Science.gov

Sample records for illumination

  1. Illuminating Development

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Through the support of the NASA SBIR program, Control Vision, Inc. developed novel video techniques for clear, high resolution, real-time imaging of high temperature, high-energy industrial processes, such as welding, plasma arc spraying (coating), arc furnaces, metal casting and refractories (ceramics) melting. The Control Vision systems use reflected laser or strobe illumination, combined with ultra-short exposure times to create video, including the allowance of particle imaging velocimetry (PIV) of fast moving powder particles buried within a plasma stream.

  2. Hotsphere illumination

    NASA Astrophysics Data System (ADS)

    Razavi, Bahar S.; Hoang, Duyen; Liu, Shibin; Kuzyakov, Yakov

    2017-04-01

    Soils are the most heterogeneous parts of the biosphere, with an extremely high differentiation of properties and processes at all spatial and temporal scales. Importance of hotspheres- environment with abundant high microbial activity- i.e.: rhizosphere, detritusphere, biopores, spermosphere and hyphasphere calls for spatially explicit methods to illuminate distribution of microbial activities (Kuzyakov and Blagodatskaya, 2015). Zymography technique has previously been adapted to visualize the spatial dynamics of enzyme activities in rhizosphere. Here, we further developed soil zymography to obtain a higher resolution of enzyme activities by enabling direct contact of substrate-saturated membranes with soil. For the first time, we aimed at quantitative imaging of enzyme activities in various hotspheres. We calculated and compared percentage of enzymatic hotspots of four hotspheres: Spermosphere, rhizosphere, detritusphere and biopores. Spatial distribution of activities of two enzymes: β-glucosidase and phosphatase were analyzed in the spermosphere and rhizosphere of maize and lentil. Zymography has been done 3 days (spermosphere), 14 days (rhizosphere) after sowing. Further, manure was placed on surface of rhizoboxes to visualize spatio-temporal distribution of the enzyme activities in detritusphere after 25 days. Biopores were produced by earthworms (Lumbricus terrestris L.) in transparent boxes for 2 weeks and enzyme distribution were measured by zymography thereafter. The developed in situ direct soil zymography visualized the heterogeneity of enzyme activities along and across the roots. Spatial patterns of enzyme activities as a function of distance along the root demonstrated plant specific patterns of enzyme distribution: it was uniform and homogenous along the lentil roots, whereas the enzyme activities in maize rhizosphere were higher at the apical or proximal root parts. For the first time were applied "spatial point pattern analysis" to determine

  3. Demand illumination control apparatus

    NASA Technical Reports Server (NTRS)

    Warren, Carl (Inventor); Arline, Jimmie (Inventor); LaPalme, Julius (Inventor)

    1981-01-01

    Solar illuminating compensating apparatus is disclosed whereby the interior of a building is illuminated to a substantially constant, predetermined level of light intensity by a combination of natural illumination from the sun and artificial illumination from electricity wherein the intensity of said artificial illumination is controlled by fully electronic means which increases the level of artificial illumination when the natural illumination is inadequate and vice versa.

  4. Hotsphere illumination

    NASA Astrophysics Data System (ADS)

    Razavi, Bahar S.; Kuzyakov, Yakov

    2016-04-01

    Soils are the most heterogeneous parts of the biosphere, with an extremely high differentiation of properties and processes at all spatial and temporal scales. Importance of the hotspheres such as rhizosphere, detritusphere, porosphere (including drilosphere and biopores), hyphasphere and spermosphere, calls for spatially explicit methods to illuminate distribution of microbial activities in these hotspheres (Kuzyakov and Blagodatskaya, 2015). Zymography technique has previously been adapted to visualize the spatial dynamics of enzyme activities in rhizosphere (Spohn and Kuzyakov, 2014). Here, we further developed soil zymography to obtain a higher resolution of enzyme activities by enabling direct contact of substrate-saturated membranes with soil. For the first time, we aimed at quantitative imaging of enzyme activities in various hotspheres. We calculated and compared percentage of enzymatic hotspots of five hotspheres: spermosphere, rhizosphere, detritusphere, drilosphere and biopores. Spatial distribution of activities of two enzymes: β-glucosidase and leucine amino peptidase were analyzed in the spermosphere, rhizosphere and detritusphere of maize and lentil. Zymography has been done 3 days (spermosphere), 14 days (rhizosphere) after sowing and 21 days after cutting plant (detritusphere). Spatial resolution of fluorescent images was improved by direct application fluorogenically labelled substrates on the soil surface. Such improvement enabled to visualize enzyme distribution of mycorrhiza hypha on the rhizobox surface. Further, to visualize the 2D distribution of the enzyme activities in porosphere, we placed earthworms (Lumbricus terrestris), (drilosphere) and ground beetle species Platynus dorsalis Pont. (Coleoptera; Carabidae), (biopore), in transparent boxes for 2weeks. The developed in situ zymography visualized the heterogeneity of enzyme activities along and across the roots. Spatial patterns of enzyme activities as a function of distance along the

  5. Lunar South Pole Illumination

    NASA Image and Video Library

    Simulated illumination conditions over the lunar South Pole region, from ~80°S to the pole. The movie runs for 28 days, centered on the LCROSS impact date on October 9th, 2009. The illumination ca...

  6. Lights illuminate surfaces superluminally

    NASA Astrophysics Data System (ADS)

    Nemiroff, Robert J.; Zhong, Qi; Lilleskov, Elias

    2016-07-01

    When a light bulb is turned on, light moves away from it at speed c, by definition. When light from this bulb illuminates a surface, however, this illumination front is not constrained to move at speed c. A simple proof is given that this illumination front always moves faster than c. Generalized, when any compact light source itself varies, this information spreads across all of the surfaces it illuminates at speeds faster than light.

  7. Illumination Under Trees

    SciTech Connect

    Max, N

    2002-08-19

    This paper is a survey of the author's work on illumination and shadows under trees, including the effects of sky illumination, sun penumbras, scattering in a misty atmosphere below the trees, and multiple scattering and transmission between leaves. It also describes a hierarchical image-based rendering method for trees.

  8. Midwestern Medieval Illuminations Archives.

    ERIC Educational Resources Information Center

    Purdue Univ., Lafayette, IN. Audio-Visual Center.

    This catalog lists the slides of medieval manuscript illuminations available at the Midwestern Medieval Illuminations Archives at the Purdue University Audio-Visual Center. Instructions are provided for ordering slides from the Center. Slide sets are listed by title, with citations including catalog number, rental price, producer/vendor code,…

  9. Grouping Illumination Frameworks

    ERIC Educational Resources Information Center

    Zdravkovic, Suncica; Economou, Elias; Gilchrist, Alan

    2012-01-01

    According to Koffka (1935), the lightness of a target surface is determined by the relationship between the target and the illumination frame of reference to which it belongs. However, each scene contains numerous illumination frames, and judging each one separately would lead to an enormous amount of computing. Grouping those frames that are in…

  10. Novel ureteroscope illumination designs

    NASA Astrophysics Data System (ADS)

    Wilson, Christopher R.; Peller, Joseph A.; Trammell, Susan R.; Irby, Pierce B.; Fried, Nathaniel M.

    2017-02-01

    Limitations of current ureteroscope illumination configurations include presence of shadows and hot spots in images, further degraded by stone debris during laser lithotripsy, which may result in a decrease in stone ablation efficiency, increase in surgical operation time, and potential collateral tissue trauma. Previous studies have reported accidental ureteral tissue perforation from Nitinol stone basket wires during Holmium laser lithotripsy, due in part to poor visibility. Although saline irrigation is routinely used during ureteroscopy to flush stone debris and improve visibility, sub-optimal illumination may still compound these problems. Current illumination geometries and sources are inadequate to produce necessary uniform illumination for optimal visibility and safety during ureteroscopy. By moving away from single and double point source geometry and towards a ring configuration, illumination becomes more uniform in both axes, reducing shadows and increasing depth discernibility. Uric acid and calcium oxalate based stones were chosen for illumination and reflection spectroscopy. Porcine ureters were used as soft tissue samples for comparison. The percent difference in reflection between ureter and stones was greater than 40% for the wavelength ranges of 470-540 nm, and 600-700 nm, making these spectral regions most suitable for high contrast illumination, possibly through narrow band imaging techniques via multiple laser sources and/or optical filters. These improved ureteroscope illumination designs and approaches may potentially reduce complications due to limited visibility during laser lithotripsy and hence increase patient safety.

  11. Shackleton Crater Illumination

    NASA Image and Video Library

    Simulated illumination conditions near the lunar South Pole. The 30km x 30km region highlights the Shackleton crater. The movie runs for 28 days, centered on the LCROSS impact date on October 9th, ...

  12. Illuminating black holes

    NASA Astrophysics Data System (ADS)

    Barr, Ian A.; Bull, Anne; O'Brien, Eileen; Drillsma-Milgrom, Katy A.; Milgrom, Lionel R.

    2016-07-01

    Two-dimensional shadows formed by illuminating vortices are shown to be visually analogous to the gravitational action of black holes on light and surrounding matter. They could be useful teaching aids demonstrating some of the consequences of general relativity.

  13. Lightness, illumination, and gradients.

    PubMed

    Todorović, Dejan

    2006-01-01

    The illumination interpretation approach claims that lightness illusions can be explained as misapplications of lightness constancy mechanisms, processes which usually enable veridical extraction of surface reflectance from luminance distributions by discounting illumination. In particular, luminance gradients are thought to provide cues about the interactions of light and surfaces. Several examples of strong lightness illusions are discussed for which explanations based on illumination interpretation can be proposed. In criticisms of this approach, a variety of demonstrations of similarly structured control displays are presented, which involve equivalent lightness effects that cannot readily be accounted for by illumination interpretation mechanisms. Furthermore, a number of known and novel displays are presented that demonstrate effects of gradients on the qualitative appearance of uniform regions. Finally, some simple simulations of neural effects of luminance distributions are discussed.

  14. Wood's lamp illumination (image)

    MedlinePlus

    A Wood's lamp emits ultraviolet light and can be a diagnostic aid in determining if someone has a fungal ... is an infection on the area where the Wood's lamp is illuminating, the area will fluoresce. Normally ...

  15. Illumination in diverse codimensions

    NASA Technical Reports Server (NTRS)

    Banks, David C.

    1994-01-01

    This paper derives a model of diffuse and specular illumination in arbitrarily large dimensions, based on a few characteristics of material and light in three-space. It then describes how to adjust for the anomaly of excess brightness in large codimensions. If a surface is grooved or furry, it can be illuminated with a hybrid model that incorporates both the one dimensional geometry (the grooves or fur) and the two dimensional geometry (the surface).

  16. Natural light illumination system.

    PubMed

    Whang, Allen Jong-Woei; Chen, Yi-Yung; Yang, Shu-Hua; Pan, Po-Hsuan; Chou, Kao-Hsu; Lee, Yu-Chi; Lee, Zong-Yi; Chen, Chi-An; Chen, Cheng-Nan

    2010-12-10

    In recent years, green energy has undergone a lot of development and has been the subject of many applications. Many research studies have focused on illumination with sunlight as a means of saving energy and creating healthy lighting. Natural light illumination systems have collecting, transmitting, and lighting elements. Today, most daylight collectors use dynamic concentrators; these include Sun tracking systems. However, this design is too expensive to be cost effective. To create a low-cost collector that can be easily installed on a large building, we have designed a static concentrator, which is prismatic and cascadable, to collect sunlight for indoor illumination. The transmission component uses a large number of optical fibers. Because optical fibers are expensive, this means that most of the cost for the system will be related to transmission. In this paper, we also use a prismatic structure to design an optical coupler for coupling n to 1. With the n-to-1 coupler, the number of optical fibers necessary can be greatly reduced. Although this new natural light illumination system can effectively guide collected sunlight and send it to the basement or to other indoor places for healthy lighting, previously there has been no way to manage the collected sunlight when lighting was not desired. To solve this problem, we have designed an optical switch and a beam splitter to control and separate the transmitted light. When replacing traditional sources, the lighting should have similar characteristics, such as intensity distribution and geometric parameters, to those of traditional artificial sources. We have designed, simulated, and optimized an illumination lightpipe with a dot pattern to redistribute the collected sunlight from the natural light illumination system such that it equals the qualities of a traditional lighting system. We also provide an active lighting module that provides lighting from the natural light illumination system or LED auxiliary

  17. Bright field illumination system

    NASA Technical Reports Server (NTRS)

    Huber, Edward D. (Inventor)

    1998-01-01

    A Bright Field Illumination system for inspecting a range of characteristically different kinds of defects, depressions, and ridges in a selected material surface. The system has an illumination source placed near a first focus of an elliptical reflector. In addition, a camera facing the inspected area is placed near the illumination source and the first focus. The second focus of the elliptical reflector is located at a distance approximately twice the elliptical reflector's distance above the inspected surface. The elliptical reflector directs the light from the source onto the inspected surface. Due to the shape of the elliptical reflector, light that is specularly reflected from the inspected surface is directed into the camera is which located at the position of the reflected second focus of the ellipse. This system creates a brightly lighted background field against which damage sites appear as high contrast dark objects which can be easily detected by a person or an automated inspection system. In addition, the Bright Field Illumination system and method can be used in combination with a vision inspection system providing for multiplexed illumination and data handling of multiple kinds of surface characteristics including abrupt and gradual surface variations and differences between measured characteristics of different kinds and prior instruments.

  18. OLED area illumination source

    SciTech Connect

    Foust, Donald Franklin; Duggal, Anil Raj; Shiang, Joseph John; Nealon, William Francis; Bortscheller, Jacob Charles

    2008-03-25

    The present invention relates to an area illumination light source comprising a plurality of individual OLED panels. The individual OLED panels are configured in a physically modular fashion. Each OLED panel comprising a plurality of OLED devices. Each OLED panel comprises a first electrode and a second electrode such that the power being supplied to each individual OLED panel may be varied independently. A power supply unit capable of delivering varying levels of voltage simultaneously to the first and second electrodes of each of the individual OLED panels is also provided. The area illumination light source also comprises a mount within which the OLED panels are arrayed.

  19. Nonimaging optical illumination system

    DOEpatents

    Winston, R.; Ries, H.

    1996-12-17

    A nonimaging illumination optical device for producing a selected far field illuminance over an angular range. The optical device includes a light source, a light reflecting surface, and a family of light edge rays defined along a reference line with the reflecting surface defined in terms of the reference line as a parametric function R(t) where t is a scalar parameter position and R(t)=k(t)+Du(t) where k(t) is a parameterization of the reference line, and D is a distance from a point on the reference line to the reflection surface along the desired edge ray through the point. 35 figs.

  20. Nonimaging optical illumination system

    DOEpatents

    Winston, R.; Ries, H.

    1998-10-06

    A nonimaging illumination optical device for producing a selected far field illuminance over an angular range. The optical device includes a light source a light reflecting surface, and a family of light edge rays defined along a reference line with the reflecting surface defined in terms of the reference lines a parametric function R(t) where t is a scalar parameter position and R(t)=k(t)+Du(t) where k(t) is a parameterization of the reference line, and D is a distance from a point on the reference line to the reflection surface along the desired edge ray through the point. 35 figs.

  1. Nonimaging optical illumination system

    SciTech Connect

    Winston, R.; Ries, H.

    2000-02-01

    A nonimaging illumination optical device for producing a selected far field illuminance over an angular range. The optical device includes a light source, a light reflecting surface, and a family of light edge rays defined along a reference line with the reflecting surface defined in terms of the reference line 104 as a parametric function R(t) where t is a scalar parameter position and R(t) = k(t) + Du(t) where k(t) is a parameterization of the reference line 104, and D is a distance from a point on the reference line 104 to the reflection surface 108 along the desired edge ray through the point.

  2. Predicting Ground Illuminance

    NASA Astrophysics Data System (ADS)

    Lesniak, Michael V.; Tregoning, Brett D.; Hitchens, Alexandra E.

    2015-01-01

    Our Sun outputs 3.85 x 1026 W of radiation, of which roughly 37% is in the visible band. It is directly responsible for nearly all natural illuminance experienced on Earth's surface, either in the form of direct/refracted sunlight or in reflected light bouncing off the surfaces and/or atmospheres of our Moon and the visible planets. Ground illuminance, defined as the amount of visible light intercepting a unit area of surface (from all incident angles), varies over 7 orders of magnitude from day to night. It is highly dependent on well-modeled factors such as the relative positions of the Sun, Earth, and Moon. It is also dependent on less predictable factors such as local atmospheric conditions and weather.Several models have been proposed to predict ground illuminance, including Brown (1952) and Shapiro (1982, 1987). The Brown model is a set of empirical data collected from observation points around the world that has been reduced to a smooth fit of illuminance against a single variable, solar altitude. It provides limited applicability to the Moon and for cloudy conditions via multiplicative reduction factors. The Shapiro model is a theoretical model that treats the atmosphere as a three layer system of light reflectance and transmittance. It has different sets of reflectance and transmittance coefficients for various cloud types.In this paper we compare the models' predictions to ground illuminance data from an observing run at the White Sands missile range (data was obtained from the United Kingdom's Meteorology Office). Continuous illuminance readings were recorded under various cloud conditions, during both daytime and nighttime hours. We find that under clear skies, the Shapiro model tends to better fit the observations during daytime hours with typical discrepancies under 10%. Under cloudy skies, both models tend to poorly predict ground illuminance. However, the Shapiro model, with typical average daytime discrepancies of 25% or less in many cases

  3. Predicting Ground Illuminance

    NASA Astrophysics Data System (ADS)

    Lesniak, Michael V.

    2014-01-01

    Our Sun outputs 3.85 × 1026 W of radiation, of which ≈37% is in the visible band. It is directly responsible for nearly all natural illuminance experienced on Earth's surface, either in the form of direct/refracted sunlight or in reflected light bouncing off the surfaces and/or atmospheres of our Moon and the visible planets. Ground illuminance, defined as the amount of visible light intercepting a unit area of surface (from all incident angles), varies over 7 orders of magnitude from day to night. It is highly dependent on well-modeled factors such as the relative positions of the Sun, Earth, and Moon. It is also dependent on less predictable factors such as local atmospheric conditions and weather. Several models have been proposed to predict ground illuminance, including Brown (1952) and Shapiro (1982, 1987). The Brown model is a set of empirical data collected from observation points around the world that has been reduced to a smooth fit of illuminance against a single variable, solar altitude. It provides limited applicability to the Moon and for cloudy conditions via multiplicative reduction factors. The Shapiro model is a theoretical model that treats the atmosphere as a three layer system of light reflectance and transmittance. It has different sets of reflectance and transmittance coefficients for various cloud types. Ground illuminance data from an observing run at the White Sands missile range were obtained from the United Kingdom Meteorology Office. Based on available weather reports, five days of clear sky observations were selected. These data are compared to the predictions of the two models. We find that neither of the models provide an accurate treatment during twilight conditions when the Sun is at or a few degrees below the horizon. When the Sun is above the horizon, the Shapiro model straddles the observed data, ranging between 90% and 120% of the recorded illuminance. During the same times, the Brown model is between 70% and 90% of the

  4. Nonimaging optical illumination system

    DOEpatents

    Winston, Roland; Ries, Harald

    1996-01-01

    A nonimaging illumination optical device for producing a selected far field illuminance over an angular range. The optical device includes a light source 102, a light reflecting surface 108, and a family of light edge rays defined along a reference line 104 with the reflecting surface 108 defined in terms of the reference line 104 as a parametric function R(t) where t is a scalar parameter position and R(t)=k(t)+Du(t) where k(t) is a parameterization of the reference line 104, and D is a distance from a point on the reference line 104 to the reflection surface 108 along the desired edge ray through the point.

  5. Nonimaging optical illumination system

    DOEpatents

    Winston, Roland; Ries, Harald

    1998-01-01

    A nonimaging illumination optical device for producing a selected far field illuminance over an angular range. The optical device includes a light source 102, a light reflecting surface 108, and a family of light edge rays defined along a reference line 104 with the reflecting surface 108 defined in terms of the reference line 104 as a parametric function R(t) where t is a scalar parameter position and R(t)=k(t)+Du(t) where k(t) is a parameterization of the reference line 104, and D is a distance from a point on the reference line 104 to the reflection surface 108 along the desired edge ray through the point.

  6. Nonimaging optical illumination system

    DOEpatents

    Winston, Roland; Ries, Harald

    2000-01-01

    A nonimaging illumination optical device for producing a selected far field illuminance over an angular range. The optical device includes a light source 102, a light reflecting surface 108, and a family of light edge rays defined along a reference line 104 with the reflecting surface 108 defined in terms of the reference line 104 as a parametric function R(t) where t is a scalar parameter position and R(t)=k(t)+Du(t) where k(t) is a parameterization of the reference line 104, and D is a distance from a point on the reference line 104 to the reflection surface 108 along the desired edge ray through the point.

  7. Nonimaging Optical Illumination System

    DOEpatents

    Winston, Roland

    1994-02-22

    A nonimaging illumination or concentration optical device. An optical device is provided having a light source, a light reflecting surface with an opening and positioned partially around the light source which is opposite the opening of the light reflecting surface. The light reflecting surface is disposed to produce a substantially uniform intensity output with the reflecting surface defined in terms of a radius vector R.sub.i in conjunction with an angle .phi..sub.i between R.sub.i, a direction from the source and an angle .theta..sub.i between direct forward illumination and the light ray reflected once from the reflecting surface. R.sub.i varies as the exponential of tan (.phi..sub.i -.theta..sub.i)/2 integrated over .phi..sub.i.

  8. Nonimaging Optical Illumination System

    DOEpatents

    Winston, Roland

    1994-08-02

    A nonimaging illumination optical device for producing selected intensity output over an angular range. The device includes a light reflecting surface (24, 26) around a light source (22) which is disposed opposite the aperture opening of the light reflecting surface (24, 26). The light source (22) has a characteristic dimension which is small relative to one or more of the distance from the light source (22) to the light reflecting surface (24, 26) or the angle subtended by the light source (22) at the light reflecting surface (24, 26).

  9. ILLUMINATION RESPONSE OF CDZNTE

    SciTech Connect

    Teague, L.; Washington, A.; Duff, M.

    2011-08-02

    CdZnTe (CZT) semiconducting crystals are of interest for use as room temperature X- and {gamma}-ray spectrometers. Several studies have focused on understanding the various electronic properties of these materials, such as the surface and bulk resistivities and the distribution of the electric field within the crystal. Specifically of interest is how these properties are influenced by a variety of factors including structural heterogeneities, such as secondary phases (SPs) and line defects as well as environmental effects. Herein, we report the bulk current, surface current, electric field distribution and performance of a spectrometer-grade CZT crystal exposed to above band-gap energy illumination.

  10. Parallel hierarchical global illumination

    SciTech Connect

    Snell, Quinn O.

    1997-10-08

    Solving the global illumination problem is equivalent to determining the intensity of every wavelength of light in all directions at every point in a given scene. The complexity of the problem has led researchers to use approximation methods for solving the problem on serial computers. Rather than using an approximation method, such as backward ray tracing or radiosity, the authors have chosen to solve the Rendering Equation by direct simulation of light transport from the light sources. This paper presents an algorithm that solves the Rendering Equation to any desired accuracy, and can be run in parallel on distributed memory or shared memory computer systems with excellent scaling properties. It appears superior in both speed and physical correctness to recent published methods involving bidirectional ray tracing or hybrid treatments of diffuse and specular surfaces. Like progressive radiosity methods, it dynamically refines the geometry decomposition where required, but does so without the excessive storage requirements for ray histories. The algorithm, called Photon, produces a scene which converges to the global illumination solution. This amounts to a huge task for a 1997-vintage serial computer, but using the power of a parallel supercomputer significantly reduces the time required to generate a solution. Currently, Photon can be run on most parallel environments from a shared memory multiprocessor to a parallel supercomputer, as well as on clusters of heterogeneous workstations.

  11. Physical device illumination color correction

    NASA Astrophysics Data System (ADS)

    Vrhel, Michael J.; Trussell, H. Joel

    1993-08-01

    The problem of calibrating a hard copy color device for a number of viewing illuminants is discussed. Four methods are introduced and implemented using a HP PaintJet XL300 printer. In each case it is assumed that the printer is calibrated for one particular illuminant, via a look-up-table or similar approach. The methods for calibrating with respect to a number of illuminants involve performing simple transformations on the input tristimulus values.

  12. Split-illumination electron holography

    SciTech Connect

    Tanigaki, Toshiaki; Aizawa, Shinji; Suzuki, Takahiro; Park, Hyun Soon; Inada, Yoshikatsu; Matsuda, Tsuyoshi; Taniyama, Akira; Shindo, Daisuke; Tonomura, Akira

    2012-07-23

    We developed a split-illumination electron holography that uses an electron biprism in the illuminating system and two biprisms (applicable to one biprism) in the imaging system, enabling holographic interference micrographs of regions far from the sample edge to be obtained. Using a condenser biprism, we split an electron wave into two coherent electron waves: one wave is to illuminate an observation area far from the sample edge in the sample plane and the other wave to pass through a vacuum space outside the sample. The split-illumination holography has the potential to greatly expand the breadth of applications of electron holography.

  13. Improved array illuminators.

    PubMed

    Lohmann, A W; Sinzinger, S

    1992-09-10

    The job of an array illuminator is to provide an array of optical gates or smart pixels with photon power or with synchronous clock signals. So far it has been common to take the power from one big laser and distribute it to perhaps a million gates. An obvious alternative is to assign one private small source to each gate. We favor an in-between approach: a few medium-size sources share the job of providing photons. This hybrid approach has several advantages, such as better homogeneity, less coherent noise, and a distributed risk of source failure. We propose several setups and present some experimental results. Our concept calls for an array of incoherent point sources. We simulate such an array experimentally with a single source, which is virtually expanded into a source array by grating diffraction. Ordinarily these virtual sources are mutually coherent, which is undesirable for our aims. We destroy the mutual coherence by moving the grating during the photographic recording of the output array.

  14. Illuminated push-button switch

    NASA Technical Reports Server (NTRS)

    Iwagiri, T.

    1983-01-01

    An illuminated push-button switch is described. It is characterized by the fact that is consists of a switch group, an operator button opening and closing the switch group, and a light-emitting element which illuminates the face of the operator button.

  15. Illuminated push-button switch

    NASA Astrophysics Data System (ADS)

    Iwagiri, T.

    1983-05-01

    An illuminated push-button switch is described. It is characterized by the fact that is consists of a switch group, an operator button opening and closing the switch group, and a light-emitting element which illuminates the face of the operator button.

  16. Optical tomography with structured illumination.

    PubMed

    Lukic, Vladimir; Markel, Vadim A; Schotland, John C

    2009-04-01

    We consider the image reconstruction problem for optical tomography with structured illumination. A fast image reconstruction algorithm is proposed that reduces the required number of measurements of the optical field compared to methods that utilize point-source illumination. The results are illustrated with numerical simulations.

  17. Do humans discount the illuminant?

    NASA Astrophysics Data System (ADS)

    McCann, John J.

    2005-03-01

    In constancy experiments, humans report very small changes in appearance with substantial illumination changes. Hermann von Helmholtz introduced the term "discounting the illuminant" to describe 19th century thinking about underlying mechanisms of constancy. It uses an indirect approach. Since observers see objects as constant, observers "must" be able to detect the spatial and spectral changes in illumination and automatically compensate by altering the signals from the quanta catches of retinal receptors. Instead of solving the problem directly by calculating an object"s reflectance from the array of scene radiances, Helmholtz chose to solve the problem of identifying the illumination. Twentieth century experiments by Hubel and Wiesel, Campbell, Land, and Gibson demonstrate the power of mechanisms using spatial comparisons. This paper analyses a series of different experiments looking for unequivocal evidence that either supports "discounting the illuminant" or supports spatial comparisons as the underlying mechanism of constancy.

  18. Adaptive illumination reduces photobleaching in structured illumination microscopy

    PubMed Central

    Chakrova, Nadya; Canton, Alicia Soler; Danelon, Christophe; Stallinga, Sjoerd; Rieger, Bernd

    2016-01-01

    Photobleaching is a major factor limiting the observation time in fluorescence microscopy. We achieve photobleaching reduction in structured illumination microscopy (SIM) by locally adjusting the illumination intensities according to the sample. Adaptive SIM is enabled by a digital micro-mirror device (DMD), which provides a projection of the grayscale illumination patterns. We demonstrate a reduction in photobleaching by a factor of three in adaptive SIM compared to the non-adaptive SIM based on a spot grid scanning approach. Our proof-of-principle experiments show great potential for DMD-based microscopes to become a more useful tool in live-cell SIM imaging. PMID:27867730

  19. Biological Effects Of Artificial Illumination

    NASA Astrophysics Data System (ADS)

    Corth, Richard

    1980-10-01

    We are increasingly being warned of the possible effects of so called "polluted" light, that is light that differs in spectral content from that of sunlight. We should be concerned, we are told, because all animals and plants have evolved under this natural daylight and therefore any difference between that illuminant and the artificial illuminants that are on the market today, is suspect. The usual presentation of the differences between the sunlight and the artificial illuminants are as shown in Figure 1. Here we are shown the spectral power distribution of sunlight and Cool White fluorescent light. The spectral power distributions of each have been normalized to some convenient wavelength so that each can be seen and easily compared on the same figure. But this presentation is misleading for one does not experience artificial illuminants at the same intensity as one experiences sunlight. Sunlight intensities are ordinarily found to be in the 8000 to 10,000 footcandle range whereas artificial illuminants are rarely experienced at intensity levels greater than 100 footcandles. Therefore a representative difference between the two types of illumination conditions is more accurately represented as in Figure 2. Thus if evolutionary adaptations require that humans and other animals be exposed to sunlight to ensure wellbeing, it is clear that one must be exposed to sunlight intensities. It is not feasible to expect that artificially illuminated environments will be lit to the same intensity as sunlight

  20. Matching illumination of solid objects.

    PubMed

    Pont, Sylvia C; Koenderink, Jan J

    2007-04-01

    The appearance of objects is determined by their surface reflectance and roughness and by the light field. Conversely, human observers might derive properties of the light field from the appearance of objects. The inverse problem has no unique solution, so perceptual interactions between reflectance, roughness, and lightfield are to be expected. In two separate experiments, we tested whether observers are able to match the illumination of spheres under collimated illumination only (matching of illumination direction) and under more or less diffuse illumination (matching of illumination direction and directedness of the beam). We found that observers are quite able to match collimated illumination directions of two rendered Lambertian spheres. Matching of the collimated beam directions of a Lambertian sphere and that of a real object with arbitrary reflectance and roughness properties resulted in similar results for the azimuthal angle, but in higher variance for the polar angle. Translucent objects and a tennis ball were found to be systematic outliers. If the directedness of the beam was also varied, the direction settings showed larger variance for more diffuse illumination. The directedness settings showed an overall quite large variance and, interestingly, interacted with the polar angle settings. We discuss possible photometrical mechanisms behind these effects.

  1. Relative illumination and image distortion

    NASA Astrophysics Data System (ADS)

    Siew, Ronian

    2017-04-01

    Applying flux conserving properties between the entrance and exit pupils of a lens system, as well as ideas concerning irradiance magnification in the low numerical aperture limit, it is shown that some basic radiometric equations may be recast into an expression for relative illumination that reveals effects from image distortion and a lesser known quantity called "differential distortion." The expression presented offers a rapid means for estimating the effects of image distortion on relative illumination, which may be useful for basic analysis prior to applying the more comprehensive formulary for relative illumination that has been provided by Reshidko and Sasian.

  2. Structured illumination temporal compressive microscopy

    PubMed Central

    Yuan, Xin; Pang, Shuo

    2016-01-01

    We present a compressive video microscope based on structured illumination with incoherent light source. The source-side illumination coding scheme allows the emission photons being collected by the full aperture of the microscope objective, and thus is suitable for the fluorescence readout mode. A 2-step iterative reconstruction algorithm, termed BWISE, has been developed to address the mismatch between the illumination pattern size and the detector pixel size. Image sequences with a temporal compression ratio of 4:1 were demonstrated. PMID:27231586

  3. Hourly Illumination of Shackleton Crater

    NASA Image and Video Library

    Illumination of Shackleton crater, a 21-km-diameter (12.5 mile-diameter) structure situated adjacent to the Moon’s south pole. The resolution is 30 meters (approximately 100 feet) per pixel. Fra...

  4. Laser sources for object illumination

    SciTech Connect

    Albrecht, G.F.

    1994-11-15

    The considerations which formulate the specifications for a laser illuminator are explained, using the example of an underwater object. Depending on the parameters which define the scenario, widely varying laser requirements result.

  5. An Army Illumination Model (AAIM)

    DTIC Science & Technology

    2008-11-01

    6639000 India Chennai 13.060 80.250 24 Population Country City Latitude Longitude 11680000 India Delhi 28.667 77.233 6833000 India Hyderabad 17.385...providing illumination levels for cities , the model now includes values for lunar illumination under clear or (partially) cloudy skies at ground level...function of population and distance (>10 km) from city center under clear and overcast conditions. A technical overview of the model, along with

  6. Image plane sweep volume illumination.

    PubMed

    Sundén, Erik; Ynnerman, Anders; Ropinski, Timo

    2011-12-01

    In recent years, many volumetric illumination models have been proposed, which have the potential to simulate advanced lighting effects and thus support improved image comprehension. Although volume ray-casting is widely accepted as the volume rendering technique which achieves the highest image quality, so far no volumetric illumination algorithm has been designed to be directly incorporated into the ray-casting process. In this paper we propose image plane sweep volume illumination (IPSVI), which allows the integration of advanced illumination effects into a GPU-based volume ray-caster by exploiting the plane sweep paradigm. Thus, we are able to reduce the problem complexity and achieve interactive frame rates, while supporting scattering as well as shadowing. Since all illumination computations are performed directly within a single rendering pass, IPSVI does not require any preprocessing nor does it need to store intermediate results within an illumination volume. It therefore has a significantly lower memory footprint than other techniques. This makes IPSVI directly applicable to large data sets. Furthermore, the integration into a GPU-based ray-caster allows for high image quality as well as improved rendering performance by exploiting early ray termination. This paper discusses the theory behind IPSVI, describes its implementation, demonstrates its visual results and provides performance measurements.

  7. Specimen illumination apparatus with optical cavity for dark field illumination

    DOEpatents

    Pinkel, Daniel; Sudar, Damir; Albertson, Donna

    1999-01-01

    An illumination apparatus with a specimen slide holder, an illumination source, an optical cavity producing multiple reflection of illumination light to a specimen comprising a first and a second reflective surface arranged to achieve multiple reflections of light to a specimen is provided. The apparatus can further include additional reflective surfaces to achieve the optical cavity, a slide for mounting the specimen, a coverslip which is a reflective component of the optical cavity, one or more prisms for directing light within the optical cavity, antifading solutions for improving the viewing properties of the specimen, an array of materials for analysis, fluorescent components, curved reflective surfaces as components of the optical cavity, specimen detection apparatus, optical detection equipment, computers for analysis of optical images, a plane polarizer, fiberoptics, light transmission apertures, microscopic components, lenses for viewing the specimen, and upper and lower mirrors above and below the specimen slide as components of the optical cavity. Methods of using the apparatus are also provided.

  8. Research on highly uniform laser illumination system

    NASA Astrophysics Data System (ADS)

    Zhao, Huifu

    2016-10-01

    A new laser illumination system was designed based on the analysis of regular homogenization technology. It was widely used in the field of security without sunlight and other lighting. The new laser illumination system used eccentric motor to drive a light shaping scatterer to vibrate at a frequency that faster than the electronic shutter of cameras, making multiple light superimposed in integration time to form a uniform illumination effect. The laser illumination system can eliminate interference fringes and laser speckles, and realize the purpose of homogenization illumination. Experimental results show that the new laser illumination system makes the energy efficiency reach up to 90% and the illumination uniformity reach up to 94% in the effective area. The new laser illumination system improves the uniformity of illumination and utilization rate of laser energy, thus improves the image quality of the illuminated target.

  9. Multiple-illumination photoacoustic tomography

    NASA Astrophysics Data System (ADS)

    Barber, Quinn M.; Zemp, Roger J.

    2016-03-01

    Previously we described the potential for multiple illumination photoacoustic tomography to provide quantitative reconstructions, however this work used only simulated data. We have developed a custom photoacoustic-ultrasound tomography system capable of multiple illuminations and parallel acquisition from a 256 element 5 MHz transducer ring array with 8-cm diameter. The multiple illumination scheme uses a free-space light delivery geometry where a rotational stage scans a pulsed laser beam onto different incident locations around the sample. For each illumination location a photoacoustic image is reconstructed using a modified backprojection algorithm. Images from different source locations have the potential to be combined to form an improved deep-tissue image using our previously developed iterative algorithms. We complement the photoacoustic imaging data with unique ultrasound imaging data. Most previous ultrasound tomography methods have used migration algorithms, iterative ray-based analysis, wave-equation modeling, or frequency-based algorithms that all demand large amounts of data and computational power. We propose a new UST method that offers isotropic resolution, provides scattering contrast, as well as the potential for measuring ultrasound scattering anisotropy and decoupling density and compressibility contributions. The imaging system is driven by a Verasonics scan engine and programmed for both ultrasound and photoacoustic imaging modes. Resolution has been measured to be 150 μm for ultrasound and 200 μm for photoacoustic images. Imaging capabilities are demonstrated on phantoms with custom-tailored ultrasound scattering and optical properties, as well as in murine models.

  10. Beam splitting on weak illumination.

    PubMed

    Snyder, A W; Buryak, A V; Mitchell, D J

    1998-01-01

    We demonstrate, in both two and three dimensions, how a self-guided beam in a non-Kerr medium is split into two beams on weak illumination. We also provide an elegant physical explanation that predicts the universal character of the observed phenomenon. Possible applications of our findings to guiding light with light are also discussed.

  11. Structured line illumination Raman microscopy

    PubMed Central

    Watanabe, Kozue; Palonpon, Almar F.; Smith, Nicholas I.; Chiu, Liang-da; Kasai, Atsushi; Hashimoto, Hitoshi; Kawata, Satoshi; Fujita, Katsumasa

    2015-01-01

    In the last couple of decades, the spatial resolution in optical microscopy has increased to unprecedented levels by exploiting the fluorescence properties of the probe. At about the same time, Raman imaging techniques have emerged as a way to image inherent chemical information in a sample without using fluorescent probes. However, in many applications, the achievable resolution is limited to about half the wavelength of excitation light. Here we report the use of structured illumination to increase the spatial resolution of label-free spontaneous Raman microscopy, generating highly detailed spatial contrast from the ensemble of molecular information in the sample. Using structured line illumination in slit-scanning Raman microscopy, we demonstrate a marked improvement in spatial resolution and show the applicability to a range of samples, including both biological and inorganic chemical component mapping. This technique is expected to contribute towards greater understanding of chemical component distributions in organic and inorganic materials. PMID:26626144

  12. Lunar-illuminated outdoor hologram

    NASA Astrophysics Data System (ADS)

    Jepsen, Mary Lou; Dawson, Paula H.

