistability and multistability in such structures. Optical bistability and multistability are modelled by a nonlinear transfer matrix method. The second component is focused on the modelling and experimental measurement of second-harmonic generation in such structures. It is found that coupled cavity structures can reduce the threshold and index change for bistable operation, but single cavity structures can do the same. However, there is a clear advantage in using coupled cavity structures for multistability in that the threshold for multistability can be reduced. Second-harmonic generation is enhanced by field localization due to the resonant effect at the fundamental wavelength in single and coupled cavity structures by simulated and measured results. The work in this thesis makes three significant contributions. First, in the successful fabrication of thin film coupled cavity structures, the simulated linear transmissions of such structures match those of the fabricated structures almost exactly. Second, the newly defined figure of merit at the maximum transmission point on the bistable curve can be used to compare the material damage tolerance to any other Kerr effect nonlinear gate. Third, the simulated second-harmonic generation agrees excellently with experimental results. More generally optical thin film fabrication has commercial applications in many industry sections, such as electronics, opto-electronics, optical coating, solar cell and MEMS.

Elucidation of the mechanisms of optical clearing in collagen tissue with multiphoton imaging

NASA Astrophysics Data System (ADS)

Hovhannisyan, Vladimir; Hu, Po-Sheng; Chen, Shean-Jen; Kim, Chang-Seok; Dong, Chen-Yuan

2013-04-01

Optical clearing (OC) is a promising method to overcome limitations in biomedical depth-resolved optical studies. Mechanisms of OC in purified bovine Achilles tendon, chicken skin, and chicken tendon were studied using time-lapsed, three-dimensional second harmonic generation (SHG) and two-photon fluorescence microscopic imaging. Quantified nonlinear optical measurements allowed temporal separation of two processes in collagen OC with glycerol. The first one is a fast process of tissue dehydration accompanied with collagen shrinkage and the second relatively slow process is glycerol penetration into the interfibrillar space of collagen alongside with CF swelling. The use of 50% glycerol induced less-expressed OC via partial substitution of water molecules with glycerol molecules. We also found that phosphate-buffered saline- and glycerol-treatments were reversible, and fiber morphology and SHG signal intensity were recovered after the removal of immersion agents. It was shown that tissue OC was a dynamic process and elucidation of its physical mechanisms may help choose optimal diagnostic, treatment, and modification regimes for collagen-based as well as other types of biomaterials.

Comparison of optics and performance of a distal sensor high definition cystoscope, a distal sensor standard definition cystoscope, and a fiberoptic cystoscope.

PubMed

Lusch, Achim; Liss, Michael A; Greene, Peter; Abdelshehid, Corollos; Menhadji, Ashleigh; Bucur, Philip; Alipanah, Reza; McDougall, Elspeth; Landman, Jaime

2013-12-01

To evaluate performance characteristics and optics of a new generation high-definition distal sensor (HD-DS) flexible cystoscope, a standard-definition distal sensor (SD-DS) cystoscope, and a standard fiberoptic (FO) cystoscope. Three new cystoscopes (HD-DS, SD-DS, and FO) were compared for active deflection, irrigation flow, and optical characteristics. Each cystoscope was evaluated with an empty working channel and with various accessories. Optical characteristics (resolution, grayscale imaging, color representation, depth of field, and image brightness) were measured using United States Air Force (USAF)/Edmund Optics test targets and illumination meter. We digitally recorded a porcine cystoscopy in both clear and blood fields, with subsequent video analysis by 8 surgeons via questionnaire. The HD-DS had a higher resolution than the SD-DS and the FO at both 20 mm (6.35 vs 4.00 vs 2.24 line pairs/mm) and 10 mm (14.3 vs 7.13 vs 4.00 line pairs/mm) evaluations, respectively (P <.001 and P <.001). Color representation and depth of field (P = .001 and P <.001) were better in the HD-DS. When compared to the FO, the HD-DS and SD-DS demonstrated superior deflection up and irrigant flow with and without accessory present in the working channel, whereas image brightness was superior in the FO (P <.001, P = .001, and P <.001, respectively). Observers deemed the HD-DS cystoscope superior in visualization in clear and bloody fields, as well as for illumination. The new HD-DS provided significantly improved visualization in a clear and a bloody field, resolution, color representation, and depth of field compared to SD-DS and FO. Clinical correlation of these findings is pending. Copyright © 2013 Elsevier Inc. All rights reserved.

Instruction manual, optical effects module electronic controller and processor, model OEMCP

NASA Technical Reports Server (NTRS)

1975-01-01

The OEM-1 electronic module is discussed; it is comprised of four subsystems: the signal processing and display; the stepper motor controls; the chopper controls; and the dc-dc invertor. The OEM-1 module controls the sample wheel so that the relative transmittance of the samples can be compared to the clear aperture position. The 3-1/2 digit digital voltmeter displays the clear aperture signal level as well as the ratio of the remaining sample positions relative to the clear aperture position. The sample wheel position is decoded so that the signals and ratios can be correlated to the data. The OEM is automatically reset to the I sub o on initial turn-on and can be reset to the '0' position by actuating a front panel switch. The sample wheel can be interrupted to change samples or induce a longer integration time if desired by a front panel command. Integration times from 1 - 50 seconds are provided at the front panel, and BCD data for external interfacing is provided.

High-Temperature Optical Window Design

NASA Technical Reports Server (NTRS)

Roeloffs, Norman; Taranto, Nick

1995-01-01

A high-temperature optical window is essential to the optical diagnostics of high-temperature combustion rigs. Laser Doppler velocimetry, schlieren photography, light sheet visualization, and laser-induced fluorescence spectroscopy are a few of the tests that require optically clear access to the combustor flow stream. A design was developed for a high-temperature window that could withstand the severe environment of the NASA Lewis 3200 F Lean Premixed Prevaporized (LPP) Flame Tube Test Rig. The development of this design was both time consuming and costly. This report documents the design process and the lessons learned, in an effort to reduce the cost of developing future designs for high-temperature optical windows.

The role of cerebral spinal fluid in light propagation through the mouse head: improving fluorescence tomography with Monte Carlo modeling

NASA Astrophysics Data System (ADS)

Ancora, Daniele; Zacharopoulos, Athanasios; Ripoll, Jorge; Zacharakis, Giannis

2016-03-01

Optical Neuroimaging is a highly dynamical field of research owing to the combination of many advanced imaging techniques and computational tools that uncovered unexplored paths through the functioning of the brain. Light propagation modelling through such complicated structures has always played a crucial role as the basis for a high resolution and quantitative imaging where even the slightest improvement could lead to significant results. Fluorescence Diffuse Optical Tomography (fDOT), a widely used technique for three dimensional imaging of small animals and tissues, has been proved to be inaccurate for neuroimaging the mouse head without the knowledge of a-priori anatomical information of the subject. Commonly a normalized Born approximation model is used in fDOT reconstruction based on forward photon propagation using Diffusive Equation (DE) which has strong limitations in the optically clear regime. The presence of the Cerebral Spinal Fluid (CSF) instead, a thin optically clear layer surrounding the brain, can be more accurately taken into account using Monte Carlo approaches which nowadays is becoming more usable thanks to parallelized GPU algorithms. In this work we discuss the results of a synthetic experimental comparison, resulting to the increase of the accuracy for the Born approximation by introducing the CSF layer in a realistic mouse head structure with respect to the current model. We point out the importance of such clear layer for complex geometrical models, while for simple slab phantoms neglecting it does not introduce a significant error.

Lick Observatory, California, and 20th Century Leadership in Optical Astronomy

NASA Astrophysics Data System (ADS)

Miller, Joseph

2008-04-01

With the establishment of the Lick Observatory on Mt. Hamilton in California in 1888 it was immediately established that an observatory located on a relatively high site far from city lights was a far superior location for optical astronomy than the previously common city locations. A few years after its beginning, astronomers at Lick convincingly demonstrated the clear advantage of the reflecting telescope for astrophysical research. Not only was a reflector achromatic over all wavelengths, but it could be made with a small focal ratio that provided high photographic speed. Furthermore, since light did not pass through the optic and it could be supported from behind, it could easily be made in large sizes. Over the first half of the 20^th century the establishment of the Mt. Wilson and Palomar Observatories expanded California's dominance in optical astronomy. Also with the new larger telescopes came major progress in the in design of focal plane instrumentation that allowed these telescopes to be superb tools for astrophysical research. The California observatories of the 20th century were largely independent of Federal funding for operations. Their facilities were were maintained and mostly used by their permanent staffs. This led to a style of doing forefront research that was highly effective, as both long-term survey-type programs and more speculative investigations with less-clear payoffs at the outset could be supported. Also the, the close connection of the scientists doing the research to the development of the telescopes and instruments they used for their research conferred advantages. At present, this style of doing astronomical observational research is a relatively small fraction of all this kind of research. At the end of the 20^th century the California pioneering advancement in ground-based optical astronomy was repeated with the creation of the Keck Observatory. A joint project of the University of California and the California Institute of Technology, this observatory features two 10-m telescopes, current the largest general-purpose optical/infrared telescopes in the world. However, California skies were abandoned in favor of a much superior site in Hawaii.

SU-G-IeP4-08: Initial Investigations of Up-Converting Nanoparticles (UCNP) for 3D Tissue Imaging in Optical-ECT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoon, S; Dewhirst, M; Oldham, M

Purpose: Near-IR absorptive up-converting nanoparticles (UCNPs) is a novel contrast for optical-ECT that allows auto-fluorescence-free 3D imaging of labeled cells in a matrix of large (∼1cm{sup 3}) unsectioned normal tissue. This has the potential to image small metastases or dormant cells that is difficult with down-converting fluorescing dyes due to auto-fluorescence. The feasibility of imaging UCNP in agarose phantoms and a mouse lung is demonstrated, aided by a 3D-printed optical-ECT stage designed to excite UCNP in a mouse lung. Methods: The UCNP, NaYF{sub 4}:Yb/Er (20/2%), studied in this work up-converts 980nm light to visible light peaking sharply at ∼540nm. Tomore » characterize the UCNP emission as a function of UCNP concentration, cylindrical 2.5%wt agarose phantoms infused with UCNP at concentrations of 25µg/mL and 50µg/mL were exposed to 1.5W 980nm laser coupled to an optical fiber. The fiber was held stably at 1cm above the stage via a custom 3D-printed stage. An optically cleared lung harvested from a BALBc mice was then injected with 100µL of 1mg/mL UCNP solution ex vivo. Tomographic imaging of the UCNP emission in lung was performed. Results: The laser beam tract is visualized within the agarose phantom. A line profile of UCNP emission at 25µg/mL versus 50µg/mL shows that increasing the UCNP concentration increases emission count. UCNPs injected into a cleared mouse lung disperse throughout the respiratory tract, allowing for visualization and 3D reconstruction. Excitation before and after UCNP injection shows the tissue exhibits no auto-fluorescence at 980nm, allowing clear view of the UCNP without any obscuring features such as conventional down-converting fluorescent tags. Conclusion: We confirm that up-conversion in tissue circumvents completely tissue auto-fluorescence, which allowed background-free 3D reconstruction of the UCNP distribution. We also confirm that raising the UCNP concentration increases emission and that UCNPs are retained in agarose samples during the optical clearing process.« less

Electronic states and optical properties of single donor in GaN conical quantum dot with spherical edge

NASA Astrophysics Data System (ADS)

El Aouami, A.; Feddi, E.; El-Yadri, M.; Aghoutane, N.; Dujardin, F.; Duque, C. A.; Phuc, Huynh Vinh

2018-02-01

In this paper we present a theoretical investigation of quantum confinement effects on the electron and single donor states in GaN conical quantum dot with spherical edge. In the framework of the effective mass approximation, the Schrödinger equations of electron and donor have been solved analytically in an infinite potential barrier model. Our calculations show that the energies of electron and donor impurity are affected by the two characteristic parameters of the structure which are the angle Ω and the radial dimension R. We show that, despite the fact that the reduction of the two parameters Ω and R leads to the same confinement effects, the energy remains very sensitive to the variation of the radial part than the variation of the angular part. The analysis of the photoionization cross-section corresponding to optical transitions between the conduction band and the first donor energy level shows clearly that the reduction of the radius R causes a shift in resonance peaks towards the high energies. On the other hand, the optical transitions between 1 s - 1 p , 1 p - 1 d and 1 p - 2 s show that the increment of the conical aperture Ω (or reduction of R) implies a displacement of the excitation energy to higher energies.

Evaluation of insertion characteristics of less invasive Si optoneural probe with embedded optical fiber

NASA Astrophysics Data System (ADS)

Morikawa, Takumi; Harashima, Takuya; Kino, Hisashi; Fukushima, Takafumi; Tanaka, Tetsu

2017-04-01

A less invasive Si optoneural probe with an embedded optical fiber was proposed and successfully fabricated. The diameter of the optical fiber was completely controlled by hydrogen fluoride etching, and the thinned optical fiber can propagate light without any leakage. This optical fiber was embedded in a trench formed inside a probe shank, which causes less damage to tissues. In addition, it was confirmed that the optical fiber embedded in the probe shank successfully irradiated light to optically stimulate gene transfected neurons. The electrochemical impedance of the probe did not change despite the light irradiation. Furthermore, probe insertion characteristics were evaluated in detail and less invasive insertion was clearly indicated for the Si optoneural probe with the embedded optical fiber compared with conventional optical neural probes. This neural probe with the embedded optical fiber can be used as a simple and easy tool for optogenetics and brain science.

Improved room-temperature luminescence of core-shell InGaAs/GaAs nanopillars via lattice-matched passivation

NASA Astrophysics Data System (ADS)

Komolibus, Katarzyna; Scofield, Adam C.; Gradkowski, Kamil; Ochalski, Tomasz J.; Kim, Hyunseok; Huffaker, Diana L.; Huyet, Guillaume

2016-02-01

Optical properties of GaAs/InGaAs/GaAs nanopillars (NPs) grown on GaAs(111)B were investigated. Employment of a mask-etching technique allowed for an accurate control over the geometry of NP arrays in terms of both their diameter and separation. This work describes both the steady-state and time-resolved photoluminescence of these structures as a function of the ensemble geometry, composition of the insert, and various shell compounds. The effects of the NP geometry on a parasitic radiative recombination channel, originating from an overgrown lateral sidewall layer, are discussed. Optical characterization reveals a profound influence of the core-shell lattice mismatch on the carrier lifetime and emission quenching at room temperature. When the lattice-matching conditions are satisfied, an efficient emission from the NP arrays at room temperature and below the band-gap of silicon is observed, clearly highlighting their potential application as emitters in optical interconnects integrated with silicon platforms.

Multimodality stereotactic brain tissue identification: the NASA smart probe project

NASA Technical Reports Server (NTRS)

Andrews, R.; Mah, R.; Aghevli, A.; Freitas, K.; Galvagni, A.; Guerrero, M.; Papsin, R.; Reed, C.; Stassinopoulos, D.

1999-01-01

Real-time tissue identification can benefit procedures such as stereotactic brain biopsy, functional neurosurgery and brain tumor excision. Optical scattering spectroscopy has been shown to be effective at discriminating cancer from noncancerous conditions in the colon, bladder and breast. The NASA Smart Probe extends the concept of 'optical biopsy' by using neural network techniques to combine the output from 3 microsensors contained within a cannula 2. 7 mm in diameter (i.e. the diameter of a stereotactic brain biopsy needle). Experimental data from 5 rats show the clear differentiation between tissues such as brain, nerve, fat, artery and muscle that can be achieved with optical scattering spectroscopy alone. These data and previous findings with other modalities such as (1) analysis of the image from a fiberoptic neuroendoscope and (2) the output from a microstrain gauge suggest the Smart Probe multiple microsensor technique shows promise for real-time tissue identification in neurosurgical procedures. Copyright 2000 S. Karger AG, Basel.

Effect of Shot Noise on Simultaneous Sensing in Frequency Division Multiplexed Diffuse Optical Tomographic Imaging Process.

PubMed

Jang, Hansol; Lim, Gukbin; Hong, Keum-Shik; Cho, Jaedu; Gulsen, Gultekin; Kim, Chang-Seok

2017-11-28

Diffuse optical tomography (DOT) has been studied for use in the detection of breast cancer, cerebral oxygenation, and cognitive brain signals. As optical imaging studies have increased significantly, acquiring imaging data in real time has become increasingly important. We have developed frequency-division multiplexing (FDM) DOT systems to analyze their performance with respect to acquisition time and imaging quality, in comparison with the conventional time-division multiplexing (TDM) DOT. A large tomographic area of a cylindrical phantom 60 mm in diameter could be successfully reconstructed using both TDM DOT and FDM DOT systems. In our experiment with 6 source-detector (S-D) pairs, the TDM DOT and FDM DOT systems required 6.18 and 1 s, respectively, to obtain a single tomographic data set. While the absorption coefficient of the reconstruction image was underestimated in the case of the FDM DOT, we experimentally confirmed that the abnormal region can be clearly distinguished from the background phantom using both methods.

Mapping the conduction band edge density of states of γ-In2Se3 by diffuse reflectance spectra

NASA Astrophysics Data System (ADS)

Kumar, Pradeep; Vedeshwar, Agnikumar G.

2018-03-01

It is demonstrated that the measured diffuse reflectance spectra of γ-In2Se3 can be used to map the conduction band edge density of states through Kubelka-Munk analysis. The Kubelka-Munk function derived from the measured spectra almost mimics the calculated density of states in the vicinity of conduction band edge. The calculation of density of states was carried out using first-principles approach yielding the structural, electronic, and optical properties. The calculations were carried out implementing various functionals and only modified Tran and Blaha (TB-MBJ) results tally closest with the experimental result of band gap. The electronic and optical properties were calculated using FP-LAPW + lo approach based on the Density Functional Theory formalism implementing only TB-mBJ functional. The electron and hole effective masses have been calculated as me * = 0.25 m 0 and mh * = 1.11 m 0 , respectively. The optical properties clearly indicate the anisotropic nature of γ-In2Se3.

Macro optical projection tomography for large scale 3D imaging of plant structures and gene activity

PubMed Central

Lee, Karen J. I.; Calder, Grant M.; Hindle, Christopher R.; Newman, Jacob L.; Robinson, Simon N.; Avondo, Jerome J. H. Y.

2017-01-01

Abstract Optical projection tomography (OPT) is a well-established method for visualising gene activity in plants and animals. However, a limitation of conventional OPT is that the specimen upper size limit precludes its application to larger structures. To address this problem we constructed a macro version called Macro OPT (M-OPT). We apply M-OPT to 3D live imaging of gene activity in growing whole plants and to visualise structural morphology in large optically cleared plant and insect specimens up to 60 mm tall and 45 mm deep. We also show how M-OPT can be used to image gene expression domains in 3D within fixed tissue and to visualise gene activity in 3D in clones of growing young whole Arabidopsis plants. A further application of M-OPT is to visualise plant-insect interactions. Thus M-OPT provides an effective 3D imaging platform that allows the study of gene activity, internal plant structures and plant-insect interactions at a macroscopic scale. PMID:28025317

Electronic structure and optical properties of CuAlO2 under biaxial strain.

PubMed

Ghosh, C K; Sarkar, D; Mitra, M K; Chattopadhyay, K K

2012-06-13

An ab initio calculation has been carried out to investigate the biaxial strain ( - 10.71% < ε < 9.13%) effect on elastic, electronic and optical properties of CuAlO(2). All the elastic constants (c(11), c(12), c(13), c(33)) except c(44) decrease (increase) during tensile (compressive) strain. The band gap is found to decrease in the presence of tensile as well as compressive strain. The relative decrease of the band gap is asymmetric with respect to the sign of the strain. Significant differences between the parallel and perpendicular components of the dielectric constant and the optical properties have been observed due to anisotropic crystal structure. It is further noticed that these properties are easily tunable by strain. Importantly, the collective oscillation of the valence electrons has been identified for light polarized perpendicular to the c-axis. From calculations, it is clear that the tensile strain can enhance the hole mobility as well as the transparency of CuAlO(2).

Electronic structure and optical properties of CuAlO2 under biaxial strain

NASA Astrophysics Data System (ADS)

Ghosh, C. K.; Sarkar, D.; Mitra, M. K.; Chattopadhyay, K. K.

2012-06-01

An ab initio calculation has been carried out to investigate the biaxial strain ( - 10.71% < ɛ < 9.13%) effect on elastic, electronic and optical properties of CuAlO2. All the elastic constants (c11, c12, c13, c33) except c44 decrease (increase) during tensile (compressive) strain. The band gap is found to decrease in the presence of tensile as well as compressive strain. The relative decrease of the band gap is asymmetric with respect to the sign of the strain. Significant differences between the parallel and perpendicular components of the dielectric constant and the optical properties have been observed due to anisotropic crystal structure. It is further noticed that these properties are easily tunable by strain. Importantly, the collective oscillation of the valence electrons has been identified for light polarized perpendicular to the c-axis. From calculations, it is clear that the tensile strain can enhance the hole mobility as well as the transparency of CuAlO2.

Assessment of satellite derived diffuse attenuation coefficients ...

EPA Pesticide Factsheets

Optical data collected in coastal waters off South Florida and in the Caribbean Sea between January 2009 and December 2010 were used to evaluate products derived with three bio-optical inversion algorithms applied to MOIDS/Aqua, MODIS/Terra, and SeaWiFS satellite observations. The products included the diffuse attenuation coefficient at 490 nm (Kd_490) and for the visible range (Kd_PAR), and euphotic depth (Zeu, corresponding to 1% of the surface incident photosynthetically available radiation or PAR). Above-water hyperspectral reflectance data collected over optically shallow waters of the Florida Keys between June 1997 and August 2011 were used to help understand algorithm performance over optically shallow waters. The in situ data covered a variety of water types in South Florida and the Caribbean Sea, ranging from deep clear waters, turbid coastal waters, and optically shallow waters (Kd_490 range of ~0.03 – 1.29m-1). An algorithm based on Inherent Optical Properties (IOPs) showed the best performance (RMSD < 13% and R2 ~1.0 for MODIS/Aqua and SeaWiFS). Two algorithms based on empirical regressions performed well for offshore clear waters, but underestimated Kd_490 and Kd_PAR in coastal waters due to high turbidity or shallow bottom contamination. Similar results were obtained when only in situ data were used to evaluate algorithm performance. The excellent agreement between satellite-derived remote sensing reflectance (Rrs) and in situ Rrs suggested that

X-ray diffraction and Raman investigations of thickness dependent stress effects on Pb(ZrxTi1-x)O3 thin films

NASA Astrophysics Data System (ADS)

Lappalainen, Jyrki; Lantto, Vilho; Frantti, Johannes; Hiltunen, Jussi

2006-06-01

Microstructure, film orientation, and optical transmission spectra of polycrystalline Nd-modified Pb(ZrxTi1-x)O3 films were studied as a function of film thickness. Pulsed laser deposition was used for the fabrication of films with thickness from 80to465nm on single-crystal MgO(100) substrates. Raman spectroscopy, x-ray diffraction, and spectrophotometry measurements were utilized in the film characterization. With the decreasing film thickness, films first oriented with c axis perpendicular to film surface, and then, after some critical thickness, changed to a-axis orientation. At the same time, compressive stress increased up to 1.3GPa and a clear blueshift of the optical absorption edge was found in transmission spectra.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biedermann, G. W.; McGuinness, H. J.; Rakholia, A. V.

Here, we demonstrate matter-wave interference in a warm vapor of rubidium atoms. Established approaches to light-pulse atom interferometry rely on laser cooling to concentrate a large ensemble of atoms into a velocity class resonant with the atom optical light pulse. In our experiment, we show that clear interference signals may be obtained without laser cooling. This effect relies on the Doppler selectivity of the atom interferometer resonance. Lastly, this interferometer may be configured to measure accelerations, and we demonstrate that multiple interferometers may be operated simultaneously by addressing multiple velocity classes.

Effects of dopant induced defects on structural, multiferroic and optical properties of Bi1-x Pb x FeO3 (0 ≤ x ≤ 0.3) ceramics

NASA Astrophysics Data System (ADS)

Hassnain Jaffari, G.; Aftab, M.; Samad, Abdus; Mumtaz, Fiza; Awan, M. S.; Shah, S. Ismat

2018-01-01

Bi1-x Pb x FeO3 (0 ≤ x ≤ 0.3) has been characterized in detail with an aim to identify role of defect such as dopant, various vacancies, grain boundaries etc, and their effect on structural, optical and multiferroic properties. Structural analysis revealed that Pb substitution transforms the rhombohedral phase of BiFeO3 to the pseudocubic phase for x ≥ 0.15, consistently all vibrational Raman modes associated with the rhombohedral phase are found disappeared. Optical response revealed weakening of the d-d transitions with Pb addition indicating change in the Fe atoms environment consistent with the transition from non-centrosymmetric to the centrosymmetric structure. Transport and dielectric responses are explained in terms of hopping due to the presence of defects like oxygen vacancies and grain boundary conduction. In the high temperature regime, grain boundary conduction led to decrease in resistivity with the presence of a hump that is associated with hopping conduction. Extrinsic contributions in the transport properties correlate well with dielectric response. Magnetic and ferroelectric responses are also presented where role of oxygen vacancies defects has been clearly identified.

A Flexible High-Performance Photoimaging Device Based on Bioinspired Hierarchical Multiple-Patterned Plasmonic Nanostructures.

PubMed

Lee, Yoon Ho; Lee, Tae Kyung; Kim, Hongki; Song, Inho; Lee, Jiwon; Kang, Saewon; Ko, Hyunhyub; Kwak, Sang Kyu; Oh, Joon Hak

2018-03-01

In insect eyes, ommatidia with hierarchical structured cornea play a critical role in amplifying and transferring visual signals to the brain through optic nerves, enabling the perception of various visual signals. Here, inspired by the structure and functions of insect ommatidia, a flexible photoimaging device is reported that can simultaneously detect and record incoming photonic signals by vertically stacking an organic photodiode and resistive memory device. A single-layered, hierarchical multiple-patterned back reflector that can exhibit various plasmonic effects is incorporated into the organic photodiode. The multiple-patterned flexible organic photodiodes exhibit greatly enhanced photoresponsivity due to the increased light absorption in comparison with the flat systems. Moreover, the flexible photoimaging device shows a well-resolved spatiotemporal mapping of optical signals with excellent operational and mechanical stabilities at low driving voltages below half of the flat systems. Theoretical calculation and scanning near-field optical microscopy analyses clearly reveal that multiple-patterned electrodes have much stronger surface plasmon coupling than flat and single-patterned systems. The developed methodology provides a versatile and effective route for realizing high-performance optoelectronic and photonic systems. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photopions from nuclei in the distorted-wave impulse approximation

NASA Astrophysics Data System (ADS)

Girija, V.; Devanathan, V.