    1992-05-01

    The first step in the construction of a very deep, large source size, white light illuminated hologram is discussed. We outline the steps taken thus far in the creation of our computer- generated master hologram slit. Our goal is to computer generate a 2 meter master slit for optical transfer via Benton rainbow holography technique. The transfer hologram will ultimately be re-illuminated by the moon and fill a space of approximately 8000 cubic meters. Discussion of the relative merits of synthetic stereographic methods and CGH methods is presented as well as several novel hybrid techniques. The CGH test prints thus far created are evaluated for several types of aberrations and methods of pre-distortion and distortion correction are proposed.

  13. Laser illuminated flat panel display

    SciTech Connect

    Veligdan, J.T.

    1995-12-31

    A 10 inch laser illuminated flat panel Planar Optic Display (POD) screen has been constructed and tested. This POD screen technology is an entirely new concept in display technology. Although the initial display is flat and made of glass, this technology lends itself to applications where a plastic display might be wrapped around the viewer. The display screen is comprised of hundreds of planar optical waveguides where each glass waveguide represents a vertical line of resolution. A black cladding layer, having a lower index of refraction, is placed between each waveguide layer. Since the cladding makes the screen surface black, the contrast is high. The prototype display is 9 inches wide by 5 inches high and approximately I inch thick. A 3 milliwatt HeNe laser is used as the illumination source and a vector scanning technique is employed.

  14. DARK-FIELD ILLUMINATION SYSTEM

    DOEpatents

    Norgren, D.U.

    1962-07-24

    A means was developed for viewing objects against a dark background from a viewing point close to the light which illuminates the objects and under conditions where the back scattering of light by the objects is minimal. A broad light retro-directing member on the opposite side of the objects from the light returns direct light back towards the source while directing other light away from the viewing point. The viewing point is offset from the light and thus receives only light which is forwardly scattered by an object while returning towards the source. The object is seen, at its true location, against a dark background. The invention is particularly adapted for illuminating and viewing nuclear particle tracks in a liquid hydrogen bubble chamber through a single chamber window. (AEC)

  15. Illumination box and camera system

    DOEpatents

    Haas, Jeffrey S.; Kelly, Fredrick R.; Bushman, John F.; Wiefel, Michael H.; Jensen, Wayne A.; Klunder, Gregory L.

    2002-01-01

    A hand portable, field-deployable thin-layer chromatography (TLC) unit and a hand portable, battery-operated unit for development, illumination, and data acquisition of the TLC plates contain many miniaturized features that permit a large number of samples to be processed efficiently. The TLC unit includes a solvent tank, a holder for TLC plates, and a variety of tool chambers for storing TLC plates, solvent, and pipettes. After processing in the TLC unit, a TLC plate is positioned in a collapsible illumination box, where the box and a CCD camera are optically aligned for optimal pixel resolution of the CCD images of the TLC plate. The TLC system includes an improved development chamber for chemical development of TLC plates that prevents solvent overflow.

  16. Experimental realization of quantum illumination.

    PubMed

    Lopaeva, E D; Ruo Berchera, I; Degiovanni, I P; Olivares, S; Brida, G; Genovese, M

    2013-04-12

    We present the first experimental realization of the quantum illumination protocol proposed by Lloyd [Science 321, 1463 (2008)] and S. Tan et al. [Phys. Rev. Lett. 101, 253601 (2008)], achieved in a simple feasible experimental scheme based on photon-number correlations. A main achievement of our result is the demonstration of a strong robustness of the quantum protocol to noise and losses that challenges some widespread wisdom about quantum technologies.

  17. Scanned Laser Illuminator/Receiver

    DTIC Science & Technology

    1976-11-01

    matching high sensitivity, high resolution receiver. A CW- pumped Nd:YAG laser operated in a pulsed mode and providing a fan-shaped illumination beam...greatly improve the linearity of the scanner and to permit variable scan rate (non-resonant) operation. A cw- pumped NdiYAG laser is used as the...illustrate parallel development of the PIN diode /CCD sensor hybrid and the 100W laser . Al- though a detailed cost analysis for procurement of this large

  18. Illumination influences working memory: an EEG study.

    PubMed

    Park, Jin Young; Min, Byoung-Kyong; Jung, Young-Chul; Pak, Hyensou; Jeong, Yeon-Hong; Kim, Eosu

    2013-09-05

    Illumination conditions appear to influence working efficacy in everyday life. In the present study, we obtained electroencephalogram (EEG) correlates of working-memory load, and investigated how these waveforms are modulated by illumination conditions. We hypothesized that illumination conditions may affect cognitive performance. We designed an EEG study to monitor and record participants' EEG during the Sternberg working memory task under four different illumination conditions. Illumination conditions were generated with a factorial design of two color-temperatures (3000 and 7100 K) by two illuminance levels (150 and 700 lx). During a working memory task, we observed that high illuminance led to significantly lower frontal EEG theta activity than did low illuminance. These differences persisted despite no significant difference in task performance between illumination conditions. We found that the latency of an early event-related potential component, such as N1, was significantly modulated by the illumination condition. The fact that the illumination condition affects brain activity but not behavioral performance suggests that the lighting conditions used in the present study did not influence the performance stage of behavioral processing. Nevertheless, our findings provide objective evidence that illumination conditions modulate brain activity. Further studies are necessary to refine the optimal lighting parameters for facilitating working memory.

  19. Applications of TM polarized illumination

    NASA Astrophysics Data System (ADS)

    Smith, Bruce; Zhou, Jianming; Xie, Peng

    2008-03-01

    The use of transverse electric (TE) polarization has dominated illumination schemes as selective polarization is used for high-NA patterning. The benefits of TE polarization are clear - the interference of diffracted beams remains absolute at oblique angles. Transverse magnetic (TM) polarization is usually considered less desirable as imaging modulation from interference at large angle falls off rapidly as the 1/cosθ. Significant potential remains, however, for the use of TM polarization at large angles when its reflection component is utilized. By controlling the resist/substrate interface reflectivity, high modulation for TM polarization can be maintained for angles up to 90° in the resist. This can potentially impact the design of illumination away from most recent TE-only schemes for oblique imaging angles (high NA). We demonstrate several cases of TM illumination combined with tuned substrate reflectivity for 0.93NA, 1.20NA, and 1.35NA and compare results to TE and unpolarized cases. The goal is to achieve a flat response through polarization at large imaging angles. An additional application of TM illumination is its potential use for double patterning. As double patterning and double exposure approaches are sought in order to meet the needs of 32nm device generations and beyond, materials and process engineering challenges become prohibitive. We have devised a method for frequency doubling in a single exposure using an unconventional means of polarization selection and by making use of the reflective component produced at the photoresist/substrate interface. In doing so, patterns can be deposited into a photoresist film with double density. As an example, using a projection system numerical aperture of 1.20, with water as an immersion fluid, and a conventional polyacrylate 193nm photoresist, pattern resolution at 20nm half-pitch are obtainable (which is 0.125lambda/NA). The process to transfer this geometry into a hardmask layer uses conventional materials

  20. Pluto Moon Nix, Half Illuminated

    NASA Image and Video Library

    2015-12-18

    This recently received panchromatic image of Pluto's small satellite Nix taken by the Multispectral Visible Imaging Camera (MVIC) aboard New Horizons is one of the best images of Pluto's third-largest moon generated by the NASA mission. Taken on July 14, 2015, at a range of about 14,000 miles (23,000 kilometers) from Nix, the illuminated surface is about 12 miles (19 kilometers) by 29 miles (47 kilometers). The unique perspective of this image provides new details about Nix's geologic history and impact record. http://photojournal.jpl.nasa.gov/catalog/PIA20287

  1. Synchrotron-based EUV lithography illuminator simulator

    DOEpatents

    Naulleau, Patrick P.

    2004-07-27

    A lithographic illuminator to illuminate a reticle to be imaged with a range of angles is provided. The illumination can be employed to generate a pattern in the pupil of the imaging system, where spatial coordinates in the pupil plane correspond to illumination angles in the reticle plane. In particular, a coherent synchrotron beamline is used along with a potentially decoherentizing holographic optical element (HOE), as an experimental EUV illuminator simulation station. The pupil fill is completely defined by a single HOE, thus the system can be easily modified to model a variety of illuminator fill patterns. The HOE can be designed to generate any desired angular spectrum and such a device can serve as the basis for an illuminator simulator.

  2. Atmospheric effects on active illumination

    NASA Astrophysics Data System (ADS)

    Shaw, Scot E. J.; Kansky, Jan E.

    2005-08-01

    For some beam-control applications, we can rely on the cooperation of the target when gathering information about the target location and the state of the atmosphere between the target and the beam-control system. The typical example is a cooperative point-source beacon on the target. Light from such a beacon allows the beam-control system to track the target accurately, and, if higher-order adaptive optics is to be employed, to make wave-front measurements and apply appropriate corrections with a deformable mirror. In many applications, including directed-energy weapons, the target is not cooperative. In the absence of a cooperative beacon, we must find other ways to collect the relevant information. This can be accomplished with an active-illumination system. Typically, this means shining one or more lasers at the target and observing the reflected light. In this paper, we qualitatively explore a number of difficulties inherent to active illumination, and suggest some possible mitigation techniques.

  3. Segmentation and estimation of spatially varying illumination.

    PubMed

    Lin Gu; Huynh, Cong Phuoc; Robles-Kelly, Antonio

    2014-08-01

    In this paper, we present an unsupervised method for segmenting the illuminant regions and estimating the illumination power spectrum from a single image of a scene lit by multiple light sources. Here, illuminant region segmentation is cast as a probabilistic clustering problem in the image spectral radiance space. We formulate the problem in an optimization setting, which aims to maximize the likelihood of the image radiance with respect to a mixture model while enforcing a spatial smoothness constraint on the illuminant spectrum. We initialize the sample pixel set under each illuminant via a projection of the image radiance spectra onto a low-dimensional subspace spanned by a randomly chosen subset of spectra. Subsequently, we optimize the objective function in a coordinate-ascent manner by updating the weights of the mixture components, sample pixel set under each illuminant, and illuminant posterior probabilities. We then estimate the illuminant power spectrum per pixel making use of these posterior probabilities. We compare our method with a number of alternatives for the tasks of illumination region segmentation, illumination color estimation, and color correction. Our experiments show the effectiveness of our method as applied to one hyperspectral and three trichromatic image data sets.

  4. Negative illumination thermoradiative solar cell.

    PubMed

    Liao, Tianjun; Zhang, Xin; Chen, Xiaohang; Lin, Bihong; Chen, Jincan

    2017-08-15

    The negative illumination thermoradiative solar cell (NITSC) consisting of a concentrator, an absorber, and a thermoradiative cell (TRC) is established, where the radiation and reflection losses from the absorber to the environment and the radiation loss from the TRC to the environment are taken into consideration. The power output and overall efficiency of the NITSC are analytically derived. The operating temperature of the TRC is determined through the thermal equilibrium equations, and the efficiency of the NITSC is calculated through the optimization of the output voltage of the TRC and the concentrating factor for a given value of the bandgap. Moreover, the maximum efficiencies of the NITSC at different conditions and the optimal values of the bandgap are determined, and consequently, the corresponding optimum operating conditions are obtained. The results obtained here will be helpful for the optimum design and operation of TRCs.

  5. Fully depleted back illuminated CCD

    DOEpatents

    Holland, Stephen Edward

    2001-01-01

    A backside illuminated charge coupled device (CCD) is formed of a relatively thick high resistivity photon sensitive silicon substrate, with frontside electronic circuitry, and an optically transparent backside ohmic contact for applying a backside voltage which is at least sufficient to substantially fully deplete the substrate. A greater bias voltage which overdepletes the substrate may also be applied. One way of applying the bias voltage to the substrate is by physically connecting the voltage source to the ohmic contact. An alternate way of applying the bias voltage to the substrate is to physically connect the voltage source to the frontside of the substrate, at a point outside the depletion region. Thus both frontside and backside contacts can be used for backside biasing to fully deplete the substrate. Also, high resistivity gaps around the CCD channels and electrically floating channel stop regions can be provided in the CCD array around the CCD channels. The CCD array forms an imaging sensor useful in astronomy.

  6. Background illumination and automated perimetry.

    PubMed

    Klewin, K M; Radius, R L

    1986-03-01

    Visual field function in the right and left eyes of 31 normal volunteers was evaluated with an automated projection perimeter (OCTOPUS). Serial visual field evaluations were repeated in these same eyes with neutral filters of increasing optical density. We compared the results of threshold determinations with the different neutral filters in place before the examined eye. Significant reduction in threshold sensitivity at several test spots throughout the central 30 degrees visual field was seen with neutral density filters of 0.5 log units or greater. The low level of background illumination of the OCTOPUS perimeter (4.0 apostilbs) may allow relatively minor reduction in light transmission by the ocular media to produce significant changes in the recorded level of threshold sensitivity during visual field evaluation.

  7. Free-form illumination optics

    NASA Astrophysics Data System (ADS)

    Mohedano, Rubén; Chaves, Julio; Hernández, Maikel

    2016-04-01

    In many illumination problems, the beam pattern needed and/or some geometrical constraints lead to very asymmetric design conditions. These asymmetries have been solved in the past by means of arrangements of rotationally symmetric or linear lamps aimed in different directions whose patterns overlap to provide the asymmetric prescriptions or by splitting one single lamp into several sections, each one providing a part of the pattern. The development of new design methods yielding smooth continuous free-form optical surfaces to solve these challenging design problems, combined with the proper CAD modeling tools plus the development of multiple axes diamond turn machines, give birth to a new generation of optics. These are able to offer the performance and other advanced features, such as efficiency, compactness, or aesthetical advantages, and can be manufactured at low cost by injection molding. This paper presents two examples of devices with free-form optical surfaces, a camera flash, and a car headlamp.

  8. Off-axis illumination of lithography tool

    NASA Astrophysics Data System (ADS)

    Xing, Han; Lin, Li; Bin, Ma

    2013-12-01

    Lithography tool is a necessary part for LSI and VLSI. The illumination system design is an important part in the lithography optical system design. Off-axis illumination technology is an effective way to reducing resolution of lithography. The paper introduction the basic components of lithography tool, the principle of off-axis illumination reducing the resolution of lithography and focus on the two implementations of OAI technology, finally point out advantages and disadvantage of the two implementations.

  9. Structured illumination fluorescence Fourier ptychographic microscopy

    NASA Astrophysics Data System (ADS)

    Xiu, Peng; Chen, Youhua; Kuang, Cuifang; Fang, Yue; Wang, Yifan; Fan, Jiannan; Xu, Yingke; Liu, Xu

    2016-12-01

    We apply a Fourier ptychographic algorithm for fluorescent samples using structured illumination. The samples are illuminated with structured light patterns and the raw imaging data using traditional structured illumination fluorescence microscopy (SIM) are acquired. We then extract equivalent oblique illuminated images of fluorescent samples from the SIM images. An optimized Fourier ptychography algorithm is proposed, which ensures the fidelity of the reconstructed the super-resolution results. This method can break the diffraction limit to a resolution of λ/4, and has a better signal-to-noise ratio (SNR) than SIM, especially when the background noise is high.

  10. Illumination system characterization for hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Katrašnik, Jaka; Pernuš, Franjo; Likar, Boštjan

    2011-03-01

    Near-infrared hyperspectral imaging is becoming a popular tool in the biomedical field, especially for detection and analysis of different types of cancers, analysis of skin burns and bruises, imaging of blood vessels and for many other applications. As in all imaging systems, proper illumination is crucial to attain optimal image quality that is needed for best performance of image analysis algorithms. In hyperspectral imaging based on filters (AOTF, LCTF and filter wheel) the acquired spectral signature has to be representative in all parts of the imaged object. Therefore, the whole object must be equally well illuminated - without shadows and specular reflections. As there are no restrictions imposed on the material and geometry of the object, the desired object illumination can only be achieved with completely diffuse illumination. In order to minimize shadows and specular reflections in diffuse illumination the light illuminating the object must be spatially, angularly and spectrally uniform. We present and test two diffuse illumination system designs that try to achieve optimal uniformity of the above mentioned properties. The illumination uniformity properties were measured with an AOTF based hyperspectral imaging system utilizing a standard white diffuse reflectance target and a specially designed calibration target for estimating the spatial and angular illumination uniformity.

  11. Improved Interference configuration for structured illumination microscopy

    NASA Astrophysics Data System (ADS)

    Chen, Houkai; Wei, Shibiao; Wu, Xiaojing; Yang, Yong; Zhang, Yuquan; Du, Luping; Liu, Jun; Zhu, Siwei; Yuan, Xiaocong

    2017-02-01

    We present an improved structured illumination configuration for structured illumination microscopy (SIM) based on spatial light modulator. Precise phase shifts and rotation of illumination fringes can be dynamically controlled using a spatial light modulator. The method is different from the conventional illumination configuration that are based on interference of ±1 diffractive order light. The experimental setup requires less optical elements making it compact, reliable, and suitable for integration. The method has been applied in the standing-wave total internal reflection fluorescent microscopy. High lateral resolution of sub-100 nm was achieved in single directional resolution enhancement experiments.

  12. Polarimetric target detection under uneven illumination.

    PubMed

    Huang, Bingjing; Liu, Tiegen; Han, Jiahui; Hu, Haofeng

    2015-09-07

    In polarimetric imaging, the uneven illumination could cause the significant spatial intensity fluctuations in the scene, and thus hampers the target detection. In this paper, we propose a method of illumination compensation and contrast optimization for Stokes polarimetric imaging, which allows significantly increasing the performance of target detection under uneven illumination. We show with numerical simulation and real-world experiment that, based on the intensity information contained in the polarization information, the contrast can be effectively enhanced by proper approach, which is of particular importance in practical applications with spatial illumination fluctuations, such as remote sensing.

  13. Illumination discrimination in real and simulated scenes

    PubMed Central

    Radonjić, Ana; Pearce, Bradley; Aston, Stacey; Krieger, Avery; Dubin, Hilary; Cottaris, Nicolas P.; Brainard, David H.; Hurlbert, Anya C.

    2016-01-01

    Characterizing humans' ability to discriminate changes in illumination provides information about the visual system's representation of the distal stimulus. We have previously shown that humans are able to discriminate illumination changes and that sensitivity to such changes depends on their chromatic direction. Probing illumination discrimination further would be facilitated by the use of computer-graphics simulations, which would, in practice, enable a wider range of stimulus manipulations. There is no a priori guarantee, however, that results obtained with simulated scenes generalize to real illuminated scenes. To investigate this question, we measured illumination discrimination in real and simulated scenes that were well-matched in mean chromaticity and scene geometry. Illumination discrimination thresholds were essentially identical for the two stimulus types. As in our previous work, these thresholds varied with illumination change direction. We exploited the flexibility offered by the use of graphics simulations to investigate whether the differences across direction are preserved when the surfaces in the scene are varied. We show that varying the scene's surface ensemble in a manner that also changes mean scene chromaticity modulates the relative sensitivity to illumination changes along different chromatic directions. Thus, any characterization of sensitivity to changes in illumination must be defined relative to the set of surfaces in the scene.

  14. Secure communication via quantum illumination

    NASA Astrophysics Data System (ADS)

    Shapiro, Jeffrey H.; Zhang, Zheshen; Wong, Franco N. C.

    2014-10-01

    In the quantum illumination protocol for secure communication, Alice prepares entangled signal and idler beams via spontaneous parametric downconversion. She sends the signal beam to Bob, while retaining the idler. Bob imposes message modulation on the beam he receives from Alice, amplifies it, and sends it back to her. Alice then decodes Bob's information by making a joint quantum measurement on the light she has retained and the light she has received from him. The basic performance analysis for this protocol—which demonstrates its immunity to passive eavesdropping, in which Eve can only listen to Alice and Bob's transmissions—is reviewed, along with the results of its first proof-of-principle experiment. Further analysis is then presented, showing that secure data rates in excess of 1 Gbps may be possible over 20-km-long fiber links with technology that is available or under development. Finally, an initial scheme for thwarting active eavesdropping, in which Eve injects her own light into Bob's terminal, is proposed and analyzed.

  15. Extinction-Optimized Volume Illumination.

    PubMed

    Ament, Marco; Zirr, Tobias; Dachsbacher, Carsten

    2016-05-16

    We present a novel method to optimize the attenuation of light for the single scattering model in direct volume rendering. A common problem of single scattering is the high dynamic range between lit and shadowed regions due to the exponential attenuation of light along a ray. Moreover, light is often attenuated too strong between a sample point and the camera, hampering the visibility of important features. Our algorithm employs an importance function to selectively illuminate important structures and make them visible from the camera. With the importance function, more light can be transmitted to the features of interest, while contextual structures cast shadows which provide visual cues for perception of depth. At the same time, more scattered light is transmitted from the sample point to the camera to improve the primary visibility of important features. We formulate a minimization problem that automatically determines the extinction along a view or shadow ray to obtain a good balance between sufficient transmittance and attenuation. In contrast to previous approaches, we do not require a computationally expensive solution of a global optimization, but instead provide a closed-form solution for each sampled extinction value along a view or shadow ray and thus achieve interactive performance.

  16. 3D structured illumination microscopy

    NASA Astrophysics Data System (ADS)

    Dougherty, William M.; Goodwin, Paul C.

    2011-03-01

    Three-dimensional structured illumination microscopy achieves double the lateral and axial resolution of wide-field microscopy, using conventional fluorescent dyes, proteins and sample preparation techniques. A three-dimensional interference-fringe pattern excites the fluorescence, filling in the "missing cone" of the wide field optical transfer function, thereby enabling axial (z) discrimination. The pattern acts as a spatial carrier frequency that mixes with the higher spatial frequency components of the image, which usually succumb to the diffraction limit. The fluorescence image encodes the high frequency content as a down-mixed, moiré-like pattern. A series of images is required, wherein the 3D pattern is shifted and rotated, providing down-mixed data for a system of linear equations. Super-resolution is obtained by solving these equations. The speed with which the image series can be obtained can be a problem for the microscopy of living cells. Challenges include pattern-switching speeds, optical efficiency, wavefront quality and fringe contrast, fringe pitch optimization, and polarization issues. We will review some recent developments in 3D-SIM hardware with the goal of super-resolved z-stacks of motile cells.

  17. Translating Rimbaud's "Illuminations": Games with Words

    ERIC Educational Resources Information Center

    Slote, Daniel

    1978-01-01

    Rimbaud's "Illuminations," one vast word-game, is used as an example of one of the most interesting challenges in translation--the rendering of plays on words. The process is discussed and illustrated by the analysis of numerous segments from "Illuminations." It is concluded that a satisfactory translation is almost impossible.…

  18. Translating Rimbaud's "Illuminations": Games with Words

    ERIC Educational Resources Information Center

    Slote, Daniel

    1978-01-01

    Rimbaud's "Illuminations," one vast word-game, is used as an example of one of the most interesting challenges in translation--the rendering of plays on words. The process is discussed and illustrated by the analysis of numerous segments from "Illuminations." It is concluded that a satisfactory translation is almost impossible.…

  19. Reflectance and Illumination Recovery in the Wild.

    PubMed

    Lombardi, Stephen; Nishino, Ko

    2016-01-01

    The appearance of an object in an image encodes invaluable information about that object and the surrounding scene. Inferring object reflectance and scene illumination from an image would help us decode this information: reflectance can reveal important properties about the materials composing an object; the illumination can tell us, for instance, whether the scene is indoors or outdoors. Recovering reflectance and illumination from a single image in the real world, however, is a difficult task. Real scenes illuminate objects from every visible direction and real objects vary greatly in reflectance behavior. In addition, the image formation process introduces ambiguities, like color constancy, that make reversing the process ill-posed. To address this problem, we propose a Bayesian framework for joint reflectance and illumination inference in the real world. We develop a reflectance model and priors that precisely capture the space of real-world object reflectance and a flexible illumination model that can represent real-world illumination with priors that combat the deleterious effects of image formation. We analyze the performance of our approach on a set of synthetic data and demonstrate results on real-world scenes. These contributions enable reliable reflectance and illumination inference in the real world.

  20. Illumination preference, illumination constancy and colour discrimination by bumblebees in an environment with patchy light.

    PubMed

    Arnold, Sarah E J; Chittka, Lars

    2012-07-01

    Patchy illumination presents foraging animals with a challenge, as the targets being sought may appear to vary in colour depending on the illumination, compromising target identification. We sought to explore how the bumblebee Bombus terrestris copes with tasks involving flower colour discrimination under patchy illumination. Light patches varied between unobscured daylight and leaf-shade, as a bee might encounter in and around woodland. Using a flight arena and coloured filters, as well as one or two different colours of artificial flower, we quantified how bees chose to forage when presented with foraging tasks under patchy illumination. Bees were better at discriminating a pair of similar colours under simulated unobscured daylight illumination than when foraging under leaf-shade illumination. Accordingly, we found that bees with prior experience of simulated daylight but not leaf-shade illumination initially preferred to forage in simulated daylight when all artificial flowers contained rewards as well as when only one colour was rewarding, whereas bees with prior experience of both illuminants did not exhibit this preference. Bees also switched between illuminants less than expected by chance. This means that bees prefer illumination conditions with which they are familiar, and in which rewarding flower colours are easily distinguishable from unrewarding ones. Under patchy illumination, colour discrimination performance was substantially poorer than in homogenous light. The bees' abilities at coping with patchy light may therefore impact on foraging behaviour in the wild, particularly in woodlands, where illumination can change over short spatial scales.

  1. Illuminant spectrum estimation at a pixel.

    PubMed

    Ratnasingam, Sivalogeswaran; Hernández-Andrés, Javier

    2011-04-01

    In this paper, an algorithm is proposed to estimate the spectral power distribution of a light source at a pixel. The first step of the algorithm is forming a two-dimensional illuminant invariant chromaticity space. In estimating the illuminant spectrum, generalized inverse estimation and Wiener estimation methods were applied. The chromaticity space was divided into small grids and a weight matrix was used to estimate the illuminant spectrum illuminating the pixels that fall within a grid. The algorithm was tested using a different number of sensor responses to determine the optimum number of sensors for accurate colorimetric and spectral reproduction. To investigate the performance of the algorithm realistically, the responses were multiplied with Gaussian noise and then quantized to 10 bits. The algorithm was tested with standard and measured data. Based on the results presented, the algorithm can be used with six sensors to obtain a colorimetrically good estimate of the illuminant spectrum at a pixel.

  2. Chromatic illumination discrimination ability reveals that human colour constancy is optimised for blue daylight illuminations.

    PubMed

    Pearce, Bradley; Crichton, Stuart; Mackiewicz, Michal; Finlayson, Graham D; Hurlbert, Anya

    2014-01-01

    The phenomenon of colour constancy in human visual perception keeps surface colours constant, despite changes in their reflected light due to changing illumination. Although colour constancy has evolved under a constrained subset of illuminations, it is unknown whether its underlying mechanisms, thought to involve multiple components from retina to cortex, are optimised for particular environmental variations. Here we demonstrate a new method for investigating colour constancy using illumination matching in real scenes which, unlike previous methods using surface matching and simulated scenes, allows testing of multiple, real illuminations. We use real scenes consisting of solid familiar or unfamiliar objects against uniform or variegated backgrounds and compare discrimination performance for typical illuminations from the daylight chromaticity locus (approximately blue-yellow) and atypical spectra from an orthogonal locus (approximately red-green, at correlated colour temperature 6700 K), all produced in real time by a 10-channel LED illuminator. We find that discrimination of illumination changes is poorer along the daylight locus than the atypical locus, and is poorest particularly for bluer illumination changes, demonstrating conversely that surface colour constancy is best for blue daylight illuminations. Illumination discrimination is also enhanced, and therefore colour constancy diminished, for uniform backgrounds, irrespective of the object type. These results are not explained by statistical properties of the scene signal changes at the retinal level. We conclude that high-level mechanisms of colour constancy are biased for the blue daylight illuminations and variegated backgrounds to which the human visual system has typically been exposed.

  3. Chromatic Illumination Discrimination Ability Reveals that Human Colour Constancy Is Optimised for Blue Daylight Illuminations

    PubMed Central

    Pearce, Bradley; Crichton, Stuart; Mackiewicz, Michal; Finlayson, Graham D.; Hurlbert, Anya

    2014-01-01

    The phenomenon of colour constancy in human visual perception keeps surface colours constant, despite changes in their reflected light due to changing illumination. Although colour constancy has evolved under a constrained subset of illuminations, it is unknown whether its underlying mechanisms, thought to involve multiple components from retina to cortex, are optimised for particular environmental variations. Here we demonstrate a new method for investigating colour constancy using illumination matching in real scenes which, unlike previous methods using surface matching and simulated scenes, allows testing of multiple, real illuminations. We use real scenes consisting of solid familiar or unfamiliar objects against uniform or variegated backgrounds and compare discrimination performance for typical illuminations from the daylight chromaticity locus (approximately blue-yellow) and atypical spectra from an orthogonal locus (approximately red-green, at correlated colour temperature 6700 K), all produced in real time by a 10-channel LED illuminator. We find that discrimination of illumination changes is poorer along the daylight locus than the atypical locus, and is poorest particularly for bluer illumination changes, demonstrating conversely that surface colour constancy is best for blue daylight illuminations. Illumination discrimination is also enhanced, and therefore colour constancy diminished, for uniform backgrounds, irrespective of the object type. These results are not explained by statistical properties of the scene signal changes at the retinal level. We conclude that high-level mechanisms of colour constancy are biased for the blue daylight illuminations and variegated backgrounds to which the human visual system has typically been exposed. PMID:24586299

  4. City Lights Illuminate the Nile

    NASA Image and Video Library

    2017-09-27

    NASA image acquired October 13, 2012 The Nile River Valley and Delta comprise less than 5 percent of Egypt’s land area, but provide a home to roughly 97 percent of the country’s population. Nothing makes the location of human population clearer than the lights illuminating the valley and delta at night. On October 13, 2012, the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite captured this nighttime view of the Nile River Valley and Delta. This image is from the VIIRS “day-night band,” which detects light in a range of wavelengths from green to near-infrared and uses filtering techniques to observe signals such as gas flares, auroras, wildfires, city lights, and reflected moonlight. The city lights resemble a giant calla lily, just one with a kink in its stem near the city of Luxor. Some of the brightest lights occur around Cairo, but lights are abundant along the length of the river. Bright city lights also occur along the Suez Canal and around Tel Aviv. Away from the lights, however, land and water appear uniformly black. This image was acquired near the time of the new Moon, and little moonlight was available to brighten land and water surfaces. NASA Earth Observatory image by Jesse Allen and Robert Simmon, using VIIRS Day-Night Band data from the Suomi National Polar-orbiting Partnership. Suomi NPP is the result of a partnership between NASA, the National Oceanic and Atmospheric Administration, and the Department of Defense. Caption by Michon Scott. Instrument: Suomi NPP - VIIRS Credit: NASA Earth Observatory Click here to view all of the Earth at Night 2012 images Click here to read more about this image NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency

  5. Long-range laser-illuminated imaging

    NASA Astrophysics Data System (ADS)

    Dayton, David C.; Browne, Stephen L.; Sandven, Steven C.; Gonglewski, John D.; Gallegos, Joe; Shilko, Michael L., Sr.

    2000-11-01

    We demonstrate the utility of laser illuminated imaging for clandestine night time surveillance from a simulated airborne platform at standoff ranges in excess 20 km. In order to reduce the necessary laser per pulse energy required for illumination at such long ranges, and to mitigate atmospheric turbulence effects on image resolution, we have investigated a unique multi-frame post-processing technique. It is shown that in the presence of atmospheric turbulence and coherent speckle effects, this approach can produce superior results to conventional scene flood illumination.

  6. Multilevel phase gratings for array illuminators.

    PubMed

    Arrizón, V; Ojeda-Castañeda, J

    1994-09-01

    We describe a variety of multilevel phase structures that can be used to generate Lohmann's array illuminators. We report several experimental verifications of the synthesis of such multilevel phase structures by using simple binary curves in a conventional optical processor.

  7. An illuminated flute needle for vitreoretinal surgery.

    PubMed

    Davison, C N; Rosen, P H

    1994-06-01

    We have developed a simple self-illuminated flute needle for internal drainage of subretinal fluid during three-port vitrectomy. This instrument facilitates visualization and drainage through peripheral retinal breaks.

  8. Structured illumination microscopy with interleaved reconstruction (SIMILR).

    PubMed

    Ma, Ying; Li, Di; Smith, Zachary J; Li, Dong; Chu, Kaiqin

    2017-07-13

    Structured illumination microscopy (SIM) is the commonly used super-resolution (SR) technique for imaging subcellular dynamics. However, due to its need for multiple illumination patterns, the frame rate is just a fraction of that of conventional microscopy and is thus too slow for fast dynamic studies. A new SR image reconstruction method that maximizes the use of each subframe of the acquisition series is proposed for improving the super-resolved frame rate by N times for N illumination directions. The method requires no changes in raw data and is appropriate for many versions of SIM setup, including those implementing fast illumination pattern generation mechanism based on spatial light modulator or digital micromirror device. The performance of the proposed method is demonstrated through imaging the highly dynamic endoplasmic reticulum where continuous rapid growths or shape changes of tiny structures are observed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Saturated pattern-illuminated Fourier ptychography microscopy

    NASA Astrophysics Data System (ADS)

    Fang, Yue; Chen, Youhua; Kuang, Cuifang; Xiu, Peng; Liu, Qiulan; Ge, Baoliang; Liu, Xu

    2017-01-01

    We report a series of simulation studies which extends pattern-illuminated Fourier ptychography microscopy by integrating with the nonlinearity arising from saturation of the fluorophore excited state for super-resolution fluorescence imaging. This extended technique, termed Saturated pattern-illuminated Fourier ptychography (SpiFP) microscopy, could achieve a resolution four times that of wide field when the illuminating light intensity approaches the saturation threshold in simulations. Increasing light intensity leads to further resolution enhancement. In order to demonstrate the performance of SpiFP, we make a comparison between SpiFP and saturated structure illumination microscopy in simulations, and prove that the SpiFP exhibits superior robustness to noise, aberration correcting ability, and pattern’s flexibility. Introducing the saturation of the fluorescent emission brings in notable improvements in imaging performance, implying its potential in nanoscale-sized biological observations by wide-field microscopy.

  10. 29 CFR 1926.56 - Illumination.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... work is in progress: Table D-3—Minimum Illumination Intensities in Foot-Candles Foot-candles Area or... underground work areas: (Exception: minimum of 10 foot-candles is required at tunnel and shaft heading during...

  11. 29 CFR 1926.56 - Illumination.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... work is in progress: Table D-3—Minimum Illumination Intensities in Foot-Candles Foot-candles Area or... underground work areas: (Exception: minimum of 10 foot-candles is required at tunnel and shaft heading during...

  12. 29 CFR 1926.56 - Illumination.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... work is in progress: Table D-3—Minimum Illumination Intensities in Foot-Candles Foot-candles Area or... underground work areas: (Exception: minimum of 10 foot-candles is required at tunnel and shaft heading during...

  13. 29 CFR 1926.56 - Illumination.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... work is in progress: Table D-3—Minimum Illumination Intensities in Foot-Candles Foot-candles Area or... underground work areas: (Exception: minimum of 10 foot-candles is required at tunnel and shaft heading during...

  14. 29 CFR 1926.56 - Illumination.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... work is in progress: Table D-3—Minimum Illumination Intensities in Foot-Candles Foot-candles Area or... underground work areas: (Exception: minimum of 10 foot-candles is required at tunnel and shaft heading during...

  15. Illumination control apparatus for compensating solar light

    NASA Technical Reports Server (NTRS)

    Owens, L. J. (Inventor)

    1978-01-01

    An illumination control apparatus is presented for supplementing light from solar radiation with light from an artificial light source to compensate for periods of insufficient levels of solar light. The apparatus maintains a desired illumination level within an interior space comprising an artificial light source connected to an electrical power source with a switch means for selectively energizing said light source. An actuator means for controlling the on-off operation of the switch means is connected to a light sensor which responses to the illumination level of the interior space. A limit switch carried adjacent to the actuator limits the movement of the actuator within a predetermined range so as to prevent further movement thereof during detection of erroneous illumination conditions.

  16. Insulator Surface Flashover Due to UV Illumination

    DTIC Science & Technology

    2009-06-01

    The surface of an insulator under vacuum and under electrical charge will flashover when illuminated by a critical dose of ultra-violet (UV...fluence (energy per unit area) required to induce surface flashover of vacuum insulators for some candid insulator materials: High Density... Insulator Surface Flashover Due to UV Illumination1 J. B. Javedani, T.L. Houck, D.A. Lahowe, G.E. Vogtlin and D.A. Goerz Lawrence Livermore

  17. A novel ultralow-illumination endoscope system.

    PubMed

    Kim, Keri; Kubota, Misao; Ohkawa, Yuji; Shiraishi, Takashi; Kawai, Teruo; Kobayashi, Akira; Yamashita, Hiromasa; Chiba, Toshio

    2011-06-01

    Endoscopic surgery has become an accepted major type of minimally invasive surgery. However, complications arising from heat generated by sources of endoscopic illumination can include surgical fire or burns, and intense illumination during ob-gyn/fetoscopic surgery might damage fetal ocular development. Fiber-optic bundles for illumination within the endoscope essentially double the outer diameter of the endoscope, which is a major obstacle to miniaturization and decreasing costs. Light cables also decrease the maneuverability of the endoscope We developed a novel endoscope with ultralow illumination to visualize dark body cavities and investigated its feasibility in vivo. An adaptor was created to connect a conventional endoscope to an ultrahigh-sensitivity camera developed by the Japan Broadcasting Corporation (NHK) for broadcasting. The ability to visualize rabbit visceral blood vessels in vivo by the new prototype and by a current endoscope under ultralow illumination provided by a standard light source was compared. In addition, the performance of the two endoscopes was compared using only an extracorporeal flashlight without any specific light source placed within body cavities. The new endoscope could visualize the target under ultralow illumination of approximately 100 lx. Very little could be visualized using the current endoscope, whereas the prototype generated clear images of the rabbit blood vessels under both ultralow illumination and extracorporeal illumination provided by a flashlight. The potential for damage caused by a light source can be minimized using our new endoscope, which results in safer and less invasive procedures. Further studies are under way to develop a nonilluminated endoscope without a light cable or source and to miniaturize the camera to decrease costs and improve the maneuverability of the entire endoscope system.

  18. Surface color perception under two illuminants: the second illuminant reduces color constancy

    NASA Technical Reports Server (NTRS)

    Yang, Joong Nam; Shevell, Steven K.

    2003-01-01

    This study investigates color perception in a scene with two different illuminants. The two illuminants, in opposite corners, simultaneously shine on a (simulated) scene with an opaque dividing wall, which controls how much of the scene is illuminated by each source. In the first experiment, the height of the dividing wall was varied. This changed the amount of each illuminant reaching objects on the opposite side of the wall. Results showed that the degree of color constancy decreased when a region on one side of the wall had cues to both illuminants, suggesting that cues from the second illuminant are detrimental to color constancy. In a later experiment, color constancy was found to improve when the specular highlight cues from the second illuminant were altered to be consistent with the first illuminant. This corroborates the influence of specular highlights in surface color perception, and suggests that the reduced color constancy in the first experiment is due to the inconsistent, though physically correct, cues from the two illuminants.

  19. Surface color perception under two illuminants: the second illuminant reduces color constancy

    NASA Technical Reports Server (NTRS)

    Yang, Joong Nam; Shevell, Steven K.

    2003-01-01

    This study investigates color perception in a scene with two different illuminants. The two illuminants, in opposite corners, simultaneously shine on a (simulated) scene with an opaque dividing wall, which controls how much of the scene is illuminated by each source. In the first experiment, the height of the dividing wall was varied. This changed the amount of each illuminant reaching objects on the opposite side of the wall. Results showed that the degree of color constancy decreased when a region on one side of the wall had cues to both illuminants, suggesting that cues from the second illuminant are detrimental to color constancy. In a later experiment, color constancy was found to improve when the specular highlight cues from the second illuminant were altered to be consistent with the first illuminant. This corroborates the influence of specular highlights in surface color perception, and suggests that the reduced color constancy in the first experiment is due to the inconsistent, though physically correct, cues from the two illuminants.

  20. Deterministic phase retrieval employing spherical illumination

    NASA Astrophysics Data System (ADS)

    Martínez-Carranza, J.; Falaggis, K.; Kozacki, T.

    2015-05-01

    Deterministic Phase Retrieval techniques (DPRTs) employ a series of paraxial beam intensities in order to recover the phase of a complex field. These paraxial intensities are usually generated in systems that employ plane-wave illumination. This type of illumination allows a direct processing of the captured intensities with DPRTs for recovering the phase. Furthermore, it has been shown that intensities for DPRTs can be acquired from systems that use spherical illumination as well. However, this type of illumination presents a major setback for DPRTs: the captured intensities change their size for each position of the detector on the propagation axis. In order to apply the DPRTs, reescalation of the captured intensities has to be applied. This condition can increase the error sensitivity of the final phase result if it is not carried out properly. In this work, we introduce a novel system based on a Phase Light Modulator (PLM) for capturing the intensities when employing spherical illumination. The proposed optical system enables us to capture the diffraction pattern of under, in, and over-focus intensities. The employment of the PLM allows capturing the corresponding intensities without displacing the detector. Moreover, with the proposed optical system we can control accurately the magnification of the captured intensities. Thus, the stack of captured intensities can be used in DPRTs, overcoming the problems related with the resizing of the images. In order to prove our claims, the corresponding numerical experiments will be carried out. These simulations will show that the retrieved phases with spherical illumination are accurate and can be compared with those that employ plane wave illumination. We demonstrate that with the employment of the PLM, the proposed optical system has several advantages as: the optical system is compact, the beam size on the detector plane is controlled accurately, and the errors coming from mechanical motion can be suppressed easily.

  1. Illumination compensation in ground based hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Wendel, Alexander; Underwood, James

    2017-07-01

    Hyperspectral imaging has emerged as an important tool for analysing vegetation data in agricultural applications. Recently, low altitude and ground based hyperspectral imaging solutions have come to the fore, providing very high resolution data for mapping and studying large areas of crops in detail. However, these platforms introduce a unique set of challenges that need to be overcome to ensure consistent, accurate and timely acquisition of data. One particular problem is dealing with changes in environmental illumination while operating with natural light under cloud cover, which can have considerable effects on spectral shape. In the past this has been commonly achieved by imaging known reference targets at the time of data acquisition, direct measurement of irradiance, or atmospheric modelling. While capturing a reference panel continuously or very frequently allows accurate compensation for illumination changes, this is often not practical with ground based platforms, and impossible in aerial applications. This paper examines the use of an autonomous unmanned ground vehicle (UGV) to gather high resolution hyperspectral imaging data of crops under natural illumination. A process of illumination compensation is performed to extract the inherent reflectance properties of the crops, despite variable illumination. This work adapts a previously developed subspace model approach to reflectance and illumination recovery. Though tested on a ground vehicle in this paper, it is applicable to low altitude unmanned aerial hyperspectral imagery also. The method uses occasional observations of reference panel training data from within the same or other datasets, which enables a practical field protocol that minimises in-field manual labour. This paper tests the new approach, comparing it against traditional methods. Several illumination compensation protocols for high volume ground based data collection are presented based on the results. The findings in this paper are

  2. Quantitative phase imaging with programmable illumination

    NASA Astrophysics Data System (ADS)

    Kim, Taewoo; Edwards, Chris; Goddard, Lynford L.; Popescu, Gabriel

    2015-03-01

    Even with the recent rapid advances in the field of microscopy, non-laser light sources used for light microscopy have not been developing significantly. Most current optical microscopy systems use halogen bulbs as their light sources to provide a white-light illumination. Due to the confined shapes and finite filament size of the bulbs, little room is available for modification in the light source, which prevents further advances in microscopy. By contrast, commercial projectors provide a high power output that is comparable to the halogen lamps while allowing for great flexibility in patterning the illumination. In addition to their high brightness, the illumination can be patterned to have arbitrary spatial and spectral distributions. Therefore, commercial projectors can be adopted as a flexible light source to an optical microscope by careful alignment to the existing optical path. In this study, we employed a commercial projector source to a quantitative phase imaging system called spatial light interference microscopy (SLIM), which is an outside module for an existing phase contrast (PC) microscope. By replacing the ring illumination of PC with a ring-shaped pattern projected onto the condenser plane, we were able to recover the same result as the original SLIM. Furthermore, the ring illumination is replaced with multiple dots aligned along the same ring to minimize the overlap between the scattered and unscattered fields. This new method minimizes the halo artifact of the imaging system, which allows for a halo-free high-resolution quantitative phase microscopy system.

  3. Lunar Polar Illumination for Power Analysis

    NASA Technical Reports Server (NTRS)

    Fincannon, James

    2008-01-01

    This paper presents illumination analyses using the latest Earth-based radar digital elevation model (DEM) of the lunar south pole and an independently developed analytical tool. These results enable the optimum sizing of solar/energy storage lunar surface power systems since they quantify the timing and durations of illuminated and shadowed periods. Filtering and manual editing of the DEM based on comparisons with independent imagery were performed and a reduced resolution version of the DEM was produced to reduce the analysis time. A comparison of the DEM with lunar limb imagery was performed in order to validate the absolute heights over the polar latitude range, the accuracy of which affects the impact of long range, shadow-casting terrain. Average illumination and energy storage duration maps of the south pole region are provided for the worst and best case lunar day using the reduced resolution DEM. Average illumination fractions and energy storage durations are presented for candidate low energy storage duration south pole sites. The best site identified using the reduced resolution DEM required a 62 hr energy storage duration using a fast recharge power system. Solar and horizon terrain elevations as well as illumination fraction profiles are presented for the best identified site and the data for both the reduced resolution and high resolution DEMs compared. High resolution maps for three low energy storage duration areas are presented showing energy storage duration for the worst case lunar day, surface height, and maximum absolute surface slope.

  4. Quantum Estimation Methods for Quantum Illumination

    NASA Astrophysics Data System (ADS)

    Sanz, M.; Las Heras, U.; García-Ripoll, J. J.; Solano, E.; Di Candia, R.

    2017-02-01

    Quantum illumination consists in shining quantum light on a target region immersed in a bright thermal bath with the aim of detecting the presence of a possible low-reflective object. If the signal is entangled with the receiver, then a suitable choice of the measurement offers a gain with respect to the optimal classical protocol employing coherent states. Here, we tackle this detection problem by using quantum estimation techniques to measure the reflectivity parameter of the object, showing an enhancement in the signal-to-noise ratio up to 3 dB with respect to the classical case when implementing only local measurements. Our approach employs the quantum Fisher information to provide an upper bound for the error probability, supplies the concrete estimator saturating the bound, and extends the quantum illumination protocol to non-Gaussian states. As an example, we show how Schrödinger's cat states may be used for quantum illumination.

  5. Quantum Estimation Methods for Quantum Illumination.

    PubMed

    Sanz, M; Las Heras, U; García-Ripoll, J J; Solano, E; Di Candia, R

    2017-02-17

    Quantum illumination consists in shining quantum light on a target region immersed in a bright thermal bath with the aim of detecting the presence of a possible low-reflective object. If the signal is entangled with the receiver, then a suitable choice of the measurement offers a gain with respect to the optimal classical protocol employing coherent states. Here, we tackle this detection problem by using quantum estimation techniques to measure the reflectivity parameter of the object, showing an enhancement in the signal-to-noise ratio up to 3 dB with respect to the classical case when implementing only local measurements. Our approach employs the quantum Fisher information to provide an upper bound for the error probability, supplies the concrete estimator saturating the bound, and extends the quantum illumination protocol to non-Gaussian states. As an example, we show how Schrödinger's cat states may be used for quantum illumination.

  6. Contrast edge colors under different natural illuminations.

    PubMed

    Nieves, Juan Luis; Nascimento, Sérgio M C; Romero, Javier

    2012-02-01

    Essential to sensory processing in the human visual system is natural illumination, which can vary considerably not only across space but also along the day depending on the atmospheric conditions and the sun's position in the sky. In this work, edges derived from the three postreceptoral Luminance, Red-Green, and Blue-Yellow signals were computed from hyperspectral images of natural scenes rendered with daylights of Correlated Color Temperatures (CCTs) from 2735 to 25,889 K; for low CCT, the same analysis was performed using Planckian illuminants up to 800 K. It was found that average luminance and chromatic edge contrasts were maximal for low correlated color temperatures and almost constants above 10,000 K. The magnitude of these contrast changes was, however, only about 2% across the tested daylights. Results suggest that the postreceptoral opponent and nonopponent color vision mechanisms produce almost constant responses for color edge detection under natural illumination.

  7. Content adaptive illumination for Fourier ptychography.

    PubMed

    Bian, Liheng; Suo, Jinli; Situ, Guohai; Zheng, Guoan; Chen, Feng; Dai, Qionghai

    2014-12-01

    Fourier ptychography (FP) is a recently reported technique, for large field-of-view and high-resolution imaging. Specifically, FP captures a set of low-resolution images, under angularly varying illuminations, and stitches them together in the Fourier domain. One of FP's main disadvantages is its long capturing process, due to the requisite large number of incident illumination angles. In this Letter, utilizing the sparsity of natural images in the Fourier domain, we propose a highly efficient method, termed adaptive Fourier ptychography (AFP), which applies content adaptive illumination for FP, to capture the most informative parts of the scene's spatial spectrum. We validate the effectiveness and efficiency of the reported framework, with both simulated and real experiments. Results show that the proposed AFP could shorten the acquisition time of conventional FP, by around 30%-60%.

  8. 30 CFR 57.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Illumination of surface working areas. 57.17001... Illumination § 57.17001 Illumination of surface working areas. Illumination sufficient to provide safe working conditions shall be provided in and on all surface structures, paths, walkways, stairways, switch...

  9. 30 CFR 56.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Illumination of surface working areas. 56.17001... NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Illumination § 56.17001 Illumination of surface working areas. Illumination sufficient to provide safe...

  10. 30 CFR 57.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Illumination of surface working areas. 57.17001... Illumination § 57.17001 Illumination of surface working areas. Illumination sufficient to provide safe working conditions shall be provided in and on all surface structures, paths, walkways, stairways, switch...

  11. 30 CFR 56.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Illumination of surface working areas. 56.17001... NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Illumination § 56.17001 Illumination of surface working areas. Illumination sufficient to provide safe working...

  12. 30 CFR 56.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Illumination of surface working areas. 56.17001... NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Illumination § 56.17001 Illumination of surface working areas. Illumination sufficient to provide safe working...

  13. 30 CFR 57.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Illumination of surface working areas. 57.17001... Illumination § 57.17001 Illumination of surface working areas. Illumination sufficient to provide safe working conditions shall be provided in and on all surface structures, paths, walkways, stairways, switch panels...

  14. 30 CFR 57.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Illumination of surface working areas. 57.17001... Illumination § 57.17001 Illumination of surface working areas. Illumination sufficient to provide safe working conditions shall be provided in and on all surface structures, paths, walkways, stairways, switch panels...

  15. 30 CFR 56.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Illumination of surface working areas. 56.17001... NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Illumination § 56.17001 Illumination of surface working areas. Illumination sufficient to provide safe working...

  16. 30 CFR 57.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Illumination of surface working areas. 57.17001... Illumination § 57.17001 Illumination of surface working areas. Illumination sufficient to provide safe working conditions shall be provided in and on all surface structures, paths, walkways, stairways, switch panels...

  17. Illumination-compensated non-contact imaging photoplethysmography via dual-mode temporally coded illumination

    NASA Astrophysics Data System (ADS)

    Amelard, Robert; Scharfenberger, Christian; Wong, Alexander; Clausi, David A.

    2015-03-01

    Non-contact camera-based imaging photoplethysmography (iPPG) is useful for measuring heart rate in conditions where contact devices are problematic due to issues such as mobility, comfort, and sanitation. Existing iPPG methods analyse the light-tissue interaction of either active or passive (ambient) illumination. Many active iPPG methods assume the incident ambient light is negligible to the active illumination, resulting in high power requirements, while many passive iPPG methods assume near-constant ambient conditions. These assumptions can only be achieved in environments with controlled illumination and thus constrain the use of such devices. To increase the number of possible applications of iPPG devices, we propose a dual-mode active iPPG system that is robust to changes in ambient illumination variations. Our system uses a temporally-coded illumination sequence that is synchronized with the camera to measure both active and ambient illumination interaction for determining heart rate. By subtracting the ambient contribution, the remaining illumination data can be attributed to the controlled illuminant. Our device comprises a camera and an LED illuminant controlled by a microcontroller. The microcontroller drives the temporal code via synchronizing the frame captures and illumination time at the hardware level. By simulating changes in ambient light conditions, experimental results show our device is able to assess heart rate accurately in challenging lighting conditions. By varying the temporal code, we demonstrate the trade-off between camera frame rate and ambient light compensation for optimal blood pulse detection.

  18. Design Principles of Nonimaging Waveguide Illumination Systems

    NASA Astrophysics Data System (ADS)

    Hough, Thomas Arthur

    1995-01-01

    Optical systems that illuminate objects or filter planes with light exiting thick waveguides are called waveguide illumination systems. In this dissertation, we develop the optical theory that describes flux transport in waveguide illumination systems. We constructed three computer-controlled light detection systems to measure and map the flux exiting waveguide illumination system components. The goniophotometer measures and maps the intensity distributions of waveguide illumination system light sources. As an example, we use the goniophotometer to measure the intensity distribution from an incandescent light bulb. We then model the intensity pattern according to radiometric theory. The translational photometer measures and maps the existence of thick waveguides. Data from the translational photometer is evaluated for uniformity with the output uniformity index (OUI). The OUI is a statistical figure of merit based on the standard deviation. The transrotational photometer measures the angular distribution of the flux exiting thick waveguides. By applying Snell's law to the transrotational photometer data, we determine the angular distribution of the flux propagating in the waveguide. We use imaging optics theory to show that thick waveguides are nonimaging systems. We then expand existing nonimaging optics theory to describe flux transport in thick waveguides. We define the angular edge rays, and use the angular edge ray concept to develop the flux confinement properties of a thick waveguide in terms of its geometry and index of refraction. We use FCD analysis to develop a closed-form functional solution for the flux lost due to a bend in a thick rectangular waveguide. We perform an experiment that verifies the predictions of this model. In the experiment, we use the translational photometer to measure the total flux exiting a series of waveguides with bends in them. The bends range from zero to 90 degrees. Finally, we present a new streamlined technique for the

  19. Concentrated and piped sunlight for indoor illumination.

    PubMed

    Fraas, L M; Pyle, W R; Ryason, P R

    1983-02-15

    A concept for indoor illumination of buildings using sunlight is described. For this system, a tracking concentrator on the building roof follows the sun and focuses sunlight into a lightguide. A system of transparent lightguides distributes the sunlight to interior rooms. Recent advances in the transparency of acrylic plastic optical fibers suggest that acrylic lightguides could be successfully used for piping sunlight. The proposed system displaces electricity currently used for indoor lighting. It is argued that using sunlight directly for indoor illumination would be about twenty-five times more cost-effective than using sunlight to generate electricity with solar cells for powering electric lamps for indoor lighting.

  20. Fiber-type dosimeter with improved illuminator

    DOEpatents

    Fox, Richard J.

    1987-01-01

    A single-piece, molded plastic, Cassigrainian-type condenser arrangement is incorporated in a tubular-shaped personal pocket dosimeter of the type which combines an ionization chamber with an optically-read fiber electrometer to provide improved illumination of the electrometer fiber. The condenser routes incoming light from one end of the dosimeter tubular housing around a central axis charging pin assembly and focuses the light at low angles to the axis so that it falls within the acceptance angle of the electrometer fiber objective lens viewed through an eyepiece lens disposed in the opposite end of the dosimeter. This results in improved fiber illumination and fiber image contrast.

  1. Fiber-type dosimeter with improved illuminator

    DOEpatents

    Fox, R.J.

    1985-12-23

    A single-piece, molded plastic, Cassigrainian-type condenser arrangement is incorporated in a tubular-shaped personal pocket dosimeter of the type which combines an ionization chamber with an optically-read fiber electrometer to provide improved illumination of the electrometer fiber. The condenser routes incoming light from one end of the dosimeter tubular housing around a central axis charging pin assembly and focuses the light at low angles to the axis so that it falls within the acceptance angle of the electrometer fiber objective lens viewed through an eyepiece lens disposed in the opposite end of the dosimeter. This results in improved fiber illumination and fiber image contrast.

  2. Organic light emitting devices for illumination

    DOEpatents

    Hack, Michael [Lambertville, NJ; Lu, Min-Hao Michael [Lawrenceville, NJ; Weaver, Michael S [Princeton, NJ

    2012-01-24

    An organic light emitting device an a method of obtaining illumination from such a device is provided. The device has a plurality of regions, each region having an organic emissive layer adapted to emit a different spectrum of light. The regions in combination emit light suitable for illumination purposes. The area of each region may be selected such that the device is more efficient than an otherwise equivalent device having regions of equal size. The regions may have an aspect ratio of at least about four. All parts of any given region may be driven at the same current.

  3. Highlight area inpainting guided by illumination model

    NASA Astrophysics Data System (ADS)

    Wang, Yifan; Jiang, Zhiguo; Shi, Jun

    2014-01-01

    In this paper, we proposed a two-step algorithm based on the combination of the exemplar-based algorithm and the illumination model to deal with specular images, especially those contain saturated pixels in the highlight areas. First the proposed modified exemplar-based algorithm is employed to process the unsaturated specular pixels under the supervision of illumination model. Then we inpaint the rest regions in which the pixels are saturated with original exemplar-based algorithm to obtain the final result. Experimental results demonstrate that the proposed algorithm performs better on the images with saturated pixels in the highlight areas compared with classical highlight removal and image inpainting algorithms.

  4. Resolution enhancement using simultaneous couple illumination

    NASA Astrophysics Data System (ADS)

    Hussain, Anwar; Martínez Fuentes, José Luis

    2016-10-01

    A super-resolution technique based on structured illumination created by a liquid crystal on silicon spatial light modulator (LCOS-SLM) is presented. Single and simultaneous pairs of tilted beams are generated to illuminate a target object. Resolution enhancement of an optical 4f system is demonstrated by using numerical simulations. The resulting intensity images are recorded at a charged couple device (CCD) and stored in the computer memory for further processing. One dimension enhancement can be performed with only 15 images. Two dimensional complete improvement requires 153 different images. The resolution of the optical system is extended three times compared to the band limited system.

  5. Fused off-axis object illumination direct-to-digital holography with a plurality of illumination sources

    DOEpatents

    Price, Jeffery R.; Bingham, Philip R.

    2005-11-08

    Systems and methods are described for rapid acquisition of fused off-axis illumination direct-to-digital holography. A method of recording a plurality of off-axis object illuminated spatially heterodyne holograms, each of the off-axis object illuminated spatially heterodyne holograms including spatially heterodyne fringes for Fourier analysis, includes digitally recording, with a first illumination source of an interferometer, a first off-axis object illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis; and digitally recording, with a second illumination source of the interferometer, a second off-axis object illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis.

  6. Efficient illumination for microsecond tracking microscopy.

    PubMed

    Dulin, David; Barland, Stephane; Hachair, Xavier; Pedaci, Francesco

    2014-01-01

    The possibility to observe microsecond dynamics at the sub-micron scale, opened by recent technological advances in fast camera sensors, will affect many biophysical studies based on particle tracking in optical microscopy. A main limiting factor for further development of fast video microscopy remains the illumination of the sample, which must deliver sufficient light to the camera to allow microsecond exposure times. Here we systematically compare the main illumination systems employed in holographic tracking microscopy, and we show that a superluminescent diode and a modulated laser diode perform the best in terms of image quality and acquisition speed, respectively. In particular, we show that the simple and inexpensive laser illumination enables less than 1 μs camera exposure time at high magnification on a large field of view without coherence image artifacts, together with a good hologram quality that allows nm-tracking of microscopic beads to be performed. This comparison of sources can guide in choosing the most efficient illumination system with respect to the specific application.

  7. Diffuse-Illumination Systems for Growing Plants

    NASA Technical Reports Server (NTRS)

    May, George; Ryan, Robert

    2010-01-01

    Agriculture in both terrestrial and space-controlled environments relies heavily on artificial illumination for efficient photosynthesis. Plant-growth illumination systems require high photon flux in the spectral range corresponding with plant photosynthetic active radiation (PAR) (400 700 nm), high spatial uniformity to promote uniform growth, and high energy efficiency to minimize electricity usage. The proposed plant-growth system takes advantage of the highly diffuse reflective surfaces on the interior of a sphere, hemisphere, or other nearly enclosed structure that is coated with highly reflective materials. This type of surface and structure uniformly mixes discrete light sources to produce highly uniform illumination. Multiple reflections from within the domelike structures are exploited to obtain diffuse illumination, which promotes the efficient reuse of photons that have not yet been absorbed by plants. The highly reflective surfaces encourage only the plant tissue (placed inside the sphere or enclosure) to absorb the light. Discrete light sources, such as light emitting diodes (LEDs), are typically used because of their high efficiency, wavelength selection, and electronically dimmable properties. The light sources are arranged to minimize shadowing and to improve uniformity. Different wavelengths of LEDs (typically blue, green, and red) are used for photosynthesis. Wavelengths outside the PAR range can be added for plant diagnostics or for growth regulation

  8. Freeform LED lens for rectangularly prescribed illumination

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Liu, Sheng; Chen, Fei; Qin, Zong; Liu, Zongyuan; Luo, Xiaobing

    2009-10-01

    Freeform lenses are playing a more and more important role in LED secondary optics design. In this study, based on the new light energy mapping relationship, edge ray principle, Snell's law and error control of surface construction, a modified discontinuous freeform lens design method was presented for rectangularly prescribed illumination, with the advantages of a flexible energy mapping relationship, accurate light irradiation control and easier to manufacture. A polymethyl methacrylate (PMMA) discontinuous freeform lens was designed as an example for LED tunnel illumination according to this method. The numerical simulation results demonstrated that the light pattern of the lens was in good agreement with the expected illumination performance when using a point source. Tolerance analyses were also conducted. An extended light source had little effect on the light output efficiency (LOE) of the lens but significantly decreased the effective illumination area. Installation errors had more effect on the uniformity and shape of the light pattern than the LOE of the lens. The tolerances of vertical, horizontal and rotational deviation of this lens were 0.4 mm, 0.4 mm and 2°, respectively.

  9. Evolving illumination parameters for improved target recognition

    NASA Astrophysics Data System (ADS)

    Courte, D.; Tamburino, L.; Rizki, M.

    2006-05-01

    Color is an important feature for object recognition in security and military applications. Unfortunately, color is sensitive to the environmental operating conditions so its use for automatic target recognition is often limited. Recently a number of research efforts have focused on techniques for developing algorithms to improve color constancy across images. Many of these approaches attempt to improve the color constancy of a particular type of surface area such as skin. In contrast, we present an approach that attempts to address color constancy of many surfaces across a wide range of external environmental conditions in the absence of direct knowledge of illumination. Our approach builds on existing techniques by using evolutionary learning to synthesize features that characterize the illuminations that influence perception of color. Once the illumination of each image in a collection is estimated, it can be used to map the colors in an image to the illumination conditions in any other image. This would allows us to take an image from that collection, transform its colors to reference colors that can then be combined with other types of features (e.g. geometrical, statistical, and textural) to cerate automatic target recognition systems that are relatively insensitive to their operating conditions. To demonstrate our technique, we process images of a parking area under a wide variety of seasonal weather conditions collected across large timescales of hours, days, and months.

  10. Lighting design for globally illuminated volume rendering.

    PubMed

    Zhang, Yubo; Ma, Kwan-Liu

    2013-12-01

    With the evolution of graphics hardware, high quality global illumination becomes available for real-time volume rendering. Compared to local illumination, global illumination can produce realistic shading effects which are closer to real world scenes, and has proven useful for enhancing volume data visualization to enable better depth and shape perception. However, setting up optimal lighting could be a nontrivial task for average users. There were lighting design works for volume visualization but they did not consider global light transportation. In this paper, we present a lighting design method for volume visualization employing global illumination. The resulting system takes into account view and transfer-function dependent content of the volume data to automatically generate an optimized three-point lighting environment. Our method fully exploits the back light which is not used by previous volume visualization systems. By also including global shadow and multiple scattering, our lighting system can effectively enhance the depth and shape perception of volumetric features of interest. In addition, we propose an automatic tone mapping operator which recovers visual details from overexposed areas while maintaining sufficient contrast in the dark areas. We show that our method is effective for visualizing volume datasets with complex structures. The structural information is more clearly and correctly presented under the automatically generated light sources.

  11. 29 CFR 1918.92 - Illumination.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... operations, illumination for cargo transfer operations shall be of a minimum light intensity of five foot-candles (54 lux). Where work tasks require more light to be performed safely, supplemental lighting shall be used. (b) Intensity measurement. The lighting intensity shall be measured at the...

  12. 29 CFR 1918.92 - Illumination.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... operations, illumination for cargo transfer operations shall be of a minimum light intensity of five foot-candles (54 lux). Where work tasks require more light to be performed safely, supplemental lighting shall be used. (b) Intensity measurement. The lighting intensity shall be measured at the...

  13. 29 CFR 1918.92 - Illumination.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... operations, illumination for cargo transfer operations shall be of a minimum light intensity of five foot-candles (54 lux). Where work tasks require more light to be performed safely, supplemental lighting shall be used. (b) Intensity measurement. The lighting intensity shall be measured at the...

  14. 29 CFR 1918.92 - Illumination.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... operations, illumination for cargo transfer operations shall be of a minimum light intensity of five foot-candles (54 lux). Where work tasks require more light to be performed safely, supplemental lighting shall be used. (b) Intensity measurement. The lighting intensity shall be measured at the...

  15. 29 CFR 1926.26 - Illumination.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Illumination. 1926.26 Section 1926.26 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION General Safety and Health Provisions § 1926.26...

  16. 29 CFR 1926.26 - Illumination.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 8 2012-07-01 2012-07-01 false Illumination. 1926.26 Section 1926.26 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION General Safety and Health Provisions § 1926.26...

  17. 29 CFR 1926.26 - Illumination.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 8 2013-07-01 2013-07-01 false Illumination. 1926.26 Section 1926.26 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION General Safety and Health Provisions § 1926.26...

  18. Deconvolution methods for structured illumination microscopy.

    PubMed

    Chakrova, Nadya; Rieger, Bernd; Stallinga, Sjoerd

    2016-07-01

    We compare two recently developed multiple-frame deconvolution approaches for the reconstruction of structured illumination microscopy (SIM) data: the pattern-illuminated Fourier ptychography algorithm (piFP) and the joint Richardson-Lucy deconvolution (jRL). The quality of the images reconstructed by these methods is compared in terms of the achieved resolution improvement, noise enhancement, and inherent artifacts. Furthermore, we study the issue of object-dependent resolution improvement by considering the modulation transfer functions derived from different types of objects. The performance of the considered methods is tested in experiments and benchmarked with a commercial SIM microscope. We find that the piFP method resolves periodic and isolated structures equally well, whereas the jRL method provides significantly higher resolution for isolated objects compared to periodic ones. Images reconstructed by the piFP and jRL algorithms are comparable to the images reconstructed using the generalized Wiener filter applied in most commercial SIM microscopes. An advantage of the discussed algorithms is that they allow the reconstruction of SIM images acquired under different types of illumination, such as multi-spot or random illumination.

  19. 49 CFR 230.86 - Required illumination.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and.... Each steam locomotive used between sunset and sunrise shall be equipped with an operable headlight that provides illumination sufficient for a steam locomotive engineer in the cab to see, in a clear atmosphere...

  20. 49 CFR 230.86 - Required illumination.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and.... Each steam locomotive used between sunset and sunrise shall be equipped with an operable headlight that provides illumination sufficient for a steam locomotive engineer in the cab to see, in a clear atmosphere...

  1. 49 CFR 230.86 - Required illumination.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and.... Each steam locomotive used between sunset and sunrise shall be equipped with an operable headlight that provides illumination sufficient for a steam locomotive engineer in the cab to see, in a clear atmosphere...

  2. Lit appearance modeling of illumination systems

    NASA Astrophysics Data System (ADS)

    Koshel, R. John

    2002-09-01

    In illumination systems the look and feel are often more important than objective criterion, such as uniformity and efficiency. The reason for this is two fold: the lit appearance often sells an item and substantial variation in the illumination distribution (up to 50%) over a broad region is not noticeable to an observer. Therefore, subjective criterion, such as the lit appearance, typically plays a crucial role in the development of an illumination system. Additionally, by using computer models to ascertain the lit appearance before manufacture of the system, it allows the designer to modify the system while not demanding investment to produce prototypes. I discuss methods of determining the lit appearance for illumination systems. This modeling includes the inclusion of material and surface properties, such as surface finish, spectral transmission, and internal scattering; the response of the human eye; and the amount of rays that must be traced. By archiving the ray data, animations as a function of position and angle can be developed. Examples are developed to highlight the utility of this technique. These examples include taillights for the automotive industry and a backlit LCD screen for a laptop. Animations of these models demonstrate their luminance.

  3. Adaptive Illumination Patterns for Radar Applications

    DTIC Science & Technology

    2006-03-01

    Losses . . . . . . . . . . . . . . . . . . . . . . . . . 44 Ri Range to the i th range ring . . . . . . . . . . . . . . . . . 44 R Signal-Dependent...Interval . . . . . . . . . . . . . . . . . . . 23 R /H Range-to-Height Ratio . . . . . . . . . . . . . . . . . . . . 51 RMB Reed Mallet and Brennan Rule...as follows: 16 AIP-TIPD Planar Array Radar Model Extensions I - I l r rr r l t i Space Time Illumination Patterns (STIP) i Ill i ti tt r ( I

  4. Selective plane illumination microscopy on a chip.

    PubMed

    Paiè, Petra; Bragheri, Francesca; Bassi, Andrea; Osellame, Roberto

    2016-04-26

    Selective plane illumination microscopy can image biological samples at a high spatiotemporal resolution. Complex sample preparation and system alignment normally limit the throughput of the method. Using femtosecond laser micromachining, we created an integrated optofluidic device that allows obtaining continuous flow imaging, three-dimensional reconstruction and high-throughput analysis of large multicellular spheroids at a subcellular resolution.

  5. 29 CFR 1915.92 - Illumination.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... shall be adequately illuminated. (b) Temporary lights shall meet the following requirements: (1) Temporary lights shall be equipped with guards to prevent accidental contact with the bulb, except that guards are not required when the construction of the reflector is such that the bulb is deeply recessed...

  6. 29 CFR 1917.123 - Illumination. 9

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-candles. The illumination in other work areas (for example, farm areas) shall be of an average minimum light intensity of 1 foot-candle except for security purposes when a minimum light intensity of 1/2 foot-candle shall be maintained. Where occasional work tasks require more light than that which is...

  7. 29 CFR 1917.123 - Illumination. 9

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-candles. The illumination in other work areas (for example, farm areas) shall be of an average minimum light intensity of 1 foot-candle except for security purposes when a minimum light intensity of 1/2 foot-candle shall be maintained. Where occasional work tasks require more light than that which is...

  8. 29 CFR 1917.123 - Illumination. 9

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-candles. The illumination in other work areas (for example, farm areas) shall be of an average minimum light intensity of 1 foot-candle except for security purposes when a minimum light intensity of 1/2 foot-candle shall be maintained. Where occasional work tasks require more light than that which is...

  9. 29 CFR 1917.123 - Illumination. 9

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-candles. The illumination in other work areas (for example, farm areas) shall be of an average minimum light intensity of 1 foot-candle except for security purposes when a minimum light intensity of 1/2 foot-candle shall be maintained. Where occasional work tasks require more light than that which is...

  10. 29 CFR 1917.123 - Illumination. 9

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-candles. The illumination in other work areas (for example, farm areas) shall be of an average minimum light intensity of 1 foot-candle except for security purposes when a minimum light intensity of 1/2 foot-candle shall be maintained. Where occasional work tasks require more light than that which is...

  11. 29 CFR 1918.92 - Illumination.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) Walking, working, and climbing areas. Walking, working, and climbing areas shall be illuminated. Unless conditions described in the regulations of the U.S. Coast Guard (33 CFR 154.570) exist for specific... surface, in the plane in which the task/working surface is present. (c) Arrangement of lights. Lights...

  12. Multi-Perspective Illumination: A Case Study.

    ERIC Educational Resources Information Center

    Melton, R. F.; Zimmer, R. S.

    1987-01-01

    This description of an illuminative evaluation process as a qualitative research method focuses on a study of concerns about financial constraints in the British Open University. Interviews and open-ended discussions were used to encourage participation and input by a wide variety of individuals with differing perspectives on the problem. (LRW)

  13. 49 CFR 230.86 - Required illumination.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and.... Each steam locomotive used between sunset and sunrise shall be equipped with an operable headlight that provides illumination sufficient for a steam locomotive engineer in the cab to see, in a clear atmosphere...

  14. 49 CFR 230.86 - Required illumination.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and.... Each steam locomotive used between sunset and sunrise shall be equipped with an operable headlight that provides illumination sufficient for a steam locomotive engineer in the cab to see, in a clear atmosphere...

  15. A Quantitative Measure of Field Illumination

    PubMed Central

    Brown, Claire M.; Reilly, Andrew

    2015-01-01

    In this paper, we describe a statistically based algorithm to quantify the uniformity of illumination in an optical light microscopy imaging system that outputs a single quality factor (QF) score. The importance of homogeneous field illumination in quantitative light microscopy is well understood and often checked. However, there is currently no standard automatic quantitative measure of the uniformity of the field illumination. Images from 89 different laser-scanning confocal microscopes (LSCMs), which were collected as part of an international study on microscope quality assessment, were used as a “training” set to build the algorithm. To validate the algorithm and verify its robustness, images from 33 additional microscopes, including LSCM and wide-field (WF) microscopes, were used. The statistical paradigm used for developing the quality scoring scale was a regression approach to supervised learning. Three intensity profiles across each image—2 corner-to-corner diagonals and a center horizontal—were used to generate pixel-intensity data. All of the lines passed through the center of the image. The intensity profile data then were converted into a single-field illumination QF score in the range of 0–100, with 0 having extreme variation, and therefore, essentially unusable, and 100 having no deviation, i.e., straight lines with a constant uniform intensity. Empirically, a QF ≥ 83 was determined to be the minimum acceptable value based on manufacturer acceptance tests and reasonably achievable values. This new QF is an invaluable metric to ascertain objectively and easily the uniformity of illumination quality, provide a traceable reference for monitoring field uniformity over time, and make a direct comparison among different microscopes. The QF can also be used as an indicator of system failure and the need for alignment or service of the instrument. PMID:25802488

  16. Reflectance, illumination, and appearance in color constancy

    PubMed Central

    McCann, John J.; Parraman, Carinna; Rizzi, Alessandro

    2013-01-01

    We studied color constancy using a pair of identical 3-D Color Mondrian displays. We viewed one 3-D Mondrian in nearly uniform illumination, and the other in directional, nonuniform illumination. We used the three dimensional structures to modulate the light falling on the painted surfaces. The 3-D structures in the displays were a matching set of wooden blocks. Across Mondrian displays, each corresponding facet had the same paint on its surface. We used only 6 chromatic, and 5 achromatic paints applied to 104 block facets. The 3-D blocks add shadows and multiple reflections not found in flat Mondrians. Both 3-D Mondrians were viewed simultaneously, side-by-side. We used two techniques to measure correlation of appearance with surface reflectance. First, observers made magnitude estimates of changes in the appearances of identical reflectances. Second, an author painted a watercolor of the 3-D Mondrians. The watercolor's reflectances quantified the changes in appearances. While constancy generalizations about illumination and reflectance hold for flat Mondrians, they do not for 3-D Mondrians. A constant paint does not exhibit perfect color constancy, but rather shows significant shifts in lightness, hue and chroma in response to the structure in the nonuniform illumination. Color appearance depends on the spatial information in both the illumination and the reflectances of objects. The spatial information of the quanta catch from the array of retinal receptors generates sensations that have variable correlation with surface reflectance. Models of appearance in humans need to calculate the departures from perfect constancy measured here. This article provides a dataset of measurements of color appearances for computational models of sensation. PMID:24478738

  17. Illumination Normalization of Face Image Based on Illuminant Direction Estimation and Improved Retinex

    PubMed Central

    Yi, Jizheng; Mao, Xia; Chen, Lijiang; Xue, Yuli; Rovetta, Alberto; Caleanu, Catalin-Daniel

    2015-01-01

    Illumination normalization of face image for face recognition and facial expression recognition is one of the most frequent and difficult problems in image processing. In order to obtain a face image with normal illumination, our method firstly divides the input face image into sixteen local regions and calculates the edge level percentage in each of them. Secondly, three local regions, which meet the requirements of lower complexity and larger average gray value, are selected to calculate the final illuminant direction according to the error function between the measured intensity and the calculated intensity, and the constraint function for an infinite light source model. After knowing the final illuminant direction of the input face image, the Retinex algorithm is improved from two aspects: (1) we optimize the surround function; (2) we intercept the values in both ends of histogram of face image, determine the range of gray levels, and stretch the range of gray levels into the dynamic range of display device. Finally, we achieve illumination normalization and get the final face image. Unlike previous illumination normalization approaches, the method proposed in this paper does not require any training step or any knowledge of 3D face and reflective surface model. The experimental results using extended Yale face database B and CMU-PIE show that our method achieves better normalization effect comparing with the existing techniques. PMID:25906370

  18. Compact laser illumination system for endoscopic interventions.

    PubMed

    Blase, Bastian

    2015-08-01

    External cold light sources as well as LEDs are commonly used for abdominal illumination in minimally invasive surgery. Still, both feature certain disadvantages. A new illumination system for endoscopes based on laser diodes is placed in the handle. No external light cables are needed. High conversion and coupling efficiencies and small package size allow for several diodes to be integrated, enabling color mixing and the adjustment of color temperatures. An optical module to collimate and combine the light is described. The heat to be dissipated is stored in a passive latent heat storage based on phase change materials surrounding the optical module. Thereby, operation time is considerably extended, as the handle's temperature is stabilized. To reduce the negative effect of coherent light on optical rough surfaces leading to patterns of spots, several devices for speckle reduction are developed and tested. By combining these components, an assembly of a powerful RGB laser light module for the integration in standard sized endoscopes is formed.