1982-11-01

The formalism for photoproduction of pions from nuclei has been developed in the distorted-wave impulse approximation, taking into account the effect of the change in pion momentum in nuclear medium. Detailed calculations have been done for the reaction 16O(γ, π+)16N for photon energies from 170 to 380 MeV, with a view to investigate the effect due to the gradient operator ∇-->π for momentum of the pion and test the sensitivity of the photopion cross sections to the details of the pion-nucleus optical potential. The results clearly establish that the gradient operator increases the cross sections throughout the energy region considered, the increase being small at lower energies. Also with ∇-->π, the cross sections are rendered less sensitive to the optical potential. The calculated differential cross sections agree very well with the recent experimental data of Shoda et al. for γ-ray energy of 200 MeV. However, the cross sections obtained at medium energies are higher when compared to the available experimental data. NUCLEAR REACTIONS π+ photoproduction from 16O; distorted wave impulse approximation; pion-nucleus optical potentials; gradient operator for the pion momentum.

Investigation of percolation thickness of sputter coated thin NiCr films on clear float glass

NASA Astrophysics Data System (ADS)

Erkan, Selen; Arpat, Erdem; Peters, Sven

2017-11-01

Percolation thickness of reactively sputtered nickel chromium (NiCr) thin films is reported in this study. Nickel-chromium films with the thicknesses in between 1 and 10 nm were deposited on 4 mm clear glass substrate by dc magnetron sputtering. Optical properties such as refractive index, extinction coefficient and also sheet resistance, carrier concentration and mobility of NiCr films were determined by a combination of variable-angle spectroscopic ellipsometry and four point probe measurements. We show both the percolation phenomena in atmosphere and critical percolation thickness for thin NiCr films by both electrical and optical techniques. The two techniques gave consistent results with each other.

Aerosol Optical Depth Determinations for BOREAS

NASA Technical Reports Server (NTRS)

Wrigley, R. C.; Livingston, J. M.; Russell, P. B.; Guzman, R. P.; Ried, D.; Lobitz, B.; Peterson, David L. (Technical Monitor)

1994-01-01

Automated tracking sun photometers were deployed by NASA/Ames Research Center aboard the NASA C-130 aircraft and at a ground site for all three Intensive Field Campaigns (IFCs) of the Boreal Ecosystem-Atmosphere Study (BOREAS) in central Saskatchewan, Canada during the summer of 1994. The sun photometer data were used to derive aerosol optical depths for the total atmospheric column above each instrument. The airborne tracking sun photometer obtained data in both the southern and northern study areas at the surface prior to takeoff, along low altitude runs near the ground tracking sun photometer, during ascents to 6-8 km msl, along remote sensing flightlines at altitude, during descents to the surface, and at the surface after landing. The ground sun photometer obtained data from the shore of Candle Lake in the southern area for all cloud-free times. During the first IFC in May-June ascents and descents of the airborne tracking sun photometer indicated the aerosol optical depths decreased steadily from the surface to 3.5 kni where they leveled out at approximately 0.05 (at 525 nm), well below levels caused by the eruption of Mt. Pinatubo. On a very clear day, May 31st, surface optical depths measured by either the airborne or ground sun photometers approached those levels (0.06-0.08 at 525 nm), but surface optical depths were often several times higher. On June 4th they increased from 0.12 in the morning to 0.20 in the afternoon with some evidence of brief episodes of pollen bursts. During the second IFC surface aerosol optical depths were variable in the extreme due to smoke from western forest fires. On July 20th the aerosol optical depth at 525 nm decreased from 0.5 in the morning to 0.2 in the afternoon; they decreased still further the next day to 0.05 and remained consistently low throughout the day to provide excellent conditions for several remote sensing missions flown that day. Smoke was heavy for the early morning of July 24th but cleared partially by 10:30 local time and cleared fully by 11:30. Heavy smoke characterized the rest of the IFC in both study areas.

FURTHER CONSTRAINTS ON THE OPTICAL TRANSMISSION SPECTRUM OF HAT-P-1b

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montalto, M.; Santos, N. C.; Martins, J. H. C.

We report on novel observations of HAT-P-1 aimed at constraining the optical transmission spectrum of the atmosphere of its transiting hot-Jupiter exoplanet. Ground-based differential spectrophotometry was performed over two transit windows using the DOLORES spectrograph at the Telescopio Nazionale Galileo. Our measurements imply an average planet to star radius ratio equal to R{sub p}/R{sub *} = (0.1159 ± 0.0005). This result is consistent with the value obtained from recent near-infrared measurements of this object, but differs from previously reported optical measurements, being lower by around 4.4 exoplanet scale heights. Analyzing the data over five different spectral bins of ∼600 Åmore » wide, we observed a single peaked spectrum (3.7 σ level) with a blue cutoff corresponding to the blue edge of the broad absorption wing of sodium and an increased absorption in the region in-between 6180 and 7400 Å. We also infer that the width of the broad absorption wings due to alkali metals is likely narrower than the one implied by solar abundance clear atmospheric models. We interpret the result as evidence that HAT-P-1b has a partially clear atmosphere at optical wavelengths with a more modest contribution from an optical absorber than previously reported.« less

Further Constraints on the Optical Transmission Spectrum of HAT-P-1b

NASA Astrophysics Data System (ADS)

Montalto, M.; Iro, N.; Santos, N. C.; Desidera, S.; Martins, J. H. C.; Figueira, P.; Alonso, R.

2015-09-01

We report on novel observations of HAT-P-1 aimed at constraining the optical transmission spectrum of the atmosphere of its transiting hot-Jupiter exoplanet. Ground-based differential spectrophotometry was performed over two transit windows using the DOLORES spectrograph at the Telescopio Nazionale Galileo. Our measurements imply an average planet to star radius ratio equal to Rp/R* = (0.1159 ± 0.0005). This result is consistent with the value obtained from recent near-infrared measurements of this object, but differs from previously reported optical measurements, being lower by around 4.4 exoplanet scale heights. Analyzing the data over five different spectral bins of ∼600 Å wide, we observed a single peaked spectrum (3.7 σ level) with a blue cutoff corresponding to the blue edge of the broad absorption wing of sodium and an increased absorption in the region in-between 6180 and 7400 Å. We also infer that the width of the broad absorption wings due to alkali metals is likely narrower than the one implied by solar abundance clear atmospheric models. We interpret the result as evidence that HAT-P-1b has a partially clear atmosphere at optical wavelengths with a more modest contribution from an optical absorber than previously reported.

Controlling morphology and chain aggregation in semiconducting conjugated polymers: the role of solvent on optical gain in MEH-PPV.

PubMed

Lampert, Zach E; Reynolds, C Lewis; Papanikolas, John M; Aboelfotoh, M Osama

2012-10-25

We report the results of a detailed investigation that addresses the influence of polymer morphology and chain aggregation, as controlled by the chemical nature of the solvent, on the optical gain properties of the conjugated polymer poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV). Using the variable stripe length technique in the picosecond regime, we have extensively studied the optical gain performance of asymmetric planar waveguides formed with thin MEH-PPV films spin-cast from concentrated chlorobenzene (CB) and tetrahydrofuran (THF) solutions onto thermally oxidized silicon substrates. CB and THF solvents were chosen based on their known ability to promote and effectively limit aggregate formation, respectively. Very large net gain coefficients are demonstrated, reaching values of 330 and 365 cm(-1), respectively, when optically pumping the waveguides with a maximum energy density of 85 μJ/cm(2). Our results clearly demonstrate that polymer morphology, and hence, the chain conformation dependence of the degree of aggregation in the films as controlled by the solvent, has minimal impact on the net gain. Moreover, the waveguides exhibit low loss coefficients of 10-20 cm(-1) at the ASE wavelength. These results question the importance of polymer morphology and aggregate formation in polymer-based optical devices operating at high excitation densities in the stimulated emission regime as would be characteristic of lasers and optical amplifiers.

Novel fluorescent contrast agents for optical imaging of in vivo tumors based on a receptor-targeted dye-peptide conjugate platform

NASA Astrophysics Data System (ADS)

Bugaj, Joseph E.; Achilefu, Samuel I.; Dorshow, Richard B.; Rajagopalan, Raghavan

2001-04-01

We have designed, synthesized, and evaluated the efficacy of novel dye-peptide conjugates that are receptor specific. Contrary to the traditional approach of conjugating dyes to large proteins and antibodies, we used small peptide-dye conjugates that target over-expressed receptors on tumors. Despite the fact that the peptide and the dye probe have similar molecular mass, our results demonstrate that the affinity of the peptide for its receptor and the dye fluorescence properties are both retained. The use of small peptides has several advantages over large biomolecules, including ease of synthesis of a variety of compounds for potential combinatorial screening of new targets, reproducibility of high purity compounds, diffusiveness to solid tumors, and the ability to incorporate a variety of functional groups that modify the pharmacokinetics of the peptide-dye conjugates. The efficacy of these new fluorescent optical contrast agents was evaluated in vivo in well-characterized rat tumor lines expressing somatostatin (sst2) and bombesin receptors. A simple continuous wave optical imaging system was employed. The resulting optical images clearly show that successful specific tumor targeting was achieved. Thus, we have demonstrated that small peptide- dye conjugates are effective as contrast agents for optical imaging of tumors.

Scattering and Absorption Properties of Biomaterials for Dental Restorative Applications

NASA Astrophysics Data System (ADS)

Fernandez-Oliveras, A.; Rubiño, M.; Pérez, M. M.

2013-08-01

The physical understanding of the optical properties of dental biomaterials is mandatory for their final success in restorative applications.Light propagation in biological media is characterized by the absorption coefficient, the scattering coefficient, the scattering phase function,the refractive index, and the surface conditions (roughness). We have employed the inverse adding-doubling (IAD) method to combine transmittance and reflectance measurements performed using an integrating-sphere setup with the results of the previous scattering-anisotropygoniometric measurements. This has led to the determination of the absorption and the scattering coefficients. The aim was to optically characterize two different dental-resin composites (nanocomposite and hybrid) and one type of zirconia ceramic, and comparatively study them. The experimental procedure was conducted under repeatability conditions of measurement in order to determine the uncertainty associated to the optical properties of the biomaterials. Spectral variations of the refraction index and the scattering anisotropy factor were also considered. The whole experimental procedure fulfilled all the necessary requirements to provide optical-property values with lower associated uncertainties. The effective transport coefficient presented a similar spectral behavior for the two composites but completely different for the zirconia ceramic. The results demonstrated that the scattering anisotropy exerted a clearly distinct impact on the optical properties of the zirconia ceramic compared with those of the dental-resin composites.

Silicon-integrated thin-film structure for electro-optic applications

DOEpatents

McKee, Rodney A.; Walker, Frederick Joseph

2000-01-01

A crystalline thin-film structure suited for use in any of an number of electro-optic applications, such as a phase modulator or a component of an interferometer, includes a semiconductor substrate of silicon and a ferroelectric, optically-clear thin film of the perovskite BaTiO.sub.3 overlying the surface of the silicon substrate. The BaTiO.sub.3 thin film is characterized in that substantially all of the dipole moments associated with the ferroelectric film are arranged substantially parallel to the surface of the substrate to enhance the electro-optic qualities of the film.

Optical based tactile shear and normal load sensor

DOEpatents

Salisbury, Curt Michael

2015-06-09

Various technologies described herein pertain to a tactile sensor that senses normal load and/or shear load. The tactile sensor includes a first layer and an optically transparent layer bonded together. At least a portion of the first layer is made of optically reflective material. The optically transparent layer is made of resilient material (e.g., clear silicone rubber). The tactile sensor includes light emitter/light detector pair(s), which respectively detect either normal load or shear load. Light emitter(s) emit light that traverses through the optically transparent layer and reflects off optically reflective material of the first layer, and light detector(s) detect and measure intensity of reflected light. When a normal load is applied, the optically transparent layer compresses, causing a change in reflected light intensity. When shear load is applied, a boundary between optically reflective material and optically absorptive material is laterally displaced, causing a change in reflected light intensity.

Use of A-Train Aerosol Observations to Constrain Direct Aerosol Radiative Effects (DARE) Comparisons with Aerocom Models and Uncertainty Assessments

NASA Technical Reports Server (NTRS)

Redemann, J.; Shinozuka, Y.; Kacenelenbogen, M.; Segal-Rozenhaimer, M.; LeBlanc, S.; Vaughan, M.; Stier, P.; Schutgens, N.

2017-01-01

We describe a technique for combining multiple A-Train aerosol data sets, namely MODIS spectral AOD (aerosol optical depth), OMI AAOD (absorption aerosol optical depth) and CALIOP aerosol backscatter retrievals (hereafter referred to as MOC retrievals) to estimate full spectral sets of aerosol radiative properties, and ultimately to calculate the 3-D distribution of direct aerosol radiative effects (DARE). We present MOC results using almost two years of data collected in 2007 and 2008, and show comparisons of the aerosol radiative property estimates to collocated AERONET retrievals. Use of the MODIS Collection 6 AOD data derived with the dark target and deep blue algorithms has extended the coverage of the MOC retrievals towards higher latitudes. The MOC aerosol retrievals agree better with AERONET in terms of the single scattering albedo (ssa) at 441 nm than ssa calculated from OMI and MODIS data alone, indicating that CALIOP aerosol backscatter data contains information on aerosol absorption. We compare the spatio-temporal distribution of the MOC retrievals and MOC-based calculations of seasonal clear-sky DARE to values derived from four models that participated in the Phase II AeroCom model intercomparison initiative. Overall, the MOC-based calculations of clear-sky DARE at TOA over land are smaller (less negative) than previous model or observational estimates due to the inclusion of more absorbing aerosol retrievals over brighter surfaces, not previously available for observationally-based estimates of DARE. MOC-based DARE estimates at the surface over land and total (land and ocean) DARE estimates at TOA are in between previous model and observational results. Comparisons of seasonal aerosol property to AeroCom Phase II results show generally good agreement best agreement with forcing results at TOA is found with GMI-MerraV3. We discuss sampling issues that affect the comparisons and the major challenges in extending our clear-sky DARE results to all-sky conditions. We present estimates of clear-sky and all-sky DARE and show uncertainties that stem from the assumptions in the spatial extrapolation and accuracy of aerosol and cloud properties, in the diurnal evolution of these properties, and in the radiative transfer calculations.

Excitons in one-dimensional van der Waals materials: Sb2S3 nanoribbons

NASA Astrophysics Data System (ADS)

Caruso, Fabio; Filip, Marina R.; Giustino, Feliciano

2015-09-01

Antimony sulphide Sb2S3 has emerged as a promising material for a variety of energy applications ranging from solar cells to thermoelectrics and solid-state batteries. The most distinctive feature of Sb2S3 is its crystal structure, which consists of parallel 1-nm-wide ribbons held together by weak van der Waals forces. This structure clearly suggests that it should be possible to isolate individual Sb2S3 ribbons using micromechanical or liquid-phase exfoliation techniques. However, it is not clear yet how to identify the ribbons postexfoliation using standard optical probes. Using state-of-the-art first-principles calculations based on many-body perturbation theory, here we show that individual ribbons of Sb2S3 carry optical signatures clearly distinct from those of bulk Sb2S3 . In particular, we find a large blueshift of the optical absorption edge (from 1.38 to 2.30 eV) resulting from the interplay between a reduced screening and the formation of bound excitons. In addition, we observe a transition from an indirect band gap to a direct gap, suggesting an enhanced photoluminescence in the green. These unique fingerprints will enable extending the research on van der Waals materials to the case of one-dimensional chalchogenides.

Collision models in quantum optics

NASA Astrophysics Data System (ADS)

Ciccarello, Francesco

2017-12-01

Quantum collision models (CMs) provide advantageous case studies for investigating major issues in open quantum systems theory, and especially quantum non-Markovianity. After reviewing their general definition and distinctive features, we illustrate the emergence of a CM in a familiar quantum optics scenario. This task is carried out by highlighting the close connection between the well-known input-output formalism and CMs. Within this quantum optics framework, usual assumptions in the CMs' literature - such as considering a bath of noninteracting yet initially correlated ancillas - have a clear physical origin.

Wood lens design philosophy based on a binary additive manufacturing technique

NASA Astrophysics Data System (ADS)

Marasco, Peter L.; Bailey, Christopher

2016-04-01

Using additive manufacturing techniques in optical engineering to construct a gradient index (GRIN) optic may overcome a number of limitations of GRIN technology. Such techniques are maturing quickly, yielding additional design degrees of freedom for the engineer. How best to employ these degrees of freedom is not completely clear at this time. This paper describes a preliminary design philosophy, including assumptions, pertaining to a particular printing technique for GRIN optics. It includes an analysis based on simulation and initial component measurement.

Strain gauge using Si-based optical microring resonator.

PubMed

Lei, Longhai; Tang, Jun; Zhang, Tianen; Guo, Hao; Li, Yanna; Xie, Chengfeng; Shang, Chenglong; Bi, Yu; Zhang, Wendong; Xue, Chenyang; Liu, Jun

2014-12-20

This paper presents a strain gauge using the mechanical-optical coupling method. The Si-based optical microring resonator was employed as the sensing element, which was embedded on the microcantilevers. The experimental results show that applying external strain triggers a clear redshift of the output resonant spectrum of the structure. The sensitivity of 93.72  pm/MPa was achieved, which also was verified using theoretical simulations. This paper provides what we believe is a new method to develop micro-opto-electromechanical system (MOEMS) sensors.

Note: computer controlled rotation mount for large diameter optics.

PubMed

Rakonjac, Ana; Roberts, Kris O; Deb, Amita B; Kjærgaard, Niels

2013-02-01

We describe the construction of a motorized optical rotation mount with a 40 mm clear aperture. The device is used to remotely control the power of large diameter laser beams for a magneto-optical trap. A piezo-electric ultrasonic motor on a printed circuit board provides rotation with a precision better than 0.03° and allows for a very compact design. The rotation unit is controlled from a computer via serial communication, making integration into most software control platforms straightforward.

Aerosol optical properties and radiative effects: Assessment of urban aerosols in central China using 10-year observations

NASA Astrophysics Data System (ADS)

Zhang, Ming; Ma, Yingying; Gong, Wei; Liu, Boming; Shi, Yifan; Chen, ZhongYong

2018-06-01

Poor air quality episodes are common in central China. Here, based on 10 years of ground-based sun-photometric observations, aerosol optical and radiative forcing characteristics were analyzed in Wuhan, the biggest metropolis in central China. Aerosol optical depth (AOD) in the last decade declined significantly, while the Ångström exponent (AE) showed slight growth. Single scattering albedo (SSA) at 440 nm reached the lowest value (0.87) in winter and highest value (0.93) in summer. Aerosol parameters derived from sun-photometric observations were used as input in a radiative transfer model to calculate aerosol radiative forcing (ARF) on the surface in ultraviolet (UV), visible (VIS), near-infrared (NIR), and shortwave (SW) spectra. ARFSW sustained decreases (the absolute values) over the last 10 years. In terms of seasonal variability, due to the increases in multiple scattering effects and attenuation of the transmitted radiation as AOD increased, ARF in summer displayed the largest value (-73.94 W/m2). After eliminating the influence of aerosol loading, the maximum aerosol radiative forcing efficiency in SW range (ARFESW) achieved a value of -64.5 W/m2/AOD in April. The ARFE change in each sub-interval spectrum was related to the change in SSA and effective radius of fine mode particles (Refff), that is, ARFE increased with the decreases in SSA and Refff. The smallest contribution of ARFENIR to ARFESW was 34.11% under strong absorbing and fine particle conditions, and opposite results were found for the VIS range, whose values were always over 51.82%. Finally, due to the serious air pollution and frequency of haze day, aerosol characteristics in haze and clear days were analyzed. The percentage of ARFENIR increased from 35.71% on clear-air days to 37.63% during haze periods, while both the percentage of ARFEUV and ARFENIR in ARFESW kept decreasing. The results of this paper should help us to better understand the effect of aerosols on solar spectral radiation and to develop improved the aerosol models over central China.

Worldwide estimates and uncertainty assessments of laser propagation for diverse geometries for paths in the altitude regime of 3 km and below at wavelengths 0.355 μm to 10.6 μm

NASA Astrophysics Data System (ADS)

Fiorino, Steven T.; Bartell, Richard J.; Perram, Glen P.; Krizo, Matthew J.; Fedyk, Daniel J.; Wisdom, Brett W.; Cusumano, Salvatore J.

2007-04-01

The directed energy modeling and simulation community can make important direct contributions to the joint warfighting community by establishing clear and fully integrated future program requirements. These requirements are best determined via analysis of the expected variability/uncertainty in system performance arising from spatial, spectral and temporal variations in operating conditions. In this study of atmospheric effects on HEL systems, the parameter space is explored using the Air Force Institute of Technology Center for Directed Energy's (AFIT/CDE) High Energy Laser End-to-End Operational Simulation (HELEEOS) parametric one-on-one engagement level model. HELEEOS is anchored to respected wave optics codes and all significant degradation effects-including optical turbulence and molecular, aerosol, and liquid water drop/droplet absorption and scattering-are represented in the model. Beam spread effects due to thermal blooming caused by the various absorbers are considered when appropriate. Power delivered in a 5 cm diameter circular area normalized by the total transmitted power is the primary performance metric used in the study, with results presented in the form of histograms. The expected performance of laser systems operating at both low and high powers is assessed at 24 wavelengths between 0.355 μm and 10.6 μm for a number of widely dispersed land and maritime locations worldwide. Scenarios evaluated include both up and down looking generally oblique engagement geometries over ranges up to 6000 meters in which anticipated clear air aerosols and thin layers of fog, and very light rain are simulated. Seasonal and boundary layer variations (summer and winter) for nighttime conditions for a range of relative humidity percentile conditions are considered to determine optimum employment techniques to exploit or defeat the environmental conditions. Each atmospheric particulate/obscurant is evaluated based on its wavelength-dependent forward and off-axis scattering characteristics and absorption effects on laser energy delivered. In addition to realistic vertical profiles of molecular and aerosol absorption and scattering, correlated optical turbulence profiles in probabilistic (percentile) format are used, a feature unique to HELEEOS.

TH-EF-207A-06: High-Resolution Optical-CT/ECT Imaging of Unstained Mice Femur, Brain, Spleen, and Tumor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoon, S; Dewhirst, M; Oldham, M

2016-06-15

Purpose: Optical transmission and emission computed tomography (optical-CT/ECT) provides high-resolution 3D attenuation and emission maps in unsectioned large (∼1cm{sup 3}) ex vivo tissue samples at a resolution of 12.9µm{sup 3} per voxel. Here we apply optical-CT/ECT to investigate high-resolution structure and auto-fluorescence in a range of optically cleared mice organs, including, for the first time, mouse bone (femur), opening the potential for study of bone metastasis and bone-mediated immune response. Methods: Three BALBc mice containing 4T1 flank tumors were sacrificed to obtain spleen, brain, tumor, and femur. Tissues were washed in 4% PFA, fixed in EtOH solution (for 5, 10,more » 10, and 2 days respectively), and then optically cleared for 3 days in BABBs. The femur was also placed in 0.25M aqueous EDTA for 15–30 days to remove calcium. Optical-CT/ECT attenuation and emission maps at 633nm (the latter using 530nm excitation light) were obtained for all samples. Bi-telecentric optical-CT was compared side-by-side with conventional optical projection tomography (OPT) imaging to evaluate imaging capability of these two rival techniques. Results: Auto-fluorescence mapping of femurs reveals vasculatures and fluorescence heterogeneity. High signals (A.U.=10) are reported in the medullary cavity but not in the cortical bone (A.U.=1). The brain strongly and uniform auto-fluoresces (A.U.=5). Thick, optically dense organs such as the spleen and the tumor (0.12, 0.46OD/mm) are reconstructed at depth without significant loss of resolution, which we attribute to the bi-telecentric optics of optical-CT. The attenuation map of tumor reveals vasculature, attenuation heterogeneity, and possibly necrotic tissue. Conclusion: We demonstrate the feasibility of optical-CT/ECT imaging of un-sectioned mice bones (femurs) and spleen with high resolution. This result, and the characterization of unstained organs, are important steps enabling future studies involving optical-CT/ECT applied to study metastasis and immunologic responses via fluorescence staining.« less

20-Gbps optical LiFi transport system.

PubMed

Ying, Cheng-Ling; Lu, Hai-Han; Li, Chung-Yi; Cheng, Chun-Jen; Peng, Peng-Chun; Ho, Wen-Jeng

2015-07-15

A 20-Gbps optical light-based WiFi (LiFi) transport system employing vertical-cavity surface-emitting laser (VCSEL) and external light injection technique with 16-quadrature amplitude modulation (QAM)-orthogonal frequency-division multiplexing (OFDM) modulating signal is proposed. Good bit error rate (BER) performance and clear constellation map are achieved in our proposed optical LiFi transport systems. An optical LiFi transport system, delivering 16-QAM-OFDM signal over a 6-m free-space link, with a data rate of 20 Gbps, is successfully demonstrated. Such a 20-Gbps optical LiFi transport system provides the advantage of a free-space communication link for high data rates, which can accelerate the visible laser light communication (VLLC) deployment.

Two-dimensional PSF prediction of multiple-reflection optical systems with rough surfaces

NASA Astrophysics Data System (ADS)

Tayabaly, Kashmira; Spiga, Daniele; Sironi, Giorgia; Pareschi, Giovani; Lavagna, Michele

2016-09-01

The focusing accuracy in reflective optical systems, usually expressed in terms of the Point Spread Function (PSF) is chiefly determined by two factors: the deviation of the mirror shape from the nominal design and the surface finishing. While the effects of the former are usually well described by the geometrical optics, the latter is diffractive/interferential in nature and determined by a distribution of defects that cover several decades in the lateral scale (from a few millimeters to a few microns). Clearly, reducing the level of scattered light is crucial to improve the focusing of the collected radiation, particularly for astronomical telescopes that aim to detect faint light signals from our Universe. Telescopes are typically arranged in multiple reflections configuration and the behavior of the multiply-scattered radiation becomes difficult to predict and control. Also it is difficult to disentangle the effect of surface scattering from the PSF degradation caused by the shape deformation of the optical elements. This paper presents a simple and unifying method for evaluating the contribution of optical surfaces defects to the two-dimensional PSF of a multi-reflections system, regardless of the classification of a spectral range as "geometry" or "roughness". This method, entirely based on Huygens-Fresnel principle in the far-field approximation, was already applied in grazing-incidence X-ray mirrors and experimentally validated for a single reflection system, accounting for the real surface topography of the optics. In this work we show the extension of this formalism to a double reflection system and introducing real microroughness data. The formalism is applied to a MAGIC-I panel mirror that was fully characterized, allowing us to predict the PSF and the validation with real measurements of the double reflection ASTRI telescope, a prototype of CTA-SST telescope.