  19. Multispectral computational ghost imaging with multiplexed illumination

    NASA Astrophysics Data System (ADS)

    Huang, Jian; Shi, Dongfeng

    2017-07-01

    Computational ghost imaging has attracted wide attention from researchers in many fields over the last two decades. Multispectral imaging as one application of computational ghost imaging possesses spatial and spectral resolving abilities, and is very useful for surveying scenes and extracting detailed information. Existing multispectral imagers mostly utilize narrow band filters or dispersive optical devices to separate light of different wavelengths, and then use multiple bucket detectors or an array detector to record them separately. Here, we propose a novel multispectral ghost imaging method that uses one single bucket detector with multiplexed illumination to produce a colored image. The multiplexed illumination patterns are produced by three binary encoded matrices (corresponding to the red, green and blue colored information, respectively) and random patterns. The results of the simulation and experiment have verified that our method can be effective in recovering the colored object. Multispectral images are produced simultaneously by one single-pixel detector, which significantly reduces the amount of data acquisition.

  20. Insulator Surface Flashover Due to UV Illumination

    SciTech Connect

    Javedani, J B; Houck, T L; Lahowe, D A; Vogtlin, G E; Goerz, D A

    2009-07-27

    The surface of an insulator under vacuum and under electrical charge will flashover when illuminated by a critical dose of ultra-violet (UV) radiation - depending on the insulator size and material, insulator cone angle, the applied voltage and insulator shot-history. A testbed comprised of an excimer laser (KrF, 248 nm, {approx}16 MW, 30 ns FWHM,), a vacuum chamber, and a negative polarity dc high voltage power supply ({le} -60 kV) were assembled to test 1.0 cm thick angled insulators for surface-flashover. Several candidate insulator materials, e.g. High Density Polyethylene (HDPE), Rexolite{reg_sign} 1400, Macor{trademark} and Mycalex, of varying cone angles were tested against UV illumination. Commercial energy meters were used to measure the UV fluence of the pulsed laser beam. In-house designed and fabricated capacitive probes (D-dots, >12 GHz bandwidth) were embedded in the anode electrode underneath the insulator to determine the time of UV arrival and time of flashover. Of the tested insulators, the +45 degree Rexolite insulator showed more resistance to UV for surface flashover; at UV fluence level of less than 13 mJ/cm{sup 2}, it was not possible to induce a flashover for up to -60 kV of DC potential across the insulator's surface. The probes also permitted the electrical charge on the insulator before and after flashover to be inferred. Photon to electron conversion efficiency for the surface of Rexolite insulator was determined from charge-balance equation. In order to understand the physical mechanism leading to flashover, we further experimented with the +45 degree Rexolite insulator by masking portions of the UV beam to illuminate only a section of the insulator surface; (1) the half nearest the cathode and subsequently, (2) the half nearest the anode. The critical UV fluence and time to flashover were measured and the results in each case were then compared with the base case of full-beam illumination. It was discovered that the time for the

  1. Pulsed laser illumination of photovoltaic cells

    NASA Technical Reports Server (NTRS)

    Yater, Jane A.; Lowe, Roland A.; Jenkins, Phillip P.; Landis, Geoffrey A.

    1994-01-01

    In future space missions, free electron lasers (FEL) may be used to illuminate photovoltaic array receivers to provide remote power. Both the radio-frequency (RF) and induction FEL provide FEL produce pulsed rather than continuous output. In this work we investigate cell response to pulsed laser light which simulates the RF FEL format. The results indicate that if the pulse repetition is high, cell efficiencies are only slightly reduced compared to constant illumination at the same wavelength. The frequency response of the cells is weak, with both voltage and current outputs essentially dc in nature. Comparison with previous experiments indicates that the RF FEL pulse format yields more efficient photovoltaic conversion than does an induction FEL pulse format.

  2. Pulsed laser illumination of photovoltaic cells

    NASA Technical Reports Server (NTRS)

    Yater, Jane A.; Lowe, Roland A.; Jenkins, Phillip P.; Landis, Geoffrey A.

    1995-01-01

    In future space missions, free electron lasers (FEL) may be used to illuminate photovoltaic receivers to provide remote power. Both the radio-frequency (RF) and induction FEL produce pulsed rather than continuous output. In this work we investigate cell response to pulsed laser light which simulates the RF FEL format. The results indicate that if the pulse repetition is high, cell efficiencies are only slightly reduced compared to constant illumination at the same wavelength. The frequency response of the cells is weak, with both voltage and current outputs essentially dc in nature. Comparison with previous experiments indicates that the RF FEL pulse format yields more efficient photovoltaic conversion than does an induction FEL format.

  3. LED illuminator for a microdisplay projector

    NASA Astrophysics Data System (ADS)

    Magarill, Simon

    2012-10-01

    An illumination system for a microdisplay projector with a two-step imaging system is described here. In the first step, an imaging condenser creates an image of the LED at the color combiner entrance window. In the second step, we relay the image of the integrator exit window onto the micro-display. The illuminator demonstrates high collection efficiency, small footprint, and efficient mixing of light from RGB LEDs that provides required uniformity. A variety of approaches to collecting light emitted from LEDs of various types are compared, leading to the two-step design. A design example using a 0.55" diagonal DLP-based optical engine is presented with the following characteristics: Footprint: 3.9"x3.3"x2.0" (25.7 cubic inches) Light output: 338 white lumens Efficiency: 4.7 lm/watt

  4. Microscope illumination systems for 157 nm

    NASA Astrophysics Data System (ADS)

    Pesch, Alexander; Uhlendorf, Kristina; Deparnay, Arnaud; Erdmann, Lars; Kuschnerus, Peter; Engel, Thomas; Brunner, Robert

    2003-05-01

    The image quality of an inspection microscope depends strongly on the performance of the illumination system. Especially in the case of laser-based illumination it is necessary to transform the original beam profile into a homogeneous light spot with a flat top field distribution. Simultaneously, speckles caused by the coherence of the laser have to be reduced. Here we discuss different ways to homogenize the multi mode beam profile of a pulsed compact 157 nm excimer laser. A variety of setups, combining dynamic acting diffusers, microlens arrays and primary lenses were realized and characterized in several geometrical arrangements. The homogenizers were evaluated and characterized especially with respect to the statistical behavior on the integrated pulse number.

  5. Alternative Packaging for Back-Illuminated Imagers

    NASA Technical Reports Server (NTRS)

    Pain, Bedabrata

    2009-01-01

    An alternative scheme has been conceived for packaging of silicon-based back-illuminated, back-side-thinned complementary metal oxide/semiconductor (CMOS) and charge-coupled-device image-detector integrated circuits, including an associated fabrication process. This scheme and process are complementary to those described in "Making a Back-Illuminated Imager With Back-Side Connections" (NPO-42839), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), page 38. To avoid misunderstanding, it should be noted that in the terminology of imaging integrated circuits, "front side" or "back side" does not necessarily refer to the side that, during operation, faces toward or away from a source of light or other object to be imaged. Instead, "front side" signifies that side of a semiconductor substrate upon which the pixel pattern and the associated semiconductor devices and metal conductor lines are initially formed during fabrication, and "back side" signifies the opposite side. If the imager is of the type called "back-illuminated," then the back side is the one that faces an object to be imaged. Initially, a back-illuminated, back-side-thinned image-detector is fabricated with its back side bonded to a silicon handle wafer. At a subsequent stage of fabrication, the front side is bonded to a glass wafer (for mechanical support) and the silicon handle wafer is etched away to expose the back side. The frontside integrated circuitry includes metal input/output contact pads, which are rendered inaccessible by the bonding of the front side to the glass wafer. Hence, one of the main problems is to make the input/output contact pads accessible from the back side, which is ultimately to be the side accessible to the external world. The present combination of an alternative packaging scheme and associated fabrication process constitute a solution of the problem.

  6. Moonbase night power by laser illumination

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.

    1992-01-01

    Moonbase solar-power concepts must somehow address the energy storage problem posed by the 354-hour lunar night. Attention is presently given to the feasibility of laser-array illumination of a lunar base, using technology that is projected to be available in the near term. Beam-spreading due to atmospheric distortions could be reduced through the use of adaptive optics to compensate for atmospheric turbulence.

  7. Shape, Illumination, and Reflectance from Shading

    DTIC Science & Technology

    2013-05-29

    Shape, Illumination, and Reflectance from Shading Jonathan Barron Jitendra Malik Electrical Engineering and Computer Sciences University of...S) AND ADDRESS(ES) University of California at Berkeley, Electrical Engineering and Computer Sciences,Berkeley,CA,94720 8. PERFORMING ORGANIZATION...images [2], [3]. We will construct priors similar to those used � J.T. Barron and J. Malik are with the Department of Electrical Engi- neering and

  8. Reinterpretation and improvement of Talbot array illuminators.

    PubMed

    Arrizón, V; Rojo-Velázquez, G

    2000-09-10

    We show that the transmittance of a finite Talbot array illuminator (TAI) can be expressed by the phase distribution of a pixelated lens, modulated by a discrete phase grating (G). Thus the TAI reconstruction field is given by the convolution of the grating's Fourier transform, with the point-spread function of the pixelated lens. On the basis of this approach we propose a method to improve the performance of a finite TAI by modifying the basic cell of the grating factor G.

  9. Optical mapping at increased illumination intensities

    NASA Astrophysics Data System (ADS)

    Kanaporis, Giedrius; Martišienė, Irma; Jurevičius, Jonas; Vosyliūtė, Rūta; Navalinskas, Antanas; Treinys, Rimantas; Matiukas, Arvydas; Pertsov, Arkady M.

    2012-09-01

    Voltage-sensitive fluorescent dyes have become a major tool in cardiac and neuro-electrophysiology. Achieving high signal-to-noise ratios requires increased illumination intensities, which may cause photobleaching and phototoxicity. The optimal range of illumination intensities varies for different dyes and must be evaluated individually. We evaluate two dyes: di-4-ANBDQBS (excitation 660 nm) and di-4-ANEPPS (excitation 532 nm) in the guinea pig heart. The light intensity varies from 0.1 to 5 mW/mm2, with the upper limit at 5 to 10 times above values reported in the literature. The duration of illumination was 60 s, which in guinea pigs corresponds to 300 beats at a normal heart rate. Within the identified duration and intensity range, neither dye shows significant photobleaching or detectable phototoxic effects. However, light absorption at higher intensities causes noticeable tissue heating, which affects the electrophysiological parameters. The most pronounced effect is a shortening of the action potential duration, which, in the case of 532-nm excitation, can reach ˜30%. At 660-nm excitation, the effect is ˜10%. These findings may have important implications for the design of optical mapping protocols in biomedical applications.

  10. Pulsed Laser Illumination of Photovoltaic Cells

    NASA Technical Reports Server (NTRS)

    Yater, Jane A.; Lowe, Roland; Jenkins, Philip; Landis, Geoffrey A.

    1994-01-01

    In future space missions, free electron lasers (FEL) may be used to illuminate photovoltaic array receivers to provide remote power. The induction FEL and the radio-frequency (RF) FEL both produce pulsed rather than continuous output. In this work, we investigate cell response to pulsed laser light which simulates the RF FEL format, producing 50 ps pulses at a frequency of 78 MHz. A variety of Si, GaAs, CaSb and CdInSe2 (CIS) solar cells are tested at average incident powers between 4 mW/sq cm and 425 mW/sq cm. The results indicate that if the pulse repetition is high, cell efficiencies are only slightly reduced by using a pulsed laser source compared to constant illumination at the same wavelength. Because the pulse separation is less than or approximately equal to the minority carrier lifetime, the illumination conditions are effectively those of a continuous wave laser. The time dependence of the voltage and current response of the cells are also measured using a sampling oscilloscope equipped with a high frequency voltage probe and current transformer. The frequency response of the cells is weak, with both voltage and current outputs essentially dc in nature. Comparison with previous experiments shows that the RF FEL pulse format yields much more efficient photovoltaic conversion of light than does an induction FEL pulse format.

  11. Illumination analysis of LAPAN's IR micro bolometer

    NASA Astrophysics Data System (ADS)

    Bustanul, A.; Irwan, P.; Andi M., T.

    2016-10-01

    We have since 2 years ago been doing a research in term of an IR Micrometer Bolometer which aims to fulfill our office, LAPAN, desire to put it as one of payloads into LAPAN's next micro satellite project, either at LAPAN A4 or at LAPAN A5. Due to the lack of experience on the subject, everything had been initiated by spectral radiance analysis adjusted by catastrophes sources in Indonesia, mainly wild fire (forest fire) and active volcano. Based on the result of the appropriate spectral radiance wavelength, 3.8 - 4 μm, and field of view (FOV), we, then, went through the further analysis, optical analysis. Focusing in illumination matter, the process was done by using Zemax software. Optical pass Interference and Stray light were two things that become our concern throughout the work. They could also be an evaluation of the performance optimization of illumination analysis of our optical design. The results, graphs, show that our design performance is close diffraction limited and the image blur of the geometrical produced by Lapan's IR Micro Bolometer lenses is in the pixel area range. Therefore, our optical design performance is relatively good and will produce image with high quality. In this paper, the Illumination analysis and process of LAPAN's Infra Red (IR) Micro Bolometer is presented.

  12. Pulsed Laser Illumination of Photovoltaic Cells

    NASA Technical Reports Server (NTRS)

    Yater, Jane A.; Lowe, Roland; Jenkins, Philip; Landis, Geoffrey A.

    1994-01-01

    In future space missions, free electron lasers (FEL) may be used to illuminate photovoltaic array receivers to provide remote power. The induction FEL and the radio-frequency (RF) FEL both produce pulsed rather than continuous output. In this work, we investigate cell response to pulsed laser light which simulates the RF FEL format, producing 50 ps pulses at a frequency of 78 MHz. A variety of Si, GaAs, CaSb and CdInSe2 (CIS) solar cells are tested at average incident powers between 4 mW/sq cm and 425 mW/sq cm. The results indicate that if the pulse repetition is high, cell efficiencies are only slightly reduced by using a pulsed laser source compared to constant illumination at the same wavelength. Because the pulse separation is less than or approximately equal to the minority carrier lifetime, the illumination conditions are effectively those of a continuous wave laser. The time dependence of the voltage and current response of the cells are also measured using a sampling oscilloscope equipped with a high frequency voltage probe and current transformer. The frequency response of the cells is weak, with both voltage and current outputs essentially dc in nature. Comparison with previous experiments shows that the RF FEL pulse format yields much more efficient photovoltaic conversion of light than does an induction FEL pulse format.

  13. 47 CFR 80.969 - Illumination of operating controls.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... illuminate the operating controls at the principal operating position. (b) Instead of dial lights, a light from an electric lamp may be provided to illuminate the operating controls of the radiotelephone at...

  14. 47 CFR 80.969 - Illumination of operating controls.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... illuminate the operating controls at the principal operating position. (b) Instead of dial lights, a light from an electric lamp may be provided to illuminate the operating controls of the radiotelephone at...

  15. Bessel light sheet structured illumination microscopy

    NASA Astrophysics Data System (ADS)

    Noshirvani Allahabadi, Golchehr

    Biomedical study researchers using animals to model disease and treatment need fast, deep, noninvasive, and inexpensive multi-channel imaging methods. Traditional fluorescence microscopy meets those criteria to an extent. Specifically, two-photon and confocal microscopy, the two most commonly used methods, are limited in penetration depth, cost, resolution, and field of view. In addition, two-photon microscopy has limited ability in multi-channel imaging. Light sheet microscopy, a fast developing 3D fluorescence imaging method, offers attractive advantages over traditional two-photon and confocal microscopy. Light sheet microscopy is much more applicable for in vivo 3D time-lapsed imaging, owing to its selective illumination of tissue layer, superior speed, low light exposure, high penetration depth, and low levels of photobleaching. However, standard light sheet microscopy using Gaussian beam excitation has two main disadvantages: 1) the field of view (FOV) of light sheet microscopy is limited by the depth of focus of the Gaussian beam. 2) Light-sheet images can be degraded by scattering, which limits the penetration of the excitation beam and blurs emission images in deep tissue layers. While two-sided sheet illumination, which doubles the field of view by illuminating the sample from opposite sides, offers a potential solution, the technique adds complexity and cost to the imaging system. We investigate a new technique to address these limitations: Bessel light sheet microscopy in combination with incoherent nonlinear Structured Illumination Microscopy (SIM). Results demonstrate that, at visible wavelengths, Bessel excitation penetrates up to 250 microns deep in the scattering media with single-side illumination. Bessel light sheet microscope achieves confocal level resolution at a lateral resolution of 0.3 micron and an axial resolution of 1 micron. Incoherent nonlinear SIM further reduces the diffused background in Bessel light sheet images, resulting in

  16. 32 CFR 707.10 - Wake illumination light.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 5 2012-07-01 2012-07-01 false Wake illumination light. 707.10 Section 707.10... RESPECT TO ADDITIONAL STATION AND SIGNAL LIGHTS § 707.10 Wake illumination light. Naval vessels may display a white spot light located near the stern to illuminate the wake....

  17. 32 CFR 707.10 - Wake illumination light.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 5 2011-07-01 2011-07-01 false Wake illumination light. 707.10 Section 707.10... RESPECT TO ADDITIONAL STATION AND SIGNAL LIGHTS § 707.10 Wake illumination light. Naval vessels may display a white spot light located near the stern to illuminate the wake....

  18. 32 CFR 707.10 - Wake illumination light.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 5 2010-07-01 2010-07-01 false Wake illumination light. 707.10 Section 707.10... RESPECT TO ADDITIONAL STATION AND SIGNAL LIGHTS § 707.10 Wake illumination light. Naval vessels may display a white spot light located near the stern to illuminate the wake....

  19. 32 CFR 707.10 - Wake illumination light.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 5 2013-07-01 2013-07-01 false Wake illumination light. 707.10 Section 707.10... RESPECT TO ADDITIONAL STATION AND SIGNAL LIGHTS § 707.10 Wake illumination light. Naval vessels may display a white spot light located near the stern to illuminate the wake....

  20. 21 CFR 892.1890 - Radiographic film illuminator.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Radiographic film illuminator. 892.1890 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1890 Radiographic film illuminator. (a) Identification. A radiographic film illuminator is a device containing a visible light source covered with...

  1. 21 CFR 892.1890 - Radiographic film illuminator.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Radiographic film illuminator. 892.1890 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1890 Radiographic film illuminator. (a) Identification. A radiographic film illuminator is a device containing a visible light source covered with...

  2. 21 CFR 892.1890 - Radiographic film illuminator.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Radiographic film illuminator. 892.1890 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1890 Radiographic film illuminator. (a) Identification. A radiographic film illuminator is a device containing a visible light source covered with...

  3. 21 CFR 892.1890 - Radiographic film illuminator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Radiographic film illuminator. 892.1890 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1890 Radiographic film illuminator. (a) Identification. A radiographic film illuminator is a device containing a visible light source covered with...

  4. 21 CFR 892.1890 - Radiographic film illuminator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Radiographic film illuminator. 892.1890 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1890 Radiographic film illuminator. (a) Identification. A radiographic film illuminator is a device containing a visible light source covered with...

  5. 36 CFR § 910.38 - Building exterior illumination.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 3 2013-07-01 2012-07-01 true Building exterior illumination... PENNSYLVANIA AVENUE DEVELOPMENT AREA Standards Uniformly Applicable to the Development Area § 910.38 Building exterior illumination. Exterior illumination of a building shall be in conformance with the standards...

  6. 30 CFR 56.17001 - Illumination of surface working areas.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Illumination of surface working areas. 56.17001... § 56.17001 Illumination of surface working areas. Illumination sufficient to provide safe working conditions shall be provided in and on all surface structures, paths, walkways, stairways, switch...

  7. 30 CFR 75.1719-1 - Illumination in working places.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... working place, the areas within a miner's normal field of vision which shall be illuminated in the working... are operated, the areas which shall be illuminated shall be as follows: (i) The face, and (ii) The... equipment is operated to load material, the areas which shall be illuminated shall be as follows: (i)...

  8. 30 CFR 75.1719-1 - Illumination in working places.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... working place, the areas within a miner's normal field of vision which shall be illuminated in the working... are operated, the areas which shall be illuminated shall be as follows: (i) The face, and (ii) The... equipment is operated to load material, the areas which shall be illuminated shall be as follows: (i)...

  9. 32 CFR 707.10 - Wake illumination light.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 5 2014-07-01 2014-07-01 false Wake illumination light. 707.10 Section 707.10... RESPECT TO ADDITIONAL STATION AND SIGNAL LIGHTS § 707.10 Wake illumination light. Naval vessels may display a white spot light located near the stern to illuminate the wake....

  10. 21 CFR 886.1160 - Color vision plate illuminator.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Color vision plate illuminator. 886.1160 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1160 Color vision plate illuminator. (a) Identification. A color vision plate illuminator is an AC-powered device that is a lamp intended...

  11. 21 CFR 886.1160 - Color vision plate illuminator.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Color vision plate illuminator. 886.1160 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1160 Color vision plate illuminator. (a) Identification. A color vision plate illuminator is an AC-powered device that is a lamp intended...

  12. 21 CFR 886.1160 - Color vision plate illuminator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Color vision plate illuminator. 886.1160 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1160 Color vision plate illuminator. (a) Identification. A color vision plate illuminator is an AC-powered device that is a lamp intended...

  13. 21 CFR 886.1160 - Color vision plate illuminator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Color vision plate illuminator. 886.1160 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1160 Color vision plate illuminator. (a) Identification. A color vision plate illuminator is an AC-powered device that is a lamp intended...

  14. 21 CFR 886.1160 - Color vision plate illuminator.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Color vision plate illuminator. 886.1160 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1160 Color vision plate illuminator. (a) Identification. A color vision plate illuminator is an AC-powered device that is a lamp intended...

  15. Open LED Illuminator: A Simple and Inexpensive LED Illuminator for Fast Multicolor Particle Tracking in Neurons

    PubMed Central

    Bosse, Jens B.; Tanneti, Nikhila S.; Hogue, Ian B.; Enquist, Lynn W.

    2015-01-01

    Dual-color live cell fluorescence microscopy of fast intracellular trafficking processes, such as axonal transport, requires rapid switching of illumination channels. Typical broad-spectrum sources necessitate the use of mechanical filter switching, which introduces delays between acquisition of different fluorescence channels, impeding the interpretation and quantification of highly dynamic processes. Light Emitting Diodes (LEDs), however, allow modulation of excitation light in microseconds. Here we provide a step-by-step protocol to enable any scientist to build a research-grade LED illuminator for live cell microscopy, even without prior experience with electronics or optics. We quantify and compare components, discuss our design considerations, and demonstrate the performance of our LED illuminator by imaging axonal transport of herpes virus particles with high temporal resolution. PMID:26600461

  16. Ultra Deep Wave Equation Imaging and Illumination

    SciTech Connect

    Alexander M. Popovici; Sergey Fomel; Paul Sava; Sean Crawley; Yining Li; Cristian Lupascu

    2006-09-30

    In this project we developed and tested a novel technology, designed to enhance seismic resolution and imaging of ultra-deep complex geologic structures by using state-of-the-art wave-equation depth migration and wave-equation velocity model building technology for deeper data penetration and recovery, steeper dip and ultra-deep structure imaging, accurate velocity estimation for imaging and pore pressure prediction and accurate illumination and amplitude processing for extending the AVO prediction window. Ultra-deep wave-equation imaging provides greater resolution and accuracy under complex geologic structures where energy multipathing occurs, than what can be accomplished today with standard imaging technology. The objective of the research effort was to examine the feasibility of imaging ultra-deep structures onshore and offshore, by using (1) wave-equation migration, (2) angle-gathers velocity model building, and (3) wave-equation illumination and amplitude compensation. The effort consisted of answering critical technical questions that determine the feasibility of the proposed methodology, testing the theory on synthetic data, and finally applying the technology for imaging ultra-deep real data. Some of the questions answered by this research addressed: (1) the handling of true amplitudes in the downward continuation and imaging algorithm and the preservation of the amplitude with offset or amplitude with angle information required for AVO studies, (2) the effect of several imaging conditions on amplitudes, (3) non-elastic attenuation and approaches for recovering the amplitude and frequency, (4) the effect of aperture and illumination on imaging steep dips and on discriminating the velocities in the ultra-deep structures. All these effects were incorporated in the final imaging step of a real data set acquired specifically to address ultra-deep imaging issues, with large offsets (12,500 m) and long recording time (20 s).

  17. Image Correlation Microscopy for Uniform Illumination

    PubMed Central

    Gaborski, Thomas R.; Sealander, Michael N.; Ehrenberg, Morton; Waugh, Richard E.; McGrath, James L.

    2011-01-01

    Image cross-correlation microscopy (ICM) is a technique that quantifies the motion of fluorescent features in an image by measuring the temporal autocorrelation function decay in a time-lapse image sequence. ICM has traditionally employed laser-scanning microscopes because the technique emerged as an extension of laser-based fluorescence correlation spectroscopy (FCS). In this work, we show that image correlation can also be used to measure fluorescence dynamics in uniform illumination or wide-field imaging systems and we call our new approach uniform illumination image correlation microscopy (UI-ICM). Wide-field microscopy is not only a simpler, less expensive imaging modality, but it offers the capability of greater temporal resolution over laser-scanning systems. In traditional laser-scanning ICM, lateral mobility is calculated from the temporal de-correlation of an image, where the characteristic length is the illuminating laser beam width. In wide-field microscopy, the diffusion length is defined by the feature size using the spatial autocorrelation function (SACF). Correlation function decay in time occurs as an object diffuses from its original position. We show that theoretical and simulated comparisons between Gaussian and uniform features indicate the temporal autocorrelation function (TACF) depends strongly on particle size and not particle shape. In this report, we establish the relationships between the SACF feature size, TACF characteristic time and the diffusion coefficient for UI-ICM using analytical, Monte-Carlo and experimental validation with particle tracking algorithms. Additionally, we demonstrate UI-ICM analysis of adhesion molecule domain aggregation and diffusion on the surface of human neutrophils. PMID:20055917

  18. Iterative Adaptive Sampling For Accurate Direct Illumination

    DTIC Science & Technology

    2004-08-01

    couple of innings of office baseball with me. • Vikash Goel , for all the time you spent with me on my car and for all the interesting conversations on...for all the work you do maintaining our network and computer systems. vi • Linda Stephenson, for keeping me on Don’s radar at all times and for...Symposium on Interactive 3D Graphics, pages 105–106, April 1995. [MH84] Gene S. Miller and C. Robert Hoffman. Illumination and reflection maps: Simulated

  19. Surface sampling techniques using ultraviolet illumination

    NASA Astrophysics Data System (ADS)

    Smith, E. M.; Aronson, J. R.; Cornish, R. M.; Goodwin, B. E.; Simon, I.

    1984-11-01

    In laboratory and preliminary field tests, a system that uses photography in the presence of a 254 nm UV illumination source has been shown useful for detection of explosives residues on surfaces. Analytes (TNT, 2, 4-DNT, 2, 6-DNT, Tetryl, RDX and DPA) can be detected at 10 to 20 microgram/sq cm on concrete, transite or stainless steel. The method was not successful for wood or brick surfaces or for the analyte PETN. An alternative thermal image radiometric method of detection was unsuccessful.

  20. Thermoelectric Nanowire Arrays Response to Illumination

    NASA Astrophysics Data System (ADS)

    Huber, Tito; Scott, Reum; Johnson, Scott; Brower, Tina; Nikolaeva, Albina; Konopko, Leonid

    Bismuth nanowire arrays configured on devices where they are capped with a transparent indium tin oxide electrode generate electric power when exposed to light. The arrays feature poor optical reflectivity and, possibly, light trapping. We show experimental results that indicate that the arrays respond to illumination owing to the thermoelectric conversion of heat absorbed at the surface. The unique features of the energy pathway are manifested through a strong temporal and photon wavelength dependence of the photoresponse. Energy conversion in thermoelectrics with light trapping surfaces is a path to fast infrared light detection and across-the-spectrum solar energy harvesting.

  1. OSIRIS-REx Solar Array Illumination Test

    NASA Image and Video Library

    2016-08-05

    Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, illumination testing is underway on the power-producing solar arrays for the agency’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, or OSIRIS-REx spacecraft. Targeted for liftoff Sept. 8, 2016, OSIRIS-Rex will be the first U.S. mission to sample an asteroid, retrieve at least two ounces of surface material and return it to Earth for study. The asteroid, Bennu, may hold clues to the origin of the solar system and the source of water and organic molecules found on Earth.

  2. OSIRIS-REx Solar Array Illumination Test

    NASA Image and Video Library

    2016-08-05

    Inside the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, illumination testing is underway on the power -producing solar arrays for the agency’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, or OSIRIS-REx spacecraft. Targeted for liftoff Sept. 8, 2016, OSIRIS-Rex will be the first U.S. mission to sample an asteroid, retrieve at least two ounces of surface material and return it to Earth for study. The asteroid, Bennu, may hold clues to the origin of the solar system and the source of water and organic molecules found on Earth.

  3. THE RELATION BETWEEN VISUAL ACUITY AND ILLUMINATION

    PubMed Central

    Hecht, Selig

    1928-01-01

    1. Visual acuity varies in a definite manner with the illumination. At low intensities visual acuity increases slowly in proportion to log I; at higher intensities it increases nearly ten times more rapidly in relation to log I; at the highest illuminations it remains constant regardless of the changes in log I. 2. These variations in visual acuity measure the variations in the resolving power of the retina. The retina is a surface composed of discrete rods and cones. Therefore its resolving power depends on the number of elements present in a unit area. The changes in visual acuity then presuppose that the number of elements in the retina is variable. This cannot be true anatomically; therefore it must be assumed functionally. 3. To explain on such a basis the variations of visual acuity, it is postulated that the thresholds of the cones and of the rods are distributed in relation to the illumination in a statistical manner similar to that of other populations. In addition the rods as a whole have thresholds lower than the cones. Then at low intensities the increase in visual acuity depends on the augmentation of the functional rod population which accompanies intensity increase; and at higher intensities the increase in visual acuity depends on the augmentation of the functional cone population. The number of cones per unit foveal area is much greater than the number of rods per unit peripheral area, which accounts for the relative rates of increase of rod and cone visual acuity with intensity. At the highest illuminations all the cones are functional and no increase in visual acuity is possible. 4. If this division into rod visual acuity and cone visual acuity is correct, a completely color-blind person should have only rod visual acuity. It is shown by a study of the data of two such individuals that this is true. 5. The rod and cone threshold distribution has been presented as a purely statistical assumption. It can be shown, however, that it is really a

  4. Illuminating Rationale and Uses for Light Therapy

    PubMed Central

    Shirani, Afshin; St. Louis, Erik K.

    2009-01-01

    Light therapy is increasingly applied in a variety of sleep medicine and psychiatric conditions including circadian rhythm sleep disorders, seasonal affective disorder, and dementia. This article reviews the neural underpinnings of circadian neurobiology crucial for understanding the influence of light therapy on brain function, common mood and sleep disorders in which light therapy may be effectively used, and applications of light therapy in clinical practice. Citation: Shirani A; St. Louis EK. Illuminating rationale and uses for light therapy. J Clin Sleep Med 2009;5(2):155-163. PMID:19968050

  5. Organic light emitting devices for illumination

    SciTech Connect

    Hack, Michael; Lu, Min-Hao Michael; Weaver, Michael S.

    2010-02-16

    An organic light emitting device is provided. The device has a plurality of regions, each region having an organic emissive layer adapted to emit a different spectrum of light. The regions in combination emit light suitable for illumination purposes. The area of each region may be selected such that the device is more efficient that an otherwise equivalent device having regions of equal size. The regions may have an aspect ratio of at least about four. All parts of any given region may be driven at the same current.

  6. HMC and fibroblast illuminating experiments using microdisplay

    NASA Astrophysics Data System (ADS)

    Ou, Chung-Jen; Shen, Ching-I.; Ou, Chung-Ming

    2010-02-01

    Techniques like optical neural guiding, photodynamic therapy and photosynthesis of the cell all required specific spatial energy distribution. Influences factors like the wavelength, polarization, spatial intensity distribution are all required, and the appropriate illumination condition for the cells inside the incubator are required to meet more complicated conditions. We report the system that using of the spatial light modulator to provide a multi-points control for the cell culturing. This system is modified from the commercialized projection system to reduce the cost. It is now possible to apply it to other bio-culturing related applications. Results for Human Melanocyte HMC, Glia cell and fibroblast cell are discussed.

  7. Methods for describing illumination colour uniformities

    NASA Astrophysics Data System (ADS)

    Rotscholl, Ingo; Trampert, Klaus; Herrmann, Franziska; Neumann, Cornelius

    2015-02-01

    Optimizing angular or spatial colour homogeneity has become an important task in many general lighting applications and first requires a valid description of illumination colour homogeneity. We analyse different frequently used methods to describe colour distributions in theory and with measurement data. It is described why information about chromaticity coordinates, correlated colour temperature and global chromaticity coordinate distances are not sufficient for describing colour homogeneity perception of light distributions. We present local chromaticity coordinate distances as expandable and easy implementable method for describing colour homogeneity distributions that is adaptable to the field of view by only one intuitive, physiological meaningful parameter.

  8. Development of flying spot illumination system for stage lighting

    NASA Astrophysics Data System (ADS)

    Asakawa, Hisashi; Ishii, Katsunori; Koshiro, Hikari; Baba, Junko; Wakaki, Moriaki

    2014-02-01

    The system to control the area of illumination is important for the luminaires used for stages and TV studios. Presently the methods to change the distance between a lamp and lenses, or to use a zooming projection of the aperture illuminated by the lamp are used to control the area. However, these methods require many optical components or mechanical components. Moreover, the energy of the light source is partially consumed by the absorption of the shutter on adjusting the illumination area. On the other hand, the control of the illuminance over the illuminated area is not possible by the methods. In this study, we developed the lighting system which enables to control both the illuminated area and the illuminance distribution within the area by scanning the beam from a LED array light source. The area of illumination was expanded along one dimension by scanning the LED beam using a rotating polygon mirror. The selection of the illuminated width and the control of the illuminance distribution were achieved by synchronizing the pulse width modulation (PWM) control of the LED with the rotation of the mirror using a time sharing control. As a result, various illuminance distributions can be realized at real time by using software control for the luminaire. The developed system has the merits of compact and high efficiency.

  9. Can illumination estimates provide the basis for color constancy?

    PubMed

    Granzier, Jeroen J M; Brenner, Eli; Smeets, Jeroen B J

    2009-03-24

    Objects hardly appear to change color when the spectral distribution of the illumination changes: a phenomenon known as color constancy. Color constancy could either be achieved by relying on properties that are insensitive to changes in the illumination (such as spatial color contrast) or by compensating for the estimated chromaticity of the illuminant. We examined whether subjects can judge the illuminant's color well enough to account for their own color constancy. We found that subjects were very poor at judging the color of a lamp from the light reflected by the scene it illuminated. They were much better at judging the color of a surface within the scene. We conclude that color constancy must be achieved by relying on relationships that are insensitive to the illumination rather than by explicitly judging the color of the illumination.

  10. Decoupling Illumination from Isosurface Generation Using 4D Light Transport

    PubMed Central

    Banks, David C.; Beason, Kevin M.

    2014-01-01

    One way to provide global illumination for the scientist who performs an interactive sweep through a 3D scalar dataset is to pre-compute global illumination, resample the radiance onto a 3D grid, then use it as a 3D texture. The basic approach of repeatedly extracting isosurfaces, illuminating them, and then building a 3D illumination grid suffers from the non-uniform sampling that arises from coupling the sampling of radiance with the sampling of isosurfaces. We demonstrate how the illumination step can be decoupled from the isosurface extraction step by illuminating the entire 3D scalar function as a 3-manifold in 4-dimensional space. By reformulating light transport in a higher dimension, one can sample a 3D volume without requiring the radiance samples to aggregate along individual isosurfaces in the pre-computed illumination grid. PMID:19834238

  11. Effects of illuminants and illumination time on lettuce growth, yield and nutritional quality in a controlled environment

    NASA Astrophysics Data System (ADS)

    Shen, Y. Z.; Guo, S. S.; Ai, W. D.; Tang, Y. K.

    2014-07-01

    Effects of illuminants and illumination time on the growth of lettuce were researched. Red-blue light-emitting diodes (LEDs, 90% red light +10% blue light) and white light fluorescent (WF) lamps were compared as the illuminants for plant cultivation. Under each type of illuminant, lettuce was grown at 4 illumination times: 12 h, 16 h, 20 h and 24 h, with the same light intensity of 600 μmolm-2s-1. The leaf net photosynthetic rate (Pn) under the two illuminants was comparable but the shape of lettuce was obviously affected by the illuminant. The WF lamps produced more compact plant, while red-blue LED resulted in less but longer leaves. However, the total leaf area was not significantly affected by the illuminant. The red-blue LED produced nearly same aboveground biomass with far less energy consumption relative to WF lamps. The underground biomass was lowered under red-blue LED in comparison with WF lamps. Red-blue LED could improve the nutritional quality of lettuce by increasing the concentration of soluble sugar and vitamin C (VC) and reducing the concentration of nitrate. Under each type of illuminant, longer illumination time resulted in higher Pn, more leaves and larger leaf area. The total chlorophyll concentration increased while the concentration ratio of chlorophyll a/b decreased with the extension of illumination time. Illumination time had highly significant positive correlation with biomass. Moreover, when total daily light input was kept the same, longer illumination time increased the biomass significantly as well. In addition, longer illumination time increased the concentration of crude fiber, soluble sugar and VC and reduced the concentration of nitrate. In summary, red-blue LEDs and 24 h illumination time were demonstrated to be more suitable for lettuce cultivation in the controlled environment.

  12. Design and analysis of illumination systems

    NASA Astrophysics Data System (ADS)

    Zoechling, Guenter

    1991-01-01

    Illuminance at a detector is calculated by means of raytracing. A method of synthesis already known from related fields - is demonstrated: the Edge Ray Principle. 1. 1 Concepts of photometry 1. ANALYSIS We have to recall the basic physical concepts of photometry namely luminance light intensity light flux and illuminance [21 The definition of a Lambertian Source is given here again due to its fundamental importance: we call a radiating surface a Lambertian Source its luminance is independent of surface coordinates and viewing angle. An equivalent formulation is: the source obeys ''Lamberts cosine law of intensity'' for any surface element dA and any angle B dl L * cos B * dA (1) L luminance dA surface element at source I intensity B angle between surface normal and viewing direction The Lambertian Source has several interesting attributes for instance that we cannot judge its position or shape by just looking at it. A more precise formulation of this phenomenon can be stated as following: 1. 2 Pseudo luminance of the hole Let D be some area on a detector H be a hole in an opaque screen (both not necessarily small) and Si and S2 be lambertian radiating surfaces (alternatively existing) then the following theorem holds: SPIE Vol. 1354 International Lens Design Conference (1990) / 617 y D (p y H (p Fig. i

  13. Modeling polarized illumination for OPC/RET

    NASA Astrophysics Data System (ADS)

    Song, Hua; Zhang, Qiaolin; Shiely, James

    2007-10-01

    Recent research has shown that properly polarized light source enhances image contrast in photolithography for manufacturing integrated circuit (IC) devices, thus improves the effectiveness of optical proximity correction (OPC) and other resolution enhancement techniques (RET). However, current OPC/RET modeling software can only model the light source polarization of simple types, such as TE, TM, X, Y, or sector polarization with relatively simple configuration. Realistic polarized light used in scanners is more complex than the aforementioned simple ones. As a result, simulation accuracy and quality of the OPC result will be compromised by the simplification of the light source polarization modeling in the traditional approach. With ever shrinking CD error budget in the manufacturing of IC's at advanced technology nodes, more accurate and comprehensive light source modeling for lithography simulations and OPC/RET is needed. In this paper, we present a modeling framework that takes arbitrarily polarized light source. Based on polarization state vector descriptions of the light source, it unifies optical simulations of unpolarized, partially polarized, and completely polarized illuminations. We built this framework into Synopsys' OPC modeling tool ProGen. Combined with ProGen's existing capability to handle vectorial aberration by the projection lens, large angle effects due to high NA, and thin film effects, this framework represents a general vectorial model for optical imaging with the state-of-the-art scanners. Numerical experiments were performed to study CD impact of various illumination polarization modeling schemes in the context of OPC/RET.

  14. Construction of an instant structured illumination microscope

    PubMed Central

    Curd, Alistair; Cleasby, Alexa; Makowska, Katarzyna; York, Andrew; Shroff, Hari; Peckham, Michelle

    2015-01-01

    A challenge in biological imaging is to capture high-resolution images at fast frame rates in live cells. The “instant structured illumination microscope” (iSIM) is a system designed for this purpose. Similarly to standard structured illumination microscopy (SIM), an iSIM provides a twofold improvement over widefield microscopy, in x, y and z, but also allows much faster image acquisition, with real-time display of super-resolution images. The assembly of an iSIM is reasonably complex, involving the combination and alignment of many optical components, including three micro-optics arrays (two lenslet arrays and an array of pinholes, all with a pitch of 222 μm) and a double-sided scanning mirror. In addition, a number of electronic components must be correctly controlled. Construction of the system is therefore not trivial, but is highly desirable, particularly for live-cell imaging. We report, and provide instructions for, the construction of an iSIM, including minor modifications to a previous design in both hardware and software. The final instrument allows us to rapidly acquire fluorescence images at rates faster than 100 fps, with approximately twofold improvement in resolution in both x–y and z; sub-diffractive biological features have an apparent size (full width at half maximum) of 145 nm (lateral) and 320 nm (axial), using a 1.49 NA objective and 488 nm excitation. PMID:26210400

  15. Robust Face Image Matching under Illumination Variations

    NASA Astrophysics Data System (ADS)

    Yang, Chyuan-Huei Thomas; Lai, Shang-Hong; Chang, Long-Wen

    2004-12-01

    Face image matching is an essential step for face recognition and face verification. It is difficult to achieve robust face matching under various image acquisition conditions. In this paper, a novel face image matching algorithm robust against illumination variations is proposed. The proposed image matching algorithm is motivated by the characteristics of high image gradient along the face contours. We define a new consistency measure as the inner product between two normalized gradient vectors at the corresponding locations in two images. The normalized gradient is obtained by dividing the computed gradient vector by the corresponding locally maximal gradient magnitude. Then we compute the average consistency measures for all pairs of the corresponding face contour pixels to be the robust matching measure between two face images. To alleviate the problem due to shadow and intensity saturation, we introduce an intensity weighting function for each individual consistency measure to form a weighted average of the consistency measure. This robust consistency measure is further extended to integrate multiple face images of the same person captured under different illumination conditions, thus making our robust face matching algorithm. Experimental results of applying the proposed face image matching algorithm on some well-known face datasets are given in comparison with some existing face recognition methods. The results show that the proposed algorithm consistently outperforms other methods and achieves higher than 93% recognition rate with three reference images for different datasets under different lighting conditions.

  16. Gaussian Hypothesis Testing and Quantum Illumination

    NASA Astrophysics Data System (ADS)

    Wilde, Mark M.; Tomamichel, Marco; Lloyd, Seth; Berta, Mario

    2017-09-01

    Quantum hypothesis testing is one of the most basic tasks in quantum information theory and has fundamental links with quantum communication and estimation theory. In this paper, we establish a formula that characterizes the decay rate of the minimal type-II error probability in a quantum hypothesis test of two Gaussian states given a fixed constraint on the type-I error probability. This formula is a direct function of the mean vectors and covariance matrices of the quantum Gaussian states in question. We give an application to quantum illumination, which is the task of determining whether there is a low-reflectivity object embedded in a target region with a bright thermal-noise bath. For the asymmetric-error setting, we find that a quantum illumination transmitter can achieve an error probability exponent stronger than a coherent-state transmitter of the same mean photon number, and furthermore, that it requires far fewer trials to do so. This occurs when the background thermal noise is either low or bright, which means that a quantum advantage is even easier to witness than in the symmetric-error setting because it occurs for a larger range of parameters. Going forward from here, we expect our formula to have applications in settings well beyond those considered in this paper, especially to quantum communication tasks involving quantum Gaussian channels.

  17. Construction of an instant structured illumination microscope.

    PubMed

    Curd, Alistair; Cleasby, Alexa; Makowska, Katarzyna; York, Andrew; Shroff, Hari; Peckham, Michelle

    2015-10-15

    A challenge in biological imaging is to capture high-resolution images at fast frame rates in live cells. The "instant structured illumination microscope" (iSIM) is a system designed for this purpose. Similarly to standard structured illumination microscopy (SIM), an iSIM provides a twofold improvement over widefield microscopy, in x, y and z, but also allows much faster image acquisition, with real-time display of super-resolution images. The assembly of an iSIM is reasonably complex, involving the combination and alignment of many optical components, including three micro-optics arrays (two lenslet arrays and an array of pinholes, all with a pitch of 222 μm) and a double-sided scanning mirror. In addition, a number of electronic components must be correctly controlled. Construction of the system is therefore not trivial, but is highly desirable, particularly for live-cell imaging. We report, and provide instructions for, the construction of an iSIM, including minor modifications to a previous design in both hardware and software. The final instrument allows us to rapidly acquire fluorescence images at rates faster than 100 fps, with approximately twofold improvement in resolution in both x-y and z; sub-diffractive biological features have an apparent size (full width at half maximum) of 145 nm (lateral) and 320 nm (axial), using a 1.49 NA objective and 488 nm excitation. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  18. Surface color perception and equivalent illumination models.

    PubMed

    Brainard, David H; Maloney, Laurence T

    2011-05-02

    Vision provides information about the properties and identity of objects. The ease with which we perceive object properties belies the difficulty of the underlying information-processing task. In the case of object color, retinal information about object reflectance is confounded with information about the illumination as well as about the object's shape and pose. There is no obvious rule that allows transformation of the retinal image to a color representation that depends primarily on object surface reflectance. Under many circumstances, however, object color appearance is remarkably stable across scenes in which the object is viewed. Here, we review a line of experiments and theory that aim to understand how the visual system stabilizes object color appearance. Our emphasis is on models derived from explicit analysis of the computational problem of estimating the physical properties of illuminants and surfaces from the retinal image, and experiments that test these models. We argue that this approach has considerable promise for allowing generalization from simplified laboratory experiments to richer scenes that more closely approximate natural viewing. We discuss the relation between the work we review and other theoretical approaches available in the literature.

  19. Laser scattering by transcranial rat brain illumination

    NASA Astrophysics Data System (ADS)

    Sousa, Marcelo V. P.; Prates, Renato; Kato, Ilka T.; Sabino, Caetano P.; Suzuki, Luis C.; Ribeiro, Martha S.; Yoshimura, Elisabeth M.

    2012-06-01

    Due to the great number of applications of Low-Level-Laser-Therapy (LLLT) in Central Nervous System (CNS), the study of light penetration through skull and distribution in the brain becomes extremely important. The aim is to analyze the possibility of precise illumination of deep regions of the rat brain, measure the penetration and distribution of red (λ = 660 nm) and Near Infra-Red (NIR) (λ = 808 nm) diode laser light and compare optical properties of brain structures. The head of the animal (Rattus Novergicus) was epilated and divided by a sagittal cut, 2.3 mm away from mid plane. This section of rat's head was illuminated with red and NIR lasers in points above three anatomical structures: hippocampus, cerebellum and frontal cortex. A high resolution camera, perpendicularly positioned, was used to obtain images of the brain structures. Profiles of scattered intensities in the laser direction were obtained from the images. There is a peak in the scattered light profile corresponding to the skin layer. The bone layer gives rise to a valley in the profile indicating low scattering coefficient, or frontal scattering. Another peak in the region related to the brain is an indication of high scattering coefficient (μs) for this tissue. This work corroborates the use of transcranial LLLT in studies with rats which are subjected to models of CNS diseases. The outcomes of this study point to the possibility of transcranial LLLT in humans for a large number of diseases.

  20. Backlight illumination design using constant extinction

    NASA Astrophysics Data System (ADS)

    Baumgart, Jörg

    2013-08-01

    Light guiding backlights are a good solution to attain ambient or display illuminations. Generally, they are attained using intended macroscopic defects (dots). Their size, shape and density are designed using ray tracing software. Smaller defects have the fascinating feature that they may not be perceived by the eye. Such a light guide will therefore look transparent and undisturbed. However, such microscopic or even nanoscaled defects are well beyond the limitations of geometrical optics and therefore need other approaches for their design. An interesting alternative to surface defects are particles inside the material or a well-defined surface roughness. In contrast to a defect structure, particle densities or surface roughness cannot be changed without difficulty. These may, however, be much more easily manufactured. In this paper, a simple analytical method for the design of such light guides will be presented. This method is compared to the results of commercial software and will be used to design a homogeneous illumination adopting constant particle density inside the material.

  1. Illuminating Chaucer through Poetry, Manuscript Illuminations, and a Critical Rap Album

    ERIC Educational Resources Information Center

    Lynch, Tom Liam

    2007-01-01

    Drawing connections between Chaucer, Eminem, and social issues, New York City high school teacher Tom Liam Lynch helped students become familiar with "The Canterbury Tales." Students wrote poems of rhymed couplets about today's social and political issues, created illuminated manuscripts, and recorded a rap CD. A book and album were…

  2. Illuminating Chaucer through Poetry, Manuscript Illuminations, and a Critical Rap Album

    ERIC Educational Resources Information Center

    Lynch, Tom Liam

    2007-01-01

    Drawing connections between Chaucer, Eminem, and social issues, New York City high school teacher Tom Liam Lynch helped students become familiar with "The Canterbury Tales." Students wrote poems of rhymed couplets about today's social and political issues, created illuminated manuscripts, and recorded a rap CD. A book and album were…

  3. Effects of artificial illumination on the nocturnal foraging of waders

    NASA Astrophysics Data System (ADS)

    Santos, Carlos D.; Miranda, Ana C.; Granadeiro, José P.; Lourenço, Pedro M.; Saraiva, Sara; Palmeirim, Jorge M.

    2010-03-01

    Large areas of natural and semi-natural habitats are exposed to artificial illumination from adjacent urban areas and roads. Estuarine and coastal wetlands are particularly exposed to such illumination because shorelines often are heavily utilized by man. However, the impact of artificial illumination on the waders that forage in these highly productive habitats is virtually unknown. We evaluated the effects of artificial illumination on the nocturnal habitat selection and foraging behaviour of six wader species with different feeding strategies: three visual foragers, two species that alternate visual and tactile strategies (mixed foragers), and one tactile forager. We quantified the number of birds and their foraging behaviour at sites affected and not affected by streetlights, and also before and after illuminating experimental sites. Areas illuminated by streetlights were used more during the night by visual foragers, and to a lesser extent by mixed foragers, than non-illuminated areas. Visual foragers increased their foraging effort in illuminated areas, and mixed foragers changed to more efficient visual foraging strategies. These behavioural shifts improved prey intake rate by an average of 83% in visual and mixed foragers. We have showed that artificial illumination has a positive effect on the nocturnal foraging of waders, but on the other hand may draw them to degraded areas close to urban centres, and potentially raises their exposure to predators. Our findings suggest that artificial illumination is worth investigation as a tool in the management of intertidal habitats for waders.

  4. Material-illumination ambiguities and the perception of solid objects.

    PubMed

    Pont, Sylvia C; te Pas, Susan F

    2006-01-01

    The appearance of objects depends on their material, shape, and on the illumination conditions. Conversely, object appearance provides us with cues about the illumination and the material. This so-called inverse problem is basically underdetermined and therefore we expect that material and illumination perception are confounded. To gain insight into the relevant mechanisms, we rendered a set of artificial spheres for vastly different canonical light fields and reflectance functions. We used four physics-based bidirectional reflectance distribution functions (BRDFs) representing glossy, pitted, velvety, and matte material. The six illumination conditions were collimated illumination from four directions, hemispherical diffuse illumination, and fully diffuse (Ganzfeld) illumination. In three sub-experiments we presented pairs of stimuli and asked human observers to judge whether the material was the same, whether the illumination was the same, and for a subset in which either the illumination or the material was the same to judge which of the two was constant. We found that observers made many errors in all sub-experiments. In experiment 2 the illumination direction was chosen at random. Using an interactive interface, we asked human observers to match the illumination direction of a sphere of one of the four materials with that of a Lambertian sphere. We found systematical material-dependent deviations from veridical performance. Theoretical analysis of the radiance patterns suggests that judgments were based mainly on the position of the shadow edge. In conclusion, we found no evidence for 'material constancy' for perception of smooth rendered spheres despite vast quantitative and qualitative differences in illumination and in BRDF between the stimuli. Although human observers demonstrated some 'illumination constancy', they made systematic errors depending on the material reflectance, suggesting that they used mainly the location of the shadow edge. Our results

  5. Infrared Beam Induced Contrast With Double Illumination

    NASA Astrophysics Data System (ADS)

    Castaldini, A.; Cavallini, A.

    1988-07-01

    Over the last few years scanning optical microscopy (SOM) has been largely developed as a tool to explore the physical properties of materials. In particular the optical beam induced current (OBIC) mode of the SOM has been used to map the electronic properties of semiconducting devices. A new type of scanning microscopy method, as well as some results obtained by it, will be reported in this paper. Though similar, to a certain extent, to the standard scanning optical microscopy, this new investigation technique, from now on refered to as infrared beam induced contrast (IRBIC), differs from it in substance. The chopped light from a quartz halogen lamp is focused by a conventional microscope rearranged on the specimen surface, and a pin-hole is positioned so as to reduce the probe size (not the resolving power) to 1.5um. The resulting beam power density is of the order of 1mW*cm-2. Such a low power density presents some disadvantages in comparison with the traditional laser sources, but, on the other hand, it allows a very high sensitivity in the investigation of the defect electrical activity. With this experimental set-up the specimen front surface is probed with band-gap radiation. Its back surface is illuminated by continuous light in the infrared, coming through a monochromator from a glow-bar. The radiation wavelength can be selected continuously so as the photon energy ranges over the whole valence-to-conduction energy gap. When the specimen is probed, the photoinduced carriers are separated by the built-in field due to the depletion zone of a p-n junction or a Schottky barrier, and the photocurrent is amplified by the lock-in technique. The application of a back-surface radiation of less than the band-gap energy modifies, in some way, the photoconductive response to the band-gap probe since the secondary illumination changes the occupancy of the traps in the forbidden gap active in the photoconductive process. This phenomenon, known as "quenching" of

  6. Junction-side illuminated silicon detector arrays

    DOEpatents

    Iwanczyk, Jan S.; Patt, Bradley E.; Tull, Carolyn

    2004-03-30

    A junction-side illuminated detector array of pixelated detectors is constructed on a silicon wafer. A junction contact on the front-side may cover the whole detector array, and may be used as an entrance window for light, x-ray, gamma ray and/or other particles. The back-side has an array of individual ohmic contact pixels. Each of the ohmic contact pixels on the back-side may be surrounded by a grid or a ring of junction separation implants. Effective pixel size may be changed by separately biasing different sections of the grid. A scintillator may be coupled directly to the entrance window while readout electronics may be coupled directly to the ohmic contact pixels. The detector array may be used as a radiation hardened detector for high-energy physics research or as avalanche imaging arrays.

  7. Pathway illuminated: visualizing protein kinase C signaling.

    PubMed

    Violin, Jonathan D; Newton, Alexandra C

    2003-12-01

    Protein kinase C has been at the center of cell signaling since the discovery 25 years ago that it transduces signals that promote phospholipid hydrolysis. In recent years, the use of genetically encoded fluorescent reporters has enabled studies of the regulation of protein kinase C signaling in living cells. Advances in imaging techniques have unveiled unprecedented detail of the signal processing mechanics of protein kinase C, from the second messengers calcium and diacylglycerol that regulate protein kinase C activity, to the locations and kinetics of different protein kinase C isozymes, to the spatial and temporal dynamics of substrate phosphorylation by this key enzyme. This review discusses how fluorescence imaging studies have illuminated the fidelity with which protein kinase C transduces rapidly changing extracellular information into intracellular phosphorylation signals.

  8. Achromatic illumination system for small targets

    DOEpatents

    Sigler, Robert D.

    1979-01-01

    A pair of light beams is directed to provide illumination that is substantially uniform from all directions on a small target by a system comprising a pair of corrector windows, a pair of planar reflecting surfaces, a pair of paraboloidal mirrors and a reflecting mirror cavity. The components are arranged so that each of the beams passes through a corrector and is reflected from the planar surface to the paraboloidal mirror, from which it is focused through a hole in the planar surface to the interior of the cavity. The surface of the interior portion of the cavity is shaped to reflect the focused beam three times before the focused reflected beam strikes the target.

  9. Illumination for Worm Tracking and Behavioral Imaging

    PubMed Central

    Yemini, Eviatar; Kerr, Rex A.; Schafer, William R.

    2016-01-01

    Neurobiological research in genetically tractable organisms relies heavily on robust assays for behavioral phenotypes. The simple body plan of the nematode Caenorhabditis elegans makes it particularly amenable to the use of automated microscopy and image analysis to describe behavioral patterns quantitatively. This protocol provides an approach for obtaining uniform illumination during worm tracking. Good lighting can be more of an art than a science. Once the system is set up, it will be necessary to play with it, testing the results after each adjustment to ensure that the analysis software is able to clearly identify the worm and its boundaries. Although the protocol was developed for use in a single-worm tracker, it addresses factors important for the generation of reproducible, standardized images in all systems. PMID:22135668

  10. Adaptive multispectral illumination for retinal microsurgery.

    PubMed

    Sznitman, Raphael; Rother, Diego; Handa, Jim; Gehlbach, Peter; Hager, Gregory D; Taylor, Russell

    2010-01-01

    It has been shown that excessive white light exposure during retinal microsurgery can induce retinal damage. To address this problem, one can illuminate the retina with a device that alternates between white, and less damaging limited-spectrum light. The surgeon is then presented with a fully colored video by recoloring the limited-spectrum light frames, using information from the white-light frames. To obtain accurately colored images, while reducing phototoxicity, we have developed a novel algorithm that monitors the quality of the recolored images and determines when white light may be substituted by limited-spectrum light. We show qualitatively and quantitatively that our system can provide reliable images using a significantly smaller light dose as compared to other state-of-the-art coloring schemes.

  11. Implementation of phase-shift focus monitor with modified illumination

    NASA Astrophysics Data System (ADS)

    Nakao, Shuji; Maejima, Shinroku; Ueno, Atsushi; Yamashita, Shigenori; Miyazaki, Junji; Tokui, Akira; Tsujita, Kouichirou; Arimoto, Ichiriou

    2002-07-01

    For the convenience of practical use of phase shift focus monitor (PSFM), which has been developed by T. Brunner, imaging characteristics of PSFM are investigated under modified illumination by optical image calculations and printing experiments. Although the mechanism of pattern shift with focus offset under modified illumination is different from that for conventional high coherent illumination, sufficient sensitivity for precise focus monitoring is predicted by optical image calculations. Also, it is revealed that reduction of NA, i.e., localizing illumination at the peripheral part of pupil is effective to obtain higher sensitivity. By experiments, predicted characteristics are observed and similar sensitivity to that in conventional high coherent illumination is confirmed both for annular and quadrupole illuminations.

  12. Multiple Illuminant Colour Estimation via Statistical Inference on Factor Graphs.

    PubMed

    Mutimbu, Lawrence; Robles-Kelly, Antonio

    2016-08-31

    This paper presents a method to recover a spatially varying illuminant colour estimate from scenes lit by multiple light sources. Starting with the image formation process, we formulate the illuminant recovery problem in a statistically datadriven setting. To do this, we use a factor graph defined across the scale space of the input image. In the graph, we utilise a set of illuminant prototypes computed using a data driven approach. As a result, our method delivers a pixelwise illuminant colour estimate being devoid of libraries or user input. The use of a factor graph also allows for the illuminant estimates to be recovered making use of a maximum a posteriori (MAP) inference process. Moreover, we compute the probability marginals by performing a Delaunay triangulation on our factor graph. We illustrate the utility of our method for pixelwise illuminant colour recovery on widely available datasets and compare against a number of alternatives. We also show sample colour correction results on real-world images.

  13. Illumination Decomposition for Photograph With Multiple Light Sources.

    PubMed

    Zhang, Ling; Yan, Qingan; Liu, Zheng; Zou, Hua; Xiao, Chunxia

    2017-09-01

    Illumination decomposition for a single photograph is an important and challenging problem in image editing operation. In this paper, we present a novel coarse-to-fine strategy to perform illumination decomposition for photograph with multiple light sources. We first reconstruct the lighting environment of the image using the estimated geometry structure of the scene. With the position of lights, we detect the shadow regions as well as the highlights in the projected image for each light. Then, using the illumination cues from shadows, we estimate the coarse illumination decomposed image emitted by each light source. Finally, we present a light-aware illumination optimization model, which efficiently produces the finer illumination decomposition results, as well as recover the texture detail under the shadow. We validate our approach on a number of examples, and our method effectively decomposes the input image into multiple components corresponding to different light sources.

  14. Laser agile illumination for object tracking and classification - Feasibility study

    NASA Technical Reports Server (NTRS)

    Scholl, Marija S.; Vanzyl, Jakob J.; Meinel, Aden B.; Meinel, Marjorie P.; Scholl, James W.

    1988-01-01

    The 'agile illumination' concept for discrimination between ICBM warheads and decoys involves a two-aperture illumination with coherent light, diffraction of light by propagation, and a resulting interference pattern on the object surface. A scanning two-beam interference pattern illuminates one object at a time; depending on the shape, momentum, spinning, and tumbling characteristics of the interrogated object, different temporal signals will be obtained for different classes of objects.

  15. Laser agile illumination for object tracking and classification - Feasibility study

    NASA Technical Reports Server (NTRS)

    Scholl, Marija S.; Vanzyl, Jakob J.; Meinel, Aden B.; Meinel, Marjorie P.; Scholl, James W.

    1988-01-01

    The 'agile illumination' concept for discrimination between ICBM warheads and decoys involves a two-aperture illumination with coherent light, diffraction of light by propagation, and a resulting interference pattern on the object surface. A scanning two-beam interference pattern illuminates one object at a time; depending on the shape, momentum, spinning, and tumbling characteristics of the interrogated object, different temporal signals will be obtained for different classes of objects.

  16. Fundamental study of illumination transformation for color vision deficiencies

    NASA Astrophysics Data System (ADS)

    Bao, Shi; Tanaka, Go; Tajima, Johji

    2015-02-01

    An object's color depends on its reflectance and illumination, and dichromats cannot distinguish specific color pairs. It is considered that there is an appropriate illumination under which a dichromat can distinguish confusing color pairs. In this study, a fundamental investigation of an illumination transformation to assist dichromats is carried out. Because the appropriate illumination depends on the object, we propose a search algorithm for the optimum light source spectrum for an object. In experiments, the effectiveness of the proposed method is examined using digital images and an sRGB display.

  17. Energy efficient LED layout optimization for near-uniform illumination

    NASA Astrophysics Data System (ADS)

    Ali, Ramy E.; Elgala, Hany

    2016-09-01

    In this paper, we consider the problem of designing energy efficient light emitting diodes (LEDs) layout while satisfying the illumination constraints. Towards this objective, we present a simple approach to the illumination design problem based on the concept of the virtual LED. We formulate a constrained optimization problem for minimizing the power consumption while maintaining a near-uniform illumination throughout the room. By solving the resulting constrained linear program, we obtain the number of required LEDs and the optimal output luminous intensities that achieve the desired illumination constraints.

  18. High Efficiency, Illumination Quality OLEDs for Lighting

    SciTech Connect

    Joseph Shiang; James Cella; Kelly Chichak; Anil Duggal; Kevin Janora; Chris Heller; Gautam Parthasarathy; Jeffery Youmans; Joseph Shiang

    2008-03-31

    The goal of the program was to demonstrate a 45 lumen per watt white light device based upon the use of multiple emission colors through the use of solution processing. This performance level is a dramatic extension of the team's previous 15 LPW large area illumination device. The fundamental material system was based upon commercial polymer materials. The team was largely able to achieve these goals, and was able to deliver to DOE a 90 lumen illumination source that had an average performance of 34 LPW a 1000 cd/m{sup 2} with peak performances near 40LPW. The average color temperature is 3200K and the calculated CRI 85. The device operated at a brightness of approximately 1000cd/m{sup 2}. The use of multiple emission colors particularly red and blue, provided additional degrees of design flexibility in achieving white light, but also required the use of a multilayered structure to separate the different recombination zones and prevent interconversion of blue emission to red emission. The use of commercial materials had the advantage that improvements by the chemical manufacturers in charge transport efficiency, operating life and material purity could be rapidly incorporated without the expenditure of additional effort. The program was designed to take maximum advantage of the known characteristics of these material and proceeded in seven steps. (1) Identify the most promising materials, (2) assemble them into multi-layer structures to control excitation and transport within the OLED, (3) identify materials development needs that would optimize performance within multilayer structures, (4) build a prototype that demonstrates the potential entitlement of the novel multilayer OLED architecture (5) integrate all of the developments to find the single best materials set to implement the novel multilayer architecture, (6) further optimize the best materials set, (7) make a large area high illumination quality white OLED. A photo of the final deliverable is shown. In

  19. Illuminance and luminance distributions of a prototype ambient illumination system for Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Mullican, R. C.; Hayes, B. C.

    1991-01-01

    Preliminary results of research conducted in the late 1970's indicate that perceptual qualities of an enclosure can be influenced by the distribution of illumination within the enclosure. Subjective impressions such as spaciousness, perceptual clarity, and relaxation or tenseness, among others, appear to be related to different combinations of surface luminance. A prototype indirect ambient illumination system was developed which will allow crew members to alter surface luminance distributions within an enclosed module, thus modifying perceptual cues to match crew preferences. A traditional lensed direct lighting system was compared to the prototype utilizing the full-scale mockup of Space Station Freedom developed by Marshall Space Flight Center. The direct lensed system was installed in the habitation module with the indirect prototype deployed in the U.S. laboratory module. Analysis centered on the illuminance and luminance distributions resultant from these systems and the implications of various luminaire spacing options. All test configurations were evaluated for compliance with NASA Standard 3000, Man-System Integration Standards.

  20. Low-Cost Illumination-Grade LEDs

    SciTech Connect

    Epler, John

    2013-08-31

    Solid State Lighting is a cost-effective, energy-conserving technology serving a rapidly expand- ing multi-billion dollar market. This program was designed to accelerate this lighting revolution by reducing the manufacturing cost of Illumination-Grade LEDs. The technical strategy was to investigate growth substrate alternatives to standard planar sapphire, select the most effective and compatible option, and demonstrate a significant increase in Lumen/$ with a marketable LED. The most obvious alternate substrate, silicon, was extensively studied in the first two years of the program. The superior thermal and mechanical properties of Si were expected to improve wavelength uniformity and hence color yield in the manufacture of high-power illumination- grade LEDs. However, improvements in efficiency and epitaxy uniformity on standard c-plane sapphire diminished the advantages of switching to Si. Furthermore, the cost of sapphire decreased significantly and the cost of processing Si devices using our thin film process was higher than expected. We concluded that GaN on Si was a viable technology but not a practical option for Philips Lumileds. Therefore in 2012 and 2013, we sought and received amendments which broadened the scope to include other substrates and extended the time of execution. Proprietary engineered substrates, off-axis (non-c-plane) sapphire, and c-plane patterned sapphire substrates (PSS) were all investigated in the final 18 months of this program. Excellent epitaxy quality was achieved on all three candidates; however we eliminated engineered substrates and non-c-plane sapphire because of their higher combined cost of substrate, device fabrication and packaging. Ultimately, by fabricating a flip-chip (FC) LED based upon c-plane PSS we attained a 42% reduction in LED manufacturing cost relative to our LUXEON Rebel product (Q1-2012). Combined with a flux gain from 85 to 102 Lm, the LUXEON Q delivered a 210% increase in Lm/$ over this time period. The

  1. THE RELATION BETWEEN VISUAL ACUITY AND ILLUMINATION

    PubMed Central

    Shlaer, Simon

    1937-01-01

    1. An apparatus for measuring the visual acuity of the eye at different illuminations is described. The test object is continuously variable in size and is presented at a fixed distance from the eye in the center of a 30° field. Observation of the field is through an artificial pupil. The maximum intensity obtainable is more than enough to cover the complete physiological range for the eye with white light though only 110 watts are consumed by the source. Means for varying the intensity over a range of 1:1010 in small steps are provided. 2. The relation of visual acuity and illumination for two trained observers was measured, using two different types of test object, a broken circle and a grating. The measurements with both test objects show a break at a visual acuity of 0.16, all values below that being mediated by the rods and those above by the cones. The grating gives higher visual acuities at intensities less than about 30 photons and lower visual acuities above that. The maximum visual acuity attainable with the grating under the same conditions is about 30 per cent lower than that with the C. It is shown that the limiting factor in the resolution of the eye for the grating is the diameter of the pupil when it is less than 2.3 mm. and the size of the central cones when the pupil is larger than that. The value of the diameter of the cone derived on that basis from the visual acuity data agrees with that derived from direct cone count in a unit of area. 3. The data for the cones made with both test objects are adequately described by one and the same form of the stationary state equation derived by Hecht for the photoreceptor system. This fact, together with certain considerations about the difference in the nature of the two test objects with regard to the resolvable area, leads to the conclusion that detail perception is a function of a distance rather than an area. All the data for the rods can likewise be described by another variety of the same equation

  2. Wide-field fundus imaging with trans-palpebral illumination

    NASA Astrophysics Data System (ADS)

    Toslak, Devrim; Thapa, Damber; Chen, Yanjun; Erol, Muhammet Kazim; Chan, R. V. Paul; Yao, Xincheng

    2017-02-01

    In conventional fundus imaging devices, transpupillary illumination is used for illuminating the inside of the eye. In this method, the illumination light is directed into the posterior segment of the eye through the cornea and passes the pupillary area. As a result of sharing the pupillary area for the illumination beam and observation path, pupil dilation is typically necessary for wide-angle fundus examination, and the field of view is inherently limited. An alternative approach is to deliver light from the sclera. It is possible to image a wider retinal area with transcleral-illumination. However, the requirement of physical contact between the illumination probe and the sclera is a drawback of this method. We report here trans-palpebral illumination as a new method to deliver the light through the upper eyelid (palpebra). For this study, we used a 1.5 mm diameter fiber with a warm white LED light source. To illuminate the inside of the eye, the fiber illuminator was placed at the location corresponding to the pars plana region. A custom designed optical system was attached to a digital camera for retinal imaging. The optical system contained a 90 diopter ophthalmic lens and a 25 diopter relay lens. The ophthalmic lens collected light coming from the posterior of the eye and formed an aerial image between the ophthalmic and relay lenses. The aerial image was captured by the camera through the relay lens. An adequate illumination level was obtained to capture wide angle fundus images within ocular safety limits, defined by the ISO 15004-2: 2007 standard. This novel trans-palpebral illumination approach enables wide-angle fundus photography without eyeball contact and pupil dilation.

  3. Illumination-invariant hand gesture recognition

    NASA Astrophysics Data System (ADS)

    Mendoza-Morales, América I.; Miramontes-Jaramillo, Daniel; Kober, Vitaly

    2015-09-01

    In recent years, human-computer interaction (HCI) has received a lot of interest in industry and science because it provides new ways to interact with modern devices through voice, body, and facial/hand gestures. The application range of the HCI is from easy control of home appliances to entertainment. Hand gesture recognition is a particularly interesting problem because the shape and movement of hands usually are complex and flexible to be able to codify many different signs. In this work we propose a three step algorithm: first, detection of hands in the current frame is carried out; second, hand tracking across the video sequence is performed; finally, robust recognition of gestures across subsequent frames is made. Recognition rate highly depends on non-uniform illumination of the scene and occlusion of hands. In order to overcome these issues we use two Microsoft Kinect devices utilizing combined information from RGB and infrared sensors. The algorithm performance is tested in terms of recognition rate and processing time.

  4. Tachistoscopic illumination and masking of real scenes

    PubMed Central

    Chichka, David; Philbeck, John W.; Gajewski, Daniel A.

    2014-01-01

    Tachistoscopic presentation of scenes has been valuable for studying the emerging properties of visual scene representations. The spatial aspects of this work have generally been focused on the conceptual locations (e.g., next to the refrigerator) and the directional locations of objects in 2D arrays and/or images. Less is known about how the perceived egocentric distance of objects develops. Here we describe a novel system for presenting brief glimpses of a real-world environment, followed by a mask. The system includes projectors with mechanical shutters for projecting the fixation and masking images, a set of LED floodlights for illuminating the environment, and computer-controlled electronics to set the timing and initiate the process. Because a real environment is used, most visual distance and depth cues may be manipulated using traditional methods. The system is inexpensive, robust, and its components are readily available in the marketplace. This paper describes the system and the timing characteristics of each component. Verification of the ability to control exposure to time scales as low as a few milliseconds is demonstrated. PMID:24519496

  5. Efficient White SSL Component for General Illumination

    SciTech Connect

    Sean Evans

    2011-01-31

    Cree has developed a new, high-efficiency, low-cost, light emitting diode (LED) module that should be capable of replacing standard, halogen, fluorescent and metal halide lamps based on the total cost of ownership. White LEDs are produced by combining one or more saturated color LEDs with a phosphor or other light down-converting media to achieve white broad-band illumination. This two year project addressed LED chip, package and phosphor efficiency improvements to establish a technology platform suitable for low-cost, high-efficiency commercial luminaires. New phosphor materials with improved quantum efficiency at 'real-life' operating conditions were developed along with new package technology to improve the efficiency of warm white LED modules compared to the baseline technology. Specifically, Cree has successfully demonstrated warm white LED modules providing 540 lumens at a correlated color temperature (CCT) of 3000 K. The LED module had an efficacy of 102.8 lumens per watt (LPW) using 1 mm2 chips biased at 350 mA - a 27% improvement over the technology at project start (81 LPW at 3000K). The white modules also delivered an efficacy of 88 LPW at elevated junction temperatures of 125 C. In addition, a proof-of-concept 4-inch downlight luminaire produced a flux of 1183 lumens at a CCT of 2827 K and a color rendering index (CRI) of 80 using this project's phosphor developments.

  6. Creating a crystalline silicon (111) needle by optical vortex illumination

    NASA Astrophysics Data System (ADS)

    Izumisawa, Kai; Ablez, Ablimit; Nakamura, Yuri; Sugimoto, Tatsuyuki; Fujiwara, Honami; Miyamoto, Katsuhiko; Morita, Ryuji; Omatsu, Takashige

    2017-04-01

    We reported on crystalline silicon structures formed on a silicon (111) substrate through picosecond optical vortex pulse illumination. A crystalline silicon needle with a height of 20 µm was structured through single vortex pulse illumination. Sixteen overlaid vortex pulses shaped the silicon into a crystalline pillar with a height of 45 µm.

  7. 36 CFR 910.38 - Building exterior illumination.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Building exterior... PENNSYLVANIA AVENUE DEVELOPMENT AREA Standards Uniformly Applicable to the Development Area § 910.38 Building exterior illumination. Exterior illumination of a building shall be in conformance with the...

  8. 36 CFR 910.38 - Building exterior illumination.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Building exterior... PENNSYLVANIA AVENUE DEVELOPMENT AREA Standards Uniformly Applicable to the Development Area § 910.38 Building exterior illumination. Exterior illumination of a building shall be in conformance with the...

  9. Lightness of an object under two illumination levels.

    PubMed

    Zdravković, Suncica; Economou, Elias; Gilchrist, Alan

    2006-01-01

    Anchoring theory (Gilchrist et al, 1999 Psychological Review 106 795-834) predicts a wide range of lightness errors, including failures of constancy in multi-illumination scenes and a long list of well-known lightness illusions seen under homogeneous illumination. Lightness values are computed both locally and globally and then averaged together. Local values are computed within a given region of homogeneous illumination. Thus, for an object that extends through two different illumination levels, anchoring theory produces two values, one for the patch in brighter illumination and one for the patch in dimmer illumination. Observers can give matches for these patches separately, but they can also give a single match for the whole object. Anchoring theory in its current form is unable to predict these object matches. We report eight experiments in which we studied the relationship between patch matches and object matches. The results show that the object match represents a compromise between the match for the patch in the field of highest illumination and the patch in the largest field of illumination. These two principles are parallel to the rules found for anchoring lightness: highest luminance rule and area rule.

  10. Fraunhofer Diffraction Patterns from Apertures Illuminated with Nonparallel Light.

    ERIC Educational Resources Information Center

    Klingsporn, Paul E.

    1979-01-01

    Discusses several aspects of Fraunhofer diffraction patterns from apertures illuminated by diverging light. Develops a generalization to apertures of arbitrary shape which shows that the sizes of the pattern are related by a simple scale factor. Uses the Abbe theory of image formation by diffraction to discuss the intensity of illumination of the…

  11. Transfer between Pose and Illumination Training in Face Recognition

    ERIC Educational Resources Information Center

    Liu, Chang Hong; Bhuiyan, Md. Al-Amin; Ward, James; Sui, Jie

    2009-01-01

    The relationship between pose and illumination learning in face recognition was examined in a yes-no recognition paradigm. The authors assessed whether pose training can transfer to a new illumination or vice versa. Results show that an extensive level of pose training through a face-name association task was able to generalize to a new…

  12. Nonthermal illumination effects on ultra-shallow junction formation

    NASA Astrophysics Data System (ADS)

    Vaidyanathan, Ramakrishnan; Felch, Susan; Graoui, Houda; Foad, Majeed A.; Kondratenko, Yevgeniy; Seebauer, Edmund G.

    2011-05-01

    In this letter, we present direct and unambiguous experimental evidence for nonthermal illumination effects in boron or arsenic implanted silicon. Both, dopant diffusion and activation vary significantly with illumination. Depending on annealing temperature, diffusion is either enhanced or inhibited. The results have significant implications for modeling and formation of ultrashallow junctions.

  13. 36 CFR 910.38 - Building exterior illumination.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 3 2012-07-01 2012-07-01 false Building exterior... PENNSYLVANIA AVENUE DEVELOPMENT AREA Standards Uniformly Applicable to the Development Area § 910.38 Building exterior illumination. Exterior illumination of a building shall be in conformance with the standards...