Starch-based Antimicrobial Films Incorporated with Lauric Acid and Chitosan

NASA Astrophysics Data System (ADS)

Salleh, E.; Muhamad, I. I.

2010-03-01

Antimicrobial (AM) packaging is one of the most promising active packaging systems. Starch-based film is considered an economical material for antimicrobial packaging. This study aimed at the development of food packaging based on wheat starch incorporated with lauric acid and chitosan as antimicrobial agents. The purpose is to restrain or inhibit the growth of spoilage and/or pathogenic microorganisms that are contaminating foods. The antimicrobial effect was tested on B. substilis and E. coli. Inhibition of bacterial growth was examined using two methods, i.e. zone of inhibition test on solid media and liquid culture test (optical density measurements). The control and AM films (incorporated with chitosan and lauric acid) were produced by casting method. From the observations, AM films exhibited inhibitory zones. Interestingly, a wide clear zone on solid media was observed for B. substilis growth inhibition whereas inhibition for E. coli was not as effective as B. substilis. From the liquid culture test, the AM films clearly demonstrated a better inhibition against B. substilis than E. coli.

Analysis of the weekly cycle of aerosol optical depth using AERONET and MODIS data

NASA Astrophysics Data System (ADS)

Xia, Xiangao; Eck, Tom F.; Holben, Brent N.; Phillippe, Goloub; Chen, Hongbin

2008-07-01

Multi-year Aerosol Robotic Network (AERONET) and Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) data are used to study AOD weekly variations at the global scale. A clear weekly cycle of AOD is observed in the United States (U.S.) and Central Europe. AOD during the weekday is larger than that during the weekend in 36 out of 43 AERONET sites in the U.S. The average U.S. weekend effect (the percent difference in AOD during the weekday and the weekend) is 3.8%. A weekly periodicity with lower AODs on Sunday and Monday and higher AODs from Wednesday until Saturday is revealed over Central Europe and the average weekend effect there is 4.0%. The weekly cycle in urban sites is greater than that in rural sites. AOD during the weekday is also significantly larger than that during the weekend in urban AERONET sites in South America and South Korea. However, a reversed AOD weekly cycle is observed in the Middle East and India. AODs on Thursday and Friday, the "weekend" for Middle East cultures, are relatively lower than AODs on other days. There is no clear weekly variation of AOD over eastern China. The striking feature in this region is the occurrence of much higher AOD on Sunday and this phenomenon is independent of season. The analysis of MODIS aerosol data is in good agreement with that of AERONET data.

A study of the physical, chemical, and optical properties of ambient aerosol particles in Southeast Asia during hazy and nonhazy days

NASA Astrophysics Data System (ADS)

See, S. W.; Balasubramanian, R.; Wang, W.

2006-05-01

Many Southeast Asian countries have been constantly plagued by recurring smoke haze episodes as a result of traditional slash-and-burn practices in agricultural areas to clear crop lands or uncontrolled forest fires. However, our current knowledge on the physiochemical and optical properties of ambient aerosols associated with regional haze phenomenon is still fairly limited. Therefore a comprehensive field study was carried out in Singapore from March 2001 to March 2002 under varying weather conditions to gain a better understanding of the characteristics. The physical (size distribution of mass and number concentrations), chemical (mass concentrations of chemical components: 14 ions, 24 metals, elemental carbon (EC) and organic carbon (OC)), and optical (light absorption (bap) and scattering (bsp) by particles) characteristics of ambient aerosol particles were investigated. The results are reported separately for clear and hazy days by categorizing the days as clear or hazy on the basis of visibility data. It was observed that the average concentrations of PM2.5 and most chemical components increased approximately by a factor of 2 on hazy days. Backward air trajectories together with the hot spot distributions in the region indicated that the degradation in Singapore's air quality on hazy days was attributable to large-scale forest fires in Sumatra. This visibility degradation was quantitatively measured on the basis of the light absorption and scattering by particles. As expected, scattering rather than absorption controlled atmospheric visibility, and PM2.5 particles present on hazy days were more efficient at scattering light than those found on clear days.

Polarimetric imaging of turbid inhomogeneous slab media based on backscattering using a pencil beam for illumination: Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Otsuki, Soichi

2018-04-01

Polarimetric imaging of absorbing, strongly scattering, or birefringent inclusions is investigated in a negligibly absorbing, moderately scattering, and isotropic slab medium. It was proved that the reduced effective scattering Mueller matrix is exactly calculated from experimental or simulated raw matrices even if the medium is anisotropic and/or heterogeneous, or the outgoing light beam exits obliquely to the normal of the slab surface. The calculation also gives a reasonable approximation of the reduced matrix using a light beam with a finite diameter for illumination. The reduced matrix was calculated using a Monte Carlo simulation and was factorized in two dimensions by the Lu-Chipman polar decomposition. The intensity of backscattered light shows clear and modestly clear differences for absorbing and strongly scattering inclusions, respectively, whereas it shows no difference for birefringent inclusions. Conversely, some polarization parameters, for example, the selective depolarization coefficients exhibit only a slight difference for the absorbing inclusions, whereas they showed clear difference for the strongly scattering or birefringent inclusions. Moreover, these quantities become larger with increasing the difference in the optical properties of the inclusions relative to the surrounding medium. However, it is difficult to recognize inclusions that buried at the depth deeper than 3 mm under the surface. Thus, the present technique can detect the approximate shape and size of these inclusions, and considering the depth where inclusions lie, estimate their optical properties. This study reveals the possibility of the polarization-sensitive imaging of turbid inhomogeneous media using a pencil beam for illumination.

Picosecond laser fabrication of nanostructures on ITO film surface assisted by pre-deposited Au film

NASA Astrophysics Data System (ADS)

Yang, H. Z.; Jiang, G. D.; Wang, W. J.; Mei, X. S.; Pan, A. F.; Zhai, Z. Y.

2017-10-01

With greater optical penetration depth and lower ablation threshold fluence, it is difficult to directly fabricate large scales of laser-induced periodic surface structures (LIPSSs) on indium-tin-oxide (ITO) films. This study proposed an approach to obtain optimized LIPSSs by sputtering an Au thin film on the ITO film surface. The concept behind the proposal is that the upper layer of the thin Au film can cause surface energy aggregation, inducing the initial ripple structures. The ripples deepened and become clear with lower energy due to optical trapping. The effective mechanism of Au film was analyzed and verified by a series of experiments. Linear sweep, parallel to the laser polarization direction, was performed using a Nd:VAN laser system with 10-ps Q-switched pulse, at a central wavelength of 532 nm, with a repetition rate of 1 kHz. The complete and clear features of the nanostructures, obtained with the periods of approximately 320 nm, were observed on ITO films with proper laser fluence and scanning speed. The depth of ripples was varying in the range of 15-65 nm with clear and coherent ITO films. The preferred efficiency of fabricating nanostructures and the excellent results were obtained at a scanning speed of 2.5 mm/s and a fluence of 0.189 J/cm2. In this way, the ablation and shedding of ITO films was successfully avoided. Thus, the proposed technique can be considered to be a promising method for the laser machining of special nonmetal films.

Optical clearing of the eye using the See Deep Brain technique.

PubMed

Hohberger, B; Baumgart, C; Bergua, A

2017-10-01

PurposeTissue clearing has been used in anatomy for the first time in Germany over a century ago. Neuronal tissue, like cortex, was investigated in mice using a water-based optical clearing method termed See Deep Brain (SeeDB). However, although the eye belongs to the central nervous system, this histological technique was not applied in the eye up to date. We applied SeeDB for the visualization of intraocular structures.Patients and methodsFour eyes of cornea donors (two male, two female: 73-84 years) obtained from the Cornea Bank of the Department of Ophthalmology Erlangen, four chicken eyes and two mices' optic nerve were used. Bulbi were fixed in 4% paraformaldehyde in phosphate-buffered saline and treated with increasing concentrations of aqueous fructose solution with 0.5% α-thioglycerol. After SeeDB, transscleral macrophotographs of the choroid were performed.ResultsComplete transparency of the sclera was obtained in enucleated human and chicken eyes after SeeDB treatment. Macroscopical anatomy of the choroid (partially transparent due to the remaining retinal pigment epithelium and melanocytes) showing vessels and other related structures was possible without preparing slides. Mice optic nerves were also transparent after SeeDB treatment.ConclusionThe SeeDB method allows visualization of intraocular structures through a completely translucent sclera. This innovative processing technique could facilitate comprehensive qualitative and quantitative topographical anatomical studies of human and animal eyes, preserving their 3D architecture. Supra- and intrachoroidal ganglionic plexus could potentially be visualized transsclerally. Finally, clinical-pathological correlations of intraocular diseases-for example, retinal tumors-will be possible in non-dissected eyes.

Light Extraction From Solution-Based Processable Electrophosphorescent Organic Light-Emitting Diodes

NASA Astrophysics Data System (ADS)

Krummacher, Benjamin C.; Mathai, Mathew; So, Franky; Choulis, Stelios; Choong, And-En, Vi

2007-06-01

Molecular dye dispersed solution processable blue emitting organic light-emitting devices have been fabricated and the resulting devices exhibit efficiency as high as 25 cd/A. With down-conversion phosphors, white emitting devices have been demonstrated with peak efficiency of 38 cd/A and luminous efficiency of 25 lm/W. The high efficiencies have been a product of proper tuning of carrier transport, optimization of the location of the carrier recombination zone and, hence, microcavity effect, efficient down-conversion from blue to white light, and scattering/isotropic remission due to phosphor particles. An optical model has been developed to investigate all these effects. In contrast to the common misunderstanding that light out-coupling efficiency is about 22% and independent of device architecture, our device data and optical modeling results clearly demonstrated that the light out-coupling efficiency is strongly dependent on the exact location of the recombination zone. Estimating the device internal quantum efficiencies based on external quantum efficiencies without considering the device architecture could lead to erroneous conclusions.

Effect of solvent volume on the physical properties of aluminium doped nanocrystalline zinc oxide thin films deposited using a simplified spray pyrolysis technique

NASA Astrophysics Data System (ADS)

Jabena Begum, N.; Mohan, R.; Ravichandran, K.

2013-01-01

Aluminium doped zinc oxide (AZO) thin films were deposited by employing a low cost and simplified spray technique using a perfume atomizer from starting solutions having different volumes (10, 20, … , 50 mL) of solvent. The effect of solvent volume on the structural, electrical, optical, photoluminescence (PL) and surface morphological properties was studied. The electrical resistivity of the AZO films is remarkably influenced by the variation in the solvent volume. The X-ray diffraction profiles clearly showed that all the films have preferential orientation along the (0 0 2) plane irrespective of the solvent volume. The crystallite size was found to be in the nano range of 35-46 nm. The optical transmittance in the visible region is desirably high (>85%). The AFM images show columnar morphology with varying grain size. The PL studies revealed that the AZO film deposited from 50 mL of solvent volume has good quality with lesser defect density.

Optical probing of quantum Hall effect of composite fermions and of the liquid-insulator transition

NASA Astrophysics Data System (ADS)

Rossella, F.; Bellani, V.; Dionigi, F.; Amado, M.; Diez, E.; Kowalik, K.; Biasiol, G.; Sorba, L.

2011-12-01

In the photoluminescence spectra of a two-dimensional electron gas in the fractional quantum Hall regime we observe the states at filling factors ν = 4/5, 5/7, 4/11 and 3/8 as clear minima in the intensity or area emission peak. The first three states are described as interacting composite fermions in fractional quantum Hall regime. The minimum in the intensity at ν = 3/8, which is not explained within this picture, can be an evidence of a suppression of the screening of the Coulomb interaction among the effective quasi-particles involved in this intriguing state. The magnetic field energy dispersion at very low temperatures is also discussed. At low field the emission follows a Landau dispersion with a screened magneto-Coulomb contribution. At intermediate fields the hidden symmetry manifests. At high field above ν = 1/3 the electrons correlate into an insulating phase, and the optical emission behaviour at the liquid-insulator transition is coherent with a charge ordering driven by Coulomb correlations.

Plastic Transition to Switch Nonlinear Optical Properties Showing the Record High Contrast in a Single-Component Molecular Crystal.

PubMed

Sun, Zhihua; Chen, Tianliang; Liu, Xitao; Hong, Maochun; Luo, Junhua

2015-12-23

To switch bulk nonlinear optical (NLO) effects represents an exciting new branch of NLO material science, whereas it remains a great challenge to achieve high contrast for "on/off" of quadratic NLO effects in crystalline materials. Here, we report the supereminent NLO-switching behaviors of a single-component plastic crystal, 2-(hydroxymethyl)-2-nitro-1,3-propanediol (1), which shows a record high contrast of at least ∼150, exceeding all the known crystalline switches. Such a breakthrough is clearly elucidated from the slowing down of highly isotropic molecular motions during plastic-to-rigid transition. The deep understanding of its intrinsic plasticity and superior NLO property allows the construction of a feasible switching mechanism. As a unique class of substances with short-range disorder embedded in long-range ordered crystalline lattice, plastic crystals enable response to external stimuli and fulfill specific photoelectric functions, which open a newly conceptual avenue for the designing of new functional materials.

Search for the Acoustic Faraday Effect in Superfluid ^3He-B

NASA Astrophysics Data System (ADS)

Lee, Y.; Haard, T. M.; Kycia, J. B.; Halperin, W. P.

1997-03-01

Transverse zero sound is another propagating mode predicted to exist in Fermi liquids by Landau. However, it has been difficult to achieve clear experimental evidence for propagating transverse zero sound in ^3He. A recent theoretical calculation(G.F. Moores and J.A. Sauls, JLTP 91), 13 (1993). showed that this mode may be rather easily detected at very low temperatures in the B-phase of superfluid ^3He. Futhermore, in the presence of a magnetic field the polarization of the sound wave rotates as it propagates, which is analogous to the Faraday effect in optics. We report our preliminary experimental results on the acoustic Faraday effect in ^3He-B.

Maximum entropy deconvolution of the optical jet of 3C 273

NASA Technical Reports Server (NTRS)

Evans, I. N.; Ford, H. C.; Hui, X.

1989-01-01

The technique of maximum entropy image restoration is applied to the problem of deconvolving the point spread function from a deep, high-quality V band image of the optical jet of 3C 273. The resulting maximum entropy image has an approximate spatial resolution of 0.6 arcsec and has been used to study the morphology of the optical jet. Four regularly-spaced optical knots are clearly evident in the data, together with an optical 'extension' at each end of the optical jet. The jet oscillates around its center of gravity, and the spatial scale of the oscillations is very similar to the spacing between the optical knots. The jet is marginally resolved in the transverse direction and has an asymmetric profile perpendicular to the jet axis. The distribution of V band flux along the length of the jet, and accurate astrometry of the optical knot positions are presented.

Influence of laser beam profiles on received power fluctuation

NASA Astrophysics Data System (ADS)

Dordova, Lucie; Diblik, Jan

2011-09-01

Gaussian beam is very often used for the transmission of information in optical wireless links. The usage of this optical beam has its advantages and, of course, disadvantages. This work focuses on possibilities of using laser beams with different distribution of optical intensity - Top Hat beam. Creation of the optical beam with selected optical intensity profile will be briefly described. Optical beams will propagate through the "clear" and stationary atmosphere in the experimental part of this work. These results will be compared with the data obtained after a laser beam is passed through the turbulent and attenuated atmosphere. We will use an ultrasound fog generator for laser beam attenuation testing. To create the turbulence, infra radiators will be applied. Particular results obtained from different atmospheric conditions will be compared and using different types of optical beams will be assessed.

Aerosol Radiative Forcing Derived From SeaWIFS - Retrieved Aerosol Optical Properties

NASA Technical Reports Server (NTRS)

Chou, Mong-Dah; Chan, Pui-King; Wang, Menghua; Einaudi, Franco (Technical Monitor)

2000-01-01

To understand climatic implications of aerosols over global oceans, the aerosol optical properties retrieved from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) are analyzed, and the effects of the aerosols on the Earth's radiation budgets (aerosol radiative forcing, ARF) are computed using a radiative transfer model. It is found that the distribution of the SeaWiFS-retrieved aerosol optical thickness is distinctively zonal. The maximum in the equatorial region coincides with the Intertropical Convergence Zone, and the maximum in the Southern Hemispheric high latitudes coincides with the region of prevailing westerlies. The minimum aerosol optical thickness is found in the subtropical high pressure regions, especially in the Southern Hemisphere. These zonal patterns clearly demonstrate the influence of atmospheric circulation on the oceanic aerosol distribution. Over global oceans, aerosols reduce the annual mean net downward solar flux by 5.4 W m-2 at the top of the atmosphere and by 6.1 W m-2 at the surface. The largest ARF is found in the tropical Atlantic, Arabian Sea, Bay of Bengal, the coastal regions of Southeast and East Asia, and the Southern Hemispheric high latitudes. During the period of the Indonesian big fires (September-December 1997), the cooling due to aerosols is greater than 15 W m-2 at the top of the atmosphere and greater than 30 W m(exp -1) at the surface in the vicinity of the maritime continents. The atmosphere receives extra solar radiation by greater than 15 W m(exp -1) over a large area. These large changes in radiative fluxes are expected to have enhanced the atmospheric stability, weakened the atmospheric circulation, and augmented the drought condition during that period. It would be very instructive to simulate the regional climatic. The model-calculated clear sky solar flux at the top of the atmosphere is compared with that derived from the Clouds and the Earth's Radiant Energy System (CERES). The net downward solar flux of CERES is systematically larger than the model calculations by -3 W M-2. In the equatorial region, the CERES-derived net downward solar flux is even larger than the model calculations without including aerosols. It is possible that the CERES incorrectly identified regions of high humidity and high aerosol concentration as being cloud contaminated and, hence, overestimated the clear sky net downward solar flux.

Extreme Light Management in Mesoporous Wood Cellulose Paper for Optoelectronics.

PubMed

Zhu, Hongli; Fang, Zhiqiang; Wang, Zhu; Dai, Jiaqi; Yao, Yonggang; Shen, Fei; Preston, Colin; Wu, Wenxin; Peng, Peng; Jang, Nathaniel; Yu, Qingkai; Yu, Zongfu; Hu, Liangbing

2016-01-26

Wood fibers possess natural unique hierarchical and mesoporous structures that enable a variety of new applications beyond their traditional use. We dramatically modulate the propagation of light through random network of wood fibers. A highly transparent and clear paper with transmittance >90% and haze <1.0% applicable for high-definition displays is achieved. By altering the morphology of the same wood fibers that form the paper, highly transparent and hazy paper targeted for other applications such as solar cell and antiglare coating with transmittance >90% and haze >90% is also achieved. A thorough investigation of the relation between the mesoporous structure and the optical properties in transparent paper was conducted, including full-spectrum optical simulations. We demonstrate commercially competitive multitouch touch screen with clear paper as a replacement for plastic substrates, which shows excellent process compatibility and comparable device performance for commercial applications. Transparent cellulose paper with tunable optical properties is an emerging photonic material that will realize a range of much improved flexible electronics, photonics, and optoelectronics.

Parallel Solver for Diffuse Optical Tomography on Realistic Head Models With Scattering and Clear Regions.

PubMed

Placati, Silvio; Guermandi, Marco; Samore, Andrea; Scarselli, Eleonora Franchi; Guerrieri, Roberto

2016-09-01

Diffuse optical tomography is an imaging technique, based on evaluation of how light propagates within the human head to obtain the functional information about the brain. Precision in reconstructing such an optical properties map is highly affected by the accuracy of the light propagation model implemented, which needs to take into account the presence of clear and scattering tissues. We present a numerical solver based on the radiosity-diffusion model, integrating the anatomical information provided by a structural MRI. The solver is designed to run on parallel heterogeneous platforms based on multiple GPUs and CPUs. We demonstrate how the solver provides a 7 times speed-up over an isotropic-scattered parallel Monte Carlo engine based on a radiative transport equation for a domain composed of 2 million voxels, along with a significant improvement in accuracy. The speed-up greatly increases for larger domains, allowing us to compute the light distribution of a full human head ( ≈ 3 million voxels) in 116 s for the platform used.

Tailored optical vector fields for ultrashort-pulse laser induced complex surface plasmon structuring.

PubMed

Ouyang, J; Perrie, W; Allegre, O J; Heil, T; Jin, Y; Fearon, E; Eckford, D; Edwardson, S P; Dearden, G

2015-05-18

Precise tailoring of optical vector beams is demonstrated, shaping their focal electric fields and used to create complex laser micro-patterning on a metal surface. A Spatial Light Modulator (SLM) and a micro-structured S-waveplate were integrated with a picosecond laser system and employed to structure the vector fields into radial and azimuthal polarizations with and without a vortex phase wavefront as well as superposition states. Imprinting Laser Induced Periodic Surface Structures (LIPSS) elucidates the detailed vector fields around the focal region. In addition to clear azimuthal and radial plasmon surface structures, unique, variable logarithmic spiral micro-structures with a pitch Λ ∼1μm, not observed previously, were imprinted on the surface, confirming unambiguously the complex 2D focal electric fields. We show clearly also how the Orbital Angular Momentum(OAM) associated with a helical wavefront induces rotation of vector fields along the optic axis of a focusing lens and confirmed by the observed surface micro-structures.

High-resolution imaging optomechatronics for precise liquid crystal display module bonding automated optical inspection

NASA Astrophysics Data System (ADS)

Ni, Guangming; Liu, Lin; Zhang, Jing; Liu, Juanxiu; Liu, Yong

2018-01-01

With the development of the liquid crystal display (LCD) module industry, LCD modules become more and more precise with larger sizes, which demands harsh imaging requirements for automated optical inspection (AOI). Here, we report a high-resolution and clearly focused imaging optomechatronics for precise LCD module bonding AOI inspection. It first presents and achieves high-resolution imaging for LCD module bonding AOI inspection using a line scan camera (LSC) triggered by a linear optical encoder, self-adaptive focusing for the whole large imaging region using LSC, and a laser displacement sensor, which reduces the requirements of machining, assembly, and motion control of AOI devices. Results show that this system can directly achieve clearly focused imaging for AOI inspection of large LCD module bonding with 0.8 μm image resolution, 2.65-mm scan imaging width, and no limited imaging width theoretically. All of these are significant for AOI inspection in the LCD module industry and other fields that require imaging large regions with high resolution.

Optical position sensor for determining the interface between a clear and an opaque fluid

DOEpatents

Weiss, Jonathan D [Albuquerque, NM

2006-05-23

An inexpensive, optical position sensor for measuring a position or length, x, along a one-dimensional curvilinear, coordinate system. The sensor can be used, for example, to determine the position of an interface between a clear and an opaque fluid (such as crude oil and water). In one embodiment, the sensor utilizes the principle of dual-fluorescence, where a primary fiber emits primary fluorescent light and a parallel secondary fiber collects a portion of the primary fluorescent light that is not blocked by the opaque fluid. This, in turn, excites secondary fluorescence in the secondary fiber at a longer wavelength. A light detector measures the intensity of secondary fluorescence emitted from an end of the secondary fiber, which is used to calculate the unknown position or length, x. Side-emitting fibers can be used in place of, or in addition to, fluorescent fibers. The all-optical sensor is attractive for applications involving flammable liquids.

Deep tissue volume imaging of birefringence through fibre-optic needle probes for the delineation of breast tumour

NASA Astrophysics Data System (ADS)

Villiger, Martin; Lorenser, Dirk; McLaughlin, Robert A.; Quirk, Bryden C.; Kirk, Rodney W.; Bouma, Brett E.; Sampson, David D.

2016-07-01

Identifying tumour margins during breast-conserving surgeries is a persistent challenge. We have previously developed miniature needle probes that could enable intraoperative volume imaging with optical coherence tomography. In many situations, however, scattering contrast alone is insufficient to clearly identify and delineate malignant regions. Additional polarization-sensitive measurements provide the means to assess birefringence, which is elevated in oriented collagen fibres and may offer an intrinsic biomarker to differentiate tumour from benign tissue. Here, we performed polarization-sensitive optical coherence tomography through miniature imaging needles and developed an algorithm to efficiently reconstruct images of the depth-resolved tissue birefringence free of artefacts. First ex vivo imaging of breast tumour samples revealed excellent contrast between lowly birefringent malignant regions, and stromal tissue, which is rich in oriented collagen and exhibits higher birefringence, as confirmed with co-located histology. The ability to clearly differentiate between tumour and uninvolved stroma based on intrinsic contrast could prove decisive for the intraoperative assessment of tumour margins.

Cloudy Sounding and Cloud-Top Height Retrieval From AIRS Alone Single Field-of-View Radiance Measurements

NASA Technical Reports Server (NTRS)

Weisz, Elisabeth; Li, Jun; Li, Jinlong; Zhou, Daniel K.; Huang, Hung-Lung; Goldberg, Mitchell D.; Yang, Ping

2007-01-01

High-spectral resolution measurements from the Atmospheric Infrared Sounder (AIRS) onboard the EOS (Earth Observing System) Aqua satellite provide unique information about atmospheric state, surface and cloud properties. This paper presents an AIRS alone single field-of-view (SFOV) retrieval algorithm to simultaneously retrieve temperature, humidity and ozone profiles under all weather conditions, as well as cloud top pressure (CTP) and cloud optical thickness (COT) under cloudy skies. For optically thick cloud conditions the above-cloud soundings are derived, whereas for clear skies and optically thin cloud conditions the profiles are retrieved from 0.005 hPa down to the earth's surface. Initial validation has been conducted by using the operational MODIS (Moderate Resolution Imaging Spectroradiometer) product, ECMWF (European Center of Medium range Weather Forecasts) analysis fields and radiosonde observations (RAOBs). These inter-comparisons clearly demonstrate the potential of this algorithm to process data from 38 high-spectral infrared (IR) sounder instruments.

Aeolian Removal of Dust Types from Photovoltaic Surfaces on Mars

NASA Technical Reports Server (NTRS)

Gaier, James R.; Perez-Davis, Marla E.; Marabito, Mark

1990-01-01

Dust elevated in local or global dust storms on the Martian surface could settle on photovoltaic (PV) surfaces and seriously hamper their performance. Using a recently developed technique to apply a uniform dust layer, PV surface materials were subjected to simulated Martian winds in an attempt to determine whether natural Aeolian processes on Mars would sweep off the settled dust. Three different types of dust were used; an optical polishing powder, basaltic "trap rock", and iron (III) oxide crystals. The effects of wind velocity, angle of attack, height above the Martian surface, and surface coating material were investigated. It was found that arrays mounted with an angle of attack approaching 45 degrees show the most efficient clearing. Although the angular dependence is not sharp, horizontally mounted arrays required significantly higher wind velocities to clear off the dust. From this test it appears that the arrays may be erected quite near the ground, but previous studies have suggested that saltation effects can be expected to cause such arrays to be covered by soil if they are set up less than about a meter from the ground. Particle size effects appear to dominate over surface chemistry in these experiments, but additional tests are required to confirm this. Providing that the surface chemistry of Martian dusts is not drastically different from simulated dust and that gravity differences have only minor effects, the materials used for protective coatings for photovoltaic arrays may be optimized for other considerations such as transparency, and chemical or abrasion resistance. The static threshold velocity is low enough that there are regions on Mars which experience winds strong enough to clear off a photovoltaic array if it is properly oriented. Turbulence fences proved to be an ineffective strategy to keep dust cleared from the photovoltaic surfaces.