  14. 36 CFR 910.38 - Building exterior illumination.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 3 2014-07-01 2014-07-01 false Building exterior... PENNSYLVANIA AVENUE DEVELOPMENT AREA Standards Uniformly Applicable to the Development Area § 910.38 Building exterior illumination. Exterior illumination of a building shall be in conformance with the standards...

  15. Illumination Criteria in Imaging System Design for Security Applications,

    DTIC Science & Technology

    1979-12-01

    conjunction with pole spacing and distance from the critical area to be illuminated. Streetlights or roadway luminaires are characterized by their light...found best suited for perimeter illumination, when CCTV is employed, are the floodlights and the -o 4, , streetlights (roadway luminaires). The... streetlights are preferred, however, because the asymmetrical light distribution simplifies the system architecture when designing for uniformity of The

  16. 50. STREET LIGHTING & ILLUMINATED SIGNS, NORTH & SOUTH APPROACHES, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    50. STREET LIGHTING & ILLUMINATED SIGNS, NORTH & SOUTH APPROACHES, DETAILS OF ILLUMINATED SIGNS (Sheet 2 of 3 sheets), June 29, 1932 - West End-North Side Bridge, Spanning Ohio River, approximately 1 mile downstream from confluence of Monongahela & Allegheny rivers, Pittsburgh, Allegheny County, PA

  17. Adaptive Ambient Illumination Based on Color Harmony Model

    NASA Astrophysics Data System (ADS)

    Kikuchi, Ayano; Hirai, Keita; Nakaguchi, Toshiya; Tsumura, Norimichi; Miyake, Yoichi

    We investigated the relationship between ambient illumination and psychological effect by applying a modified color harmony model. We verified the proposed model by analyzing correlation between psychological value and modified color harmony score. Experimental results showed the possibility to obtain the best color for illumination using this model.

  18. Template based illumination compensation algorithm for multiview video coding

    NASA Astrophysics Data System (ADS)

    Li, Xiaoming; Jiang, Lianlian; Ma, Siwei; Zhao, Debin; Gao, Wen

    2010-07-01

    Recently multiview video coding (MVC) standard has been finalized as an extension of H.264/AVC by Joint Video Team (JVT). In the project Joint Multiview Video Model (JMVM) for the standardization, illumination compensation (IC) is adopted as a useful tool. In this paper, a novel illumination compensation algorithm based on template is proposed. The basic idea of the algorithm is that the illumination of the current block has a strong correlation with its adjacent template. Based on this idea, firstly a template based illumination compensation method is presented, and then a template models selection strategy is devised to improve the illumination compensation performance. The experimental results show that the proposed algorithm can improve the coding efficiency significantly.

  19. High illuminance light-emitting diode headlight for medical applications

    NASA Astrophysics Data System (ADS)

    Lee, Ui-Hyung; Jung, Jae-hun; Park, Seung Hyun; Lee, Gye Seon; Ju, Young-Gu

    2010-11-01

    High brightness light emitting diodes have been used to develop high illuminance headlight for medical applications. It provides various advantages such as high illuminance, long life time, reduced infra red light, extended operation time with battery and light weight. A 3 W LED was employed to achieve the high performance medical headlight. The optical design includes two lenses for high energy transmission and high illuminance. The LED headlight shows 42,000 lux with spot diameter of 80 mm at the distance of 300 mm. For comparison purpose, 5 W LED was also used to obtain the high illuminance headlight. However, the large divergence angle and large spot size of the 5 W LED limits the illuminance to 31,000 lux with increased burden on heat dissipation. The thermal images of the heat sinks indicate that the temperature of the headlight using a 3 W LED is below 50 degree C, which is suitable for medical applications.

  20. Comparative study of strategies for illumination-invariant texture representations

    NASA Astrophysics Data System (ADS)

    Levienaise-Obadia, Barbara V.; Kittler, Josef; Christmas, William J.

    1998-12-01

    Illumination invariance is of paramount importance to annotate video sequences, stored in large video databases. However, popular texture analysis methods, such as multichannel filtering techniques, do not yield illumination-invariant texture representations. In this paper, we assess the effectiveness of three illumination normalization schemes for texture representations, derived from Gabor filter outputs. The schemes aim at overcoming intensity scaling effects, due to changes in illuminating conditions. A theoretical analysis and experimental results, enable us to select one scheme as the most promising. In this scheme, a normalizing factor is derived at each pixel, by combining the energy response of different filters at that pixel. The scheme overcomes illumination variations well, while still preserving discriminatory textural information. Further statistical analysis may shed light on other interesting properties or limitations of the scheme.

  1. Evaluation of retinal illumination in coaxial fundus camera

    NASA Astrophysics Data System (ADS)

    de Oliveira, André O.; de Matos, Luciana; Castro Neto, Jarbas C.

    2016-09-01

    Retinal images are obtained by simultaneously illuminating and imaging the retina, which is achieved using a fundus camera. This device meets low light illumination of the fundus with high resolution and reflection free images. Although the current equipment presents a sophisticated solution, it is complex to align due to the high number of off-axis components. In this work, we substitute the complex illumination system by a ring of LEDs mounted coaxially to the imaging optical system, positioning it in the place of the holed mirror of the traditional optical design. We evaluated the impact of this substitution regarding to image quality (measured through the modulation transfer function) and illumination uniformity produced by this system on the retina. The results showed there is no change in image quality and no problem was detected concerning uniformity compared to the traditional equipment. Consequently, we avoided off-axis components, easing the alignment of the equipment without reducing both image quality and illumination uniformity.

  2. Mixing and Simplex Search for Optimal Illumination in Machine Vision

    NASA Astrophysics Data System (ADS)

    Kim, HyungTae; Cho, KyeongYong; Jin, Kyungchan; Yoon, JooSung; Cho, YoungJune

    2014-07-01

    Mixed-color illumination affects the quality of images in industrial vision system and it is important to optimize color and intensity for image acquisition. This study used simplex search to find the optimal illumination in a short amount of time. A typical color mixer synthesized various color of lights by changing the inputs of RGB power LEDs and passing the lights through an optical system. The image quality under mixed-color illumination was calculated according to the sharpness. For the purpose of optimal illumination using simplex search, a probe network was organized with N + 1probing points for N inputs. The shape of the probe network, simplex, was varied through procedures of extension, contraction, and shrinkage. The inputs of the color mixer were changed until the size of the simplex became smaller than a threshold. The simplex search was tested for commercial semiconductor patterns, and was useful for finding the optimal illumination.

  3. Dactyl Dark Side Illuminated by Idashine

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Within seconds of its closest approach to the asteroid 243 Ida on August 28, 1993, the Galileo spacecraft's Solid State Imaging camera caught this glimpse of Ida's previously unknown moon orbiting the asteroid. One frame of a 15-image set designed to capture a view of Ida at the highest possible resolution landed by chance with its edge right on the little moon. The range from the spacecraft was about 2,400 kilometers (1,500 miles), and each picture element spans about 24 meters (80 feet) on the surface of the moon. Only a small sliver of the sunlit crescent is visible at the edge of the frame (which was shifted inward toward the center in this representation). Ida itself is outside this frame to the left and slightly below center, roughly 90 kilometers (56 miles) away. The darkside of this moon is illuminated by light reflected from the sunlit side of Ida, in the same way that Earthshine brightens the dark part of Earth's Moon when it shows only a thin sunlit crescent, near 'new Moon'. The smoothly curving shape of the dark edge of Ida's moon can be seen on the left. The moon's observed darkside was just barely detectable by Galileo's camera; computer enhancement has made it easier to see in this picture. The visibility of the moon's dark limb has provided valuable information on the size and shape of the tiny moon, which measures about 1.2 x 1.4 X 1.6 kilometers (0.75 x 0.87 x 1 mile). The little moon's relatively smooth egg shape contrasts markedly with the highly irregular shape of its parent, the asteroid Ida. This image was relayed to Earth from the Galileo spacecraft on June 8, 1994. The Galileo project, whose primary mission is the exploration of the Jupiter system in 1995-97, is managed for NASA's office of Space Science by the Jet Propulsion Laboratory.

  4. Illuminate Knowledge Elements in Geoscience Literature

    NASA Astrophysics Data System (ADS)

    Ma, X.; Zheng, J. G.; Wang, H.; Fox, P. A.

    2015-12-01

    There are numerous dark data hidden in geoscience literature. Efficient retrieval and reuse of those data will greatly benefit geoscience researches of nowadays. Among the works of data rescue, a topic of interest is illuminating the knowledge framework, i.e. entities and relationships, embedded in documents. Entity recognition and linking have received extensive attention in news and social media analysis, as well as in bioinformatics. In the domain of geoscience, however, such works are limited. We will present our work on how to use knowledge bases on the Web, such as ontologies and vocabularies, to facilitate entity recognition and linking in geoscience literature. The work deploys an un-supervised collective inference approach [1] to link entity mentions in unstructured texts to a knowledge base, which leverages the meaningful information and structures in ontologies and vocabularies for similarity computation and entity ranking. Our work is still in the initial stage towards the detection of knowledge frameworks in literature, and we have been collecting geoscience ontologies and vocabularies in order to build a comprehensive geoscience knowledge base [2]. We hope the work will initiate new ideas and collaborations on dark data rescue, as well as on the synthesis of data and knowledge from geoscience literature. References: 1. Zheng, J., Howsmon, D., Zhang, B., Hahn, J., McGuinness, D.L., Hendler, J., and Ji, H. 2014. Entity linking for biomedical literature. In Proceedings of ACM 8th International Workshop on Data and Text Mining in Bioinformatics, Shanghai, China. 2. Ma, X. Zheng, J., 2015. Linking geoscience entity mentions to the Web of Data. ESIP 2015 Summer Meeting, Pacific Grove, CA.

  5. Design and simulation of double annular illumination mode for microlithography

    NASA Astrophysics Data System (ADS)

    Song, Qiang; Zhu, Jing; Yang, Baoxi; Liu, Lei; Wang, Jun; Huang, Huijie

    2013-08-01

    Methods of generating various illumination patterns remain as an attractive and important micro-optics research area for the development of resolution enhancement in advanced lithography system. In the current illumination system of lithography machine, off-axis illumination is widely used as an effective approach to enhance the resolution and increase the depth of focus (DOF). This paper proposes a novel illumination mode generation unit, which transform conventional mode to double annular shaped radial polarized (DARP) mode for improving the resolution of micro-lithography. Through LightToolsTM software simulation, double annular shaped mode is obtained from the proposed generation unit. The mathematical expressions of the radius variation of inner and outer rings are deduced. The impacts of conventional and dual concentric annular illumination pattern on critical dimension uniformity were simulated on an isolated line, square hole and corner. Lithography performance was compared between DARP illumination mode and corresponding single annular modes under critical dimension of 45nm. As a result, DARP illumination mode can improve the uniformity of aerial image at 45nm node through pitch varied in 300-500 nm to a certain extent.

  6. Rock fracture image acquisition with both visible and ultraviolet illuminations

    NASA Astrophysics Data System (ADS)

    Wang, Weixing; Hakami, Eva

    2006-02-01

    Swedish Nuclear Fuel and Waste Management Company (SKB) have identified the need for a better understanding of radionuclide transport and retention processes in fractured rock since 1994. In the study, the first hard problem is to obtain rock fracture images of a good quality, since rock surface is very rough, and composed of complicated and multiple fractures, as a result, image acquisition is the first important. As a cooperation project between Sweden and China, we sampled a number of rock specimens for analyzing rock fracture network by visible and ultraviolet image technique, in the field. The samples are resin injected, in which way; opened fractures can be seen clearly by means of UV light illumination, and the rock surface information can be obtained by using visible optical illumination. We used different digital cameras and microscope to take images by two illuminations. From the same samples; we found that UV illumination image gives the clear information of fracture opening or closing, and the visible optical illumination gives the information of the rock surface (e.g. filling materials inside of fractures). By applying this technique, the minimum width of rock fracture 0.01 mm can be analyzed. This paper presents: (1) Rock fracture image acquiring techniques; (2) Rock fracture image acquisition by using UV light illumination and visible optical illumination; and (3) Conclusions. The studied method can be used both in the field and a laboratory.

  7. Wavelet-based illumination invariant preprocessing in face recognition

    NASA Astrophysics Data System (ADS)

    Goh, Yi Zheng; Teoh, Andrew Beng Jin; Goh, Kah Ong Michael

    2009-04-01

    Performance of a contemporary two-dimensional face-recognition system has not been satisfied due to the variation in lighting. As a result, many works of solving illumination variation in face recognition have been carried out in past decades. Among them, the Illumination-Reflectance model is one of the generic models that is used to separate the individual reflectance and illumination components of an object. The illumination component can be removed by means of image-processing techniques to regain an intrinsic face feature, which is depicted by the reflectance component. We present a wavelet-based illumination invariant algorithm as a preprocessing technique for face recognition. On the basis of the multiresolution nature of wavelet analysis, we decompose both illumination and reflectance components from a face image in a systematic way. The illumination component wherein resides in the low-spatial-frequency subband can be eliminated efficiently. This technique works out very advantageously for achieving higher recognition performance on YaleB, CMU PIE, and FRGC face databases.

  8. Customized illumination shapes for 193nm immersion lithography

    NASA Astrophysics Data System (ADS)

    Ling, Moh Lung; Chua, Gek Soon; Lin, Qunying; Tay, Cho Jui; Quan, Chenggen

    2008-03-01

    In this paper, a study on customized illumination shape configurations as resolution enhancement for 45nm technology node will be presented. Several new source shape configurations will be explored through simulation based on 193nm immersion lithography on 6% Attenuated Phase Shift Mask. Forbidden pitch effect is commonly encountered in the application of off axis illumination (OAI). The illumination settings are often optimized to allow maximum process window for a pitch. This is done by creating symmetrical distribution of diffraction order on the pupil plane. However, at other pitch, the distribution of diffraction order on the pupil plane results in severe degradation in image contrast and results in significant critical dimension (CD) fluctuation. The problematic pitch is often known as forbidden pitch. It has to be avoided in the design and thus limited the pitch range to be imaged for particular illumination. An approach to modify off axis illumination to minimize the effect of forbidden pitch is explored in this study. The new customized shape for one dimensional line and space pattern is modified from current off axis illumination. Simulation study is done to evaluate the performance some customized shapes. The extent of CD fluctuation and CD through pitch uniformity is analyzed to determine the performance enhancement of the new illumination shapes. From simulation result, the proposed modification have significantly improved the through pitch performance and minimized the effect of forbidden pitch.

  9. Photoactivation and optogenetics with micro mirror enhanced illumination

    NASA Astrophysics Data System (ADS)

    Rückerl, F.; Berndt, D.; Heber, J.; Shorte, S.

    2014-05-01

    Photoactivation and "optogenetics" require the precise control of the illumination path in optical microscopes. It is equally important to shape the illumination spatially as well as to have control over the intensity and the duration of the illumination. In order to achieve these goals we use programmable, diffractive Micro Mirror Arrays (MMA) as fast spatial light modulators for beam steering. By combining two MMAs with 256×256 mirrors each, our illumination setup allows for fast angular and spatial control at a wide spectral range (260-1000 nm). Illumination pulses can be as short as 50 μs, or can also extend to several seconds. The specific illumination modes of the individual areas results in a precise control over the light dose to the sample, giving significant advantage when investigating dosage dependent activation inasmuch as both the duration and the intensity can be controlled distinctly. The setup is integrated to a microscope and allows selective illumination of regions in the sample, enabling the precise, localized activation of fluorescent probes and the activation and deactivation of cellular and subcellular signaling cascades using photo activated ion channels. The high reflectivity in the UV range (up to 260nm) further allows gene silencing using UV activated constructs (e.g. caged morpholinos).

  10. The DESI shutter with integrated fiber illumination system

    NASA Astrophysics Data System (ADS)

    Derwent, Mark A.; O'Brien, Thomas P.; Pappalardo, Daniel P.; Martini, Paul; Coker, Carl T.; Pogge, Richard W.

    2016-08-01

    The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 40 million galaxies over 14,000 sq deg will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers in turn feed ten broad-band spectrographs. We describe the unique shutter design that incorporates a fiber illumination system into the shutter blade. When activated, the fiber illumination system directs intense 430-480nm wavelength light at the instrument's fiber slit in order to back-illuminate the telescope's focal plane and verify the location of the robotic fiber positioners. The back-illumination is typically active during science exposure read-outs and therefore requires the shutter to attenuate light by a factor of at least 107. This paper describes how we have integrated the fiber illumination system into the shutter blade, as well as incorporated an inflatable seal around the shutter aperture to achieve the light attenuation requirement. We also present lab results that characterize the fiber illumination and shutter attenuation. Finally, we discuss the control scheme that executes exposure and fiber illumination modes, and meets the shutter timing requirements.

  11. Spectral image analysis of mutual illumination between florescent objects.

    PubMed

    Tominaga, Shoji; Kato, Keiji; Hirai, Keita; Horiuchi, Takahiko

    2016-08-01

    This paper proposes a method for modeling and component estimation of the spectral images of the mutual illumination phenomenon between two fluorescent objects. First, we briefly describe the bispectral characteristics of a single fluorescent object, which are summarized as a Donaldson matrix. We suppose that two fluorescent objects with different bispectral characteristics are located close together under a uniform illumination. Second, we model the mutual illumination between two objects. It is shown that the spectral composition of the mutual illumination is summarized with four components: (1) diffuse reflection, (2) diffuse-diffuse interreflection, (3) fluorescent self-luminescence, and (4) interreflection by mutual fluorescent illumination. Third, we develop algorithms for estimating the spectral image components from the observed images influenced by the mutual illumination. When the exact Donaldson matrices caused by the mutual illumination influence are unknown, we have to solve a non-linear estimation problem to estimate both the spectral functions and the location weights. An iterative algorithm is then proposed to solve the problem based on the alternate estimation of the spectral functions and the location weights. In our experiments, the feasibility of the proposed method is shown in three cases: the known Donaldson matrices, weak interreflection, and strong interreflection.

  12. Effects of chromatic image statistics on illumination induced color differences.

    PubMed

    Lucassen, Marcel P; Gevers, Theo; Gijsenij, Arjan; Dekker, Niels

    2013-09-01

    We measure the color fidelity of visual scenes that are rendered under different (simulated) illuminants and shown on a calibrated LCD display. Observers make triad illuminant comparisons involving the renderings from two chromatic test illuminants and one achromatic reference illuminant shown simultaneously. Four chromatic test illuminants are used: two along the daylight locus (yellow and blue), and two perpendicular to it (red and green). The observers select the rendering having the best color fidelity, thereby indirectly judging which of the two test illuminants induces the smallest color differences compared to the reference. Both multicolor test scenes and natural scenes are studied. The multicolor scenes are synthesized and represent ellipsoidal distributions in CIELAB chromaticity space having the same mean chromaticity but different chromatic orientations. We show that, for those distributions, color fidelity is best when the vector of the illuminant change (pointing from neutral to chromatic) is parallel to the major axis of the scene's chromatic distribution. For our selection of natural scenes, which generally have much broader chromatic distributions, we measure a higher color fidelity for the yellow and blue illuminants than for red and green. Scrambled versions of the natural images are also studied to exclude possible semantic effects. We quantitatively predict the average observer response (i.e., the illuminant probability) with four types of models, differing in the extent to which they incorporate information processing by the visual system. Results show different levels of performance for the models, and different levels for the multicolor scenes and the natural scenes. Overall, models based on the scene averaged color difference have the best performance. We discuss how color constancy algorithms may be improved by exploiting knowledge of the chromatic distribution of the visual scene.

  13. Visual inspection system with flexible illumination and autofocusing

    NASA Astrophysics Data System (ADS)

    Roh, Young Jun; Lee, Duk-Young; Kim, Min-Young; Cho, Hyungsuck

    2002-10-01

    The visual information obtained from CCD camera is vulnerable to external illumination and the surface reflection properties of object images. Thus, the success of extracting aimed features from images depends mostly on the appropriate design of illumination. This paper presents a visual inspection system that is equipped with a flexible illumination and an auto-focusing unit. The proposed illumination system consists of a three-layered LED illumination device and the controllable diffusers. Each layer is composed of LEDs arranged in a ring type, and a controllable diffuser unit is located in front of each layer. The diffuser plays a role of diffusing lights emitted from the LEDs so that the characteristics of illumination is made varied. This combined configuration of the LED light sources and the adjustable diffuser creates the various lighting conditions. In addition to this flexible illumination function, the vision system is equipped with an auto-focusing unit composed of a pattern projector and a working distance adjustable zoom camera. For the auto-focusing, hill climbing algorithm is used here based on a reliable focus measure that is defined as the variance of high frequency terms in an image. Through a series of experiments, the influence of the illumination system on image quality is analyzed for various objects that have different reflective properties and shapes. As an example study, the electrical parts inspection is investigated. In this study, several types of chips with different sizes and heights are segmented and focused automatically, and then analyzed for part inspection. The results obtained from a series of experiments confirm the usefulness of the proposed system and the effectiveness of the illumination and focusing method.

  14. Research on infrared imaging illumination model based on materials

    NASA Astrophysics Data System (ADS)

    Hu, Hai-he; Feng, Chao-yin; Guo, Chang-geng; Zheng, Hai-jing; Han, Qiang; Hu, Hai-yan

    2013-09-01

    In order to effectively simulate infrared features of the scene and infrared high light phenomenon, Based on the visual light illumination model, according to the optical property of all material types in the scene, the infrared imaging illumination models are proposed to fulfill different materials: to the smooth material with specular characteristic, adopting the infrared imaging illumination model based on Blinn-Phone reflection model and introducing the self emission; to the ordinary material which is similar to black body without highlight feature, ignoring the computation of its high light reflection feature, calculating simply the material's self emission and its reflection to the surrounding as its infrared imaging illumination model, the radiation energy under zero range of visibility can be obtained according to the above two models. The OpenGl rendering technology is used to construct infrared scene simulation system which can also simulate infrared electro-optical imaging system, then gets the synthetic infrared images from any angle of view of the 3D scenes. To validate the infrared imaging illumination model, two typical 3D scenes are made, and their infrared images are calculated to compare and contrast with the real collected infrared images obtained by a long wave infrared band imaging camera. There are two major points in the paper according to the experiment results: firstly, the infrared imaging illumination models are capable of producing infrared images which are very similar to those received by thermal infrared camera; secondly, the infrared imaging illumination models can simulate the infrared specular feature of relative materials and common infrared features of general materials, which shows the validation of the infrared imaging illumination models. Quantitative analysis shows that the simulation images are similar to the collected images in the aspects of main features, but their histogram distribution does not match very well, the

  15. Seasonal variation in human illumination exposure at two different latitudes.

    PubMed

    Cole, R J; Kripke, D F; Wisbey, J; Mason, W J; Gruen, W; Hauri, P J; Juarez, S

    1995-12-01

    The authors measured ambient illumination exposure in healthy volunteers in San Diego, California (latitude 32 degrees 43' N, n = 30), and Rochester, Minnesota (latitude 44 degrees 1' N, n = 24), during each of the four quarters of the year, which were centered on the solstices and equinoxes. Subjects wore photosensors on their wrists and lapels (or foreheads while in bed) 24 h per day for an average of 5-6 days per quarter. The maximum of the two illumination readings was stored each minute. Annual average time spent per day in outdoor illumination (> or = 1000 lux) was significantly higher in San Diego than it was in Rochester (p < .04). Daily durations of illumination at or exceeding thresholds of 1, 10, 100, 1000, and 10,000 lux were highly seasonal in the sample as a whole (p < .01 at 1 lux, p < .0001 at other thresholds). Seasonal variation in outdoor illumination was far more pronounced in Rochester than it was in San Diego (interaction p < .001) but remained significant in San Diego (p < or = .03). Seasonal variation in indoor illumination was generally similar in the two cities. The median Rochester subject experienced illumination > or = 1000 lux for 2 h 23 min per day during summer and 23 min per day during winter. The corresponding times in San Diego were 2 h 10 min and 1 h 20 min. Neither age nor gender predicted illumination duration at any level. Both season and geographic location strongly influenced human illumination exposure, and behavior (choice of indoor vs. outdoor environment) was the most important mediating factor.

  16. Image encryption under spatially incoherent illumination

    NASA Astrophysics Data System (ADS)

    Xie, Zhenwei; Zang, Jinliang; Zhang, Yan

    2013-06-01

    A novel method for image encryption under spatially incoherent illumination is proposed. The LED array is used as the spatially incoherent source. Both the encryption process and decryption process are numerically simulated. Experiments are carried out to demonstrate the basic ideal of the proposed method. The incoherent light is modulated by the spatial light modulator on the input plane as the input image to be encrypted. Then a random phase only mask is used as the key to encode the image, finally a Fourier lens is adopted to image the encrypted image on the output plane. The encrypted intensity distribution is recorded by a CCD. In the numerical simulations, the random phase only mask is generated by a rand function. The incoherent image is composed of many source points, and any two points of these sources are spatially incoherent, but each point is self-spatially coherent. Under this property, the point spread function for the encryption system can be considered as the interference of two beams, one is the spherical beam and the other is the random phase beam. Once the point spread function is given, the system's optical transfer function can be calculated easily. Then the encryption system can be considered as a decryption system, and the output image is the same as the original image. The encrypted image can be calculated with the system's optical transfer function and the output image. The random phase mask, the distance between the random phase mask and the SLM, and the wavelength of the laser can be seen as the keys of the encryption systems. Only when all these parameters are correct, can one get the right decrypted image. The factors which could affect the practical experiment, such as quantization noise and displacement tolerances are also investigated. Compared with the conventional coherent encryption system, the incoherent encryption system proposed in this paper is free of the flaws of the optical elements, the dust particles on the elements, and

  17. Interactive Dynamic Volume Illumination with Refraction and Caustics.

    PubMed

    Magnus, Jens G; Bruckner, Stefan

    2017-08-29

    In recent years, significant progress has been made in developing high-quality interactive methods for realistic volume illumination. However, refraction - despite being an important aspect of light propagation in participating media - has so far only received little attention. In this paper, we present a novel approach for refractive volume illumination including caustics capable of interactive frame rates. By interleaving light and viewing ray propagation, our technique avoids memory-intensive storage of illumination information and does not require any precomputation. It is fully dynamic and all parameters such as light position and transfer function can be modified interactively without a performance penalty.

  18. A study for polarized illumination effects in photo resist

    NASA Astrophysics Data System (ADS)

    Lei, Junjiang; Bai, Min; Shiely, Jim; Zhang, Lin

    2005-06-01

    Using a polarized illumination source is a promising RET technique for improvement of wafer printability for features of 65 nm and below. Polarization effects could be considered in several different stages of lithography modeling and simulation. For example, light propagation in thin films, wave superstition and interference in the thin film stack, and mask-induced polarization all deserve special attention and delicate treatment because TE and TM waves have different behaviors through these stages. In this paper we consider effects of polarized illumination in photo resist, using the Kirchhoff approximation for masks. We discuss some theoretical aspects of our vector modeling methods and show an example of simulation for polarized illumination effects.

  19. Dark-field illuminated reflectance fiber bundle endoscopic microscope

    NASA Astrophysics Data System (ADS)

    Liu, Xuan; Huang, Yong; Kang, Jin U.

    2011-04-01

    We propose a reflectance fiber bundle microscope using a dark-field illumination configuration for applications in endoscopic medical imaging and diagnostics. Our experiment results show that dark-field illumination can effectively suppress strong specular reflection from the proximal end of the fiber bundle. We realized a lateral resolution of 4.4 μm using the dark-field illuminated fiber bundle configuration. To demonstrate the feasibility of using the system to study cell morphology, we obtained still and video images of two thyroid cancer cell lines. Our results clearly allow differentiation of different cancer cell types.

  20. Concept of epitaxial silicon structures for edge illuminated solar cells

    NASA Astrophysics Data System (ADS)

    Sarnecki, J.; Gawlik, G.; Teodorczyk, M.; Jeremiasz, O.; Kozłowski, R.; Lipiński, D.; Krzyżak, K.; Brzozowski, A.

    2011-12-01

    A new concept of edge illuminated solar cells (EISC) based on silicon epitaxial technique has been proposed. In this kind of photovoltaic (PV) devices, sun-light illuminates directly a p-n junction through the edge of the structure which is perpendicular to junction surface. The main motivation of the presented work is preparation of a working model of an edge-illuminated silicon epitaxial solar cell sufficient to cooperation with a luminescent solar concentrator (LSC) consisted of a polymer foil doped with a luminescent material. The technological processes affecting the cell I-V characteristic and PV parameters are considered.

  1. Novel non-imaging optic design for uniform illumination

    NASA Astrophysics Data System (ADS)

    Babadi, S.; Ramirez-Iniguez, R.; Boutaleb, T.; Mallick, T.

    2016-03-01

    The Dielectric Totally Internally Reflecting Concentrator (DTIRC) has been developed in the past for wireless infrared communications and solar energy applications. This paper proposes a novel non-imaging optic design based on the DTIRC family of concentrators for use in illumination applications. The novel optic can be integrated with a light emitting diode (LED) and can be tailored to meet specific requirements. The proposed optic can be used as a first or secondary optic to provide uniform illumination within a circular footprint with a desired radius. The results from this work show that, with the optimised DTIRC, it is possible to achieve a uniformity of illuminance of over 95%.

  2. IODC 2014 Illumination design problem: the Cinderella Lamp

    NASA Astrophysics Data System (ADS)

    Cassarly, William J.

    2014-12-01

    For the 3rd time, the International Optical Design Conference (IODC) included an Illumination Design contest. This year, the contest involved designing the illuminator to project the 1950 Walt Disney "Cinderella" movie using a box of optical knick-knacks. The goal of the problem was to provide the highest screen lumens with greater than 30% uniformity. There were 12 entries from 3 different countries. Three different commercial optical/illumination design packages were used. The winning solution, provided by Alois Herkommer, provided 371 screen lumens.

  3. LIME: Low-light Image Enhancement via Illumination Map Estimation.

    PubMed

    Guo, Xiaojie; Li, Yu; Ling, Haibin

    2016-12-14

    When one captures images in low-light conditions, the images often suffer from low visibility. Besides degrading the visual aesthetics of images, this poor quality may also significantly degenerate the performance of many computer vision and multimedia algorithms that are primarily designed for highquality inputs. In this paper, we propose a simple yet effective low-light image enhancement (LIME) method. More concretely, the illumination of each pixel is first estimated individually by finding the maximum value in R, G and B channels. Further, we refine the initial illumination map by imposing a structure prior on it, as the final illumination map. Having the wellconstructed illumination map, the enhancement can be achieved accordingly. Experiments on a number of challenging low-light images are present to reveal the efficacy of our LIME and show its superiority over several state-of-the-arts in terms of enhancement quality and efficiency.

  4. 46 CFR 112.43-11 - Illumination for launching operations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... EMERGENCY LIGHTING AND POWER SYSTEMS Emergency Lighting Systems § 112.43-11 Illumination for launching operations. Branch circuits supplying power to lights for survival craft launching operations must supply no...

  5. 46 CFR 112.43-11 - Illumination for launching operations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... EMERGENCY LIGHTING AND POWER SYSTEMS Emergency Lighting Systems § 112.43-11 Illumination for launching operations. Branch circuits supplying power to lights for survival craft launching operations must supply no...

  6. 46 CFR 112.43-11 - Illumination for launching operations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... EMERGENCY LIGHTING AND POWER SYSTEMS Emergency Lighting Systems § 112.43-11 Illumination for launching operations. Branch circuits supplying power to lights for survival craft launching operations must supply no...

  7. 46 CFR 112.43-11 - Illumination for launching operations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... EMERGENCY LIGHTING AND POWER SYSTEMS Emergency Lighting Systems § 112.43-11 Illumination for launching operations. Branch circuits supplying power to lights for survival craft launching operations must supply no...

  8. 46 CFR 112.43-11 - Illumination for launching operations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... EMERGENCY LIGHTING AND POWER SYSTEMS Emergency Lighting Systems § 112.43-11 Illumination for launching operations. Branch circuits supplying power to lights for survival craft launching operations must supply no...

  9. Active illuminated space object imaging and tracking simulation

    NASA Astrophysics Data System (ADS)

    Yue, Yufang; Xie, Xiaogang; Luo, Wen; Zhang, Feizhou; An, Jianzhu

    2016-10-01

    Optical earth imaging simulation of a space target in orbit and it's extraction in laser illumination condition were discussed. Based on the orbit and corresponding attitude of a satellite, its 3D imaging rendering was built. General simulation platform was researched, which was adaptive to variable 3D satellite models and relative position relationships between satellite and earth detector system. Unified parallel projection technology was proposed in this paper. Furthermore, we denoted that random optical distribution in laser-illuminated condition was a challenge for object discrimination. Great randomicity of laser active illuminating speckles was the primary factor. The conjunction effects of multi-frame accumulation process and some tracking methods such as Meanshift tracking, contour poid, and filter deconvolution were simulated. Comparison of results illustrates that the union of multi-frame accumulation and contour poid was recommendable for laser active illuminated images, which had capacities of high tracking precise and stability for multiple object attitudes.

  10. PHYTOCHEMICAL CONTENT IN BLUEBERRIES IS INFLUENCED BY UV ILLUMINATION

    USDA-ARS?s Scientific Manuscript database

    The levels of phytochemicals in blueberries were found to increase after illumination with UV-C light. Phytochemicals affected included resveratrol, myricetin 3-arabinoside, quercetin 3-galactoside, quercetin 3-arabinoside, quercetin derivative, kaempferol 3-glucoside, delphinidin-3-galactoside, cy...

  11. Illumination from space with orbiting solar-reflector spacecraft

    NASA Technical Reports Server (NTRS)

    Canady, J. E., Jr.; Allen, J. L., Jr.

    1982-01-01

    The feasibility of using orbiting mirrors to reflect sunlight to Earth for several illumination applications is studied. A constellation of sixteen 1 km solar reflector spacecraft in geosynchronous orbit can illuminate a region 333 km in diameter to 8 lux, which is brighter than most existing expressway lighting systems. This constellation can serve one region all night long or can provide illumination during mornings and evenings to five regions across the United States. Preliminary cost estimates indicate such an endeavor is economically feasible. The studies also explain how two solar reflectors can illuminate the in-orbit nighttime operations of Space Shuttle. An unfurlable, 1 km diameter solar reflector spacecraft design concept was derived. This spacecraft can be packaged in the Space, Shuttle, transported to low Earth orbit, unfurled, and solar sailed to operational orbits up to geosynchronous. The necessary technical studies and improvements in technology are described, and potential environmental concerns are discussed.

  12. Two bumblebee genomes illuminate the route to advanced social living

    USDA-ARS?s Scientific Manuscript database

    Social living represents a major evolutionary transition. Primitively eusocial bumblebees are uniquely placed to illuminate the evolutionary route from solitary to highly eusocial insect societies, for which molecular level information is largely lacking. Additionally, bumblebees are invaluable natu...

  13. Face recognition under variable illumination via sparse representation of patches

    NASA Astrophysics Data System (ADS)

    Fan, Shouke; Liu, Rui; Feng, Weiguo; Zhu, Ming

    2013-10-01

    The objective of this work is to recognize faces under variations in illumination. Previous works have indicated that the variations in illumination can dramatically reduce the performance of face recognition. To this end - ;an efficient method for face recognition which is robust under variable illumination is proposed in this paper. First of all, a discrete cosine transform(DCT) in the logarithm domain is employed to preprocess the images, removing the illumination variations by discarding an appropriate number of low-frequency DCT coefficients. Then, a face image is partitioned into several patches, and we classify the patches using Sparse Representation-based Classification, respectively. At last, the identity of a test image can be determined by the classification results of its patches. Experimental results on the Yale B database and the CMU PIE database show that excellent recognition rates can be achieved by the proposed method.

  14. On the spectral quality of scanner illumination with LEDs

    NASA Astrophysics Data System (ADS)

    Cui, Chengwu

    2013-01-01

    Document scanner illumination has evolved along with general illumination technologies. LEDs have become more and more popular as the illumination sources for document scanning. LED technologies provide a wide range of choices both in terms of structural design and spectral compositions. In this report, we examine some popular LED technologies used for document scanner. We evaluate the color rendering performance of scanner models with different illumination technologies by examining their rendering of the Macbeth ColorChecker™ in sRGB. We found that more phosphors in phosphor conversion types of white LEDs may not be necessarily advantageous in terms of scanner color rendering performance. Also CIS type of scanner may be sensitive to the peak wavelength shift and can be particularly problematic when the peaks are out of certain range.

  15. An inexpensive programmable illumination microscope with active feedback

    PubMed Central

    Tompkins, Nathan; Fraden, Seth

    2016-01-01

    We have developed a programmable illumination system capable of tracking and illuminating numerous objects simultaneously using only low-cost and reused optical components. The active feedback control software allows for a closed-loop system that tracks and perturbs objects of interest automatically. Our system uses a static stage where the objects of interest are tracked computationally as they move across the field of view allowing for a large number of simultaneous experiments. An algorithmically determined illumination pattern can be applied anywhere in the field of view with simultaneous imaging and perturbation using different colors of light to enable spatially and temporally structured illumination. Our system consists of a consumer projector, camera, 35-mm camera lens, and a small number of other optical and scaffolding components. The entire apparatus can be assembled for under $4,000. PMID:27642182

  16. Circular, explosion-proof lamp provides uniform illumination

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Circular explosion-proof fluorescent lamp is fitted around a TV camera lens to provide shadowless illumination with a low radiant heat flux. The lamp is mounted in a transparent acrylic housing sealed with clear silicone rubber.

  17. Laser Illumination Modality of Photoacoustic Imaging Technique for Prostate Cancer

    NASA Astrophysics Data System (ADS)

    Peng, Dong-qing; Peng, Yuan-yuan; Guo, Jian; Li, Hui

    2016-02-01

    Photoacoustic imaging (PAI) has recently emerged as a promising imaging technique for prostate cancer. But there was still a lot of challenge in the PAI for prostate cancer detection, such as laser illumination modality. Knowledge of absorbed light distribution in prostate tissue was essential since the distribution characteristic of absorbed light energy would influence the imaging depth and range of PAI. In order to make a comparison of different laser illumination modality of photoacoustic imaging technique for prostate cancer, optical model of human prostate was established and combined with Monte Carlo simulation method to calculate the light absorption distribution in the prostate tissue. Characteristic of light absorption distribution of transurethral and trans-rectal illumination case, and of tumor at different location was compared with each other.The relevant conclusions would be significant for optimizing the light illumination in a PAI system for prostate cancer detection.

  18. A multilinear constraint on dichromatic planes for illumination estimation.

    PubMed

    Toro, Javier; Funt, Brian

    2007-01-01

    A new multilinear constraint on the color of the scene illuminant based on the dichromatic reflection model is proposed. The formulation avoids the problem, common to previous dichromatic methods, of having to first identify pixels corresponding to the same surface material. Once pixels from two or more materials have been identified, their corresponding dichromatic planes can be intersected to yield the illuminant color. However, it is not always easy to determine which pixels from an arbitrary region of an image belong to which dichromatic plane. The image region may cover an area of the scene encompassing several different materials and, hence, pixels from several different dichromatic planes. The new multilinear constraint accounts for this multiplicity of materials and provides a mechanism for choosing the most plausible illuminant from a finite set of candidate illuminants. The performance of this new method is tested on a database of real images.

  19. Illumination requirements for operating a space remote manipulator

    NASA Technical Reports Server (NTRS)

    Chandlee, George O.; Smith, Randy L.; Wheelwright, Charles D.

    1993-01-01

    Critical issues and requirements involved in illuminating remote manipulator operations in space help establish engineering designs for these manipulators. A remote manipulator is defined as any mechanical device that is controlled indirectly or from a distance by a human operator for the purpose of performing potentially dangerous or hazardous tasks to increase safety, reliability, and efficiency. Future space flights will rely on remote manipulators for a variety of tasks including satellite repair and servicing, structural assembly, data collection and analysis, and performance of contingency tasks. Carefully designed illumination of these manipulators will assure that these tasks will be completed efficiently and successfully. Studies concerning the influence of illumination on operation of a remote manipulator are few. Available results show that illumination can influence how successfully a human operates a remote manipulator. The intent of this study was to more fully examine this topic.

  20. Critical illumination condenser for x-ray lithography

    DOEpatents

    Cohen, S.J.; Seppala, L.G.

    1998-04-07

    A critical illumination condenser system is disclosed, particularly adapted for use in extreme ultraviolet (EUV) projection lithography based on a ring field imaging system and a laser produced plasma source. The system uses three spherical mirrors and is capable of illuminating the extent of the mask plane by scanning either the primary mirror or the laser plasma source. The angles of radiation incident upon each mirror of the critical illumination condenser vary by less than eight (8) degrees. For example, the imaging system in which the critical illumination condenser is utilized has a 200 {micro}m source and requires a magnification of 26. The three spherical mirror system constitutes a two mirror inverse Cassegrain, or Schwarzschild configuration, with a 25% area obstruction (50% linear obstruction). The third mirror provides the final pupil and image relay. The mirrors include a multilayer reflective coating which is reflective over a narrow bandwidth. 6 figs.

  1. Critical illumination condenser for x-ray lithography

    DOEpatents

    Cohen, Simon J.; Seppala, Lynn G.

    1998-01-01

    A critical illumination condenser system, particularly adapted for use in extreme ultraviolet (EUV) projection lithography based on a ring field imaging system and a laser produced plasma source. The system uses three spherical mirrors and is capable of illuminating the extent of the mask plane by scanning either the primary mirror or the laser plasma source. The angles of radiation incident upon each mirror of the critical illumination condenser vary by less than eight (8) degrees. For example, the imaging system in which the critical illumination condenser is utilized has a 200 .mu.m source and requires a magnification of 26.times.. The three spherical mirror system constitutes a two mirror inverse Cassegrain, or Schwarzschild configuration, with a 25% area obstruction (50% linear obstruction). The third mirror provides the final pupil and image relay. The mirrors include a multilayer reflective coating which is reflective over a narrow bandwidth.

  2. Inverting pupil illumination from resist-based measurements

    NASA Astrophysics Data System (ADS)

    Perçin, Gokhan; Sezginer, Apo; Zach, Franz X.

    2006-03-01

    Computational models used in process proximity correction require accurate description of the pupil illumination function of the lithography projector. Traditional top-hat approximation for pupil illumination function is no longer sufficient to meet stringent CD control requirements of low-k1 applications. The pupil illumination profile can change across the exposure field, contributing to across-field linewidth variation. We present a measurement of the pupil illumination based on exposing pinhole patterns on a wafer at different dose and defocus settings, and processing SEM images of patterns printed in photoresist. The fundamental principle of the method is Abbe's formulation of image formation: the intensity-image formed in resist is an incoherent, linear superposition of images each one of which is formed by illuminating the photomask by a single plane-wave. A single plane-wave that is incident on the photomask maps to a single point in the Fourier-transform aperture of the illuminator. The pupil-fill of the illuminator is obtained from SEM images by a model-based method consisting of these steps: First, resist edges in the SEM images are detected by an edge detection algorithm based on Perona-Malik diffusion. Coordinates of the points on the resist edge are obtained with respect to a reference ruler. The image intensity at any resist edge is equal to the dose-to-clear. This provides an equation for the image intensity at each point on the edge of a pinhole image. Multiple values of dose and defocus, and multiple points on each resist edge provide a large system of equations. The result of the inversion for a 193nm 0.75 NA stepper with σ = 0.55/0.85 annular illumination at five exposure field locations is presented. The CD difference between the nominal top-hat illumination and the inverted illumination was up to 1.8 nm for 1:1 line and space features ranging from 100nm to 300nm. Variation of the illumination along the long-dimension of the slit of the

  3. Long duration exposure facility solar illumination data package

    NASA Technical Reports Server (NTRS)

    Berrios, William M.; Sampair, Thomas

    1990-01-01

    A post flight solar illumination data package was created by the LDEF thermal analysis data group in support of the LDEF science office data group. The data presented was prepared with the Thermal Radiation Analysis System (TRASYS) program. Ground tracking data was used to calculate daily orbital beta angles for the calculation of resultant fluxes. This data package will be useful in calculation of solar illumination fluent for a variety of beta angle orbital conditions encountered during the LDEF mission.

  4. Quantum Illumination-Based Target Detection and Discrimination

    DTIC Science & Technology

    2014-06-30

    demonstrated high signal-to-noise ratio (SNR) quantum-illumination target detection in a lossy, noisy environment using an optical parametric amplifier...Research Triangle Park, NC 27709-2211 quantum communication, target detection, entanglement, parametric downconversion, optical parametric amplifiers...illumination target detection in a lossy, noisy environment using an optical parametric amplifier (OPA) receiver, and explored the SNR’s dependence on

  5. Transfer function analysis in epi-illumination Fourier ptychography

    PubMed Central

    Pacheco, Shaun; Salahieh, Basel; Milster, Tom; Rodriguez, Jeffrey J.; Liang, Rongguang

    2016-01-01

    This letter explores Fourier ptychography (FP) using epi-illumination. The approach effectively modifies the FP transfer function to be coherent-like out to the incoherent limit of twice the numerical aperture over the wavelength 2NA/λ. Images reconstructed using this approach are shown to have higher contrast at finer details compared with images using incoherent illumination, indicating that the FP transfer function is superior in high spatial frequency regions. PMID:26565870

  6. Fiber Coupled Laser Diodes with Even Illumination Pattern

    NASA Technical Reports Server (NTRS)

    Howard, Richard T. (Inventor)

    2007-01-01

    An optical fiber for evenly illuminating a target. The optical fiber is coupled to a laser emitting diode and receives laser light. The la ser light travels through the fiber optic and exits at an exit end. T he exit end has a diffractive optical pattern formed thereon via etch ing, molding or cutting, to reduce the Gaussian profile present in co nventional fiber optic cables The reduction of the Gaussian provides an even illumination from the fiber optic cable.

  7. Lunar South Pole Illumination: Review, Reassessment, and Power System Implications

    NASA Technical Reports Server (NTRS)

    Fincannon, James

    2007-01-01

    This paper reviews past analyses and research related to lunar south pole illumination and presents results of independent illumination analyses using an analytical tool and a radar digital elevation model. The analysis tool enables assessment at most locations near the lunar poles for any time and any year. Average illumination fraction, energy storage duration, solar/horizon terrain elevation profiles and illumination fraction profiles are presented for various highly illuminated sites which have been identified for manned or unmanned operations. The format of the data can be used by power system designers to develop mass optimized solar and energy storage systems. Data are presented for the worse case lunar day (a critical power planning bottleneck) as well as three lunar days during lunar south pole winter. The main site under consideration by present lunar mission planners (on the Crater Shackleton rim) is shown to have, for the worse case lunar day, a 0.71 average illumination fraction and 73 to 117 hours required for energy storage (depending on power system type). Linking other sites and including towers at either site are shown to not completely eliminate the need for energy storage.

  8. Accretion Disk Illumination in Schwarzschild and Kerr Geometries: Fitting Formulae

    NASA Astrophysics Data System (ADS)

    Fukumura, Keigo; Kazanas, Demosthenes

    2007-07-01

    We describe the methodology and compute the illumination of geometrically thin accretion disks around black holes of arbitrary spin parameter a exposed to the radiation of a pointlike isotropic source at arbitrary height above the disk on its symmetry axis. We then provide analytic fitting formulae for the illumination as a function of the source height h and the black hole angular momentum a. We find that for a source on the disk symmetry axis and with h/M>3, the main effect of the parameter a is allowing the disk to extend to smaller radii (approaching r/M-->1 as a/M-->1) and thus allowing the illumination of regions of much higher rotational velocity and redshift. We also compute the illumination profiles for anisotropic emission associated with the motion of the source relative to the accretion disk and present the fractions of photons absorbed by the black hole, intercepted by the disk, or escaping to infinity for both isotropic and anisotropic emission for a/M=0 and 0.99. As the anisotropy (of a source approaching the disk) increases, the illumination profile reduces (approximately) to a single power law, whose index q, because of absorption of the beamed photons by the black hole, saturates to a value no higher than q>~3. Finally, we compute the fluorescent Fe line profiles associated with the specific illumination and compare them among various cases.

  9. Off-axis illumination direct-to-digital holography

    DOEpatents

    Thomas, Clarence E.; Price, Jeffery R.; Voelkl, Edgar; Hanson, Gregory R.

    2004-06-08

    Systems and methods are described for off-axis illumination direct-to-digital holography. A method of recording an off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis, includes: reflecting a reference beam from a reference mirror at a non-normal angle; reflecting an object beam from an object at an angle with respect to an optical axis defined by a focusing lens; focusing the reference beam and the object beam at a focal plane of a digital recorder to form the off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis; digitally recording the off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis; Fourier analyzing the recorded off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes by transforming axes of the recorded off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes in Fourier space to sit on top of a heterodyne carrier frequency defined as an angle between the reference beam and the object beam; applying a digital filter to cut off signals around an original origin; and then performing an inverse Fourier transform.

  10. Simulation of illumination for machine vision and inspection

    NASA Astrophysics Data System (ADS)

    Guivens, Norman R., Jr.

    1994-01-01

    Illumination subsystems are critical elements of most machine vision and inspection systems. The linear response of most optical detectors generally requires much more uniform illumination than the logarithmic response of the human eye to achieve a similar level of performance. Excessive illumination can saturate optical detector elements, while insufficient illumination causes excessive shot noise that can cripple system performance. Speckle from coherent or partially coherent illumination can also affect system performance. Computer simulations of machine vision and inspection systems, like SPARTA's SENSORSIM, permit accurate analysis of various illumination designs to determine their suitability for a particular application. These simulations permit rapid analysis of system configurations and variation of system parameters to identify optimal designs on a price/performance curve. SENSORSIM can also provide images or other signatures at intermediate stages of the generation process for isolation and analysis sources of degradation in a sensor system. This sort of analysis often is not possible in laboratory experiments. Although models of more limited scope may be useful for some analyses, such models cannot support analysis of phenomena that depend upon interaction among several components or subsystems. Thus, simulations like SENSORSIM provide an invaluable capability for optimizing the cost and performance of optical sensor systems.

  11. Advanced illumination control algorithm for medical endoscopy applications

    NASA Astrophysics Data System (ADS)

    Sousa, Ricardo M.; Wäny, Martin; Santos, Pedro; Morgado-Dias, F.

    2015-05-01

    CMOS image sensor manufacturer, AWAIBA, is providing the world's smallest digital camera modules to the world market for minimally invasive surgery and one time use endoscopic equipment. Based on the world's smallest digital camera head and the evaluation board provided to it, the aim of this paper is to demonstrate an advanced fast response dynamic control algorithm of the illumination LED source coupled to the camera head, over the LED drivers embedded on the evaluation board. Cost efficient and small size endoscopic camera modules nowadays embed minimal size image sensors capable of not only adjusting gain and exposure time but also LED illumination with adjustable illumination power. The LED illumination power has to be dynamically adjusted while navigating the endoscope over changing illumination conditions of several orders of magnitude within fractions of the second to guarantee a smooth viewing experience. The algorithm is centered on the pixel analysis of selected ROIs enabling it to dynamically adjust the illumination intensity based on the measured pixel saturation level. The control core was developed in VHDL and tested in a laboratory environment over changing light conditions. The obtained results show that it is capable of achieving correction speeds under 1 s while maintaining a static error below 3% relative to the total number of pixels on the image. The result of this work will allow the integration of millimeter sized high brightness LED sources on minimal form factor cameras enabling its use in endoscopic surgical robotic or micro invasive surgery.

  12. Nonuniformity Mitigation of Beam Illumination in Heavy Ion Inertial Fusion

    NASA Astrophysics Data System (ADS)

    Kawata, Shigeo; Noguchi, K.; Suzuki, T.; Kurosaki, T.; Barada, D.; Ma, Y. Y.; Ogoyski, A. I.

    2013-10-01

    In heavy ion inertial fusion wobbling heavy ion beam (HIB) illumination was proposed to realize a uniform implosion. The wobbling HIB axis oscillation is precisely controlled. The oscillating frequency may be several 100 MHz ~ 1 GHz. In the wobbling HIBs illumination, the illumination nonuniformity oscillates in time and space on a HIF target. The oscillating-HIB energy deposition may contribute to the reduction of the HIBs' illumination nonuniformity. Three-dimensional HIBs illumination computations presented here show that the few percent wobbling HIBs illumination nonuniformity oscillates with the same wobbling HIBs frequency. In general a perturbation of physical quantity would feature the instability onset. Normally the perturbation phase is unknown so that the instability growth is discussed with the growth rate. However, if the perturbation phase is known, the instability growth can be controlled by a superposition of perturbations; the well-known mechanism is a feedback control to compensate the displacement of physical quantity. If the perturbation is induced by, for example, a HIB axis wobbling, the perturbation phase could be controlled and the instability growth is mitigated by the superposition of the growing perturbations. Partly supported by JSPS, MEXT, CORE, ASHULA, Japan / US Cooperation program and ILE/Osaka University.

  13. Simultaneous cast shadows, illumination and geometry inference using hypergraphs.

    PubMed

    Panagopoulos, Alexandros; Wang, Chaohui; Samaras, Dimitris; Paragios, Nikos

    2013-02-01

    The cast shadows in an image provide important information about illumination and geometry. In this paper, we utilize this information in a novel framework in order to jointly recover the illumination environment, a set of geometry parameters, and an estimate of the cast shadows in the scene given a single image and coarse initial 3D geometry. We model the interaction of illumination and geometry in the scene and associate it with image evidence for cast shadows using a higher order Markov Random Field (MRF) illumination model, while we also introduce a method to obtain approximate image evidence for cast shadows. Capturing the interaction between light sources and geometry in the proposed graphical model necessitates higher order cliques and continuous-valued variables, which make inference challenging. Taking advantage of domain knowledge, we provide a two-stage minimization technique for the MRF energy of our model. We evaluate our method in different datasets, both synthetic and real. Our model is robust to rough knowledge of geometry and inaccurate initial shadow estimates, allowing a generic coarse 3D model to represent a whole class of objects for the task of illumination estimation, or the estimation of geometry parameters to refine our initial knowledge of scene geometry, simultaneously with illumination estimation.

  14. Shading-based Surface Detail Recovery under General Unknown Illumination.

    PubMed

    Xu, Di; Duan, Qi; Zheng, Jianmin; Zhang, Juyong; Cai, Jianfei; Cham, Tat-Jen

    2017-02-17

    Reconstructing the shape of a 3D object from multi-view images under unknown, general illumination is a fundamental problem in computer vision and high quality reconstruction is usually challenging especially when fine detail is needed and the albedo of the object is non-uniform. This paper introduces vertex overall illumination vectors to model the illumination effect and presents a total variation (TV) based approach for recovering surface details using shading and multi-view stereo (MVS). Behind the approach are the two important observations: (1) the illumination over the surface of an object often appears to be piece wise smooth and (2) the recovery of surface orientation is not sufficient for reconstructing the surface, which was often overlooked previously. Thus we propose to use TV to regularize the overall illumination vectors and use visual hull to constrain partial vertices. The reconstruction is formulated as a constrained TV-minimization problem that simultaneously treats the shape and illumination vectors as unknowns. An augmented Lagrangian method is proposed to quickly solve the TV-minimization problem. As a result, our approach is robust, stable and is able to efficiently recover high quality of surface details even when starting with a coarse model obtained using MVS. These advantages are demonstrated by extensive experiments on the state-of-the-art MVS database, which includes challenging objects with varying albedo.

  15. Illumination pattern optimization for fluorescence tomography: theory and simulation studies.

    PubMed

    Dutta, Joyita; Ahn, Sangtae; Joshi, Anand A; Leahy, Richard M

    2010-05-21

    Fluorescence molecular tomography is a powerful tool for 3D visualization of molecular targets and pathways in vivo in small animals. Owing to the high degrees of absorption and scattering of light through tissue, the fluorescence tomographic inverse problem is inherently ill-posed. In order to improve source localization and the conditioning of the light propagation model, multiple sets of data are acquired by illuminating the animal surface with different spatial patterns of near-infrared light. However, the choice of these patterns in most experimental setups is ad hoc and suboptimal. This paper presents a systematic approach for designing efficient illumination patterns for fluorescence tomography. Our objective here is to determine how to optimally illuminate the animal surface so as to maximize the information content in the acquired data. We achieve this by improving the conditioning of the Fisher information matrix. We parameterize the spatial illumination patterns and formulate our problem as a constrained optimization problem that, for a fixed number of illumination patterns, yields the optimal set of patterns. For geometric insight, we used our method to generate a set of three optimal patterns for an optically homogeneous, regular geometrical shape and observed expected symmetries in the result. We also generated a set of six optimal patterns for an optically homogeneous cuboidal phantom set up in the transillumination mode. Finally, we computed optimal illumination patterns for an optically inhomogeneous realistically shaped mouse atlas for different given numbers of patterns. The regularized pseudoinverse matrix, generated using the singular value decomposition, was employed to reconstruct the point spread function for each set of patterns in the presence of a sample fluorescent point source deep inside the mouse atlas. We have evaluated the performance of our method by examining the singular value spectra as well as plots of average spatial

  16. Illumination Conditions of the Lunar Polar Regions Using LOLA Topography

    NASA Technical Reports Server (NTRS)

    Mazarico, E.; Neumann, G. A.; Smith, D. E.; Zuber, M. T.; Torrence, M. H.

    2011-01-01

    We use high-resolution altimetry data obtained by the Lunar Orbiter Laser Altimeter instrument onboard the Lunar Reconnaissance Orbiter to characterize present illumination conditions in the polar regions of the Moon. Compared to previous studies, both the spatial and temporal extent of the simulations are increased significantly, as well as the coverage (fill ratio) of the topographic maps used, thanks to the 28 Hz firing rate of the five-beam instrument. We determine the horizon elevation in a number of directions based on 240 m-resolution polar digital elevation models reaching down to 75 latitude. The illumination of both polar regions extending to 80 can be calculated for any geometry from those horizon longitudinal profiles. We validated our modeling with recent Lunar Reconnaissance Orbiter Wide-Angle Camera images. We assessed the extent of permanently shadowed regions (PSRs, defined as areas that never receive direct solar illumination), and obtained total areas generally larger than previous studies (12,866 and 16,055 km2, in the north and south respectively). We extended our direct illumination model to account for singly-scattered light, and found that every PSR does receive some amount of scattered light during the year. We conducted simulations over long periods (several 18.6-years lunar precession cycles) with a high temporal resolution (6 h), and identified the most illuminated locations in the vicinity of both poles. Because of the importance of those sites for exploration and engineering considerations, we characterized their illumination more precisely over the near future. Every year, a location near the Shackleton crater rim in the south polar region is sunlit continuously for 240 days, and its longest continuous period in total darkness is about 1.5 days. For some locations small height gains ( 10 m) can dramatically improve their average illumination and reduce the night duration, rendering some of those particularly attractive energy-wise as

  17. Characterization of Lunar Polar Illumination from a Power System Perspective

    NASA Technical Reports Server (NTRS)

    Fincannon, James

    2008-01-01

    This paper presents the results of illumination analyses for the lunar south and north pole regions obtained using an independently developed analytical tool and two types of digital elevation models (DEM). One DEM was based on radar height data from Earth observations of the lunar surface and the other was a combination of the radar data with a separate dataset generated using Clementine spacecraft stereo imagery. The analysis tool enables the assessment of illumination at most locations in the lunar polar regions for any time and any year. Maps are presented for both lunar poles for the worst case winter period (the critical power system design and planning bottleneck) and for the more favorable best case summer period. Average illumination maps are presented to help understand general topographic trends over the regions. Energy storage duration maps are presented to assist in power system design. Average illumination fraction, energy storage duration, solar/horizon terrain elevation profiles and illumination fraction profiles are presented for favorable lunar north and south pole sites which have the potential for manned or unmanned spacecraft operations. The format of the data is oriented for use by power system designers to develop mass optimized solar and energy storage systems.

  18. Discrete-variable quantum illumination with ancillary degrees of freedom

    NASA Astrophysics Data System (ADS)

    Liu, Kai; Zhang, Qin-Wei; Gu, Yong-Jian; Li, Qing-Liang

    2017-04-01

    Quantum illumination is one of the most basic ways to realize the quantum radar for detection of low-reflectivity targets embedded in a thermal-noise bath. It preserves a strong advantage over the classical counterparts even though its fragile quantum entanglement is completely destroyed by a large amount of noise and losses. In this paper, we describe and analyze a discrete-variable quantum illumination system with ancillary degrees of freedom of entangled photon pairs. Comparing the error probability bound, i.e., the quantum Chernoff bound, we identify that this system indeed offers higher accuracy than the single-photon illumination and quantum illumination with single degree of freedom of entangled photon pairs. Furthermore, the utilization of ancillary degrees of freedom exponentially enhances signal-to-noise ratio over quantum illumination without ancillary degrees of freedom. It means that this system reduces the necessary amount of signal photons to accurately determine whether the object is present or absent in the target region, which is absolutely crucial to the stealthiness of the radar system.

  19. Colour perception with changes in levels of illumination

    NASA Astrophysics Data System (ADS)

    Baah, Kwame F.; Green, Phil; Pointer, Michael

    2012-01-01

    The perceived colour of a stimulus depends on the conditions under which it is viewed. For colours employed as an important cue or identifier, such as signage and brand colours, colour reproduction tolerances are critically important. Typically, such stimuli would be judged using a known level of illumination but, in the target environment, the level of illumination used to view the samples may be entirely different. The effect of changes in the viewing condition on the perceptibility and acceptability of small colour differences should be understood when such tolerances and associated viewing conditions, are specified. A series of psychophysical experiments was conducted to determine whether changes in illumination level significantly alter acceptability and perceptibility thresholds of uniform colour stimuli. It was found that perceived colour discrimination thresholds varied by up to 2.0 ΔE00. For the perceptual correlate of hue however, this value could be of significance if the accepted error of colour difference was at the threshold, thereby yielding the possibility of rejection with changes in illumination level. Lightness and chroma on the other hand, exhibited greater tolerance and were less likely to be rejected with illuminance changes.

  20. Constrained low-rank gamut completion for robust illumination estimation

    NASA Astrophysics Data System (ADS)

    Zhou, Jianshen; Yuan, Jiazheng; Liu, Hongzhe

    2017-02-01

    Illumination estimation is an important component of color constancy and automatic white balancing. According to recent survey and evaluation work, the supervised methods with a learning phase are competitive for illumination estimation. However, the robustness and performance of any supervised algorithm suffer from an incomplete gamut in training image sets because of limited reflectance surfaces in a scene. In order to address this problem, we present a constrained low-rank gamut completion algorithm, which can replenish gamut from limited surfaces in an image, for robust illumination estimation. In the proposed algorithm, we first discuss why the gamut completion is actually a low-rank matrix completion problem. Then a constrained low-rank matrix completion framework is proposed by adding illumination similarities among the training images as an additional constraint. An optimization algorithm is also given out by extending the augmented Lagrange multipliers. Finally, the completed gamut based on the proposed algorithm is fed into the support vector regression (SVR)-based illumination estimation method to evaluate the effect of gamut completion. The experimental results on both synthetic and real-world image sets show that the proposed gamut completion model not only can effectively improve the performance of the original SVR method but is also robust to the surface insufficiency in training samples.

  1. Color constancy supports cross-illumination color selection

    PubMed Central

    Radonjić, Ana; Cottaris, Nicolas P.; Brainard, David H.

    2015-01-01

    We rely on color to select objects as the targets of our actions (e.g., the freshest fish, the ripest fruit). To be useful for selection, color must provide accurate guidance about object identity across changes in illumination. Although the visual system partially stabilizes object color appearance across illumination changes, how such color constancy supports object selection is not understood. To study how constancy operates in real-life tasks, we developed a novel paradigm in which subjects selected which of two test objects presented under a test illumination appeared closer in color to a target object presented under a standard illumination. From subjects' choices, we inferred a selection-based match for the target via a variant of maximum likelihood difference scaling, and used it to quantify constancy. Selection-based constancy was good when measured using naturalistic stimuli, but was dramatically reduced when the stimuli were simplified, indicating that a naturalistic stimulus context is critical for good constancy. Overall, our results suggest that color supports accurate object selection across illumination changes when both stimuli and task match how color is used in real life. We compared our selection-based constancy results with data obtained using a classic asymmetric matching task and found that the adjustment-based matches predicted selection well for our stimuli and instructions, indicating that the appearance literature provides useful guidance for the emerging study of constancy in natural tasks. PMID:26024460

  2. Spectrally optimal illuminations for diabetic retinopathy detection in retinal imaging

    NASA Astrophysics Data System (ADS)

    Bartczak, Piotr; Fält, Pauli; Penttinen, Niko; Ylitepsa, Pasi; Laaksonen, Lauri; Lensu, Lasse; Hauta-Kasari, Markku; Uusitalo, Hannu

    2017-01-01

    Retinal photography is a standard method for recording retinal diseases for subsequent analysis and diagnosis. However, the currently used white light or red-free retinal imaging does not necessarily provide the best possible visibility of different types of retinal lesions, important when developing diagnostic tools for handheld devices, such as smartphones. Using specifically designed illumination, the visibility and contrast of retinal lesions could be improved. In this study, spectrally optimal illuminations for diabetic retinopathy lesion visualization are implemented using a spectrally tunable light source based on digital micromirror device. The applicability of this method was tested in vivo by taking retinal monochrome images from the eyes of five diabetic volunteers and two non-diabetic control subjects. For comparison to existing methods, we evaluated the contrast of retinal images taken with our method and red-free illumination. The preliminary results show that the use of optimal illuminations improved the contrast of diabetic lesions in retinal images by 30-70%, compared to the traditional red-free illumination imaging.

  3. Polydopamine Generates Hydroxyl Free Radicals under Ultraviolet-Light Illumination.

    PubMed

    Wang, Zehuan; Tang, Feng; Fan, Hailong; Wang, Le; Jin, Zhaoxia

    2017-06-13

    Polydopamine (PDA) generally demonstrates as an efficient free-radical scavenger. However, its free-radical chemistry under illumination is unclear, which becomes important in view of growing studies of polydopamine applications in photoprotector and photothermal therapy. In this study, for the first time, we reported an experimental investigation of the generation of hydroxyl free radicals from ultraviolet (UV)-illuminated polydopamine in an aqueous environment. By using terephthalic acid as fluorescent probe, we measured hydroxyl radicals generated from UV-illuminated polydopamine with different shapes and sizes. The morphology of PDA shows significant influence on its productions of hydroxyl free radicals. Through characterizations of UV-vis absorption spectroscopy, fluorescence spectroscopy, X-ray photoelectron spectrometry, mass spectrometry, and thermogravimetric analysis, we demonstrated the change of PDA nanomaterials brought by UV-light illumination in composition and thermal stability. We proposed a tentative mechanism for interpreting the relationship between morphology and photostability of PDA nanomaterials. These results reveal underlying complexity of polydopamine chemistry under light illumination that will deepen our understanding and benefit its further application.

  4. Adaptive optimisation of illumination beam profiles in fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Mitchell, T. J.; Saunter, C. D.; O'Nions, W.; Girkin, J. M.; Love, G. D.

    2015-03-01

    Wide-field fluorescence microscope techniques such as single/selective plane illumination microscope (SPIM) are typically configured to image large regions of a sample at once. Here the illumination beam provides uniform excitation of several biological features across the region, `sliced' to a thickness of between 5-10 microns. In this paper we propose a simple alteration to the optical configuration of a SPIM by switching the light-sheet- forming cylindrical lens with a spatial light modulator. This has the potential to adaptively reconfigure the light sheet geometry to improve the optical sectioning of specific biological features, rather than the thicker sectioning of several features at once across a larger observation field-of-view. We present a prototype version of such a system, referred to as an Adaptive-SPIM (A-SPIM) system. We then suggest that the direct recording of illumination beam shapes within the working microscope system can better facilitate the analysis and subsequent re-configuration of the illumination beam to a specific geometry, and summarise the design and operation of a device that we have developed specifically for this purpose. We finally present reconstructed quantitative three dimensional flux maps of illumination beams from three microscope configurations taken using this miniature high-dynamic range beam profiling device, comparing the beam geometry of a regular SPIM system with our prototype A-SPIM system, and suggesting future improvements.

  5. Photobioreactors with internal illumination - A survey and comparison.

    PubMed

    Heining, Martin; Buchholz, Rainer

    2015-08-01

    The idea of internally illuminated photobioreactors has existed since the 1990s and various systems were developed since. Recently, the interest in these systems has been on the rise again, due to the increased production of and research on high-value products and recombinant proteins from microalgae and plant cell cultures. While promising results in lab-scale have been achieved, the potential of photoautotrophic or mixotrophic production of these compounds is limited due to the lack of scalable photobioreactors, which could be overcome by internally illuminated systems. In this article, we review different internally illuminated photobioreactors from the last two decades and classify them into two major groups. The photobioreactors are compared based on the ratio of illuminated surface-to-culture volume and the occupied volume by internal light-emitting elements, and possible obstacles, challenges and future trends are discussed. Looking forward, new technologies and smaller light sources have improved the potential of internally illuminated photobioreactors with internal light sources and will enable these technologies to compete with systems with internal light guides, but only a few of these systems have currently achieved a relevant scale.

  6. Comparison of image reconstruction methods for structured illumination microscopy

    NASA Astrophysics Data System (ADS)

    Lukeš, Tomas; Hagen, Guy M.; Křížek, Pavel; Švindrych, Zdeněk.; Fliegel, Karel; Klíma, Miloš

    2014-05-01

    Structured illumination microscopy (SIM) is a recent microscopy technique that enables one to go beyond the diffraction limit using patterned illumination. The high frequency information is encoded through aliasing into the observed image. By acquiring multiple images with different illumination patterns aliased components can be separated and a highresolution image reconstructed. Here we investigate image processing methods that perform the task of high-resolution image reconstruction, namely square-law detection, scaled subtraction, super-resolution SIM (SR-SIM), and Bayesian estimation. The optical sectioning and lateral resolution improvement abilities of these algorithms were tested under various noise level conditions on simulated data and on fluorescence microscopy images of a pollen grain test sample and of a cultured cell stained for the actin cytoskeleton. In order to compare the performance of the algorithms, the following objective criteria were evaluated: Signal to Noise Ratio (SNR), Signal to Background Ratio (SBR), circular average of the power spectral density and the S3 sharpness index. The results show that SR-SIM and Bayesian estimation combine illumination patterned images more effectively and provide better lateral resolution in exchange for more complex image processing. SR-SIM requires one to precisely shift the separated spectral components to their proper positions in reciprocal space. High noise levels in the raw data can cause inaccuracies in the shifts of the spectral components which degrade the super-resolved image. Bayesian estimation has proven to be more robust to changes in noise level and illumination pattern frequency.

  7. Polarization and coherence-engineered illumination with applications in imaging

    NASA Astrophysics Data System (ADS)

    Brown, Dean Patterson

    In image formation, the coherence properties of the illumination source are of great importance. At the same time, the polarization properties of an optical system also play a role in the quality of an imaging system, particularly those of high numerical aperture (NA). Polarization-dependent coherence is therefore an important area of study for any imaging system. In the past few years, while there has been a unification of the ability to use coherence theory to describe vectorial fields through the use of a construct called a correlation matrix, very little has been done experimentally predicting or measuring the coherence properties of an illumination system comprised of vectorial fields. In the work that follows, we explore several arrangements in which a polarization vortex mode converter was placed in the pupil plane of an illumination system. In these arrangements, we study both theoretically and experimentally the spatially dependent coherence properties using a vectorial treatment of optical coherence. Those properties were applied to imaging systems that then results in an improvement in image contrast using polarization- and orientation-dependent coherence properties of the illumination. In this work, the main illumination systems we explored are a Gaussian Schell-model beam, a fully correlated and 'collimated' azimuthal vortex beam, a partially correlated azimuthally-polarized vortex (PCAV) illumination system, and a partially correlated radially-polarized vortex (PCRV) illumination system. For the case of PCAV and PCRV illumination, we implemented critical and Kohler illumination systems with a polarization orientation that has an azimuthal or radial symmetry in the pupil plane. We demonstrated first theoretically and then experimentally that PCAV and PCRV illumination systems have a correlation matrix that describes the correlation between electric fields as being only dependent on the separation of points at a particular plane. Further, it was

  8. Spectrally optimal illuminations for diabetic retinopathy detection in retinal imaging

    NASA Astrophysics Data System (ADS)

    Bartczak, Piotr; Fält, Pauli; Penttinen, Niko; Ylitepsa, Pasi; Laaksonen, Lauri; Lensu, Lasse; Hauta-Kasari, Markku; Uusitalo, Hannu

    2017-04-01

    Retinal photography is a standard method for recording retinal diseases for subsequent analysis and diagnosis. However, the currently used white light or red-free retinal imaging does not necessarily provide the best possible visibility of different types of retinal lesions, important when developing diagnostic tools for handheld devices, such as smartphones. Using specifically designed illumination, the visibility and contrast of retinal lesions could be improved. In this study, spectrally optimal illuminations for diabetic retinopathy lesion visualization are implemented using a spectrally tunable light source based on digital micromirror device. The applicability of this method was tested in vivo by taking retinal monochrome images from the eyes of five diabetic volunteers and two non-diabetic control subjects. For comparison to existing methods, we evaluated the contrast of retinal images taken with our method and red-free illumination. The preliminary results show that the use of optimal illuminations improved the contrast of diabetic lesions in retinal images by 30-70%, compared to the traditional red-free illumination imaging.

  9. Micromilled optical elements for edge-lit illumination panels

    NASA Astrophysics Data System (ADS)

    Ronny, Rahima Afrose; Knopf, George K.; Bordatchev, Evgueni; Nikumb, Suwas

    2013-04-01

    Edge-lit light guide panels (LGPs) with micropatterned surfaces represent a new technology for developing small- and medium-sized illumination sources for application such as automotive, residential lighting, and advertising displays. The shape, density, and spatial distribution of the micro-optical structures (MOSs) imprinted on the transparent LGP must be selected to achieve high brightness and uniform luminance over the active surface. We examine how round-tip cylindrical MOSs fabricated by precision micromilling can be used to create patterned surfaces on low-cost transparent polymethyl-methacrylate substrates for high-intensity illumination applications. The impact of varying the number, pitch, spatial distribution, and depth of the optical microstructures on lighting performance is initially investigated using LightTools™ simulation software. To illustrate the microfabrication process, several 100×100×6 mm3 LGP prototypes are constructed and tested. The prototypes include an "optimized" array of MOSs that exhibit near-uniform illumination (approximately 89%) across its active light-emitting surface. Although the average illumination was 7.3% less than the value predicted from numerical simulation, it demonstrates how LGPs can be created using micromilling operations. Customized MOS arrays with a bright rectangular pattern near the center of the panel and a sequence of MOSs that illuminate a predefined logo are also presented.

  10. Low-resolution face tracker robust to illumination variations.

    PubMed

    Zou, Wilman W; Yuen, Pong C; Chellappa, Rama

    2013-05-01

    In many practical video surveillance applications, the faces acquired by outdoor cameras are of low resolution and are affected by uncontrolled illumination. Although significant efforts have been made to facilitate face tracking or illumination normalization in unconstrained videos, the approaches developed may not be effective in video surveillance applications. This is because: 1) a low-resolution face contains limited information, and 2) major changes in illumination on a small region of the face make the tracking ineffective. To overcome this problem, this paper proposes to perform tracking in an illumination-insensitive feature space, called the gradient logarithm field (GLF) feature space. The GLF feature mainly depends on the intrinsic characteristics of a face and is only marginally affected by the lighting source. In addition, the GLF feature is a global feature and does not depend on a specific face model, and thus is effective in tracking low-resolution faces. Experimental results show that the proposed GLF-based tracker works well under significant illumination changes and outperforms many state-of-the-art tracking algorithms.

  11. The evolution of structured illumination microscopy in studies of HIV.

    PubMed

    Marno, Kelly; Al'Zoubi, Lara; Pearson, Matthew; Posch, Markus; McKnight, Áine; Wheeler, Ann P

    2015-10-15

    The resolution limit of conventional light microscopy has proven to be limiting for many biological structures such as viruses including Human immunodeficiency virus (HIV). Individual HIV virions are impossible to study using confocal microscopy as they are well below the 200 nm resolution limit of conventional light microscopes. Structured illumination microscopy (SIM) allows a twofold enhancement in image resolution compared to standard widefield illumination and so provides an excellent tool for study of HIV. Viral capsids (CAs) vary between 110 and 146 nm so this study challenges the performance of SIM microscopes. SIM microscopy was first developed in 2000, commercialised in 2007 and rapidly developed. Here we present the changes in capabilities of the SIM microscopes for study of HIV localisation as the instrumentation for structured illumination microscopy has evolved over the past 8 years.

  12. Optimizing ultrafast illumination for multiphoton-excited fluorescence imaging

    PubMed Central

    Stoltzfus, Caleb R.; Rebane, Aleksander

    2016-01-01

    We study the optimal conditions for high throughput two-photon excited fluorescence (2PEF) and three-photon excited fluorescence (3PEF) imaging using femtosecond lasers. We derive relations that allow maximization of the rate of imaging depending on the average power, pulse repetition rate, and noise characteristics of the laser, as well as on the size and structure of the sample. We perform our analysis using ~100 MHz, ~1 MHz and 1 kHz pulse rates and using both a tightly-focused illumination beam with diffraction-limited image resolution, as well loosely focused illumination with a relatively low image resolution, where the latter utilizes separate illumination and fluorescence detection beam paths. Our theoretical estimates agree with the experiments, which makes our approach especially useful for optimizing high throughput imaging of large samples with a field-of-view up to 10x10 cm2. PMID:27231620

  13. SIMToolbox: a MATLAB toolbox for structured illumination fluorescence microscopy.

    PubMed

    Křížek, Pavel; Lukeš, Tomáš; Ovesný, Martin; Fliegel, Karel; Hagen, Guy M

    2016-01-15

    SIMToolbox is an open-source, modular set of functions for MATLAB equipped with a user-friendly graphical interface and designed for processing two-dimensional and three-dimensional data acquired by structured illumination microscopy (SIM). Both optical sectioning and super-resolution applications are supported. The software is also capable of maximum a posteriori probability image estimation (MAP-SIM), an alternative method for reconstruction of structured illumination images. MAP-SIM can potentially reduce reconstruction artifacts, which commonly occur due to refractive index mismatch within the sample and to imperfections in the illumination. SIMToolbox, example data and the online documentation are freely accessible at http://mmtg.fel.cvut.cz/SIMToolbox. ghagen@uccs.edu Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  14. Quantum illumination reveals phase-shift inducing cloaking.