"High Angular Resolution Observations of Protoplanetary Disks with Adaptive Optics"

NASA Technical Reports Server (NTRS)

Roddier, Francois

1999-01-01

Significant results were obtained and published in the literature. The first optical detection of a circumbinary disk was reported in the ApJ at millimetric wavelengths. The size and inclination of this disk were found to be consistent with millimetric observations. Evidence was found for a cavity inside the disk as theory predicts from dust clearing by the stellar companion.

Pesky Critters

DTIC Science & Technology

2005-11-01

is in relation to obstacles. Clearly, existing optical sensors are too large for this proposed system. Again, the approach utilizing biomimicry ...results in our latest conflicts. The Predator, a medium altitude system cruising at 70 knots and equipped with electro- optical and infrared cameras...that exist today, but the vehicles are also platforms for new concepts outside the status quo. 206 III. Technology Biomimicry is a new

Lattice-patterned LC-polymer composites containing various nanoparticles as additives

PubMed Central

2012-01-01

In this study, we show the effect of various nanoparticle additives on phase separation behavior of a lattice-patterned liquid crystal [LC]-polymer composite system and on interfacial properties between the LC and polymer. Lattice-patterned LC-polymer composites were fabricated by exposing to UV light a mixture of a prepolymer, an LC, and SiO2 nanoparticles positioned under a patterned photomask. This resulted in the formation of an LC and prepolymer region through phase separation. We found that the incorporation of SiO2 nanoparticles significantly affected the electro-optical properties of the lattice-patterned LC-polymer composites. This effect is a fundamental characteristic of flexible displays. The electro-optical properties depend on the size and surface functional groups of the SiO2 nanoparticles. Compared with untreated pristine SiO2 nanoparticles, which adversely affect the performance of LC molecules surrounded by polymer walls, SiO2 nanoparticles with surface functional groups were found to improve the electro-optical properties of the lattice-patterned LC-polymer composites by increasing the quantity of SiO2 nanoparticles. The surface functional groups of the SiO2 nanoparticles were closely related to the distribution of SiO2 nanoparticles in the LC-polymer composites, and they influenced the electro-optical properties of the LC molecules. It is clear from our work that the introduction of nanoparticles into a lattice-patterned LC-polymer composite provides a method for controlling and improving the composite's electro-optical properties. This technique can be used to produce flexible substrates for various flexible electronic devices. PMID:22222011

Wavefront detection method of a single-sensor based adaptive optics system.

PubMed

Wang, Chongchong; Hu, Lifa; Xu, Huanyu; Wang, Yukun; Li, Dayu; Wang, Shaoxin; Mu, Quanquan; Yang, Chengliang; Cao, Zhaoliang; Lu, Xinghai; Xuan, Li

2015-08-10

In adaptive optics system (AOS) for optical telescopes, the reported wavefront sensing strategy consists of two parts: a specific sensor for tip-tilt (TT) detection and another wavefront sensor for other distortions detection. Thus, a part of incident light has to be used for TT detection, which decreases the light energy used by wavefront sensor and eventually reduces the precision of wavefront correction. In this paper, a single Shack-Hartmann wavefront sensor based wavefront measurement method is presented for both large amplitude TT and other distortions' measurement. Experiments were performed for testing the presented wavefront method and validating the wavefront detection and correction ability of the single-sensor based AOS. With adaptive correction, the root-mean-square of residual TT was less than 0.2 λ, and a clear image was obtained in the lab. Equipped on a 1.23-meter optical telescope, the binary stars with angle distance of 0.6″ were clearly resolved using the AOS. This wavefront measurement method removes the separate TT sensor, which not only simplifies the AOS but also saves light energy for subsequent wavefront sensing and imaging, and eventually improves the detection and imaging capability of the AOS.

Optical clearing of vaginal tissues, ex vivo, for minimally invasive laser treatment of female stress urinary incontinence

NASA Astrophysics Data System (ADS)

Chang, Chun-Hung; Myers, Erinn M.; Kennelly, Michael J.; Fried, Nathaniel M.

2017-01-01

Near-infrared laser energy in conjunction with applied tissue cooling is being investigated for thermal remodeling of the endopelvic fascia during minimally invasive treatment of female stress urinary incontinence. Previous computer simulations of light transport, heat transfer, and tissue thermal damage have shown that a transvaginal approach is more feasible than a transurethral approach. However, results were suboptimal, and some undesirable thermal insult to the vaginal wall was still predicted. This study uses experiments and computer simulations to explore whether application of an optical clearing agent (OCA) can further improve optical penetration depth and completely preserve the vaginal wall during subsurface treatment of the endopelvic fascia. Several different mixtures of OCA's were tested, and 100% glycerol was found to be the optimal agent. Optical transmission studies, optical coherence tomography, reflection spectroscopy, and computer simulations [including Monte Carlo (MC) light transport, heat transfer, and Arrhenius integral model of thermal damage] using glycerol were performed. The OCA produced a 61% increase in optical transmission through porcine vaginal wall at 37°C after 30 min. The MC model showed improved energy deposition in endopelvic fascia using glycerol. Without OCA, 62%, 37%, and 1% of energy was deposited in vaginal wall, endopelvic fascia, and urethral wall, respectively, compared with 50%, 49%, and 1% using OCA. Use of OCA also resulted in 0.5-mm increase in treatment depth, allowing potential thermal tissue remodeling at a depth of 3 mm with complete preservation of the vaginal wall.

Effect of task-related extracerebral circulation on diffuse optical tomography: experimental data and simulations on the forehead.

PubMed

Näsi, Tiina; Mäki, Hanna; Hiltunen, Petri; Heiskala, Juha; Nissilä, Ilkka; Kotilahti, Kalle; Ilmoniemi, Risto J

2013-03-01

The effect of task-related extracerebral circulatory changes on diffuse optical tomography (DOT) of brain activation was evaluated using experimental data from 14 healthy human subjects and computer simulations. Total hemoglobin responses to weekday-recitation, verbal-fluency, and hand-motor tasks were measured with a high-density optode grid placed on the forehead. The tasks caused varying levels of mental and physical stress, eliciting extracerebral circulatory changes that the reconstruction algorithm was unable to fully distinguish from cerebral hemodynamic changes, resulting in artifacts in the brain activation images. Crosstalk between intra- and extracranial layers was confirmed by the simulations. The extracerebral effects were attenuated by superficial signal regression and depended to some extent on the heart rate, thus allowing identification of hemodynamic changes related to brain activation during the verbal-fluency task. During the hand-motor task, the extracerebral component was stronger, making the separation less clear. DOT provides a tool for distinguishing extracerebral components from signals of cerebral origin. Especially in the case of strong task-related extracerebral circulatory changes, however, sophisticated reconstruction methods are needed to eliminate crosstalk artifacts.

The budget of biologically active ultraviolet radiation in the earth-atmosphere system

NASA Technical Reports Server (NTRS)

Frederick, John E.; Lubin, Dan

1988-01-01

This study applies the concept of a budget to describe the interaction of solar ultraviolet (UV) radiation with the earth-atmosphere system. The wavelength ranges of interest are the biologically relevant UV-B between 280 and 320 nm and the UV-A from 32000 to 400 nm. The Nimbus 7 solar backscattered ultraviolet (SBUV) instrument provides measurements of total column ozone and information concerning cloud cover which, in combination with a simple model of radiation transfer, define the fractions of incident solar irradiance absorbed in the atmosphere, reflected to space, and absorbed at the ground. Results for the month of July quantify the contribution of fractional cloud cover and cloud optical thickness to the radiation budget's three components. Scattering within a thick cloud layer makes the downward radiation field at the cloud base more isotropic than is the case for clear skies. For small solar zenith angles, typical of summer midday conditions, the effective pathlength of this diffuse irradiance through tropospheric ozone is greater than that under clear-sky conditions. The result is an enhanced absorption of UV-B radiation in the troposphere during cloud-covered conditions. Major changes in global cloud cover or cloud optical thicknesses could alter the ultraviolet radiation received by the biosphere by an amount comparable to that predicted for long-term trends in ozone.

Direct Detection of Singlet-Triplet Interconversion in OLED Magnetoelectroluminescence with a Metal-Free Fluorescence-Phosphorescence Dual Emitter

NASA Astrophysics Data System (ADS)

Ratzke, Wolfram; Bange, Sebastian; Lupton, John M.

2018-05-01

We demonstrate that a simple phenazine derivative can serve as a dual emitter for organic light-emitting diodes, showing simultaneous luminescence from the singlet and triplet excited states at room temperature without the need of heavy-atom substituents. Although devices made with this emitter achieve only low quantum efficiencies of <0.2 % , changes in fluorescence and phosphorescence intensity on the subpercent scale caused by an external magnetic field of up to 30 mT are clearly resolved with an ultra-low-noise optical imaging technique. The results demonstrate the concept of using simple reporter molecules, available commercially, to optically detect the spin of excited states formed in an organic light-emitting diode and thereby probe the underlying spin statistics of recombining electron-hole pairs. A clear anticorrelation of the magnetic-field dependence of singlet and triplet emission shows that it is the spin interconversion between singlet and triplet which dominates the magnetoluminescence response: the phosphorescence intensity decreases by the same amount as the fluorescence intensity increases. The concurrent detection of singlet and triplet emission as well as device resistance at cryogenic and room temperature constitute a useful tool to disentangle the effects of spin-dependent recombination from spin-dependent transport mechanisms.

Optically gated beating-heart imaging

PubMed Central

Taylor, Jonathan M.

2014-01-01

The constant motion of the beating heart presents an obstacle to clear optical imaging, especially 3D imaging, in small animals where direct optical imaging would otherwise be possible. Gating techniques exploit the periodic motion of the heart to computationally “freeze” this movement and overcome motion artifacts. Optically gated imaging represents a recent development of this, where image analysis is used to synchronize acquisition with the heartbeat in a completely non-invasive manner. This article will explain the concept of optical gating, discuss a range of different implementation strategies and their strengths and weaknesses. Finally we will illustrate the usefulness of the technique by discussing applications where optical gating has facilitated novel biological findings by allowing 3D in vivo imaging of cardiac myocytes in their natural environment of the beating heart. PMID:25566083

Effect of annealing temperature on physical properties of solution processed nickel oxide thin films

NASA Astrophysics Data System (ADS)

Sahoo, Pooja; Thangavel, R.

2018-05-01

In this report, NiO thin films were prepared at different annealing temperatures from nickel acetate precursor by sol-gel spin coating method. These films were characterized by different analytical techniques to obtain their structural, optical morphological and electrical properties using X-ray diffractometer (XRD), Field emission scanning electron microscopy (FESEM), UV-Vis NIR double beam spectrophotometer and Keithley 2450 source meter respectively. FESEM images clearly indicates the formation of a homogenous and porous films. Due to their porosity, they can be used in sensing applications. The optical absorption spectra elucidated that the films are highly transparent and have a suitable band gap which are in similar agreement with earlier reports. The current enhancement under illumination shows the suitability of nanostructured NiO thin films in its application in photovoltaics.

General mechanism involved in subwavelength optics of conducting microstructures: charge-oscillation-induced light emission and interference.

PubMed

Huang, Xian-Rong; Peng, Ru-Wen

2010-04-01

Interactions between light and conducting microstructures or nanostructures can result in a variety of novel phenomena, but their underlying mechanisms have not been completely understood. From calculations of surface charge density waves on conducting gratings and by comparing them with classical surface plasmons, we revealed a general yet concrete picture regarding the coupling of light to free electron oscillation on structured conducting surfaces that can lead to oscillating subwavelength charge patterns (i.e., structured surface plasmons). New wavelets emitted from these light sources then destructively interfere to form evanescent waves. This principle, usually combined with other mechanisms, is mainly a geometrical effect that can be universally involved in light scattering from all periodic and non-periodic structures containing free electrons. This picture may provide clear guidelines for developing conductor-based nano-optical devices.

Effect of microemulsions on cell viability of human dermal fibroblasts

NASA Astrophysics Data System (ADS)

Li, Juyi; Mironava, Tatsiana; Simon, Marcia; Rafailovich, Miriam; Garti, Nissim

Microemulsions are optically clear, thermostable and isotropic mixture consisting of water, oil and surfactants. Their advantages of ease preparation, spontaneous formation, long-term stability and enhanced solubility of bioactive materials make them great potentials as vehicles in food and pharmaceutical applications. In this study, comparative in vitro cytotoxicity tests were performed to select a best formulation of microemulsion with the least toxicity for human dermal fibroblasts. Three different kinds of oils and six different kinds of surfactants were used to form microemulsions by different ratios. The effect of oil type and surfactant type as well as their proportions on cell proliferation and viability were tested.

Life test results for an ensemble of CO2 lasers

NASA Technical Reports Server (NTRS)

Peruso, C. J.; Degnan, J. J.; Hochuli, U. E.

1978-01-01

The effects of cathode material, cathode operating temperature, anode configuration, window materials, and hydrogen additives on laser lifetime are determined. Internally oxidized copper and silber-copper alloy cathodes were tested. The cathode operating temperature was raised in some tubes through the use of thermal insulation. Lasers incorporating thermally insulated silver copper oxide cathodes clearly yielded the longest lifetimes-typically in excess of 22,000 hours. The use of platinum sheet versus platinum pin anodes had no observable effect on laser lifetime. Similarly, the choice of germanium, cadmium telluride, or zinc selenide as the optical window material appears to have no impact on lifetime.

Layer-by-layer design method for soft-X-ray multilayers

NASA Technical Reports Server (NTRS)

Yamamoto, Masaki; Namioka, Takeshi

1992-01-01

A new design method effective for a nontransparent system has been developed for soft-X-ray multilayers with the aid of graphic representation of the complex amplitude reflectance in a Gaussian plane. The method provides an effective means of attaining the absolute maximum reflectance on a layer-by-layer basis and also gives clear insight into the evolution of the amplitude reflectance on a multilayer as it builds up. An optical criterion is derived for the selection of a proper pair of materials needed for designing a high-reflectance multilayer. Some examples are given to illustrate the usefulness of this design method.

Signal lights - designed light for rear lamps and new upcoming technologies: innovations in automotive lighting

NASA Astrophysics Data System (ADS)

Mügge, Martin; Hohmann, Carsten

2016-04-01

Signal functions have to fulfill statutory regulations such as ECE or FMVSS108 to provide a clear signal to other road users and satisfy the same standard definitions of lighting parameters. However, as rear combination lamps are very different from one another, and these days are an increasingly powerful design element of cars, automotive manufacturers want an innovative, superior, and contrasting design. Daytime appearances with a new and unusual look and nighttime appearances with unexpected illumination are strong drivers for developing amazing innovative signal functions. The combination of LED technology and different forms of light-guiding optics, new interpretations of common optical systems to develop various styling options, the use of new materials and components for lighting effects, the introduction of OLED technology on the automotive market, and amazing new optical systems, using diffractive or holographic optics in future rear lamps, are paving the way for further, exciting design possibilities. The challenge of new signal functions is to take these possibilities and to develop the appearance and illumination effects the designer wants to reinforce the image of the car manufacturer and to fit harmoniously into the vehicle design. Lighting systems with a three-dimensional design and appearance when unlit and lit, amazing 3D effects, and surprising lighting scenarios will gain in importance. But the signal lights on cars will, in the future, be not only lighting functions in rear lamps; new functions and stylistic illuminations for coming/leaving-home scenarios will support and complete the car's overall lighting appearance. This paper describes current lighting systems realizing the styling requirements and future lighting systems offering new design possibilities and developing further stylistic, visual effects and improved technologies.

Analysis of artificial opals by scanning near field optical microscopy

NASA Astrophysics Data System (ADS)

Barrio, J.; Lozano, G.; Lamela, J.; Lifante, G.; Dorado, L. A.; Depine, R. A.; Jaque, F.; Míguez, H.

2011-04-01

Herein we present a detailed analysis of the optical response of artificial opal films realized employing a near-field scanning optical microscope in collection and transmission modes. Near-field patterns measured at the rear surface when a plane wave impinges on the front face are presented with the finding that optical intensity maps present a clear correlation with the periodic arrangement of the outer surface. Calculations based on the vector Korringa-Kohn-Rostoker method reproduce the different profiles experimentally observed as well as the response to the polarization of the incident field. These observations constitute the first experimental confirmation of the collective lattice resonances that give rise to the optical response of these three dimensional periodic structures in the high-energy range.

On the structural logic of curriculum system for the optical instrument major

NASA Astrophysics Data System (ADS)

Yan, Yufeng; Yan, Juncen; Li, Yang; Shi, Lixia

2017-08-01

The theories of optical instrument are the Interdisciplinary of Optical Engineering and Instrument Science and Technology. The undergraduates should study the knowledge about the optics, precision machine and electronics. The courses such as Theory of Machine, Engineering Optics, even include some courses about Accuracy Analysis of Instrument are offered in the college. There are a lot of correlatives among these courses. This paper focuses on the structural logic of these courses. The order of these courses is researched, The aims of all the courses are clear completely to avoid the same topics to be taught twice in different courses. Therefore, the undergraduates would get the main line of the knowledge, and the professors would teach efficiently.

Comparison of Distributed Acoustic Sensing (DAS) from Fiber-Optic Cable to Three Component Geophones in an Underground Mine

NASA Astrophysics Data System (ADS)

Speece, M. A.; Nesladek, N. J.; Kammerer, C.; Maclaughlin, M.; Wang, H. F.; Lord, N. E.

2017-12-01

We conducted experiments in the Underground Education Mining Center on the Montana Tech campus, Butte, Montana, to make a direct comparison between Digital Acoustic Sensing (DAS) and three-component geophones in a mining setting. The sources used for this project where a vertical sledgehammer, oriented shear sledgehammer, and blasting caps set off in both unstemmed and stemmed drillholes. Three-component Geospace 20DM geophones were compared with three different types of fiber-optic cable: (1) Brugg strain, (2) Brugg temperature, and (3) Optical Cable Corporation strain. We attached geophones to the underground mine walls and on the ground surface above the mine. We attached fiber-optic cables to the mine walls and placed fiber-optic cable in boreholes drilled through an underground pillar. In addition, we placed fiber-optic cables in a shallow trench at the surface of the mine. We converted the DAS recordings from strain rate to strain prior to comparison with the geophone data. The setup of the DAS system for this project led to a previously unknown triggering problem that compromised the early samples of the DAS traces often including the first-break times on the DAS records. Geophones clearly recorded the explosives; however, the large amount of energy and its close distance from the fiber-optic cables seemed to compromise the entire fiber loop. The underground hammer sources produced a rough match between the DAS records and the geophone records. However, the sources on the surface of the mine, specifically the sources oriented inline with the fiber-optic cables, produced a close match between the fiber-optic traces and the geophone traces. All three types of fiber-optic cable that were in the mine produced similar results, and one type did not clearly outperform the others. Instead, the coupling of the cable to rock appears to be the most important factor determining DAS data quality. Moreover, we observed the importance of coupling in the boreholes, where fiber-optic cables that were pressed against the rock face with a spacer outperformed fiber-optic cables that were fully embedded within the grout filling the inside of the borehole.

Synergistic effects of UVR and simulated stratification on commensalistic algal-bacterial relationship in two optically contrasting oligotrophic Mediterranean lakes

NASA Astrophysics Data System (ADS)

Carrillo, P.; Medina-Sánchez, J. M.; Durán, C.; Herrera, G.; Villafañe, V. E.; Helbling, E. W.

2014-08-01

An indirect effect of global warming is the shallowing epilimnion, causing organisms to be exposed to higher levels of ultraviolet (UVR, 280-400 nm) and photosynthetically active radiation (PAR, 400-700 nm), which could affect primary and bacterial production as well as the commensalistic algal-bacterial relationship. The combined effects of UVR and reduction in the depth of the upper mixed layer (UML) were assessed on variables related to the metabolism of algae and bacteria, during in situ experiments performed with natural microplanktonic communities from two oligotrophic lakes with contrasting UVR-transparency (clear vs. opaque) of southern Spain. The negative UVR effects on epilimnetic primary production (PP) and on heterotrophic bacterial production (HBP), intensified by high mean irradiances, were higher in the UVR-opaque than in the UVR-clear lake, and stronger on the algae than on the heterotrophic bacterial communities. Under UVR and high mean irradiance, the algal-bacterial relationship was strengthened in the UVR-clear lake, where excreted organic carbon (EOC) rates exceeded the bacterial carbon demand (BCD). This did not occur in the UVR-opaque lake. The greater UVR damage to algae and bacteria and the weakening of their commensalistic interaction found in the UVR-opaque lake indicates that these ecosystems would be especially vulnerable to stressors related to global change. Thus, our findings may have important implications for the carbon cycle in oligotrophic lakes of the Mediterranean region.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aytug, Tolga

Samsung Electronics has exclusively licensed optically clear superhydrophobic film technology from the Department of Energy’s Oak Ridge National Laboratory to improve the performance of glass displays on smartphones, tablets and other electronic devices.

Antistatic coating for acrylics

NASA Technical Reports Server (NTRS)

Hadek, V.; Rembaum, A.; Somono, R. B.

1979-01-01

After immersion in low molecular-weight solvents such as acetonitril or nitromethane, clear acrylic plastics dissipate up to 70% of induced electric charge within one minute, yet retain optical clarity.

Studies of PMMA sintering foils with and without coating by magnetron sputtering Pd

NASA Astrophysics Data System (ADS)

Cutroneo, M.; Mackova, A.; Torrisi, L.; Vad, K.; Csik, A.; Ando', L.; Svecova, B.

2017-09-01

Polymethylmethacrylate thin foils were prepared by using physical and chemical processes aimed at changing certain properties. The density and the optical properties were changed obtaining clear and opaque foils. DC magnetron sputtering method was used to cover the foils with thin metallic palladium layers. The high optical absorbent foils were obtained producing microstructured PMMA microbeads with and without thin metallic coatings. Rutherford Backscattering Spectroscopy, optical investigation and microscopy were employed to characterize the prepared foils useful in the field study of laser-matter interaction.

Optics at langley research center.

PubMed

Crumbly, K H

1970-02-01

The specialized tools of optics have played an important part in Langley's history of aeronautical and space research. Schlieren systems for photographing aeronautics and space models in wind-tunnel investigations have contributed to the available knowledge of aerodynamics. Optics continues to be an important part of Langley's research program, including new techniques for measuring the sensitivity of photomultiplier tubes, spectrographic techniques for radiation measurements of wind-tunnel models, research into large orbiting telescopes, horizon definition by ir radiation measurements, spectra of natural and artificial meteors, measurement of clear air turbulence utilizing lasers, and many others.

An electrooptic probe to determine internal electric fields in a piezoelectric transformer.

PubMed

Norgard, Peter; Kovaleski, Scott

2012-02-01

A technique using the electrooptic effect to determine the output voltage of an optically clear LiNbO(3) piezoelectric transformer was developed and explored. A brief mathematical description of the solution is provided, as well as experimental data demonstrating a linear response under ac resonant operating conditions. A technique to calibrate the diagnostic was developed and is described. Finally, a sensitivity analysis of the electrooptic response to variations in angular alignment between the LiNbO(3) transformer and the laser probe are discussed.

[Thinking about the present primary open angle glaucoma early diagnosis concepts and methods].

PubMed

Ren, Zeqin

2014-05-01

Early diagnosis of primary open-angle glaucoma has not been clear and consistent in concepts and methods. At present, according to the pathophysiology process of optic nerve damage and its detection technology, early diagnosis on the concept still belongs to the early clinical diagnosis instead of preclinical diagnosis, and on the method depends on the fundus as morphological index combined with the visual field as functional index. The direction of early clinical diagnosis mainly lies in exploring more effective diagnosis index, rather than blindly adopt new diagnostic technology.

Electronic quantization in dielectric nanolaminates

NASA Astrophysics Data System (ADS)

Willemsen, T.; Geerke, P.; Jupé, M.; Gallais, L.; Ristau, D.

2016-12-01

The scientific background in the field of the laser induced damage processes in optical coatings has been significantly extended during the last decades. Especially for the ultra-short pulse regime a clear correlation between the electronic material parameters and the laser damage threshold could be demonstrated. In the present study, the quantization in nanolaminates is investigated to gain a deeper insight into the behavior of the blue shift of the bandgap in specific coating materials as well as to find approximations for the effective mass of the electrons. The theoretical predictions are correlated to the measurements.

Atom Interferometry in a Warm Vapor

DOE PAGES

Biedermann, G. W.; McGuinness, H. J.; Rakholia, A. V.; ...

2017-04-17

Here, we demonstrate matter-wave interference in a warm vapor of rubidium atoms. Established approaches to light-pulse atom interferometry rely on laser cooling to concentrate a large ensemble of atoms into a velocity class resonant with the atom optical light pulse. In our experiment, we show that clear interference signals may be obtained without laser cooling. This effect relies on the Doppler selectivity of the atom interferometer resonance. Lastly, this interferometer may be configured to measure accelerations, and we demonstrate that multiple interferometers may be operated simultaneously by addressing multiple velocity classes.

Verification of the quantum dimension effects in electricsl condactivity with different topology of laser-induced thin-film structures

NASA Astrophysics Data System (ADS)

Arakelian, S.; Kucherik, A.; Kutrovskaya, S.; Osipov, A.; Istratov, A.; Skryabin, I.

2018-01-01

A clear physical model for the quantum states verification in nanocluster structures with jump/tunneling electroconductivity are under study in both theory and experiment. The accent is made on consideration of low-dimensional structures when the structural phase transitions occur and the tendency to high enhancement electroconductivity obtained. The results give us an opportunity to establish a basis for new physical principles to create the functional elements for the optoelectronics and photonics in hybrid set-up (optics + electrophysics) by the nanocluster technology approach.

Effect of sputtering power on crystallinity, intrinsic defects, and optical and electrical properties of Al-doped ZnO transparent conducting thin films for optoelectronic devices

NASA Astrophysics Data System (ADS)

Hu, Yu Min; Li, Jung Yu; Chen, Nai Yun; Chen, Chih Yu; Han, Tai Chun; Yu, Chin Chung

2017-02-01

The crystallinity and intrinsic defects of transparent conducting oxide (TCO) films have a high impact on their optical and electrical properties and therefore on the performance of devices incorporating such films, including flat panel displays, electro-optical devices, and solar cells. The optical and electrical properties of TCO films can be modified by tailoring their deposition parameters, which makes proper understanding of these parameters crucial. Magnetron sputtering is the most adaptable method for preparing TCO films used in industrial applications. In this study, we investigate the direct and inter-property correlation effects of sputtering power (PW) on the crystallinity, intrinsic defects, and optical and electrical properties of Al-doped ZnO (AZO) TCO films. All of the films were preferentially c-axis-oriented with a wurtzite structure and had an average transmittance of over 80% in the visible wavelength region. Scanning electron microscopy images revealed significantly increased AZO film grain sizes for PW ≥ 150 W, which may lead to increased conductivity, carrier concentration, and optical band gaps but decreased carrier mobility and in-plane compressive stress in AZO films. Photoluminescence results showed that, with increasing PW, the near band edge emission gradually dominates the defect-related emissions in which zinc interstitial (Zni), oxygen vacancy (VO), and oxygen interstitial (Oi) are possibly responsible for emissions at 3.08, 2.8, and 2.0 eV, respectively. The presence of Zni- and Oi-related emissions at PW ≥ 150 W indicates a slight increase in the presence of Al atoms substituted at Zn sites (AlZn). The presence of Oi at PW ≥ 150 W was also confirmed by X-ray photoelectron spectroscopy results. These results clearly show that the crystallinity and intrinsic-defect type of AZO films, which dominate their optical and electrical properties, may be controlled by PW. This understanding may facilitate the development of TCO-based optoelectronic devices for industrial production.

ON THE RADIO AND OPTICAL LUMINOSITY EVOLUTION OF QUASARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singal, J.; Petrosian, V.; Lawrence, A.

2011-12-20

We calculate simultaneously the radio and optical luminosity evolutions of quasars, and the distribution in radio loudness R defined as the ratio of radio and optical luminosities, using a flux-limited data set containing 636 quasars with radio and optical fluxes from White et al. We first note that when dealing with multi-variate data it is imperative to first determine the true correlations among the variables, not those introduced by the observational selection effects, before obtaining the individual distributions of the variables. We use the methods developed by Efron and Petrosian which are designed to obtain unbiased correlations, distributions, and evolutionmore » with redshift from a data set truncated due to observational biases. It is found that the population of quasars exhibits strong positive correlation between the radio and optical luminosities. With this correlation, whether intrinsic or observationally induced accounted for, we find that there is a strong luminosity evolution with redshift in both wavebands, with significantly higher radio than optical evolution. We conclude that the luminosity evolution obtained by arbitrarily separating the sources into radio-loud (R > 10) and radio-quiet (R < 10) populations introduces significant biases that skew the result considerably. We also construct the local radio and optical luminosity functions and the density evolution. Finally, we consider the distribution of the radio-loudness parameter R obtained from careful treatment of the selection effects and luminosity evolutions with that obtained from the raw data without such considerations. We find a significant difference between the two distributions and no clear sign of bi-modality in the true distribution for the range of R values considered. Our results indicate therefore, somewhat surprisingly, that there is no critical switch in the efficiency of the production of disk outflows/jets between very radio-quiet and very radio-loud quasars, but rather a smooth transition. Also, this efficiency seems higher for the high-redshift and more luminous sources in the sample considered.« less

Implementation of ISO 10110 optics drawing standards for the National Ignition Facility

NASA Astrophysics Data System (ADS)

Wang, David Y.; English, R. Edward, Jr.; Aikens, David M.

1999-11-01

The National Ignition Facility (NIF) project elected to implement ISO 10110 standard for the specifications of NIF optics drawings in 1996. More than 7,000 NIF large optics and 20,000 NIF small optics will be manufactured based on ISO 10110 indications. ISO 10110 standard meets many of the needs of the NIF optics specifications. It allows the optical engineer to quantify and clearly communicate the desired optical specifications. While no single drawing standard specifies all the requirements of high energy laser system, a combination of ISO 10110 standard with detailed notes make it possible to apply international drawing standards to the NIF laser system. This paper will briefly describe LLNL's interpretation and implementation of the ISO 10110 drawing standard, present some examples of NIF optics drawings, and discuss pros and cons of the indications from the perspective of this application. Emphasis will be given to the surface imperfection specifications, known as 5/, for the NIF optics.

Analysis of creating an innovative micro-lens made of polydimethylsiloxane polymer on the end of the optical fibers

NASA Astrophysics Data System (ADS)

Zboril, O.; Cubik, J.; Nedoma, J.; Fajkus, M.; Novak, M.; Jargus, J.; Stratil, T.; Vasinek, V.

2017-10-01

The article describes a method for fabrication of polymer optical micro-lenses using polydimethylsiloxane (PDMS) at the end of optical fibers. PDMS is an optically clear substance having a refractive index very similar to the optical fibers. Therefore it is an interesting material for optical purposes. PDMS is characterized by resistance to electromagnetic interference (EMI), enabling the use in electromagnetically noisy environments. These lenses could be used for example for the security applications. For the manufacture of the micro-lenses is used Sylgard silicone elastomer 184. When applied to the end of conventional optical fiber is cured by treatment at 100 °C +/- 5 °C. Authors performed a series of experimental measurements. The optical characteristics of the treated fibers compared with conventional fibers without micro-lenses. The fibers provided with optical lenses made of PDMS may be used for security applications, in the visible light communication (VLC) or as a microprobe.

Remote sensing of atmospheric optical depth using a smartphone sun photometer.

PubMed

Cao, Tingting; Thompson, Jonathan E

2014-01-01

In recent years, smart phones have been explored for making a variety of mobile measurements. Smart phones feature many advanced sensors such as cameras, GPS capability, and accelerometers within a handheld device that is portable, inexpensive, and consistently located with an end user. In this work, a smartphone was used as a sun photometer for the remote sensing of atmospheric optical depth. The top-of-the-atmosphere (TOA) irradiance was estimated through the construction of Langley plots on days when the sky was cloudless and clear. Changes in optical depth were monitored on a different day when clouds intermittently blocked the sun. The device demonstrated a measurement precision of 1.2% relative standard deviation for replicate photograph measurements (38 trials, 134 datum). However, when the accuracy of the method was assessed through using optical filters of known transmittance, a more substantial uncertainty was apparent in the data. Roughly 95% of replicate smart phone measured transmittances are expected to lie within ±11.6% of the true transmittance value. This uncertainty in transmission corresponds to an optical depth of approx. ±0.12-0.13 suggesting the smartphone sun photometer would be useful only in polluted areas that experience significant optical depths. The device can be used as a tool in the classroom to present how aerosols and gases effect atmospheric transmission. If improvements in measurement precision can be achieved, future work may allow monitoring networks to be developed in which citizen scientists submit acquired data from a variety of locations.

Motion compensation for in vivo subcellular optical microscopy.

PubMed

Lucotte, B; Balaban, R S

2014-04-01

In this review, we focus on the impact of tissue motion on attempting to conduct subcellular resolution optical microscopy, in vivo. Our position is that tissue motion is one of the major barriers in conducting these studies along with light induced damage, optical probe loading as well as absorbing and scattering effects on the excitation point spread function and collection of emitted light. Recent developments in the speed of image acquisition have reached the limit, in most cases, where the signal from a subcellular voxel limits the speed and not the scanning rate of the microscope. Different schemes for compensating for tissue displacements due to rigid body and deformation are presented from tissue restriction, gating, adaptive gating and active tissue tracking. We argue that methods that minimally impact the natural physiological motion of the tissue are desirable because the major reason to perform in vivo studies is to evaluate normal physiological functions. Towards this goal, active tracking using the optical imaging data itself to monitor tissue displacement and either prospectively or retrospectively correct for the motion without affecting physiological processes is desirable. Critical for this development was the implementation of near real time image processing in conjunction with the control of the microscope imaging parameters. Clearly, the continuing development of methods of motion compensation as well as significant technological solutions to the other barriers to tissue subcellular optical imaging in vivo, including optical aberrations and overall signal-to-noise ratio, will make major contributions to the understanding of cell biology within the body.

A minimally invasive optical trapping system to understand cellular interactions at onset of an immune response

PubMed Central

Glass, David G.; McAlinden, Niall; Millington, Owain R.

2017-01-01

T-cells and antigen presenting cells are an essential part of the adaptive immune response system and how they interact is crucial in how the body effectively fights infection or responds to vaccines. Much of the experimental work studying interaction forces between cells has looked at the average properties of bulk samples of cells or applied microscopy to image the dynamic contact between these cells. In this paper we present a novel optical trapping technique for interrogating the force of this interaction and measuring relative interaction forces at the single-cell level. A triple-spot optical trap is used to directly manipulate the cells of interest without introducing foreign bodies such as beads to the system. The optical trap is used to directly control the initiation of cell-cell contact and, subsequently to terminate the interaction at a defined time point. The laser beam power required to separate immune cell pairs is determined and correlates with the force applied by the optical trap. As proof of concept, the antigen-specific increase in interaction force between a dendritic cell and a specific T-cell is demonstrated. Furthermore, it is demonstrated that this interaction force is completely abrogated when T-cell signalling is blocked. As a result the potential of using optical trapping to interrogate cellular interactions at the single cell level without the need to introduce foreign bodies such as beads is clearly demonstrated. PMID:29220398

Micro-photoluminescence of GaAs/AlGaAs triple concentric quantum rings.

PubMed

Abbarchi, Marco; Cavigli, Lucia; Somaschini, Claudio; Bietti, Sergio; Gurioli, Massimo; Vinattieri, Anna; Sanguinetti, Stefano

2011-10-31

A systematic optical study, including micro, ensemble and time resolved photoluminescence of GaAs/AlGaAs triple concentric quantum rings, self-assembled via droplet epitaxy, is presented. Clear emission from localized states belonging to the ring structures is reported. The triple rings show a fast decay dynamics, around 40 ps, which is expected to be useful for ultrafast optical switching applications.

Optical Processing.

DTIC Science & Technology

1986-06-01

Further improvements are clearly necessary. 2.2.2 Future Work It would appear that transverse cross-talk is a serious problem in thermally based bistable... manufacturing purposes except under an agreement or with the consent in writing of Ferranti pic and then only on the condition that this notice is...applications which might: (a) appear to benefit from the advantages offered by optical processing (such as large parallelism and dense global inter

Autofluorescence and spectral-domain optical coherence tomography of optic disk melanocytoma.

PubMed

Guerra, Ricardo Luz Leitão; Marback, Eduardo Ferrari; Silva, Igor Sandes Pessoa da; Maia Junior, Otacílio de Oliveira; Marback, Roberto Lorens

2014-01-01

The authors report fundus autofluorescence (FAF) and spectral-domain optical coherence tomography (OCT) findings of two consecutive patients who presented with optic disk melanocytoma (ODM). A retrospective study was performed by reviewing medical records and ophthalmic imaging examinations. Optical coherence tomography findings were sloped and brightly reflective anterior tumor surface, adjacent retinal desorganization and abrupt posterior optical shadowing. Vitreous seeds were found in one patient. Fundus autofluorescence revealed outstanding hypoautofluorescence at the tumor area and isoautofluorescence at the remaining retina. Optical coherence tomography findings of the reported cases are consistent with those reported in the reviewed literature. Fundus autofluorescence has been used in the assessment of choroidal melanocytic tumors, but not yet in melanocytomas. We assume that this is the first report of these findings and believe that when its pattern has become clearly defined, fundus autofluorescence will be a useful tool to avoid misdiagnosis in suspicious cases and for follow-up.

Microoptical System And Fabrication Method Therefor

DOEpatents

Sweatt, William C.; Christenson, Todd R.

2005-03-15

Microoptical systems with clear aperture of about one millimeter or less are fabricated from a layer of photoresist using a lithographic process to define the optical elements. A deep X-ray source is typically used to expose the photoresist. Exposure and development of the photoresist layer can produce planar, cylindrical, and radially symmetric micro-scale optical elements, comprising lenses, mirrors, apertures, diffractive elements, and prisms, monolithically formed on a common substrate with the mutual optical alignment required to provide the desired system functionality. Optical alignment can be controlled to better than one micron accuracy. Appropriate combinations of structure and materials enable optical designs that include corrections for chromatic and other optical aberrations. The developed photoresist can be used as the basis for a molding operation to produce microoptical systems made of a range of optical materials. Finally, very complex microoptical systems can be made with as few as three lithographic exposures.

Transpiration purged optical probe

DOEpatents

VanOsdol, John; Woodruff, Steven

2004-01-06

An optical apparatus for clearly viewing the interior of a containment vessel by applying a transpiration fluid to a volume directly in front of the external surface of the optical element of the optical apparatus. The fluid is provided by an external source and transported by means of an annular tube to a capped end region where the inner tube is perforated. The perforation allows the fluid to stream axially towards the center of the inner tube and then axially away from an optical element which is positioned in the inner tube just prior to the porous sleeve. This arrangement draws any contaminants away from the optical element keeping it free of contaminants. In one of several embodiments, the optical element can be a lens, a viewing port or a laser, and the external source can provide a transpiration fluid having either steady properties or time varying properties.

Microoptical system and fabrication method therefor

DOEpatents

Sweatt, William C.; Christenson, Todd R.

2003-07-08

Microoptical systems with clear aperture of about one millimeter or less are fabricated from a layer of photoresist using a lithographic process to define the optical elements. A deep X-ray source is typically used to expose the photoresist. Exposure and development of the photoresist layer can produce planar, cylindrical, and radially symmetric micro-scale optical elements, comprising lenses, mirrors, apertures, diffractive elements, and prisms, monolithically formed on a common substrate with the mutual optical alignment required to provide the desired system functionality. Optical alignment can be controlled to better than one micron accuracy. Appropriate combinations of structure and materials enable optical designs that include corrections for chromatic and other optical aberrations. The developed photoresist can be used as the basis for a molding operation to produce microoptical systems made of a range of optical materials. Finally, very complex microoptical systems can be made with as few as three lithographic exposures.

Fabrication of demultiplexer for T bps optical signals by using spincoated squarylium dye J-aggregates exhibiting femtosecond optical response

NASA Astrophysics Data System (ADS)

Iwasa, Izumi; Furuki, Makoto; Tian, Minquan; Sato, Yasuhiro; Pu, Lyong S.; Tatsuura, Setoshi; Wada, Osamu

2001-06-01

We fabricated spincoated films of squarylium dye (SQ) J- aggregates exhibiting femtosecond optical response at room temperature. Optical dynamics measurements revealed that the saturable absorption of the SQ J-aggregates film exhibited a decay time of less than 100 fs at a pump energy of 80 fJ/micrometer2. With this ultrafast SQ optical film, four- output demultiplex operation for T bps pulses was demonstrated. A series of 4 optical pulses with 100 fs duration and 1 ps interval (corresponding to 1 T bps signals) were irradiated onto the SQ film synchronized with a 100 fs gate pulse at a finite angle. Four demultiplexed signals were clearly observed at different areas on the CCD camera. Multi- output serial-to-parallel demultiplexer for T bps optical signals can be formed using the SQ J-aggregates film.

Effect of energetic electrons on combustion of premixed burner flame

NASA Astrophysics Data System (ADS)

Sasaki, Koichi

2011-10-01

In many studies of plasma-assisted combustion, authors superpose discharges onto flames to control combustion reactions. This work is motivated by more fundamental point of view. The standpoint of this work is that flames themselves are already plasmas. We irradiated microwave power onto premixed burner flame with the intention of heating electrons in it. The microwave power was limited below the threshold for a discharge. We obtained the enhancement of burning velocity by the irradiation of the microwave power, which was understood by the shortening of the flame length. At the same time, we observed the increases in the optical emission intensities of OH and CH radicals. Despite the increases in the optical emission intensities, the optical emission spectra of OH and CH were not affected by the microwave irradiation, indicating that the enhancement of the burning velocity was not attributed to the increase in the gas temperature. On the other hand, we observed significant increase in the optical emission intensity of the second positive system of molecular nitrogen, which is a clear evidence for electron heating in the premixed burner flame. Therefore, it is considered that the enhancement of the burning velocity is obtained by nonequilibrium combustion chemistry which is driven by energetic electrons. By irradiating pulsed microwave power, we examined the time constants for the increases and decreases in the optical emission intensities of N2, OH, CH, and continuum radiation.

Optical and Electrical Characteristics of Silver Ion Conducting Nanocomposite Solid Polymer Electrolytes Based on Chitosan

NASA Astrophysics Data System (ADS)

Aziz, Shujahadeen B.; Rasheed, Mariwan A.; Abidin, Zul H. Z.

2017-10-01

Optical and electrical properties of nanocomposite solid polymer electrolytes based on chitosan have been investigated. Incorporation of alumina nanoparticles into the chitosan:silver triflate (AgTf) system broadened the surface plasmon resonance peaks of the silver nanoparticles and shifted the absorption edge to lower photon energy. A clear decrease of the optical bandgap in nanocomposite samples containing alumina nanoparticles was observed. The variation of the direct-current (DC) conductivity and dielectric constant followed the same trend with alumina concentration. The DC conductivity increased by two orders of magnitude, which can be attributed to hindrance of silver ion reduction. Transmission electron microscopy was used to interpret the space-charge and blocking effects of alumina nanoparticles on the DC conductivity and dielectric constant. The ion conduction mechanism was interpreted based on the dependences of the electrical and dielectric parameters. The dependence of the DC conductivity on the dielectric constant is explained empirically. Relaxation processes associated with conductivity and viscoelasticity were distinguished based on the incomplete semicircular arcs in plots of the real and imaginary parts of the electric modulus.

Optical Characterizations of VCSEL for Emission at 850 nm with Al Oxide Confinement Layers

NASA Astrophysics Data System (ADS)

Mokhtari, Merwan; Pagnod-Rossiaux, Philippe; Laruelle, Francois; Landesman, Jean-Pierre; Moreac, Alain; Levallois, Christophe; Cassidy, Daniel T.

2018-03-01

In-plane micro-photoluminescence (μ-PL) and micro-reflectivity measurements have been performed at room temperature by optical excitation perpendicular to the surface of two different structures: a complete vertical surface-emitting laser (VCSEL) structure and a VCSEL without the upper p-type distributed Bragg reflector (P-DBR). The two structures were both laterally oxidized and measurements were made on the top of oxidized and unoxidized regions. We show that, since the photoluminescence (PL) spectra consist of the cumulative effect of InGaAs/AlGaAs multi-quantum wells (MQWs) luminescence and interferences in the DBR, the presence or not of the P-DBR and oxide layers can significantly modify the spectrum. μ-PL mapping performed on full VCSEL structures clearly shows oxidized and unoxidized regions that are not resolved with visible light optical microscopy. Finally, preliminary measurements of the degree of polarization (DOP) of the PL have been made on a complete VCSEL structure before and after an oxidation process. We obtain an image of DOP measured by polarization-resolved μ-PL. These measurements allow us to evaluate the main components of strain.

Explosives detection and identification using surface plasmon-coupled emission

NASA Astrophysics Data System (ADS)

Ja, Shiou-Jyh

2012-06-01

To fight against the explosives-related threats in defense and homeland security applications, a smarter sensing device that not only detects but differentiates multiple true threats from false positives caused by environmental interferents is essential. A new optical detection system is proposed to address these issues by using the temporal and spectroscopic information generated by the surface plasmon coupling emission (SPCE) effect. Innovative SPCE optics have been designed using Zemax software to project the fluorescence signal into clear "rainbow rings" on a CCD with subnanometer wavelength resolution. The spectroscopic change of the fluorescence signal and the time history of such changes due to the presence of a certain explosive analyte are unique and can be used to identify explosives. Thanks to high optical efficiency, reporter depositions as small as 160-μm in diameter can generate a sufficient signal, allowing a dense array of different reporters to be interrogated with wavelength multiplexing and detect a wide range of explosives. We have demonstrated detection and classification of explosives, such as TNT, NT, NM, RDX, PETN, and AN, with two sensing materials in a prototype.

Cranial nerve threshold for thermal injury induced by MRI-guided high-intensity focused ultrasound (MRgHIFU): preliminary results on an optic nerve model.

PubMed

Harnof, Sagi; Zibly, Zion; Cohen, Zvi; Shaw, Andrew; Schlaff, Cody; Kassel, Neal F

2013-04-01

Future clinical applications of magnetic resonance imaging-guided high-intensity focused ultrasound (MRgHIFU) are moving toward the management of different intracranial pathologies. We sought to validate the production, safety, and efficacy of thermal injury to cranial nerves generated by MRgHIFU. In this study, five female domestic pigs underwent a standard bifrontal craniectomy under general anesthesia. Treatment was then given using an MRgHIFU system to induce hyperthermic ablative sonication (6 to 10 s; 50 to 2000 J.) Histological analyses were done to confirm nerve damage; temperature measured on the optic nerve was approximately 53.4°C (range: 39°C to 70°C.) Histology demonstrated a clear definition between a necrotic, transitional zone, and normal tissue. MRgHIFU induces targeted thermal injury to nervous tissue within a specific threshold of 50°C to 60°C with the tissue near the sonication center yielding the greatest effect; adjacent tissue showed minimal changes. Additional studies utilizing this technology are required to further establish accurate threshold parameters for optic nerve thermo-ablation.

Parameter design considerations for an oscillator IR-FEL

NASA Astrophysics Data System (ADS)

Jia, Qi-Ka

2017-01-01

An infrared oscillator FEL user facility will be built at the National Synchrotron Radiation Laboratory at in Hefei, China. In this paper, the parameter design of the oscillator FEL is discussed, and some original relevant approaches and expressions are presented. Analytic formulae are used to estimate the optical field gain and saturation power for the preliminary design. By considering both physical and technical constraints, the relation of the deflection parameter K to the undulator period is analyzed. This helps us to determine the ranges of the magnetic pole gap, the electron energy and the radiation wavelength. The relations and design of the optical resonator parameters are analyzed. Using dimensionless quantities, the interdependences between the radii of curvature of the resonator mirror and the various parameters of the optical resonator are clearly demonstrated. The effect of the parallel-plate waveguide is analyzed for the far-infrared oscillator FEL. The condition of the necessity of using a waveguide and the modified filling factor in the case of the waveguide are given, respectively. Supported by National Nature Science Foundation of China (21327901, 11375199)

A theoretical model for optical oximetry at the capillary-level by optical coherence tomography (Conference Presentation)

NASA Astrophysics Data System (ADS)

Liu, Rongrong; Spicer, Graham; Chen, Siyu; Zhang, Hao F.; Yi, Ji; Backman, Vadim

2017-02-01

Oxygen saturation (sO2) of RBCs in capillaries can indirectly assess local tissue oxygenation and metabolic function. For example, the altered retinal oxygenation in diabetic retinopathy and local hypoxia during tumor development in cancer are reflected by abnormal sO2 of local capillary networks. However, it is far from clear whether accurate label-free optical oximetry (i.e. measuring hemoglobin sO2) is feasible from dispersed red blood cells (RBCs) at the single-capillary level. The sO2-dependent hemoglobin absorption contrast present in optical scattering signal is complicated by geometry-dependent scattering from RBCs. Here we provide a theoretical model to calculate the backscattering spectra of single RBCs based on the first-order Born approximation, considering the orientation, size variation, and deformation of RBCs. We show that the oscillatory spectral behavior of RBC geometries is smoothed by variations in cell size and orientation, resulting in clear sO2-dependent spectral contrast. In addition, this spectral contrast persists with different deformations of RBCs, allowing the sO2 of individual RBCs in capillaries to be characterized. The theoretical model is verified by Mie theory and experiments using visible light optical coherence tomography (vis-OCT). Thus, this study shows for the first time the feasibility of, and provides a theoretical model for, label-free optical oximetry at the single-capillary level by backscattering-based imaging modalities, challenging the popular view that such measurements are impossible at the single-capillary level. This is promising for in vivo backscattering-based optical oximetry at the single-capillary level, to measure local capillary sO2 for early diagnosis, progression monitoring, and treatment evaluation of diabetic retinopathy and cancer.

Optical Layout Analysis of Polarization Interference Imaging Spectrometer by Jones Calculus in View of both Optical Throughput and Interference Fringe Visibility

NASA Astrophysics Data System (ADS)

Zhang, Xuanni; Zhang, Chunmin

2013-01-01

A polarization interference imaging spectrometer based on Savart polariscope was presented. Its optical throughput was analyzed by Jones calculus. The throughput expression was given, and clearly showed that the optical throughput mainly depended on the intensity of incident light, transmissivity, refractive index and the layout of optical system. The simulation and analysis gave the optimum layout in view of both optical throughput and interference fringe visibility, and verified that the layout of our former design was optimum. The simulation showed that a small deviation from the optimum layout influenced interference fringe visibility little for the optimum one, but influenced severely for others, so a small deviation is admissible in the optimum, and this can mitigate the manufacture difficulty. These results pave the way for further research and engineering design.

Enhanced linear photonic nanojet generated by core-shell optical microfibers

NASA Astrophysics Data System (ADS)

Liu, Cheng-Yang; Yen, Tzu-Ping; Chen, Chien-Wen

2017-05-01

The generation of linear photonic nanojet using core-shell optical microfiber is demonstrated numerically and experimentally in the visible light region. The power flow patterns for the core-shell optical microfiber are calculated by using the finite-difference time-domain method. The focusing properties of linear photonic nanojet are evaluated in terms of length and width along propagation and transversal directions. In experiment, the silica optical fiber is etched chemically down to 6 μm diameter and coated with metallic thin film by using glancing angle deposition. We show that the linear photonic nanojet is enhanced clearly by metallic shell due to surface plasmon polaritons. The large-area superresolution imaging can be performed by using a core-shell optical microfiber in the far-field system. The potential applications of this core-shell optical microfiber include micro-fluidics and nano-structure measurements.

High-density near-field optical disc recording using phase change media and polycarbonate substrate

NASA Astrophysics Data System (ADS)

Shinoda, Masataka; Saito, Kimihiro; Ishimoto, Tsutomu; Kondo, Takao; Nakaoki, Ariyoshi; Furuki, Motohiro; Takeda, Minoru; Akiyama, Yuji; Shimouma, Takashi; Yamamoto, Masanobu

2004-09-01

We developed a high density near field optical recording disc system with a solid immersion lens and two laser sources. In order to realize the near field optical recording, we used a phase change recording media and a molded polycarbonate substrate. The near field optical pick-up consists of a solid immersion lens with numerical aperture of 1.84. The clear eye pattern of 90.2 GB capacity (160nm track pitch and 62 nm per bit) was observed. The jitter using a limit equalizer was 10.0 % without cross-talk. The bit error rate using an adaptive PRML with 8 taps was 3.7e-6 without cross-talk. We confirmed that the near field optical disc system is a promising technology for a next generation high density optical disc system.

Optically resilient 3D micro-optics on the tips of optical fibers

NASA Astrophysics Data System (ADS)

Jonušauskas, Linas

2017-05-01

In this paper we present a study aimed at investigating an optical resiliency of polymers that could be applied in 3D femtosecond laser lithography. These include popular in lithography SU8 and OrmoClear as well as hybrid organic-inorganic zirconium containing SZ2080. We show that latter material in its pure (non-photosensitized) form has the best optical resiliency out of all tested materials. Furthermore, its 3D structurability is investigated. Despite threshold-like quality degradation outside fabrication window, we show that this material is suitable for creating complex 3D structures on the tips of optical fibers. Overall it is demonstrated, that unique capability of 3DLL to structure pure materials can lead to very compact functional fiber-based devices that could withstand high (GW/cm2) light intensities.

High efficiency coherent optical memory with warm rubidium vapour

PubMed Central

Hosseini, M.; Sparkes, B.M.; Campbell, G.; Lam, P.K.; Buchler, B.C.

2011-01-01

By harnessing aspects of quantum mechanics, communication and information processing could be radically transformed. Promising forms of quantum information technology include optical quantum cryptographic systems and computing using photons for quantum logic operations. As with current information processing systems, some form of memory will be required. Quantum repeaters, which are required for long distance quantum key distribution, require quantum optical memory as do deterministic logic gates for optical quantum computing. Here, we present results from a coherent optical memory based on warm rubidium vapour and show 87% efficient recall of light pulses, the highest efficiency measured to date for any coherent optical memory suitable for quantum information applications. We also show storage and recall of up to 20 pulses from our system. These results show that simple warm atomic vapour systems have clear potential as a platform for quantum memory. PMID:21285952

High efficiency coherent optical memory with warm rubidium vapour.

PubMed

Hosseini, M; Sparkes, B M; Campbell, G; Lam, P K; Buchler, B C

2011-02-01

By harnessing aspects of quantum mechanics, communication and information processing could be radically transformed. Promising forms of quantum information technology include optical quantum cryptographic systems and computing using photons for quantum logic operations. As with current information processing systems, some form of memory will be required. Quantum repeaters, which are required for long distance quantum key distribution, require quantum optical memory as do deterministic logic gates for optical quantum computing. Here, we present results from a coherent optical memory based on warm rubidium vapour and show 87% efficient recall of light pulses, the highest efficiency measured to date for any coherent optical memory suitable for quantum information applications. We also show storage and recall of up to 20 pulses from our system. These results show that simple warm atomic vapour systems have clear potential as a platform for quantum memory.

Design methodology for micro-discrete planar optics with minimum illumination loss for an extended source.

PubMed

Shim, Jongmyeong; Park, Changsu; Lee, Jinhyung; Kang, Shinill

2016-08-08

Recently, studies have examined techniques for modeling the light distribution of light-emitting diodes (LEDs) for various applications owing to their low power consumption, longevity, and light weight. The energy mapping technique, a design method that matches the energy distributions of an LED light source and target area, has been the focus of active research because of its design efficiency and accuracy. However, these studies have not considered the effects of the emitting area of the LED source. Therefore, there are limitations to the design accuracy for small, high-power applications with a short distance between the light source and optical system. A design method for compensating for the light distribution of an extended source after the initial optics design based on a point source was proposed to overcome such limits, but its time-consuming process and limited design accuracy with multiple iterations raised the need for a new design method that considers an extended source in the initial design stage. This study proposed a method for designing discrete planar optics that controls the light distribution and minimizes the optical loss with an extended source and verified the proposed method experimentally. First, the extended source was modeled theoretically, and a design method for discrete planar optics with the optimum groove angle through energy mapping was proposed. To verify the design method, design for the discrete planar optics was achieved for applications in illumination for LED flash. In addition, discrete planar optics for LED illuminance were designed and fabricated to create a uniform illuminance distribution. Optical characterization of these structures showed that the design was optimal; i.e., we plotted the optical losses as a function of the groove angle, and found a clear minimum. Simulations and measurements showed that an efficient optical design was achieved for an extended source.

Characterization of Optical Properties of Desert Dust and Other Aerosols Using Postive Matrix Factorization

NASA Astrophysics Data System (ADS)

Lihavainen, H.; Alghamdi, M.; Hyvärinen, A.; Hussein, T.; Neitola, K.; Khoder, M.; Abdelmaksoud, A. S.; Al-Jeelani, H.; Shabbaj, I. I.; Almehmadi, F. M.

2017-12-01

To derive the comprehensive aerosol in situ characteristics at a rural background area in Saudi Arabia, an aerosol measurements station was established to Hada Al Sham, 60 km east from the Red Sea and the city of Jeddah. The present sturdy describes the observational data from February 2013 to February 2015 of scattering and absorption coefficients, Ångström exponents and single scattering albedo over the measurement period. As expected, the scattering coefficient was dominated by large desert dust particles with low Ångström scattering exponent. Especially from February to June the Ångström scattering exponent was clearly lower and scattering coefficients higher than total averages because of the dust outbreak season. Aerosol optical properties had clear diurnal cycle. The lowest scattering and absorption coefficients and aerosol optical depths were observed around noon. The observed diurnal variation is caused by wind direction and speed, during night time very calm easterly winds are dominating whereas during daytime the stronger westerly winds are dominating (sea breeze). Positive Matrix Factorization mathematical tool was applied to the scattering and absorption coefficients and PM2.5 and coarse mode (PM10- PM2.5) mass concentrations to characterise aerosols from different sources. Analysis revealed three clearly different types of sources, anthropogenic, BC source and desert dust. These factors have clearly different seasonal and diurnal variation. The contribution of desert dust factor was dominating from February to May, whereas the contribution of anthropogenic factor is quite steady over the whole year. We estimated the mass absorption and scattering efficiencies for the factors and they agreed well with earlier observations. Hence, this method could be used to distinguish aerosol source characteristics, at least in fairly simple cases.

ClearSee: a rapid optical clearing reagent for whole-plant fluorescence imaging

PubMed Central

Kurihara, Daisuke; Mizuta, Yoko; Sato, Yoshikatsu; Higashiyama, Tetsuya

2015-01-01

Imaging techniques for visualizing and analyzing precise morphology and gene expression patterns are essential for understanding biological processes during development in all organisms. With the aid of chemical screening, we developed a clearing method using chemical solutions, termed ClearSee, for deep imaging of morphology and gene expression in plant tissues. ClearSee rapidly diminishes chlorophyll autofluorescence while maintaining fluorescent protein stability. By adjusting the refractive index mismatch, whole-organ and whole-plant imaging can be performed by both confocal and two-photon excitation microscopy in ClearSee-treated samples. Moreover, ClearSee is applicable to multicolor imaging of fluorescent proteins to allow structural analysis of multiple gene expression. Given that ClearSee is compatible with staining by chemical dyes, the technique is useful for deep imaging in conjunction with genetic markers and for plant species not amenable to transgenic approaches. This method is useful for whole imaging for intact morphology and will help to accelerate the discovery of new phenomena in plant biological research. PMID:26493404

Monitoring skin microvascular dysfunction of type 1 diabetic mice using in vivo skin optical clearing

NASA Astrophysics Data System (ADS)

Feng, Wei; Shi, Rui; Zhu, Dan

2018-02-01

To monitor skin microvascular dysfunction of alloxan-induced type 1 diabetic mice model. In this work, we used laser speckle contrast imaging and hyperspectral imaging through in vivo skin optical clearing method to simultaneously monitor the noradrenaline-induced response of microvascular blood flow and blood oxygen with the development of diabetes. The main results showed that venous and arterious blood flow steadily decreased without recovery after injecting noradrenaline (NE), furthermore the influence of NE-induced arterious blood oxygen response greatly decreased, especially for 2-weeks and 4-weeks diabetic mice. This study demonstrated that skin microvascular function was a potential research biomarker for early warning in the occurrence and development of diabetes. And it provides a feasible solution to realize visualization of cutaneous microvessels for monitoring microvascular reactivity.

Optical clearing of vaginal tissues, ex vivo, for minimally invasive laser treatment of female stress urinary incontinence

PubMed Central

Chang, Chun-Hung; Myers, Erinn M.; Kennelly, Michael J.; Fried, Nathaniel M.

2017-01-01

Abstract. Near-infrared laser energy in conjunction with applied tissue cooling is being investigated for thermal remodeling of the endopelvic fascia during minimally invasive treatment of female stress urinary incontinence. Previous computer simulations of light transport, heat transfer, and tissue thermal damage have shown that a transvaginal approach is more feasible than a transurethral approach. However, results were suboptimal, and some undesirable thermal insult to the vaginal wall was still predicted. This study uses experiments and computer simulations to explore whether application of an optical clearing agent (OCA) can further improve optical penetration depth and completely preserve the vaginal wall during subsurface treatment of the endopelvic fascia. Several different mixtures of OCA’s were tested, and 100% glycerol was found to be the optimal agent. Optical transmission studies, optical coherence tomography, reflection spectroscopy, and computer simulations [including Monte Carlo (MC) light transport, heat transfer, and Arrhenius integral model of thermal damage] using glycerol were performed. The OCA produced a 61% increase in optical transmission through porcine vaginal wall at 37°C after 30 min. The MC model showed improved energy deposition in endopelvic fascia using glycerol. Without OCA, 62%, 37%, and 1% of energy was deposited in vaginal wall, endopelvic fascia, and urethral wall, respectively, compared with 50%, 49%, and 1% using OCA. Use of OCA also resulted in 0.5-mm increase in treatment depth, allowing potential thermal tissue remodeling at a depth of 3 mm with complete preservation of the vaginal wall. PMID:28301637

Simulations of the effect of intensive biomass burning in July 2015 on Arctic radiative budget

NASA Astrophysics Data System (ADS)

Markowicz, K. M.; Lisok, J.; Xian, P.

2017-12-01

The impact of biomass burning (BB) on aerosol optical properties and radiative budget in the polar region following an intense boreal fire event in North America in July 2015 is explored in this paper. Presented data are obtained from the Navy Aerosol Analysis and Prediction System (NAAPS) reanalysis and the Fu-Liou radiative transfer model. NAAPS provides particle concentrations and aerosol optical depth (AOD) at 1° x 1° spatial and 6-hourly temporal resolution, its AOD and vertical profiles were validated with field measurements for this event. Direct aerosol radiative forcings (ARF) at the surface, the top of the atmosphere (TOA) and within the atmosphere are calculated for clear-sky and all-sky conditions, with the surface albedo and cloud properties constrained by satellite retrievals. The mean ARFs at the surface, the TOA, and within the atmosphere averaged for the north pole region (latitudes north of 75.5N) and the study period (July 5-15, 2015) are -13.1 ± 2.7, 0.3 ± 2.1, and 13.4 ± 2.7 W/m2 for clear-sky and -7.3 ± 1.8, 5.0 ± 2.6, and 12.3 ± 1.6 W/m2 for all-sky conditions respectively. Local ARFs can be a several times larger e.g. the clear-sky surface and TOA ARF reach over Alaska -85 and -30 W/m2 and over Svalbard -41 and -20 W/m2 respectively. The ARF is found negative at the surface (almost zero over high albedo region though) with the maximum forcing over the BB source region, and weaker forcing under all-sky conditions compared to the clear-sky conditions. Unlike the ARFs at the surface and within the atmosphere, which have consistent forcing signs all over the polar region, the ARF at the TOA changes signs from negative (cooling) over the source region (Alaska) to positive (heating) over bright surfaces (e.g., Greenland) because of strong surface albedo effect. NAAPS simulations also show that the transported BB particle over the Arctic are in the low-to-middle troposphere and above low-level clouds, resulting in little difference in ARFs at the TOA between clear- and all-sky conditions over the regions with high surface albedo. Over dark surfaces, the negative TOA forcing increases with AOD about 50% slower under all-sky conditions compared to clear-sky case. The boreal BB event resulted in large magnitude of ARFs and the high variabilities of the forcings over the polar region has a significant impact on the polar weather conditions and important implications for the polar climate.

Supplemental optical specifications for imaging systems: parameters of phase gradient

NASA Astrophysics Data System (ADS)

Xuan, Bin; Li, Jun-Feng; Wang, Peng; Chen, Xiao-Ping; Song, Shu-Mei; Xie, Jing-Jiang

2009-12-01

Specifications of phase error, peak to valley (PV), and root mean square (rms) are not able to represent the properties of a wavefront reasonably because of their irresponsibility for spatial frequencies. Power spectral density is a parameter that is especially effective to indicate the frequency regime. However, it seems not convenient for opticians to implement. Parameters of phase gradient, PV gradient, and rms gradient are most correlated with a point-spread function of an imaging system, and they can provide clear instruction of manufacture. The algorithms of gradient parameters have been modified in order to represent the image quality better. In order to demonstrate the analyses, an experimental spherical mirror has been worked out. It is clear that imaging performances can be maintained while manufacture difficulties are decreased when a reasonable trade-off between specifications of phase error and phase gradient is made.

Depth Estimation of Submerged Aquatic Vegetation in Clear Water Streams Using Low-Altitude Optical Remote Sensing

PubMed Central

Visser, Fleur; Buis, Kerst; Verschoren, Veerle; Meire, Patrick

2015-01-01

UAVs and other low-altitude remote sensing platforms are proving very useful tools for remote sensing of river systems. Currently consumer grade cameras are still the most commonly used sensors for this purpose. In particular, progress is being made to obtain river bathymetry from the optical image data collected with such cameras, using the strong attenuation of light in water. No studies have yet applied this method to map submergence depth of aquatic vegetation, which has rather different reflectance characteristics from river bed substrate. This study therefore looked at the possibilities to use the optical image data to map submerged aquatic vegetation (SAV) depth in shallow clear water streams. We first applied the Optimal Band Ratio Analysis method (OBRA) of Legleiter et al. (2009) to a dataset of spectral signatures from three macrophyte species in a clear water stream. The results showed that for each species the ratio of certain wavelengths were strongly associated with depth. A combined assessment of all species resulted in equally strong associations, indicating that the effect of spectral variation in vegetation is subsidiary to spectral variation due to depth changes. Strongest associations (R2-values ranging from 0.67 to 0.90 for different species) were found for combinations including one band in the near infrared (NIR) region between 825 and 925 nm and one band in the visible light region. Currently data of both high spatial and spectral resolution is not commonly available to apply the OBRA results directly to image data for SAV depth mapping. Instead a novel, low-cost data acquisition method was used to obtain six-band high spatial resolution image composites using a NIR sensitive DSLR camera. A field dataset of SAV submergence depths was used to develop regression models for the mapping of submergence depth from image pixel values. Band (combinations) providing the best performing models (R2-values up to 0.77) corresponded with the OBRA findings. A 10% error was achieved under sub-optimal data collection conditions, which indicates that the method could be suitable for many SAV mapping applications. PMID:26437410

Depth Estimation of Submerged Aquatic Vegetation in Clear Water Streams Using Low-Altitude Optical Remote Sensing.

PubMed

Visser, Fleur; Buis, Kerst; Verschoren, Veerle; Meire, Patrick

2015-09-30

UAVs and other low-altitude remote sensing platforms are proving very useful tools for remote sensing of river systems. Currently consumer grade cameras are still the most commonly used sensors for this purpose. In particular, progress is being made to obtain river bathymetry from the optical image data collected with such cameras, using the strong attenuation of light in water. No studies have yet applied this method to map submergence depth of aquatic vegetation, which has rather different reflectance characteristics from river bed substrate. This study therefore looked at the possibilities to use the optical image data to map submerged aquatic vegetation (SAV) depth in shallow clear water streams. We first applied the Optimal Band Ratio Analysis method (OBRA) of Legleiter et al. (2009) to a dataset of spectral signatures from three macrophyte species in a clear water stream. The results showed that for each species the ratio of certain wavelengths were strongly associated with depth. A combined assessment of all species resulted in equally strong associations, indicating that the effect of spectral variation in vegetation is subsidiary to spectral variation due to depth changes. Strongest associations (R²-values ranging from 0.67 to 0.90 for different species) were found for combinations including one band in the near infrared (NIR) region between 825 and 925 nm and one band in the visible light region. Currently data of both high spatial and spectral resolution is not commonly available to apply the OBRA results directly to image data for SAV depth mapping. Instead a novel, low-cost data acquisition method was used to obtain six-band high spatial resolution image composites using a NIR sensitive DSLR camera. A field dataset of SAV submergence depths was used to develop regression models for the mapping of submergence depth from image pixel values. Band (combinations) providing the best performing models (R²-values up to 0.77) corresponded with the OBRA findings. A 10% error was achieved under sub-optimal data collection conditions, which indicates that the method could be suitable for many SAV mapping applications.

The role of the [CpM(CO)2](-) chromophore in the optical properties of the [Cp2ThMCp(CO)2](+) complexes, where M = Fe, Ru and Os. A theoretical view.

PubMed

Cantero-López, Plinio; Le Bras, Laura; Páez-Hernández, Dayán; Arratia-Pérez, Ramiro

2015-12-14

The chemical bond between actinide and the transition metal unsupported by bridging ligands is not well characterized. In this paper we study the electronic properties, bonding nature and optical spectra in a family of [Cp2ThMCp(CO)2](+) complexes where M = Fe, Ru, Os, based on the relativistic two component density functional theory calculations. The Morokuma-Ziegler energy decomposition analysis shows an important ionic contribution in the Th-M interaction with around 25% of covalent character. Clearly, charge transfer occurs on Th-M bond formation, however the orbital term most likely represents a strong charge rearrangement in the fragments due to the interaction. Finally the spin-orbit-ZORA calculation shows the possible NIR emission induced by the [FeCp(CO)2](-) chromophore accomplishing the antenna effect that justifies the sensitization of the actinide complexes.

One-step microwave plasma enhanced chemical vapor deposition (MW-PECVD) for transparent superhydrophobic surface

NASA Astrophysics Data System (ADS)

Thongrom, Sukrit; Tirawanichakul, Yutthana; Munsit, Nantakan; Deangngam, Chalongrat

2018-02-01

We demonstrate a rapid and environmental friendly fabrication technique to produce optically clear superhydrophobic surfaces using poly (dimethylsiloxane) (PDMS) as a sole coating material. The inert PDMS chain is transformed into a 3-D irregular solid network through microwave plasma enhanced chemical vapor deposition (MW-PECVD) process. Thanks to high electron density in the microwave-activated plasma, coating can be done in just a single step with rapid deposition rate, typically much shorter than 10 s. Deposited layers show excellent superhydrophobic properties with water contact angles of ∼170° and roll-off angles as small as ∼3°. The plasma-deposited films can be ultrathin with thicknesses under 400 nm, greatly diminishing the optical loss. Moreover, with appropriate coating conditions, the coating layer can even enhance the transmission over the entire visible spectrum due to a partial anti-reflection effect.

Registration of adaptive optics corrected retinal nerve fiber layer (RNFL) images

PubMed Central

Ramaswamy, Gomathy; Lombardo, Marco; Devaney, Nicholas

2014-01-01

Glaucoma is the leading cause of preventable blindness in the western world. Investigation of high-resolution retinal nerve fiber layer (RNFL) images in patients may lead to new indicators of its onset. Adaptive optics (AO) can provide diffraction-limited images of the retina, providing new opportunities for earlier detection of neuroretinal pathologies. However, precise processing is required to correct for three effects in sequences of AO-assisted, flood-illumination images: uneven illumination, residual image motion and image rotation. This processing can be challenging for images of the RNFL due to their low contrast and lack of clearly noticeable features. Here we develop specific processing techniques and show that their application leads to improved image quality on the nerve fiber bundles. This in turn improves the reliability of measures of fiber texture such as the correlation of Gray-Level Co-occurrence Matrix (GLCM). PMID:24940551

Registration of adaptive optics corrected retinal nerve fiber layer (RNFL) images.

PubMed

Ramaswamy, Gomathy; Lombardo, Marco; Devaney, Nicholas

2014-06-01

Glaucoma is the leading cause of preventable blindness in the western world. Investigation of high-resolution retinal nerve fiber layer (RNFL) images in patients may lead to new indicators of its onset. Adaptive optics (AO) can provide diffraction-limited images of the retina, providing new opportunities for earlier detection of neuroretinal pathologies. However, precise processing is required to correct for three effects in sequences of AO-assisted, flood-illumination images: uneven illumination, residual image motion and image rotation. This processing can be challenging for images of the RNFL due to their low contrast and lack of clearly noticeable features. Here we develop specific processing techniques and show that their application leads to improved image quality on the nerve fiber bundles. This in turn improves the reliability of measures of fiber texture such as the correlation of Gray-Level Co-occurrence Matrix (GLCM).

Qualitative identification of food materials by complex refractive index mapping in the terahertz range.

PubMed

Shin, Hee Jun; Choi, Sung-Wook; Ok, Gyeongsik

2018-04-15

We investigated the feasibility of qualitative food analysis using complex refractive index mapping of food materials in the terahertz (THz) frequency range. We studied optical properties such as the refractive index and absorption coefficient of food materials, including insects as foreign substances, from 0.2 to 1.3 THz. Although some food materials had a complex composition, their refractive indices were approximated with effective medium values, and therefore, they could be discriminated on the complex refractive index map. To demonstrate food quality inspection with THz imaging, we obtained THz reflective images and time-of-flight imaging of hidden defects in a sugar and milk powder matrix by using time domain THz pulses. Our results indicate that foreign substances can be clearly classified and detected according to the optical parameters of the foods and insects by using THz pulses. Copyright © 2017. Published by Elsevier Ltd.

A programmable DNA origami nanospring that reveals force-induced adjacent binding of myosin VI heads

PubMed Central

Iwaki, M.; Wickham, S. F.; Ikezaki, K.; Yanagida, T.; Shih, W. M.

2016-01-01

Mechanosensitive biological nanomachines such as motor proteins and ion channels regulate diverse cellular behaviour. Combined optical trapping with single-molecule fluorescence imaging provides a powerful methodology to clearly characterize the mechanoresponse, structural dynamics and stability of such nanomachines. However, this system requires complicated experimental geometry, preparation and optics, and is limited by low data-acquisition efficiency. Here we develop a programmable DNA origami nanospring that overcomes these issues. We apply our nanospring to human myosin VI, a mechanosensory motor protein, and demonstrate nanometre-precision single-molecule fluorescence imaging of the individual motor domains (heads) under force. We observe force-induced transitions of myosin VI heads from non-adjacent to adjacent binding, which correspond to adapted roles for low-load and high-load transport, respectively. Our technique extends single-molecule studies under force and clarifies the effect of force on biological processes. PMID:27941751

Mechanisms of Optical Regression Following Corneal Laser Refractive Surgery: Epithelial and Stromal Responses

PubMed Central

MOSHIRFAR, Majid; DESAUTELS, Jordan D.; WALKER, Brian D.; MURRI, Michael S.; BIRDSONG, Orry C.; HOOPES, Phillip C. Sr

2018-01-01

Laser vision correction is a safe and effective method of reducing spectacle dependence. Photorefractive Keratectomy (PRK), Laser In Situ Keratomileusis (LASIK), and Small-Incision Lenticule Extraction (SMILE) can accurately correct myopia, hyperopia, and astigmatism. Although these procedures are nearing optimization in terms of their ability to produce a desired refractive target, the long term cellular responses of the cornea to these procedures can cause patients to regress from the their ideal postoperative refraction. In many cases, refractive regression requires follow up enhancement surgeries, presenting additional risks to patients. Although some risk factors underlying refractive regression have been identified, the exact mechanisms have not been elucidated. It is clear that cellular proliferation events are important mediators of optical regression. This review focused specifically on cellular changes to the corneal epithelium and stroma, which may influence postoperative visual regression following LASIK, PRK, and SMILE procedures. PMID:29644238

A programmable DNA origami nanospring that reveals force-induced adjacent binding of myosin VI heads.

PubMed

Iwaki, M; Wickham, S F; Ikezaki, K; Yanagida, T; Shih, W M

2016-12-12

Mechanosensitive biological nanomachines such as motor proteins and ion channels regulate diverse cellular behaviour. Combined optical trapping with single-molecule fluorescence imaging provides a powerful methodology to clearly characterize the mechanoresponse, structural dynamics and stability of such nanomachines. However, this system requires complicated experimental geometry, preparation and optics, and is limited by low data-acquisition efficiency. Here we develop a programmable DNA origami nanospring that overcomes these issues. We apply our nanospring to human myosin VI, a mechanosensory motor protein, and demonstrate nanometre-precision single-molecule fluorescence imaging of the individual motor domains (heads) under force. We observe force-induced transitions of myosin VI heads from non-adjacent to adjacent binding, which correspond to adapted roles for low-load and high-load transport, respectively. Our technique extends single-molecule studies under force and clarifies the effect of force on biological processes.

Visualization of explosion phenomena using a high-speed video camera with an uncoupled objective lens by fiber-optic

NASA Astrophysics Data System (ADS)

Tokuoka, Nobuyuki; Miyoshi, Hitoshi; Kusano, Hideaki; Hata, Hidehiro; Hiroe, Tetsuyuki; Fujiwara, Kazuhito; Yasushi, Kondo

2008-11-01

Visualization of explosion phenomena is very important and essential to evaluate the performance of explosive effects. The phenomena, however, generate blast waves and fragments from cases. We must protect our visualizing equipment from any form of impact. In the tests described here, the front lens was separated from the camera head by means of a fiber-optic cable in order to be able to use the camera, a Shimadzu Hypervision HPV-1, for tests in severe blast environment, including the filming of explosions. It was possible to obtain clear images of the explosion that were not inferior to the images taken by the camera with the lens directly coupled to the camera head. It could be confirmed that this system is very useful for the visualization of dangerous events, e.g., at an explosion site, and for visualizations at angles that would be unachievable under normal circumstances.

Probing Photocurrent Nonuniformities in the Subcells of Monolithic Perovskite/Silicon Tandem Solar Cells.

PubMed

Song, Zhaoning; Werner, Jérémie; Shrestha, Niraj; Sahli, Florent; De Wolf, Stefaan; Niesen, Björn; Watthage, Suneth C; Phillips, Adam B; Ballif, Christophe; Ellingson, Randy J; Heben, Michael J

2016-12-15

Perovskite/silicon tandem solar cells with high power conversion efficiencies have the potential to become a commercially viable photovoltaic option in the near future. However, device design and optimization is challenging because conventional characterization methods do not give clear feedback on the localized chemical and physical factors that limit performance within individual subcells, especially when stability and degradation is a concern. In this study, we use light beam induced current (LBIC) to probe photocurrent collection nonuniformities in the individual subcells of perovskite/silicon tandems. The choices of lasers and light biasing conditions allow efficiency-limiting effects relating to processing defects, optical interference within the individual cells, and the evolution of water-induced device degradation to be spatially resolved. The results reveal several types of microscopic defects and demonstrate that eliminating these and managing the optical properties within the multilayer structures will be important for future optimization of perovskite/silicon tandem solar cells.

Influences of the clearness index on UV solar radiation for two locations in the Tibetan Plateau-Lhasa and Haibei

NASA Astrophysics Data System (ADS)

Hu, Bo; Wang, Yuesi; Liu, Guangren

2008-09-01

Ultraviolet (UV) solar radiation has a significant influence on human health, the environment and climate. A series of measurements, including UV radiation (290-400 nm) and global solar radiation ( R s), were continuously recorded from August 2004 at the Lhasa and Haibei sites on the Tibetan Plateau. Both observation sites’ altitudes are above 3000 m and have similar meteorological conditions. The data from 2005-2006 was used to identify the varying characteristics of UV radiation. It’s relation to the clearness index K s, the relative optical mass m r, and R s were established. The annual mean values of total daily UV radiation are 0.92 and 0.67 MJ m-2 at Lhasa and Haibei, respectively. The UV radiation in Lhasa represented 4.6% of the global solar radiation while in Haibei this percentage was 4.2%. In the case of clear days ( K s > 0.8), these percentages ranged between 4.0% and 4.5% in Lhasa and between 5.1% and 5.5% in Haibei. In the case of cloudy days ( K s < 0.4), these percentages ranged from 4.4% to 6.8% in Lhasa and from 5.1% to 5.5% in Haibei. The maximum values of UV radiation for each relative optical mass diminished exponentially with m r. Thus, for Lhasa and Haibei, UV=46.25 m {4/-1.29}, and UV=51.76 m {r/-1.42}, respectively. The results of this study can be used to obtain more UV radiation data for the study of UV climate characteristics, the effects of UV on ecological processes and the feedback of the thinning of the stratospheric ozone, from more routine measurements R s data.

Assessment of the Effect of Air Pollution Controls on Trends in Shortwave Radiation over the United States from 1995 through 2010 from Multiple Observation Networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gan, Chuen-Meei; Pleim, Jonathan; Mathur, Rohit

2014-02-14

Long term datasets of total (all-sky) and clear-sky downwelling shortwave (SW) radiation, cloud cover fraction (cloudiness) and aerosol optical depth (AOD) are analyzed together with aerosol concentration from several networks (e.g. SURFRAD, CASTNET, IMPROVE and ARM) in the United States (US). Seven states with varying climatology are selected to better understand the effect of aerosols and clouds on SW radiation. This analysis aims to test the hypothesis that the reductions in anthropogenic aerosol burden resulting from substantial reductions in emissions of sulfur dioxide and nitrogen oxides over the past 15 years across the US has caused an increase in surfacemore » SW radiation. We show that the total and clear-sky downwelling SW radiation from seven sites have increasing trends except Penn State which shows no tendency in clear-sky SW radiation. After investigating several confounding factors, the causes can be due to the geography of the site, aerosol distribution, heavy air traffic and increasing cloudiness. Moreover, we assess the relationship between total column AOD with surface aerosol concentration to test our hypothesis. In our findings, the trends of clear-sky SW radiation, AOD, and aerosol concentration from the sites in eastern US agree well with our hypothesis. However, the sites in western US demonstrate increasing AOD associated with mostly increasing trends in surface aerosol concentration. At these sites, the changes in aerosol burden and/or direct aerosol effects alone cannot explain the observed changes in SW radiation, but other factors need to be considered such as cloudiness, aerosol vertical profiles and elevated plumes.« less

Optical temperature indicator using thermochromic semiconductors

DOEpatents

Kronberg, J.W.

1995-01-01

A reversible optical temperature indicator utilizes thermochromic semiconductors which vary in color in response to various temperature levels. The thermochromic material is enclosed in an enamel which provides protection and prevents breakdown at higher temperatures. Cadmium sulfide is the preferred semiconductor material. The indicator may be utilized as a sign or in a striped arrangement to clearly provide a warning to a user. The various color responses provide multiple levels of alarm.

Optical temperature indicator using thermochromic semiconductors

DOEpatents

Kronberg, James W.

1996-01-01

A reversible optical temperature indicator utilizes thermochromic semiconductors which vary in color in response to various temperature levels. The thermochromic material is enclosed in an enamel which provides protection and prevents breakdown at higher temperatures. Cadmium sulfide is the preferred semiconductor material. The indicator may be utilized as a sign or in a striped arrangement to clearly provide a warning to a user. The various color responses provide multiple levels of alarm.

Micro-photoluminescence of GaAs/AlGaAs triple concentric quantum rings

PubMed Central

2011-01-01

A systematic optical study, including micro, ensemble and time resolved photoluminescence of GaAs/AlGaAs triple concentric quantum rings, self-assembled via droplet epitaxy, is presented. Clear emission from localized states belonging to the ring structures is reported. The triple rings show a fast decay dynamics, around 40 ps, which is expected to be useful for ultrafast optical switching applications. PMID:22039893

41. View of electro/mechanical fiber optic system panel in transmitter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

41. View of electro/mechanical fiber optic system panel in transmitter building no. 102. Images projected to screen (panel at upper left) are projected to back side of screen located in MWOC to display changing information. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

Remote Sensing of the Optical and Physical Densities of Smoke, Dust, and Water Clouds.

DTIC Science & Technology

1982-12-01

systems to measure variability of aerosol concentration distributions along horizontal optical paths . Analysis of backscatter... extinction measurements using a single- laser lidar system operating at 1.06- and 0.53-pm wavelengths. For larger mean particle sizes the extinction ratio...clear air paths and The transmissometers were mounted across a 10-m complete blockage of the source energy. Transmisso- long aerosol tunnel that

Post Flight Analysis of Optical Specimens from MISSE7

NASA Technical Reports Server (NTRS)

Stewart, Alan F.; Finckenor, Miria

2012-01-01

More than 100 optical specimens were flown on the MISSE7 platform. These included bare substrates in addition to coatings designed to exhibit clearly defined or enhanced sensitivity to the accumulation of contamination. Measurements were performed using spectrophotometers operating from the UV through the IR as well as ellipsometry. Results will be presented in addition to discussion of the best options for design of samples for future exposure experiments.

Patterning of organic photovoltaic on R2R processed thin film barriers using IR laser sources

NASA Astrophysics Data System (ADS)

Fledderus, H.; Akkerman, H. B.; Salem, A.; Friedrich Schilling, N.; Klotzbach, U.

2017-02-01

We present the development of laser processes for flexible OPV on roll-to-roll (RR2R) produced thin film barrier with indium tin oxide (ITO) as transparent conductive (TC) bottom electrode. Direct laser structuring of ITO on such barrier films (so-called P1 process) is very challenging since the layers are all transparent, a complete electrical isolation is required, and the laser process should not influence the barrier performance underneath the scribes. Based on the optical properties off the SiN and ITTO, ultra-short pulse lasers inn picosecond and femtosecond regime with standard infrared (IR) wavelength as well as lasers with new a wavelength (22 μm regime) are tested for this purpose. To determine a process window for a specific laser a fixed methodology is adopted. Single pulse ablation tests were followed by scribing experiments where the pulse overlap was tuned by varying laser pulse fluence, writing speed and frequency. To verify that the laser scribing does not result inn barrier damage underneath, a new test method was developed based on the optical Ca-test. This method shows a clear improvement in damage analysis underneath laser scribes over normal optical inspection methods (e.g. microscope, optical profiler, SEM). This way clear process windows can be obtained for IR TC patterning.

Monte Carlo Bayesian Inference on a Statistical Model of Sub-gridcolumn Moisture Variability Using High-resolution Cloud Observations . Part II; Sensitivity Tests and Results

NASA Technical Reports Server (NTRS)

da Silva, Arlindo M.; Norris, Peter M.

2013-01-01

Part I presented a Monte Carlo Bayesian method for constraining a complex statistical model of GCM sub-gridcolumn moisture variability using high-resolution MODIS cloud data, thereby permitting large-scale model parameter estimation and cloud data assimilation. This part performs some basic testing of this new approach, verifying that it does indeed significantly reduce mean and standard deviation biases with respect to the assimilated MODIS cloud optical depth, brightness temperature and cloud top pressure, and that it also improves the simulated rotational-Ramman scattering cloud optical centroid pressure (OCP) against independent (non-assimilated) retrievals from the OMI instrument. Of particular interest, the Monte Carlo method does show skill in the especially difficult case where the background state is clear but cloudy observations exist. In traditional linearized data assimilation methods, a subsaturated background cannot produce clouds via any infinitesimal equilibrium perturbation, but the Monte Carlo approach allows finite jumps into regions of non-zero cloud probability. In the example provided, the method is able to restore marine stratocumulus near the Californian coast where the background state has a clear swath. This paper also examines a number of algorithmic and physical sensitivities of the new method and provides guidance for its cost-effective implementation. One obvious difficulty for the method, and other cloud data assimilation methods as well, is the lack of information content in the cloud observables on cloud vertical structure, beyond cloud top pressure and optical thickness, thus necessitating strong dependence on the background vertical moisture structure. It is found that a simple flow-dependent correlation modification due to Riishojgaard (1998) provides some help in this respect, by better honoring inversion structures in the background state.

An Efficient, Affordable Optically Stimulated Luminescent (OSL) Annealer.

PubMed

Abraham, Sara A; Frank, Samuel J; Kearfott, Kimberlee J

2017-07-01

Optically stimulated luminescent (OSL) dosimeters are devices used for measuring doses of ionizing radiation. Signal is stored within an OSL material so that when stimulated with light, light of a specific wavelength is emitted in proportion to the integrated ionizing radiation dose. Each interrogation of the material results in the loss of a small fraction of signal, thus allowing multiple interrogations leading to more accurate measurements of dose. In order to reuse a dosimeter, the residual signals from prior doses must be taken into account and subtracted from current readings, adding uncertainty to any future measurements. To reduce these errors when they become large, it is desirable to completely clear the stored signal or anneal the dosimeter. Traditionally, heating the material has accomplished this. In a commercially available dosimeter badge system, the OSL material Al2O3:C is incorporated into a plastic slide that would melt at the necessary high temperatures, which can reach 900 °C, required for annealing. Fortunately, due to the material's high sensitivity to light, OSLs can be optically annealed instead. In order to do this, an affordable OSL dosimeter annealer was designed with inexpensive, exchangeable blue, green, and white high intensity light-emitting diodes (LEDs). Several dosimeters were repeatedly annealed for recorded intervals and then read out. A single dosimeter was partially annealed through repeated interrogations with the LED array from a commercial reader. The signal loss due to the exposure to each light was analyzed to determine the practicality and efficiency of each color. The rate and extent of signal loss was dependent not only on the spectrum of annealing light but on the initial signal levels as well. These findings suggest that blue LEDs are the most promising for effective and rapid clearing of the OSL material Al2O3:C.

Report on the Study of Radiation Damage in Calcium Fluoride and Magnesium Fluoride Crystals for use in Excimer Laser Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

None, None

1999-10-04

A study was performed to investigate the effects of radiation damage in calcium fluoride and magnesium fluoride crystals caused by gamma rays and UV photons from excimer lasers. The purpose was to study and correlate the damage caused by these two different mechanisms in various types of material used for fabricating optical elements in high power excimer lasers and lens systems of lithography tools. These optical systems are easily damaged by the laser itself, and it is necessary to use only the most radiation resistant materials for certain key elements. It was found that a clear correlation exists between the,more » radiation induced damage caused by high energy gamma rays and that produced by UV photons from the excimer laser. This correlation allows a simple procedure to be developed to select the most radiation resistant material at the ingot level, which would be later used to fabricate various components of the optical system. This avoids incurring the additional cost of fabricating actual optical elements with material that would later be damaged under prolonged use. The result of this screening procedure can result in a considerable savings in the overall cost of the lens and laser system.« less

Endoscopic optical coherence tomography with a modified microelectromechanical systems mirror for detection of bladder cancers

NASA Astrophysics Data System (ADS)

Xie, Tuqiang; Xie, Huikai; Fedder, Gary K.; Pan, Yingtian

2003-11-01

Experimental results of a modified micromachined microelectromechanical systems (MEMS) mirror for substantial enhancement of the transverse laser scanning performance of endoscopic optical coherence tomography (EOCT) are presented. Image distortion due to buckling of MEMS mirror in our previous designs was analyzed and found to be attributed to excessive internal stress of the transverse bimorph meshes. The modified MEMS mirror completely eliminates bimorph stress and the resultant buckling effect, which increases the wobbling-free angular optical actuation to greater than 37°, exceeding the transverse laser scanning requirements for EOCT and confocal endoscopy. The new optical coherence tomography (OCT) endoscope allows for two-dimensional cross-sectional imaging that covers an area of 4.2 mm × 2.8 mm (limited by scope size) and at roughly 5 frames/s instead of the previous area size of 2.9 mm × 2.8 mm and is highly suitable for noninvasive and high-resolution imaging diagnosis of epithelial lesions in vivo. EOCT images of normal rat bladders and rat bladder cancers are compared with the same cross sections acquired with conventional bench-top OCT. The results clearly demonstrate the potential of EOCT for in vivo imaging diagnosis and precise guidance for excisional biopsy of early bladder cancers.

Effects of an Arctic under-ice phytoplankton bloom on bio-optical properties of surface waters during the Norwegian Young Sea Ice Cruise (N-ICE2015)

NASA Astrophysics Data System (ADS)

Pavlov, A. K.; Granskog, M. A.; Hudson, S. R.; Taskjelle, T.; Kauko, H.; Hamre, B.; Assmy, P.; Mundy, C. J.; Nicolaus, M.; Kowalczuk, P.; Stedmon, C. A.; Fernandez Mendez, M.

2016-02-01

A thinner and younger Arctic sea-ice cover has led to an increase in solar light transmission into the surface ocean, especially during late spring and summer. A description of the seasonal evolution of polar surface water optical properties is essential, in order to understand how changes are affecting light availability for photosynthetic organisms and the surface ocean energy budget. The development of the bio-optical properties of Arctic surface waters under predominantly first-year sea ice in the southern Nansen Basin were studied from January to June 2015 during the Norwegian Young Sea Ice Cruise (N-ICE2015). Observations included inherent optical properties, absorption by colored dissolved organic matter and particles, as well as radiometric measurements. We documented a rapid transition from relatively clear and transparent waters in winter to turbid waters in late May and June. This transition was associated with a strong under-ice phytoplankton bloom detected first under the compact ice pack and then monitored during drift across the marginal ice zone. We discuss potential implications of underwater light availability for photosynthesis, heat redistribution in the upper ocean layer, and energy budget of the sea-ice - ocean system.

Photovoltaic effect and photopolarization in Pb [(Mg1/3Nb2/3) 0.68Ti0.32] O3 crystal

NASA Astrophysics Data System (ADS)

Makhort, A. S.; Chevrier, F.; Kundys, D.; Doudin, B.; Kundys, B.

2018-01-01

Ferroelectric materials are an alternative to semiconductor-based photovoltaics and offer the advantage of above bandgap photovoltage generation. However, there are few known compounds, and photovoltaic efficiencies remain low. Here, we report the discovery of a photovoltaic effect in undoped lead magnesium niobate-lead titanate crystal and a significant improvement in the photovoltaic response under suitable electric fields and temperatures. The photovoltaic effect is maximum near the electric-field-driven ferroelectric dipole reorientation, and increases threefold near the Curie temperature (Tc). Moreover, at ferroelectric saturation, the photovoltaic response exhibits clear remanent and transient effects. The transient-remanent combinations together with electric and thermal tuning possibilities indicate photoferroelectric crystals as emerging elements for photovoltaics and optoelectronics, relevant to all-optical information storage and beyond.

Transient Thermal Analysis of a Refractive Secondary Solar Concentrator

NASA Technical Reports Server (NTRS)

Geng, Steven M.; Macosko, Robert P.

1999-01-01

A secondary concentrator is an optical device that accepts solar energy from a primary concentrator and further intensifies and directs the solar flux. The refractive secondary is one such device; fabricated from an optically clear solid material that can efficiently transmit the solar energy by way of refraction and total internal reflection. When combined with a large state-of-the-art rigid or inflatable primary concentrator, the refractive secondary enables solar concentration ratios of 10,000 to 1. In support of potential space solar thermal power and propulsion applications, the NASA Glenn Research Center is developing a single-crystal refractive secondary concentrator for use at temperatures exceeding 2000K. Candidate optically clear single-crystal materials like sapphire and zirconia are being evaluated for this application. To support this evaluation, a three-dimensional transient thermal model of a refractive secondary concentrator in a typical solar thermal propulsion application was developed. This paper describes the model and presents thermal predictions for both sapphire and zirconia prototypes. These predictions are then used to establish parameters for analyzing and testing the materials for their ability to survive thermal shock and stress.

Adaptive Optics Imaging Survey of Luminous Infrared Galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laag, E A; Canalizo, G; van Breugel, W

2006-03-13

We present high resolution imaging observations of a sample of previously unidentified far-infrared galaxies at z < 0.3. The objects were selected by cross-correlating the IRAS Faint Source Catalog with the VLA FIRST catalog and the HST Guide Star Catalog to allow for adaptive optics observations. We found two new ULIGs (with L{sub FIR} {ge} 10{sup 12} L{sub {circle_dot}}) and 19 new LIGs (with L{sub FIR} {ge} 10{sup 11} L{sub {circle_dot}}). Twenty of the galaxies in the sample were imaged with either the Lick or Keck adaptive optics systems in H or K{prime}. Galaxy morphologies were determined using the twomore » dimensional fitting program GALFIT and the residuals examined to look for interesting structure. The morphologies reveal that at least 30% are involved in tidal interactions, with 20% being clear mergers. An additional 50% show signs of possible interaction. Line ratios were used to determine powering mechanism; of the 17 objects in the sample showing clear emission lines--four are active galactic nuclei and seven are starburst galaxies. The rest exhibit a combination of both phenomena.« less

Application of gold nanoparticles as contrast agents in confocal laser scanning microscopy

NASA Astrophysics Data System (ADS)

Lemelle, A.; Veksler, B.; Kozhevnikov, I. S.; Akchurin, G. G.; Piletsky, S. A.; Meglinski, I.

2009-01-01

Confocal laser scanning microscopy (CLSM) is a modern high-resolution optical technique providing detailed image of tissue structure with high (down to microns) spatial resolution. Aiming at a concurrent improvement of imaging depth and image quality the CLSM requires the use of contrast agents. Commonly employed fluorescent contrast agents, such as fluorescent dyes and proteins, suffer from toxicity, photo-bleaching and overlapping with the tissues autofluorescence. Gold nanoparticles are potentially highly attractive to be applied as a contrast agent since they are not subject to photo-bleaching and can target biochemical cells markers associated with the specific diseases. In current report we consider the applicability of gold nano-spheres as a contrast agent to enhance quality of CLSM images of skin tissues in vitro versus the application of optical clearing agent, such as glycerol. The enhancement of CLSM image contrast was observed with an application of gold nano-spheres diffused within the skin tissues. We show that optical clearing agents such as a glycerol provide better CLSM image contrast than gold nano-spheres.

Visual abnormalities associated with enhanced optic nerve myelination.

PubMed

Yu, Minzhong; Narayanan, S Priyadarshini; Wang, Feng; Morse, Emily; Macklin, Wendy B; Peachey, Neal S

2011-02-16

Expression of the constitutively active serine/threonine kinase Akt in oligodendrocytes results in enhanced myelination in the CNS. Here, we have examined the effects of this Akt overexpression on optic nerve structure and on optic nerve function, assessed using the visual evoked potential (VEP). Transgenic mice have been generated with the Plp promoter driving expression of a modified form of Akt, in which aspartic acids are substituted for Thr308 and Ser473. These Plp-Akt-DD (Akt-DD) mice, and littermate controls, were studied at different ages. Optic nerves were examined anatomically at 2 and 6 months of age. At 2 months of age, optic nerves were substantially thicker in Akt-DD mice, reflecting an increase in myelination of optic nerve axons. By electron microscopy, myelin thickness was increased in Akt-DD optic nerve, with extended paranodal domains having excess paranodal loops, and the density of nodes of Ranvier was reduced, relative to control mice. We recorded VEPs in response to strobe flash ganzfeld stimuli presented after overnight dark- and light-adapted conditions at ages ranging from 1 to 10 months. It was possible to record a clear VEP from Akt-DD mice at all ages examined. At 1 month of age, VEP implicit times were somewhat shorter in Akt-DD transgenic mice than in control animals. Beyond 6months of age, VEP latencies were consistently delayed in Akt-DD transgenic mice. These abnormalities did not reflect an alteration in retinal function as there were no significant differences between ERGs obtained from control or Akt-DD transgenic mice. In young mice, the somewhat faster responses may reflect improved transmission due to increased myelination of optic nerve axons. In older mice, where the Akt-DD optic nerve is markedly thicker than control, it is remarkable that optic nerves continue to function. Copyright © 2010 Elsevier B.V. All rights reserved.

On the sensitivity of 4 different CPV module technologies to relevant ambient and operation conditions

NASA Astrophysics Data System (ADS)

Domínguez, César; Besson, Pierre

2014-09-01

The sensitivity of four different CPV module technologies to most operating conditions relevant to CPV systems has been studied, namely DNI, spectrum, cell and lens temperature and clearness of the sky. In order to isolate the influence of a single operation parameter, the analysis of long-term outdoor monitoring data is required. The effect of lens temperature on cell current has been found to vary greatly between modules due to the different optical architectures studied. Maximum sensitivity is found for silicone-on-glass primary lenses. The VOC thermal coefficient was found to vary between module technologies, probably due to differences in maximum local effective concentration.

Craters and nanostructures on BaF2 sample induced by a focused 46.9nm laser

NASA Astrophysics Data System (ADS)

Cui, Huaiyu; Zhang, Shuqing; Li, Jingjun; Lu, Haiqiang; Zhao, Yongpeng

2017-08-01

We successfully damaged BaF2 samples by a 46.9nm capillary discharge laser of 100μJ focused by a toroidal mirror at a grazing incidence. Ablation craters with clear boundaries were detected by optical microscope and atomic force microscope (AFM). Laser-induced nanostructures with a period of ˜1μm were observed in the ablation area under single pulse irradiation and multiple pulses irradiation. The surface behavior was compared and analyzed with that induced by the laser of 50μJ. The nanostructures were supposed to be attributed to the thermoelastic effect and the period of the structures was effected by the energy of the laser.

Temporal variations in optical and microphysical properties of mineral dust and biomass burning aerosol derived from daytime Raman lidar observations over Warsaw, Poland

NASA Astrophysics Data System (ADS)

Janicka, Lucja; Stachlewska, Iwona S.; Veselovskii, Igor; Baars, Holger

2017-11-01

In July 2013, favorable weather conditions caused a severe events of advection of biomass burning particles of Canadian forest fires to Europe. The smoke layers were widely observed, especially in Western Europe. An unusual atmospheric aerosol composition was measured at the EARLINET site in Warsaw, Central Poland, during a short event that occurred between 11 and 21 UTC on 10th July 2013. Additionally to the smoke layer, mineral dust was detected in a separate layer. The long-range dust transport pathway followed an uncommon way; originating in Western Sahara, passing above middle Atlantic, and circulating over British Islands, prior to its arrival to Poland. An effective radius of 560 nm was obtained for Saharan dust over Warsaw. This relatively small effective radius is likely due to the long time of the transport. The aerosol-polarization-Raman PollyXT-UW lidar was used for a successful daytime Raman retrieval of the aerosol optical properties at selected times during this short event. The aerosol vertical structure during the inflow over Warsaw in terms of optical properties and depolarization was analyzed, indicating clear distinction of the layers. The microphysical properties were inverted from the lidar derived optical data for selected ranges as representing the smoke and the mineral dust. For smoke, the effective radius was in the range of 0.29-0.36 μm and the complex refractive index 1.36 + 0.008i, on average. For dust, the values of 0.33-0.56 μm and 1.56 + 0.004i were obtained. An evolution of the aerosol composition over Warsaw during the day was analyzed.

Critical issues encountered in experiments and measurements involving optical turbulence

NASA Astrophysics Data System (ADS)

Eaton, Frank D.

2007-02-01

The successful design and operation of high energy laser (HEL) and laser communication systems require a comprehensive and thorough knowledge of the real turbulent atmosphere coupled with high-fidelity realistic laser beam propagation models. To date, modeling and simulation of laser beam propagation through atmospheric turbulence have relied upon a traditional theoretical basis that assumes the existence of homogeneous, isotropic, stationary, and Kolmogorov turbulence. The real impact of the refractive index structure parameter ( C2 n ) on laser beam propagation including effects of non-classical turbulence as well as inner (l °) and outer scale (L °) effects will be examined. Observations clearly show turbulence is often layered and is produced by wave activity and episodic events such as Kelvin-Helmholtz instabilities. Other critical turbulence issues involve the relationship between mechanical and optical turbulence and the effect of path variability of turbulence and inner scale on optical turbulence parameters over long paths. These issues will be examined from data obtained from five systems: a) a new measurement platform using a free-flying balloon that lifts a ring with a boom upon which are mounted several fine wire (1-μm diameter) sensors to measure high-speed temperature and velocity fluctuations, b) a new system using a kite/tethered blimp platform that obtains both profile and measurements at a fixed altitude over time, c) a 50 MHz radar at Vandenberg Air Force Base that senses at high temporal and spatial resolution to 20 km ASL, d) an instrumented aircraft system, and e) a suite of optical systems. The first four systems all provide estimates of C2 n , the eddy dissipation rate (\\Vegr), l ° and L °. Methods of calibration and problems of interpreting results from the measurement systems are discussed.

Secondary optics for Fresnel lens solar concentrators

NASA Astrophysics Data System (ADS)

Fu, Ling; Leutz, Ralf; Annen, Hans Philipp

2010-08-01

Secondary optics are used in concentrating photovoltaic (CPV) systems with Fresnel lens primaries to increase the optical system efficiency by catching refracted light that otherwise would miss the receiver, better the tracking tolerance (acceptance half-angle) and enhance the flux uniformity on the cell. Several refractive secondary optics under the same Fresnel lens primary are designed, analyzed and compared based on their optical performances, materials, manufacturability, manufacturing tolerancing and cost. The goal of this work is to show the basic two different design approaches statistical mixing as opposed to deterministic mixing. Caustics are elementary in the deterministic tailoring approach. We find that statistical mixing offers higher flexibility for the solar application. It is also shown that there are conventional, i.e. designs based on conic section ("half-egg") that work well as solar secondaries. It is also made clear that primary and secondary must be designed as optical train.

Transition from an optical precursor in coupled-resonator-induced transparency to coherent energy exchange in Autler-Townes splitting

NASA Astrophysics Data System (ADS)

Oishi, Tohru; Suzuki, Ryuta; Talukder, Aminul I.; Tomita, Makoto

2013-08-01

We investigated the transient responses of coupled optical resonators, after they were injected with square modulated temporal pulses. A sharp spike, attributed to the optical precursor in coupled-resonator-induced transparency, appeared when the coupling between the resonators was weak. As the coupling strength increased, the resonance spectrum developed clearly separated double dips of Autler-Townes splitting, and the precursor spike transformed into an oscillatory structure. These temporal oscillations were attributed to the coherent energy exchange between two resonators. Theoretical calculations were in good agreement with the experimental observations.

Time-domain diffuse optical tomography using silicon photomultipliers: feasibility study.

PubMed

Di Sieno, Laura; Zouaoui, Judy; Hervé, Lionel; Pifferi, Antonio; Farina, Andrea; Martinenghi, Edoardo; Derouard, Jacques; Dinten, Jean-Marc; Mora, Alberto Dalla

2016-11-01

Silicon photomultipliers (SiPMs) have been very recently introduced as the most promising detectors in the field of diffuse optics, in particular due to the inherent low cost and large active area. We also demonstrate the suitability of SiPMs for time-domain diffuse optical tomography (DOT). The study is based on both simulations and experimental measurements. Results clearly show excellent performances in terms of spatial localization of an absorbing perturbation, thus opening the way to the use of SiPMs for DOT, with the possibility to conceive a new generation of low-cost and reliable multichannel tomographic systems.

Delivery and reveal of localization of upconversion luminescent microparticles and quantum dots in the skin in vivo by fractional laser microablation, multimodal imaging, and optical clearing.

PubMed

Volkova, Elena K; Yanina, Irina Yu; Genina, Elina A; Bashkatov, Alexey N; Konyukhova, Julia G; Popov, Alexey P; Speranskaya, Elena S; Bucharskaya, Alla B; Navolokin, Nikita A; Goryacheva, Irina Yu; Kochubey, Vyacheslav I; Sukhorukov, Gleb B; Meglinski, Igor V; Tuchin, Valery V

2018-02-01

Delivery and spatial localization of upconversion luminescent microparticles [Y2O3:Yb, Er] (mean size ∼1.6  μm) and quantum dots (QDs) (CuInS2/ZnS nanoparticles coated with polyethylene glycol-based amphiphilic polymer, mean size ∼20  nm) inside rat skin was studied in vivo using a multimodal optical imaging approach. The particles were embedded into the skin dermis to the depth from 300 to 500  μm through microchannels performed by fractional laser microablation. Low-frequency ultrasound was applied to enhance penetration of the particles into the skin. Visualization of the particles was revealed using a combination of luminescent spectroscopy, optical coherence tomography, confocal microscopy, and histochemical analysis. Optical clearing was used to enhance the image contrast of the luminescent signal from the particles. It was demonstrated that the penetration depth of particles depends on their size, resulting in a different detection time interval (days) of the luminescent signal from microparticles and QDs inside the rat skin in vivo. We show that luminescent signal from the upconversion microparticles and QDs was detected after the particle delivery into the rat skin in vivo during eighth and fourth days, respectively. We hypothesize that the upconversion microparticles have created a long-time depot localized in the laser-created channels, as the QDs spread over the surrounding tissues. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Ferric oxide quantum dots in stable phosphate glass system and their magneto-optical study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garaje, Sunil N.; Apte, Sanjay K.; Kumar, Ganpathy

2013-02-15

Graphical abstract: We report synthesis of ferric oxide embedded low melting phosphate glass nanocomposite and also the effect of ferric oxide nanoparticles (NCs) content on the optical and magneto-optical properties of the glasses. Faraday rotation of the glass nanocomposites was measured and showed variation in Verdet constant with concentration of ferric oxide. Interestingly, the host glass itself showed fairly good Verdet constant (11.5°/T cm) and there is a threefold enhancement in the Verdet constant of ferric oxide quantum dot-glass nanocomposite. Highlights: ► We synthesize ferric oxide embedded low melting stable phosphate glass nanocomposite. ► Glasses doped with 0.25 and 2%more » ferric oxide show particle size in the range of 4–12 nm. ► The host phosphate glass itself shows fairly good Verdet constant (11.5°/T cm). ► Glasses doped with 0.25% ferric oxide show high Verdet constant (30.525°/T cm). ► The as synthesis glasses may have potential application in magneto optical devices. -- Abstract: Herein, we report the synthesis of ferric oxide embedded low melting phosphate glass nanocomposite and also the effect of ferric oxide nanoparticles content on the optical and magneto-optical properties of the glasses. The optical study clearly showed red shift in optical cut off with increasing ferric oxide concentration. The band gap of the host glass was observed to be 3.48 eV and it shifted to 3.14 eV after doping with ferric oxide. The glasses doped with 0.25 and 2% ferric oxide showed particle size of 4–6 nm and 8–12 nm, respectively. Faraday rotation of the glass nanocomposites was measured and showed variation in the Verdet constant as per increasing concentration of ferric oxide. Interestingly, the host glass itself showed fairly good Verdet constant (11.5°/T cm) and threefold enhancement was observed in the Verdet constant of ferric oxide quantum dot-glass nanocomposite.« less

A long term study of the relations between erythemal UV-B irradiance, total ozone column, and aerosol optical depth at central Argentina

NASA Astrophysics Data System (ADS)

Palancar, Gustavo G.; Olcese, Luis E.; Achad, Mariana; López, María Laura; Toselli, Beatriz M.

2017-09-01

Global ultraviolet-B irradiance (UV-B, 280-315 nm) measurements made at the campus of the University of Córdoba, Argentina were analyzed to quantify the effects of ozone and aerosols on surface UV-B erythemal irradiance (UVER). The measurements have been carried out with a YES Pyranometer during the period 2000-2013. The effect of ozone and aerosols has been quantified by means of the Radiation Amplification Factor (RAF) and by an aerosol factor (AF, analogous to RAF), respectively. The overall mean RAF under cloudless conditions was (1.2 ± 0.3) %, ranging from 0.67 to 2.10% depending on solar zenith angle (SZA) and on Aerosol Optical Depth (AOD). The RAF increased with the SZA with a clear trend. Similarly, the aerosol effect under almost-constant ozone and SZA showed that, on average, a 1% increase in AOD forced a decrease of (0.15 ± 0.04) % in the UVER, with a range of 0.06 to 0.27 and no defined trend as a function of the SZA. To analyze the effect of absorbing aerosols, an effective single scattering albedo (SSA) was determined by comparing the experimental UVER with calculations carried out with the TUV radiative transfer model.

Optical Communications from Planetary Distances

NASA Technical Reports Server (NTRS)

Davarian, F.; Farr, W.; Hemmati, H.; Piazzolla, S.

2008-01-01

Future planetary campaigns, including human missions, will require data rates difficult to realize by microwave links. Optical channels not only provide an abundance of bandwidth, they also allow for significant size, weight, and power reduction. Moreover, optical-based tracking may enhance spacecraft navigation with respect to microwave-based tracking. With all its advantages, optical communications from deep space is not without its challenges. Due to the extreme distance between the two ends of the link, specialized technologies are needed to enable communications in the deep space environment. Although some of the relevant technologies have been developed in the last decade, they remain to be validated in an appropriate domain. The required assets include efficient pulsed laser sources, modulators, transmitters, receivers, detectors, channel encoders, precise beam pointing technologies for the flight transceiver and large apertures for the ground receiver. Clearly, space qualification is required for the systems that are installed on a deep space probe. Another challenge is atmospheric effects on the optical beam. Typical candidate locations on the ground have a cloud-free line of sight only on the order of 60-70% of the time. Furthermore, atmospheric losses and background light can be problematic even during cloud-free periods. Lastly, operational methodologies are needed for efficient and cost effective management of optical links. For more than a decade, the National Aeronautics and Space Administration (NASA) has invested in relevant technologies and procedures to enable deep space optical communications capable of providing robust links with rates in the order of 1 Gb/s from Mars distance. A recent publication indicates that potential exists for 30-dB improvement in performance through technology development with respect to the state-of-the-art in the early years of this decade. The goal is to fulfill the deep space community needs from about 2020 to the foreseeable future. It is envisioned that, at least initially, optical links will be complemented by microwave assets for added robustness, especially for human missions. However, it is expected that as optical techniques mature, laser communications may be operated without conventional radio frequency links. The purpose of this paper is to briefly review the state-of-the-art in deep space laser communications and its challenges and discuss NASA-supported technology development efforts and plans for deep space optical communications at JPL.

Twilight and Daytime Colors of the Clear Sky

DTIC Science & Technology

1994-07-20

greatly, with some surprising consequences for their calorimetric gamuts . Key words: Atmospheric optics, clear-sky chromaticities, blue sky, twilight...First we calculate a chromaticity curve’s unnormal- ized clorimetric gamut g by finding the curve’s average chromaticity [here, its mean CIE (Commis...calorimetric gamut , g. Taking the spectrum locus as an upper limit on color gamut , we use its gamut to normalize any other chromaticity 20 July 1994 / Vol

Safety shield for vacuum/pressure-chamber windows

NASA Technical Reports Server (NTRS)

Shimansky, R. A.; Spencer, R.

1980-01-01

Optically-clear shatter-resistant safety shield protects workers from implosion and explosion of vacuum and pressure windows. Plastic shield is inexpensive and may be added to vacuum chambers, pressure chambers, and gas-filling systems.

Calibrated intercepts for solar radiometers used in remote sensor calibration

NASA Technical Reports Server (NTRS)

Gellman, David I.; Biggar, Stuart F.; Slater, Philip N.; Bruegge, Carol J.

1991-01-01

Calibrated solar radiometer intercepts allow spectral optical depths to be determined for days with intermittently clear skies. This is of particular importance on satellite sensor calibration days that are cloudy except at the time of image acquisition. This paper describes the calibration of four solar radiometers using the Langley-Bouguer technique for data collected on days with a clear, stable atmosphere. Intercepts are determined with an uncertainty of less than six percent, corresponding to a maximum uncertainty of 0.06 in optical depth. The spread of voltage intercepts calculated in this process is carried through three methods of radiometric calibration of satellite sensors to yield an uncertainty in radiance at the top of the atmosphere of less than one percent associated with the uncertainty in solar radiometer intercepts for a range of ground reflectances.

Optical spectroscopy and ultrafast pump-probe studies on the heavy-fermion compound CePt 2 In 7

DOE PAGES

Chen, R. Y.; Zhang, S. J.; Bauer, E. D.; ...

2016-07-29

We report optical spectroscopy and ultrafast pump-probe measurements on the antiferromagnetic heavy-fermion compound CePt 2 In 7 , a member showing stronger two dimensionality than other compounds in the CeIn 3 -derived heavy-fermion family. Here, we identify clear and typical hybridization spectral structures at low temperature from the two different spectroscopy probes. But, the strength and related energy scale of the hybridization are much weaker and smaller than that in the superconducting compounds CeCoIn 5 and CeIrIn 5 . The features are more similar to observations on the antiferromagnetic compounds CeIn 3 and CeRhIn 5 in the same family. Ourmore » results clearly indicate that the Kondo interaction and hybridizations exist in the antiferromagnetic compounds but with weaker strength.« less

Population transfer and rapid passage effects in a low pressure gas using a continuous wave quantum cascade laser.

PubMed

McCormack, E A; Lowth, H S; Bell, M T; Weidmann, D; Ritchie, G A D

2012-07-21

A continuous wave quantum cascade laser (cw-QCL) operating at 10 μm has been used to record absorption spectra of low pressure samples of OCS in an astigmatic Herriott cell. As a result of the frequency chirp of the laser, the spectra show clearly the effects of rapid passage on the absorption line shape. At the low chirp rates that can be obtained with the cw-QCL, population transfer between rovibrational quantum states is predicted to be much more efficient than in typical pulsed QCL experiments. This optical pumping is investigated by solving the Maxwell Bloch equations to simulate the propagation of the laser radiation through an inhomogeneously broadened two-level system. The calculated absorption profiles show good quantitative agreement with those measured experimentally over a range of chirp rates and optical thicknesses. It is predicted that at a low chirp rate of 0.13 MHz ns(-1), the population transfer between rovibrational quantum states is 12%, considerably more than that obtained at the higher chirp rates utilised in pulsed QCL experiments.

Aerosol Direct Radiative Effect at the Top of the Atmosphere Over Cloud Free Ocean Derived from Four Years of MODIS Data

NASA Technical Reports Server (NTRS)

Remer, L. A.; Kaufman, Y. J.

2006-01-01

A four year record of MODIS spaceborne data provides a new measurement tool to assess the aerosol direct radiative effect at the top of the atmosphere. MODIS derives the aerosol optical thickness and microphysical properties from the scattered sunlight at 0.55-2.1 microns. The monthly MODIS data used here are accumulated measurements across a wide range of view and scattering angles and represent the aerosol s spectrally resolved angular properties. We use these data consistently to compute with estimated accuracy of +/-0.6W/sq m the reflected sunlight by the aerosol over global oceans in cloud free conditions. The MODIS high spatial resolution (0.5 km) allows observation of the aerosol impact between clouds that can be missed by other sensors with larger footprints. We found that over the clear-sky global ocean the aerosol reflected 5.3+/-0.6W/sq m with an average radiative efficiency of 49+/-2W/sq m per unit optical thickness. The seasonal and regional distribution of the aerosol radiative effects are discussed. The analysis adds a new measurement perspective to a climate change problem dominated so far by models.

The Distance to the Coma Cluster from the Tully--Fisher Relation

NASA Astrophysics Data System (ADS)

Herter, T.; Vogt, N. P.; Haynes, M. P.; Giovanelli, R.

1993-12-01

As part of a survey to determine the distances to nearby (z < .04) Abell clusters via application of the Tully--Fisher (TF) relation, we have obtained 21 cm HI line widths, optical rotation curves and photometric I--band CCD images of galaxies within and near the Coma cluster. Because spiral galaxies within the cluster itself are HI deficient and thus are detected marginally or not at all in HI, distance determinations using only the radio TF relation exclude true cluster members. Our sample includes eight HI deficient galaxies within 1.5 degrees of the cluster center, for which optical velocity widths are derived from their Hα and [NII] rotation curves. The 21 cm line widths have been extracted using a new algorithm designed to optimize the measurement for TF applications, taking into account the effects of spectral resolution and smoothing. The optical width is constructed from the velocity histogram, and is therefore a global value akin to the HI width. A correction for turbulent broadening of the HI is derived from comparison of the optical and HI widths. Using a combined sample of 260 galaxies in 11 clusters and an additional 30 field objects at comparable distances, we have performed a calibration of the radio and optical analogs of the TF relation. Preliminary results show a clear linear relationship with a small offset between optical and radio widths, and good agreement in deriving Tully--Fisher distances to clusters. Our Coma sample consists of 28 galaxies with optical widths and 42 with HI line widths, with an overlapping set of 20 galaxies. We will present the data on the Coma cluster, and discuss the results of our analysis.

Airborne Lidar Detection and Characterization of Internal Waves in a Shallow Fjord

DTIC Science & Technology

2012-01-01

Graduate Center studying the statistics of optical propagation through refractive turbulence in the clear atmosphere . He then became a member of...instrumentation comprised a Seabird conductivity, temperature, depth (CTD) profiler with a Wetlabs AC-9 to measure the optical absorption and beam ...the depolarization of an initially polarized beam will be D, .=■ 2-d \\-d (10) where D is the ratio of the backscattering perpendicular to the

A filter-wheel solar radiometer for atmospheric transmission studies

NASA Technical Reports Server (NTRS)

Shaw, G. E.; Peck, R. L.; Allen, G. R.

1973-01-01

A filter-wheel solar radiometer has been developed for monitoring the atmospheric optical depth at multiple narrow-wavelength intervals in the visible and near IR regions of the spectrum. Measurements of the direct solar radiations are converted to a digital format and stored in punched tape for eventual analysis by a computer. During stable clear weather condition, the instrument is capable of providing monochromatic optical depths to an estimated rms accuracy of 0.005.

Assessment of the clear-sky bias issue using continuous PM10 data from two AERONET sites in Korea.

PubMed

Choi, Yongjoo; Ghim, Young Sung

2017-03-01

A bias in clear-sky conditions that will be involved in estimating particulate matter (PM) concentration from aerosol optical depth (AOD) was examined using PM 10 from two Aerosol Robotic Network sites in Korea. The study periods were between 2004 and 2007 at Anmyon and between 2003 and 2011 at Gosan, when both PM 10 and AOD were available. Mean PM 10 when AOD was available (PM AOD ) was higher than that from all PM 10 data (PM all ) by 5.1 and 9.9μg/m 3 at Anmyon and Gosan, which accounted for 11% and 26% of PM all , respectively. Because of a difference between mean PM 10 under daytime clear-sky conditions (PM clear ) and PM AOD , the variations in ΔPM 10 , the difference of PM all from PM clear rather than from PM AOD , were investigated. Although monthly variations in ΔPM 10 at the two sites were different, they were positively correlated to those in ΔT, similarly defined as ΔPM 10 except for temperature, at both sites. ΔPM 10 at Anmyon decreased to a negative value in January due to an influence of the Siberian continental high-pressure system while ΔPM 10 at Gosan was high in winter due to an effect of photochemical production at higher temperatures than at Anmyon. Copyright © 2016. Published by Elsevier B.V.

Photorefractive keratectomy in the cat eye: biological and optical outcomes

PubMed Central

Nagy, Lana J.; MacRae, Scott; Yoon, Geunyoung; Wyble, Matthew; Wang, Jianhua; Cox, Ian; Huxlin, Krystel R.

2007-01-01

PURPOSE To quantify optical and biomechanical properties of the feline cornea before and after photorefractive keratectomy (PRK) and assess the relative contribution of different biological factors to refractive outcome. SETTING Dept. Ophthalmology, University of Rochester, Rochester, New York, U.S.A. METHODS Adult cats underwent 6D myopic or 4D hyperopic PRK over 6 or 8mm optical zones (OZ). Pre- and post-operative wavefront aberrations were measured, along with intraocular pressure, corneal hysteresis (CH), corneal resistance factor (CRF), axial length, corneal thickness and radii of curvature. Finally, post-mortem imunohistochemistry for Vimentin and α-smooth muscle actin was performed. RESULTS PRK changed ocular defocus, increased higher order aberrations and induced myofibroblast differentiation in cats. However, the intended defocus corrections were only achieved with 8mm OZs. Long-term flattening of the epithelial and stromal surfaces was noted following myopic, but nor hyperopic PRKs. Feline intraocular pressure was unaltered by PRK, but CH and CRF decreased. Over the ensuing 6 months, ocular aberrations and intraocular pressure remained stable, while central corneal thickness, CH and CRF increased back towards normal levels. CONCLUSIONS Cat corneas exhibited optical, histological and biomechanical reactions to PRK that resembled those previously described in humans, especially when optical zone size was normalized to total corneal area. However, cats exhibited significant stromal regeneration, causing a return to pre-operative corneal thickness, CH and CRF without significant regression of optical changes induced by the surgery. Thus, the principal effects of laser refractive surgery on ocular wavefront aberrations can be achieved in spite of clear, inter-species differences in corneal biology. PMID:17531702

Adaptive optics retinal imaging: emerging clinical applications.

PubMed

Godara, Pooja; Dubis, Adam M; Roorda, Austin; Duncan, Jacque L; Carroll, Joseph

2010-12-01

The human retina is a uniquely accessible tissue. Tools like scanning laser ophthalmoscopy and spectral domain-optical coherence tomography provide clinicians with remarkably clear pictures of the living retina. Although the anterior optics of the eye permit such non-invasive visualization of the retina and associated pathology, the same optics induce significant aberrations that obviate cellular-resolution imaging in most cases. Adaptive optics (AO) imaging systems use active optical elements to compensate for aberrations in the optical path between the object and the camera. When applied to the human eye, AO allows direct visualization of individual rod and cone photoreceptor cells, retinal pigment epithelium cells, and white blood cells. AO imaging has changed the way vision scientists and ophthalmologists see the retina, helping to clarify our understanding of retinal structure, function, and the etiology of various retinal pathologies. Here, we review some of the advances that were made possible with AO imaging of the human retina and discuss applications and future prospects for clinical imaging.

Growth, spectral, linear and nonlinear optical characteristics of an efficient semiorganic acentric crystal: L-valinium L-valine chloride

NASA Astrophysics Data System (ADS)

Nageshwari, M.; Jayaprakash, P.; Kumari, C. Rathika Thaya; Vinitha, G.; Caroline, M. Lydia

2017-04-01

An efficient nonlinear optical semiorganic material L-valinium L-valine chloride (LVVCl) was synthesized and grown-up by means of slow evaporation process. Single crystal XRD evince that LVVCl corresponds to monoclinic system having acentric space group P21. The diverse functional groups existing in LVVCl were discovered with FTIR spectral investigation. The UV-Visible and photoluminescence spectrum discloses the optical and electronic properties respectively for the grown crystal. Several optical properties specifically extinction coefficient, reflectance, linear refractive index, electrical and optical conductivity were also determined. The SEM analysis was also carried out and it portrayed the surface morphology of LVVCl. The calculated value of laser damage threshold was 2.59 GW/cm2. The mechanical and dielectric property of LVVCl was investigated employing microhardness and dielectric studies. The second and third order nonlinear optical characteristics of LVVCl was characterized utilizing Kurtz Perry and Z scan technique respectively clearly suggest its suitability in the domain of optics and photonics.

Reconfigurable WDM-PON empowered by a low-cost 8-channel directly modulated laser module

NASA Astrophysics Data System (ADS)

Zhang, Yi-ming; Liu, Yu; Zhang, Zhi-ke; Zhao, Ze-ping; Tian, Ye; Zhu, Ning-hua

2017-11-01

A 10 Gbit/s 16-km-long reconfigurable wavelength-division-multiplexing passive optical network (WDM-PON) is presented empowered by a low-cost multi-channel directly modulated laser (DML) module. Compared with the case using discrete devices in conventional scheme, the proposed DML module provides a cost-effective solution with reduced complexity. The clear eye diagram and the bit error rate ( BER) of less than 2×10-7 with a sensitivity of -7 dBm are obtained. Due to the special packaging design, the crosstalk between channels under condition of simultaneous operation can be negligible.

InGaAs/InAlAs Double Quantum Wells as Starting Structures for Quantum Logic Gates

NASA Astrophysics Data System (ADS)

Marchewka, M.; Sheregii, E. M.

2011-12-01

The detection of both symmetric and anti-symmetric electron states in DQWs by an optical method is described in this paper. Values of the symmetric and anti-symmetric splitting (SAS-gap) determined in this way are used for interpretation of the beating effect in the SdH oscillations observed at low temperatures in the external magnetic field. SAS-splitting of electron states in DQWs clearly exists at room temperature and electrons in symmetric and anti-symmetric states have different statistics so these states can be identified in electron transport.

Scanning light-sheet microscopy in the whole mouse brain with HiLo background rejection.

PubMed

Mertz, Jerome; Kim, Jinhyun

2010-01-01

It is well known that light-sheet illumination can enable optically sectioned wide-field imaging of macroscopic samples. However, the optical sectioning capacity of a light-sheet macroscope is undermined by sample-induced scattering or aberrations that broaden the thickness of the sheet illumination. We present a technique to enhance the optical sectioning capacity of a scanning light-sheet microscope by out-of-focus background rejection. The technique, called HiLo microscopy, makes use of two images sequentially acquired with uniform and structured sheet illumination. An optically sectioned image is then synthesized by fusing high and low spatial frequency information from both images. The benefits of combining light-sheet macroscopy and HiLo background rejection are demonstrated in optically cleared whole mouse brain samples, using both green fluorescent protein (GFP)-fluorescence and dark-field scattered light contrast.

Scanning light-sheet microscopy in the whole mouse brain with HiLo background rejection

NASA Astrophysics Data System (ADS)

Mertz, Jerome; Kim, Jinhyun

2010-01-01

It is well known that light-sheet illumination can enable optically sectioned wide-field imaging of macroscopic samples. However, the optical sectioning capacity of a light-sheet macroscope is undermined by sample-induced scattering or aberrations that broaden the thickness of the sheet illumination. We present a technique to enhance the optical sectioning capacity of a scanning light-sheet microscope by out-of-focus background rejection. The technique, called HiLo microscopy, makes use of two images sequentially acquired with uniform and structured sheet illumination. An optically sectioned image is then synthesized by fusing high and low spatial frequency information from both images. The benefits of combining light-sheet macroscopy and HiLo background rejection are demonstrated in optically cleared whole mouse brain samples, using both green fluorescent protein (GFP)-fluorescence and dark-field scattered light contrast.

Computer-aided classification of optical images for diagnosis of osteoarthritis in the finger joints.

PubMed

Zhang, Jiang; Wang, James Z; Yuan, Zhen; Sobel, Eric S; Jiang, Huabei

2011-01-01

This study presents a computer-aided classification method to distinguish osteoarthritis finger joints from healthy ones based on the functional images captured by x-ray guided diffuse optical tomography. Three imaging features, joint space width, optical absorption, and scattering coefficients, are employed to train a Least Squares Support Vector Machine (LS-SVM) classifier for osteoarthritis classification. The 10-fold validation results show that all osteoarthritis joints are clearly identified and all healthy joints are ruled out by the LS-SVM classifier. The best sensitivity, specificity, and overall accuracy of the classification by experienced technicians based on manual calculation of optical properties and visual examination of optical images are only 85%, 93%, and 90%, respectively. Therefore, our LS-SVM based computer-aided classification is a considerably improved method for osteoarthritis diagnosis.

Composition for forming an optically transparent, superhydrophobic coating

DOEpatents

Simpson, John T.; Lewis, Linda A.

2015-12-29

A composition for producing an optically clear, well bonded superhydrophobic coating includes a plurality of hydrophobic particles comprising an average particle size of about 200 nm or less, a binder at a binder concentration of from about 0.1 wt. % to about 0.5 wt. %, and a solvent. The hydrophobic particles may be present in the composition at a particle concentration of from about 0.1 wt. % to about 1 wt. %. An optically transparent, superhydrophobic surface includes a substrate, a plurality of hydrophobic particles having an average particle size of about 200 nm or less dispersed over the substrate, and a discontinuous binder layer bonding the hydrophobic particles to the substrate, where the hydrophobic particles and the binder layer form an optically transparent, superhydrophobic coating.