    PubMed

    Las Heras, U; Di Candia, R; Fedorov, K G; Deppe, F; Sanz, M; Solano, E

    2017-08-24

    In quantum illumination entangled light is employed to enhance the detection accuracy of an object when compared with the best classical protocol. On the other hand, cloaking is a stealth technology based on covering a target with a material deflecting the light around the object to avoid its detection. Here, we propose a quantum illumination protocol especially adapted to quantum microwave technology. This protocol seizes the phase-shift induced by some cloaking techniques, such as scattering reduction, allowing for a 3 dB improvement in the detection of a cloaked target. The method can also be employed for the detection of a phase-shift in bright environments in different frequency regimes. Finally, we study the minimal efficiency required by the photocounter for which the quantum illumination protocol still shows a gain with respect to the classical protocol.

  15. A back-illuminated megapixel CMOS image sensor

    NASA Technical Reports Server (NTRS)

    Pain, Bedabrata; Cunningham, Thomas; Nikzad, Shouleh; Hoenk, Michael; Jones, Todd; Wrigley, Chris; Hancock, Bruce

    2005-01-01

    In this paper, we present the test and characterization results for a back-illuminated megapixel CMOS imager. The imager pixel consists of a standard junction photodiode coupled to a three transistor-per-pixel switched source-follower readout [1]. The imager also consists of integrated timing and control and bias generation circuits, and provides analog output. The analog column-scan circuits were implemented in such a way that the imager could be configured to run in off-chip correlated double-sampling (CDS) mode. The imager was originally designed for normal front-illuminated operation, and was fabricated in a commercially available 0.5 pn triple-metal CMOS-imager compatible process. For backside illumination, the imager was thinned by etching away the substrate was etched away in a post-fabrication processing step.

  16. Local feature descriptor invariant to monotonic illumination changes

    NASA Astrophysics Data System (ADS)

    Yan, Pu; Liang, Dong; Tang, Jun; Zhu, Ming

    2016-01-01

    This paper presents a monotonic invariant intensity descriptor (MIID) via spectral embedding and nonsubsampled contourlet transform (NSCT). To make the proposed descriptor discriminative, NSCT is used for the construction of multiple support regions. Specifically, the directed graph and the spectral feature vectors of the signless Laplacian matrix are exploited to construct the MIID. We theoretically demonstrate that the proposed descriptor is able to tackle monotonic illumination changes and many other geometric and photometric transformations. We conduct extensive experiments on the standard Oxford dataset and the complex illumination dataset to demonstrate the superiority of proposed descriptor over the existing state-of-the-art descriptors in dealing with image blur, viewpoint changes, illumination changes, and JPEG compression.

  17. Holographic illuminator for synchrotron-based projection lithography systems

    DOEpatents

    Naulleau, Patrick P.

    2005-08-09

    The effective coherence of a synchrotron beam line can be tailored to projection lithography requirements by employing a moving holographic diffuser and a stationary low-cost spherical mirror. The invention is particularly suited for use in an illuminator device for an optical image processing system requiring partially coherent illumination. The illuminator includes: (1) a synchrotron source of coherent or partially coherent radiation which has an intrinsic coherence that is higher than the desired coherence, (2) a holographic diffuser having a surface that receives incident radiation from said source, (3) means for translating the surface of the holographic diffuser in two dimensions along a plane that is parallel to the surface of the holographic diffuser wherein the rate of the motion is fast relative to integration time of said image processing system; and (4) a condenser optic that re-images the surface of the holographic diffuser to the entrance plane of said image processing system.

  18. Object tracking under nonuniform illumination with adaptive correlation filtering

    NASA Astrophysics Data System (ADS)

    Picos, Kenia; Díaz-Ramírez, Víctor H.; Kober, Vitaly

    2013-09-01

    A real-time system for illumination-invariant object tracking is proposed. The system is able to estimate at high-rate the position of a moving target in an input scene when is corrupted by the presence of a high cluttering background and nonuniform illumination. The position of the target is estimated with the help of a filter bank of space-variant correlation filters. The filters in the bank, adapt their parameters according to the local statistical parameters of the observed scene in a small region centered at coordinates of a predicted position for the target in each frame. The prediction is carried out by exploiting information of present and past frames, and by using a dynamic motion model of the target in a two-dimensional plane. Computer simulation results obtained with the proposed system are presented and discussed in terms of tracking accuracy, computational complexity, and tolerance to nonuniform illumination.

  19. Chromatic perceptive field sizes change with retinal illuminance.

    PubMed

    Pitts, Michael A; Troup, Lucy J; Volbrecht, Vicki J; Nerger, Janice L

    2005-05-18

    The effect of retinal illuminance (0.3-3.3 log td) on chromatic perceptive field size was investigated at 10 degrees eccentricity along the horizontal meridian of the temporal retina. Using the 4+1 color-naming procedure, observers described the hue and saturation of a series of monochromatic stimuli (440-660 nm, in 10-nm steps) of various test sizes (.098-5 degrees) after 30-min dark adaptation. Perceptive field sizes of the four elemental hues and the saturation component were estimated for each wavelength at each retinal illuminance. Results indicate that perceptive field sizes for blue, green, yellow, and saturation all decrease with increasing retinal illuminance; the perceptive field size for red is the smallest and invariant with intensity. The influence of rods on perceptive field size may account for some of the results; other factors are also considered.

  20. Structured illumination microscopy with unknown patterns and a statistical prior

    PubMed Central

    Yeh, Li-Hao; Tian, Lei; Waller, Laura

    2017-01-01

    Structured illumination microscopy (SIM) improves resolution by down-modulating high-frequency information of an object to fit within the passband of the optical system. Generally, the reconstruction process requires prior knowledge of the illumination patterns, which implies a well-calibrated and aberration-free system. Here, we propose a new algorithmic self-calibration strategy for SIM that does not need to know the exact patterns a priori, but only their covariance. The algorithm, termed PE-SIMS, includes a pattern-estimation (PE) step requiring the uniformity of the sum of the illumination patterns and a SIM reconstruction procedure using a statistical prior (SIMS). Additionally, we perform a pixel reassignment process (SIMS-PR) to enhance the reconstruction quality. We achieve 2× better resolution than a conventional widefield microscope, while remaining insensitive to aberration-induced pattern distortion and robust against parameter tuning. PMID:28270977

  1. Planetary science: constant illumination at the lunar north pole.

    PubMed

    Bussey, D Ben J; Fristad, Kirsten E; Schenk, Paul M; Robinson, Mark S; Spudis, Paul D

    2005-04-14

    Images returned by the spacecraft Clementine have been used to produce a quantitative illumination map of the north pole of the Moon, revealing the percentage of time that points on the surface are illuminated during the lunar day. We have used this map to identify areas that are constantly illuminated during a lunar day in summer and which may therefore be in permanent sunlight. All are located on the northern rim of Peary crater, close to the north pole. Permanently sunlit areas represent prime locations for lunar outpost sites as they have abundant solar energy, are relatively benign thermally (when compared with equatorial regions), and are close to permanently shadowed regions that may contain water ice.

  2. On the relation between zenith sky brightness and horizontal illuminance

    NASA Astrophysics Data System (ADS)

    Kocifaj, M.; Posch, Th.; Solano Lamphar, H. A.

    2015-01-01

    The effects of artificial light at night are an emergent research topic for astronomers, physicists, engineers and biologists around the world. This leads to a need for measurements of the night sky brightness (= diffuse luminance of the night sky) and nocturnal illuminance. Currently, the most sensitive light meters measure the zenith sky brightness in magV/arcsec2 or - less frequently - in cd m-2. However, the horizontal illuminance resulting only from the night sky is an important source of information that is difficult to obtain with common instruments. Here we present a set of approximations to convert the zenith luminance into horizontal illuminance. Three different approximations are presented for three idealized atmospheric conditions: homogeneous sky brightness, an isotropically scattering atmosphere and a turbid atmosphere. We also apply the resulting conversion formulae to experimental data on night sky luminance, obtained during the past three years.

  3. On illumination schemes for wide-field CARS microscopy.

    PubMed

    Toytman, I; Simanovskii, D; Palanker, D

    2009-04-27

    New system for a wide-field CARS microscopy is demonstrated, including two schemes of non-phase-matching illumination. Several advantages including high Stokes pulse energy, pulse-to-pulse stability and inherent synchronization between pump and Stokes pulses were brought by use of methane-filled Raman converter. Spatial resolution of the system with axially symmetric illumination, 0.5 microm, was found to correspond to diffraction limit of the imaging objective. Selective sensitivity to lipid-rich myelin sheaths in the nerve tissue has been demonstrated and confirmed by comparison with histological samples stained with myelin-specific dye. Single-shot imaging capability of the system has been demonstrated with a speckling-free illumination on a monolayer of 3 microm polystyrene beads.

  4. Local and Global Illumination in the Volume Rendering Integral

    SciTech Connect

    Max, N; Chen, M

    2005-10-21

    This article is intended as an update of the major survey by Max [1] on optical models for direct volume rendering. It provides a brief overview of the subject scope covered by [1], and brings recent developments, such as new shadow algorithms and refraction rendering, into the perspective. In particular, we examine three fundamentals aspects of direct volume rendering, namely the volume rendering integral, local illumination models and global illumination models, in a wavelength-independent manner. We review the developments on spectral volume rendering, in which visible light are considered as a form of electromagnetic radiation, optical models are implemented in conjunction with representations of spectral power distribution. This survey can provide a basis for, and encourage, new efforts for developing and using complex illumination models to achieve better realism and perception through optical correctness.

  5. Fundus spectroscopy and studies in retinal oximetry using intravitreal illumination

    NASA Astrophysics Data System (ADS)

    Salyer, David Alan

    This dissertation documents the development of a new illumination technique for use in the studies of retinal oximetry and fundus spectroscopy. Intravitreal illumination is a technique where the back of the eye is illuminated trans-sclerally using a scanning monochromator coupled into a fiber optic illuminator. Retinal oximetry is the process of measuring the oxygen saturation of blood contained in retinal vessels by quantitative measurement of the characteristic color shift seen as blood oxygen saturation changes from oxygenated blood (reddish) to deoxygenated blood (bluish). Retinal oximetry was first attempted in 1963 but due to a variety of problems with accuracy and difficulty of measurement, has not matured to the point of clinical acceptability or commercial viability. Accurate retinal oximetry relies in part on an adequate understanding of the spectral reflectance characteristics of the fundus. The use of intravitreal illumination allows new investigations into the spectral reflectance properties of the fundus. The results of much research in fundus reflectance and retinal oximetry is detailed in this document, providing new insight into both of these related fields of study. Intravitreal illumination has been used to study retinal vessel oximetry and fundus reflectometry resulting in several important findings that are presented in this document. Studies on enucleated swine eyes have provided new insight into the bidirectional reflectance distribution function of the fundus. Research on live swine has shown accurate measurement of retinal vessel oxygen saturation and provided the first in vivo spectral transmittance measurement of the sensory retina. A secondary discovery during this research suggests that vitrectomy alters the retinal vasculature, an finding that should spawn new research in its own right.

  6. Illumination-parameter adjustable and illumination-distribution visible LED helmet for low-level light therapy on brain injury

    NASA Astrophysics Data System (ADS)

    Wang, Pengbo; Gao, Yuan; Chen, Xiao; Li, Ting

    2016-03-01

    Low-level light therapy (LLLT) has been clinically applied. Recently, more and more cases are reported with positive therapeutic effect by using transcranial light emitting diodes (LEDs) illumination. Here, we developed a LLLT helmet for treating brain injuries based on LED arrays. We designed the LED arrays in circle shape and assembled them in multilayered 3D printed helmet with water-cooling module. The LED arrays can be adjust to touch the head of subjects. A control circuit was developed to drive and control the illumination of the LLLT helmet. The software portion provides the control of on and off of each LED arrays, the setup of illumination parameters, and 3D distribution of LLLT light dose in human subject according to the illumination setups. This LLLT light dose distribution was computed by a Monte Carlo model for voxelized media and the Visible Chinese Human head dataset and displayed in 3D view at the background of head anatomical structure. The performance of the whole system was fully tested. One stroke patient was recruited in the preliminary LLLT experiment and the following neuropsychological testing showed obvious improvement in memory and executive functioning. This clinical case suggested the potential of this Illumination-parameter adjustable and illuminationdistribution visible LED helmet as a reliable, noninvasive, and effective tool in treating brain injuries.

  7. Near-field enhanced Raman spectroscopy using side illumination optics

    NASA Astrophysics Data System (ADS)

    Hayazawa, Norihiko; Tarun, Alvarado; Inouye, Yasushi; Kawata, Satoshi

    2002-12-01

    We demonstrate near-field enhanced Raman spectroscopy with the use of a metallized cantilever tip and highly p-polarized light directed onto the tip with side illumination optics using a long working distance objective lens. The highly p-polarized light field excites surface plasmon polaritons localized at the tip apex, which results in the enhanced near-field Raman scattering. In this article, we achieved an enhancement factor of 4000 for Rhodamine 6G molecules adsorbed on a silver island film. The side illumination is also applicable to an opaque sample and to near-field photolithography.

  8. Three-dimensional illumination procedure for photodynamic therapy of dermatology

    NASA Astrophysics Data System (ADS)

    Hu, Xiao-ming; Zhang, Feng-juan; Dong, Fei; Zhou, Ya

    2014-09-01

    Light dosimetry is an important parameter that affects the efficacy of photodynamic therapy (PDT). However, the irregular morphologies of lesions complicate lesion segmentation and light irradiance adjustment. Therefore, this study developed an illumination demo system comprising a camera, a digital projector, and a computing unit to solve these problems. A three-dimensional model of a lesion was reconstructed using the developed system. Hierarchical segmentation was achieved with the superpixel algorithm. The expected light dosimetry on the targeted lesion was achieved with the proposed illumination procedure. Accurate control and optimization of light delivery can improve the efficacy of PDT.

  9. Coating strategy for enhancing illumination uniformity in a lithographic condenser

    SciTech Connect

    Gaines, D.P.; Vernon, S.P.; Sommargren, G.E.; Kania, D.R.

    1995-01-26

    A three-element Koehler condenser system has been fabricated, characterized, and integrated into an EUV lithographic system. The multilayer coatings deposited on the optics were designed to provide optimal radiation transport efficiency and illumination uniformity. Extensive EUV characterization measurements performed on the individual optics and follow-on system measurements indicated that the condenser was operating close to design goals. Multilayer d-spacings were within 0.05 nm of specifications, and reflectances were approximately 60%. Illumination uniformity was better than {plus_minus}10%. The broadband transport efficiency was 11%.

  10. Microwave holographic imaging of aircraft with spaceborne illuminating source

    NASA Technical Reports Server (NTRS)

    Berkowitz, R. S.; Dzekov, T. A.

    1976-01-01

    The conceptual development of a method for the high angular resolution and accurate angular position estimates for the surveillance and traffic control of aircraft is considered. A target volume several hundred kilometers in diameter is illuminated by a CW microwave source located on a satellite in geosynchronous orbit. Signals are received by a large array of random, conformally located receiving elements. Each element receives the direct signal from the satellite plus signals reflected from aircraft in the illuminated volume. Coherent combination of the signals received from the individual elements permits the equivalent of holographic imaging or multiple beam formation from which the useful target data can be obtained.

  11. The possible ocular hazards of LED dental illumination applications.

    PubMed

    Stamatacos, Catherine; Harrison, Janet L

    2013-01-01

    The use of high-intensity illumination via Light-Emitting Diode (LED) headlamps is gaining in popularity with dentists and student dentists. Practitioners are using LED headlamps together with magnifying loupes, overhead LED illumination and fiber-optic dental handpieces for long periods of time. Although most manufacturers of these LED illuminators advertise that their devices emit "white" light, these still consist of two spectral bands--the blue spectral band, with its peak at 445 nm, and the green with its peak at 555 nm. While manufacturers suggest that their devices emit "white" light, spectral components of LED lights from different companies are significantly different. Dental headlamp manufacturers strive to create a white LED, and they advertise that this type of light emitted from their product offers bright white-light illumination. However, the manufacturing of a white LED light is done through selection of a white LED-type based on the peak blue strength in combination with the green peak strength and thus creating a beam-forming optic, which determines the beam quality. Some LED illuminators have a strong blue-light component versus the green-light component. Blue-light is highly energized and is close in the color spectrum to ultraviolet-light. The hazards of retinal damage with the use of high-intensity blue-lights has been well-documented. There is limited research regarding the possible ocular hazards of usage of high-intensity illuminating LED devices. Furthermore, the authors have found little research, standards, or guidelines examining the possible safety issues regarding the unique dental practice setting consisting of the combined use of LED illumination systems. Another unexamined component is the effect of high-intensity light reflective glare and magnification back to the practitioner's eyes due to the use of water during dental procedures. Based on the result of Dr. Janet Harrison's observations of beginning dental students in a

  12. Teaching illumination engineering using light pollution education kits

    NASA Astrophysics Data System (ADS)

    Walker, Constance E.; Pompea, Stephen M.; Sparks, Robert T.; Dokter, Erin

    2010-08-01

    One-third of outdoor lighting escapes unused into space, causing light pollution. Light pollution is a growing concern on many fronts: energy conservation, cost, safety, health, effects on wildlife, and our ability to view the stars. How we use illumination engineering to optimize where, when, and how light is used is of significant importance. We will discuss how NOAO's light pollution education kits are used to teach illumination engineering. In particular we will address topics associated with achieving sufficient ground coverage, color rendition, types of outdoor lighting, glare and sky glow, assessment of city lights, and task-oriented lighting.

  13. High efficiency source coupler for optical waveguide illumination system

    DOEpatents

    Siminovitch, Michael J.

    2000-01-01

    A fiber optic or optical waveguide illumination system includes a source coupling system. The source coupling system includes an optical channel with an internal cavity. A light source is disposed inside the driving circuit. Coupling losses are minimized by placing the light source within the optical channel. The source cavity and the source optical channel can be shaped to enhance the amount of light captured in the channel by total internal reflection. Multiple light distribution waveguides can be connected to the source coupling channel to produce an illumination system.

  14. Dental operating lights and illumination of the dental surgery.

    PubMed

    Viohl, J

    1979-06-01

    The requirements laid down in national and international standards and draft standards provide helpful guidelines for optimum illumination (Fig. 1, Table I). General room illumination with 500 lx and illumination of the working area with 1000 lx are best achieved with a larger number of fluorescent lamps on the ceiling above and in front of the dental chair. Daylight white lamps with good colour rendering (e.g. Osram colour 19 or Philips colour 47) are a good combination with changing daylight and the colour of light of the operating light. The colour of external skin, mucous membrane and teeth appears natural. The eight surgical lights examined differ in quality (Figs. 2-9). The maximum illuminance is between 9000 and 21 000 lx and is thus sufficiently high. The evenness of light distribution within an ellipse 9 cm and 18 cm in diameter is between 1 : 4 and 1 : 15 (Figs. 10 and 11). Illuminance can be adjusted to the work in hand by means of controls. If the patient looks into the operating lights (Figs. 2c and 9c), maximum luminances of 5 cd/cm2-20 cd/cm2 occur 8 cm above the illuminance maximum in six operating lights. Luminances of more than 20 cd/cm2 cause squinting and running eyes. A light fitting with more than 200 cd/cm2 should not be used. A sharp fall in illuminance (distinct light/dark threshold) and low luminances to the patient's eyes can be achieved with very directed light. Very directed light leads to very heavy shadows. Similarly, less specifically directed light leads to softer shadows so that objects in the oral cavity can be discerned easily, but the patient is no longer dazzled. The following operating lights can be recommended if the patient is to suffer as little glare as possible: Den-Tel-Ez Daray, and Belmont Type 040, Faro Sunlight S 70, Ritter Super Starlite; as well as: Chirana Fax, Siemens Sirolux. The following can be recommended for good illumination of the oral cavity: Belmont Type 040, Chirana Fax, Emda Top Spot, Faro Sunlight S 70

  15. Holographic display with LED sources illumination and enlarged viewing angle

    NASA Astrophysics Data System (ADS)

    Chlipała, Maksymilian; Kozacki, Tomasz

    2016-09-01

    In this work we present holographic display that uses LED sources illumination and have enlarged viewing angle. In this holographic display design we employ phase only SLM because it allows to obtain reconstructions of high quality. Our setup realizes complex coding scheme and allows to reconstruct complex holographic images. Thus reconstruction of inplane holograms is possible. Holograms displayed on SLM are computer generated. For enlargement of angular field of view we use three spatially separated illumination sources and time multiplexing technique. In experimental part, where we display computer generated holograms, we show that it is possible to obtain holographic reconstructions of 3D object with extended viewing angle.

  16. Improve microwave quantum illumination via optical parametric amplifier

    NASA Astrophysics Data System (ADS)

    Xiong, Biao; Li, Xun; Wang, Xiao-Yu; Zhou, Ling

    2017-10-01

    Quantum illumination is a quantum-optical sensing technique in which an entangled source is exploited to improve the detection of a low-reflectivity object that is immersed in a bright thermal background. Entangled sources between microwave and optical fields can be exploited to improve detection in microwave quantum illumination technique. We proposed a scheme to enhance the entanglement between the output fields of microwave and optical cavity by introducing optical parametric amplifier medium in cavity optomechanical system. We show that improving signal-to-noise ratio and decreasing error probability of detection can be obtained consequently even for objects with low reflectivity in the presence of optical parametric amplifier.

  17. 3D Imaging with Structured Illumination for Advanced Security Applications

    SciTech Connect

    Birch, Gabriel Carisle; Dagel, Amber Lynn; Kast, Brian A.; Smith, Collin S.

    2015-09-01

    Three-dimensional (3D) information in a physical security system is a highly useful dis- criminator. The two-dimensional data from an imaging systems fails to provide target dis- tance and three-dimensional motion vector, which can be used to reduce nuisance alarm rates and increase system effectiveness. However, 3D imaging devices designed primarily for use in physical security systems are uncommon. This report discusses an architecture favorable to physical security systems; an inexpensive snapshot 3D imaging system utilizing a simple illumination system. The method of acquiring 3D data, tests to understand illumination de- sign, and software modifications possible to maximize information gathering capability are discussed.

  18. Infrared laser diode with visible illuminator for biomedical stimulation

    NASA Astrophysics Data System (ADS)

    Strek, Wieslaw; Podbielska, Halina; Szafranski, C.; Kuzmin, Andrei N.; Ges, J. A.; Ryabtsev, Gennadii I.

    1995-02-01

    The special laser diode device (LDD) leasing in the near infrared region (IR) with two wavelengths: (lambda) 1 equals 850 nm and (lambda) 2 equals 1000 nm, designed for laser therapy, is presented. This device is characterized by a unique feature, namely a separate built-in illuminator, operating in 670 nm. The special construction of LDD and the illuminator enables the user to visualize exactly the surface irradiated by IR radiation. The exposure time and the output of laser power are also controlled and can be displayed on the LED monitor at the front panel. This new device, described here, is compact, low cost, and user friendly.

  19. Quantitative phase retrieval with arbitrary pupil and illumination

    SciTech Connect

    Claus, Rene A.; Naulleau, Patrick P.; Neureuther, Andrew R.; Waller, Laura

    2015-10-02

    We present a general algorithm for combining measurements taken under various illumination and imaging conditions to quantitatively extract the amplitude and phase of an object wave. The algorithm uses the weak object transfer function, which incorporates arbitrary pupil functions and partially coherent illumination. The approach is extended beyond the weak object regime using an iterative algorithm. Finally, we demonstrate the method on measurements of Extreme Ultraviolet Lithography (EUV) multilayer mask defects taken in an EUV zone plate microscope with both a standard zone plate lens and a zone plate implementing Zernike phase contrast.

  20. Extraterrestrial applications of solar optics for interior illumination

    NASA Technical Reports Server (NTRS)

    Eijadi, David A.; Williams, Kyle D.

    1992-01-01

    Solar optics is a terrestrial technology that has potential extraterrestrial applications. Active solar optics (ASO) and passive solar optics (PSO) are two approaches to the transmission of sunlight to remote interior spaces. Active solar optics is most appropriate for task illumination, while PSO is most appropriate for general illumination. Research into solar optics, motivated by energy conservation, has produced lightweight and low-cost materials, products that have applications to NASA's Controlled Ecological Life Support System (CELSS) program and its lunar base studies. Specifically, prism light guides have great potential in these contexts. Several applications of solar optics to lunar base concepts are illustrated.

  1. Structured illumination microscopy of autofluorescent aggregations in human tissue.

    PubMed

    Best, Gerrit; Amberger, Roman; Baddeley, David; Ach, Thomas; Dithmar, Stefan; Heintzmann, Rainer; Cremer, Christoph

    2011-06-01

    Sections from human eye tissue were analyzed with Structured Illumination Microscopy (SIM) using a specially designed microscope setup. In this microscope the structured illumination was generated with a Twyman-Green Interferometer. This SIM technique allowed us to acquire light-optical images of autofluorophore distributions in the tissue with previously unmatched optical resolution. In this work the unique setup of the microscope made possible the application of SIM with three different excitation wavelengths (488, 568 and 647 nm), thus enabling us to gather spectral information about the autofluorescence signal.

  2. Illumination, wavelength selection, and detection in fluorescence microscopy.

    PubMed

    Spring, K R

    1991-07-01

    The presently available devices for the illumination, changing of wavelengths, and detection of the resultant fluorescence of biological samples viewed in the light microscope have been described and compared. The optimal choice for illumination is a xenon arc lamp with a filter wheel wavelength selector. The optimal choice for an imaging detector is an intensified CCD (charge-coupled-device) camera. These combinations produce the most rapid, stable, and reproducible results when fluorescence measurements are made on living epithelial cells or isolated renal tubules. Techniques for the simultaneous acquisition of fluorescence and differential interference contrast (DIC) images have also been described and compared.

  3. The possible ocular hazards of LED dental illumination applications.

    PubMed

    Stamatacos, Catherine; Harrison, Janet L

    2014-04-01

    The use of high-intensity illumination via Light-Emitting Diode (LED) headlamps is gaining in popularity with dentists and student dentists. Practitioners are using LED headlamps together with magnifying loupes, overhead LED illumination and fiber-optic dental handpieces for long periods of time. Although most manufacturers of these LED illuminators advertise that their devices emit "white" light, these still consist of two spectral bands - the blue spectral band, with its peak at 445 nm, and the green with its peak at 555 nm. While manufacturers suggest that their devices emit "white" light, spectral components of LED lights from different companies are significantly different. Dental headlamp manufacturers strive to create a white LED, and they advertise that this type of light emitted from their product offers bright white-light illumination. However, the manufacturing of a white LED light is done through selection of a white LED-type based on the peak blue strength in combination with the green peak strength and thus creating a beam-forming optic, which determines the beam quality. Some LED illuminators have a strong blue-light component versus the green-light component. Blue-light is highly energized and is close in the color spectrum to ultraviolet-light. The hazards of retinal damage with the use of high-intensity blue-lights has been well-documented. There is limited research regarding the possible ocular hazards of usage of high-intensity illuminating LED devices. Furthermore, the authors have found little research, standards, or guidelines examining the possible safety issues regarding the unique dental practice setting consisting of the combined use of LED illumination systems. Another unexamined component is the effect of high-intensity light reflective glare and magnification back to the practitioner's eyes due to the use of water during dental procedures. Based on the result of Dr. Janet Harrison's observations of beginning dental students in a

  4. Illumination-based synchronization of high-speed vision sensors.

    PubMed

    Hou, Lei; Kagami, Shingo; Hashimoto, Koichi

    2010-01-01

    To acquire images of dynamic scenes from multiple points of view simultaneously, the acquisition time of vision sensors should be synchronized. This paper describes an illumination-based synchronization method derived from the phase-locked loop (PLL) algorithm. Incident light to a vision sensor from an intensity-modulated illumination source serves as the reference signal for synchronization. Analog and digital computation within the vision sensor forms a PLL to regulate the output signal, which corresponds to the vision frame timing, to be synchronized with the reference. Simulated and experimental results show that a 1,000 Hz frame rate vision sensor was successfully synchronized with 32 μs jitters.

  5. Illumination of Arabidopsis roots induces immediate burst of ROS production

    PubMed Central

    Yokawa, Ken; Kagenishi, Tomoko; Kawano, Tomonori; Mancuso, Stefano

    2011-01-01

    Arabidopsis roots are routinely exposed to light both during their cultivation within transparent Petri dishes and during their confocal microscopy analysis. Here we report that illumination of roots which naturally grow in darkness, even for a few seconds, induces an immediate and strong burst of reactive oxygen species (ROS). Plant scientists studying roots should pay great attention to the environment of living roots, and keep them in darkness as long as possible. Results obtained using illuminated roots during in vivo microscopic analysis should also be interpreted with great caution. PMID:21957498

  6. Illumination of Arabidopsis roots induces immediate burst of ROS production.

    PubMed

    Yokawa, Ken; Kagenishi, Tomoko; Kawano, Tomonori; Mancuso, Stefano; Baluška, František

    2011-10-01

    Arabidopsis roots are routinely exposed to light both during their cultivation within transparent Petri dishes and during their confocal microscopy analysis. Here we report that illumination of roots which naturally grow in darkness, even for a few seconds, induces an immediate and strong burst of reactive oxygen species (ROS). Plant scientists studying roots should pay great attention to the environment of living roots, and keep them in darkness as long as possible. Results obtained using illuminated roots during in vivo microscopic analysis should also be interpreted with great caution.

  7. Simulation and comparison of the illuminance, uniformity, and efficiency of different forms of lighting used in basketball court illumination.

    PubMed

    Sun, Wen-Shing; Tien, Chuen-Lin; Tsuei, Chih-Hsuan; Pan, Jui-Wen

    2014-10-10

    We simulate and compare the illuminance, uniformity, and efficiency of metal-halide lamps, white LED light sources, and hybrid light box designs combining sunlight and white LED lighting used for indoor basketball court illumination. According to the optical simulation results and our examination of real situations, we find that hybrid light box designs combining sunlight and white LEDs do perform better than either metal-halide lamps or white LED lights. An evaluation of the sunlight concentrator system used in our inverted solar cell shows that the energy consumption of stadium lighting can be reduced significantly.

  8. Illumination quality measurement of the work-station

    NASA Astrophysics Data System (ADS)

    Czech, Eugeniusz; Fryc, Irena

    2004-08-01

    In practice, the problem of vision discomfort appears at a number of different work-stands. Among others, it concerns people like drivers or people working with screen monitors. As a result of extensive research into appropriate illumination, a number of recommendations have been produced in order to ensure comfort of vision at work-stands. It is assumed that if the work-stand is provided with sufficiently high level of illuminance, and if the luminance distribution is uniform, and there is no glare, then we have comfort of vision and the eye fatigue is acceptable. Currently, to measure luminance distribution in order to assess the quality of illumination, it is necessary to carry out a large number of point measurements by using the luminance meter. Another way of determining the luminance distribution coming from the sources lying in a relatively small solid angle is the application of luminance meter built by using a CCD camera. Measurements of this type require, however, a great number of exposures to determine luminance distribution coming from light sources located in a large solid angle (e.g. a halfspace). This paper presents a design model of luminance distribution meter which makes it possible to obtain data about the distribution of luminance coming from light sources located in the whole halfspace only by a single measurement. Furthermore, the meter enables simultaneous determination of all the parameters on the work-stand illumination quality.

  9. Spatial distributions of local illumination color in natural scenes.

    PubMed

    Nascimento, Sérgio M C; Amano, Kinjiro; Foster, David H

    2016-03-01

    In natural complex environments, the elevation of the sun and the presence of occluding objects and mutual reflections cause variations in the spectral composition of the local illumination across time and location. Unlike the changes in time and their consequences for color appearance and constancy, the spatial variations of local illumination color in natural scenes have received relatively little attention. The aim of the present work was to characterize these spatial variations by spectral imaging. Hyperspectral radiance images were obtained from 30 rural and urban scenes in which neutral probe spheres were embedded. The spectra of the local illumination at 17 sample points on each sphere in each scene were extracted and a total of 1904 chromaticity coordinates and correlated color temperatures (CCTs) derived. Maximum differences in chromaticities over spheres and over scenes were similar. When data were pooled over scenes, CCTs ranged from 3000 K to 20,000 K, a variation of the same order of magnitude as that occurring over the day. Any mechanisms that underlie stable surface color perception in natural scenes need to accommodate these large spatial variations in local illumination color. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  10. 10 CFR 431.202 - Definitions concerning illuminated exit signs.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 3 2013-01-01 2013-01-01 false Definitions concerning illuminated exit signs. 431.202 Section 431.202 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN... one manufacturer, having the same primary energy source, and which have essentially...

  11. 10 CFR 431.202 - Definitions concerning illuminated exit signs.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 3 2014-01-01 2014-01-01 false Definitions concerning illuminated exit signs. 431.202 Section 431.202 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN... one manufacturer, having the same primary energy source, and which have essentially...

  12. 10 CFR 431.202 - Definitions concerning illuminated exit signs.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 3 2012-01-01 2012-01-01 false Definitions concerning illuminated exit signs. 431.202 Section 431.202 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN... one manufacturer, having the same primary energy source, and which have essentially...

  13. Super-resolution thermographic imaging using blind structured illumination

    NASA Astrophysics Data System (ADS)

    Burgholzer, Peter; Berer, Thomas; Gruber, Jürgen; Mayr, Günther

    2017-07-01

    Using an infrared camera for thermographic imaging allows the contactless temperature measurement of many surface pixels simultaneously. From the measured surface data, the structure below the surface, embedded inside a sample or tissue, can be reconstructed and imaged, if heated by an excitation light pulse. The main drawback in active thermographic imaging is the degradation of the spatial resolution with the imaging depth, which results in blurred images for deeper lying structures. We circumvent this degradation by using blind structured illumination combined with a non-linear joint sparsity reconstruction algorithm. We demonstrate imaging of a line pattern and a star-shaped structure through a 3 mm thick steel sheet with a resolution four times better than the width of the thermal point-spread-function. The structured illumination is realized by parallel slits cut in an aluminum foil, where the excitation coming from a flashlight can penetrate. This realization of super-resolution thermographic imaging demonstrates that blind structured illumination allows thermographic imaging without high degradation of the spatial resolution for deeper lying structures. The groundbreaking concept of super-resolution can be transferred from optics to diffusive imaging by defining a thermal point-spread-function, which gives the principle resolution limit for a certain signal-to-noise ratio, similar to the Abbe limit for a certain optical wavelength. In future work, the unknown illumination pattern could be the speckle pattern generated by a short laser pulse inside a light scattering sample or tissue.

  14. 10 CFR 431.202 - Definitions concerning illuminated exit signs.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 3 2010-01-01 2010-01-01 false Definitions concerning illuminated exit signs. 431.202 Section 431.202 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN... energy source, which have electrical characteristics that are essentially identical, and which do not...

  15. 10 CFR 431.202 - Definitions concerning illuminated exit signs.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 3 2011-01-01 2011-01-01 false Definitions concerning illuminated exit signs. 431.202 Section 431.202 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN... energy source, which have electrical characteristics that are essentially identical, and which do not...

  16. Book Design, Part III: Illuminated Letters and Borders.

    ERIC Educational Resources Information Center

    Harms, Jeanne McLain; Lettow, Lucille

    1997-01-01

    This third in a series of articles on book design discusses and illustrates elements found within the body of the work: (1) illuminated letters, which serve as decoration, reflect cultural elements, enhance the meaning of text and illustrations, or establish motif, setting, or theme; and (2) borders, which serve as frames for text and…

  17. Illumination design for semiconductor backlight inspection and application extensions

    NASA Astrophysics Data System (ADS)

    Zhou, Wei; Rutherford, Todd; Hart, Darcy

    2013-09-01

    High speed strobe based illumination scheme is one of the most critical factors for high throughput semiconductor defect inspection applications. HB LEDs are always the first and best options for such applications due to numerous unique advantages such as excellent spatial and temporal stability, fast responding time, large and linear intensity dynamic range and no heat issue for the extremely low duty cycle applications. For some applications where a large area is required to be illuminated simultaneously, it remains a great challenge to efficiently package a large amount of HB-LEDs in a highly confined 3D space, to generate a seamless illuminated area with high luminance efficiency and spatial uniformity. A novel 3D structured collimation lens is presented in this paper. The non-circular edge shape reduces the intensity drop at the channel boundaries, while the secondary curvatures on the top of the collimator lens efficiently guides the light into desired angular space. The number of the edges and the radius of the top surface curvature are control parameters for the system level performance and the manufacture cost trade-off. The proposed 3D structured LED collimation lens also maintains the benefits of traditional LED collimation lens such as coupling efficiency and mold manufacture capability. The applications can be extended into other non-illumination area like parallelism measurement and solar panel concentrator etc.

  18. Shining new light on the Hawthorne illumination experiments.

    PubMed

    Izawa, Masumi R; French, Michael D; Hedge, Alan

    2011-10-01

    This study provides an historical and statistical analysis of archival data from the Hawthorne illumination experiments. Previous accounts of the illumination experiments are fraught with inconsistencies because they have been based on secondary sources. The general consensus has been that variations in light levels had no effect on worker productivity at Hawthorne. All reports and data were thought to have been destroyed, but an archive at Cornell University was found to contain copies of the original documentation and much of the data from all three illumination experiments. Conclusions were originally drawn from visual comparisons of productivity graphs, and the data have never been properly statistically analyzed. Archival reports, notes, photographs, and letters on the experiments were consulted. Productivity data were extracted from the tables and graphs in the reports and statistically analyzed for each experiment. Previously unpublished details of the illumination experiments emerged. An effect of lighting on productivity was found in the first treatment sequence for the first experiment, but this finding was not confirmed in the second sequence or in the second and third experiments. Experimental results provided inconsistent evidence of an association between light levels and productivity. All three experiments were found to be seriously flawed. This study challenges popular accounts of the "Hawthorne effect," and the shortcomings of these experiments also have implications for the design of field studies.

  19. Improved forest change detection with terrain illumination corrected landsat images

    USDA-ARS?s Scientific Manuscript database

    An illumination correction algorithm has been developed to improve the accuracy of forest change detection from Landsat reflectance data. This algorithm is based on an empirical rotation model and was tested on the Landsat imagery pair over Cherokee National Forest, Tennessee, Uinta-Wasatch-Cache N...

  20. On calculating metamer sets for spectrally tunable LED illuminators.

    PubMed

    Finlayson, Graham; Mackiewicz, Michal; Hurlbert, Anya; Pearce, Bradley; Crichton, Stuart

    2014-07-01

    Solid state lighting is becoming a popular light source for color vision experiments. One of the advantages of light emitting diodes (LEDs) is the possibility to shape the target light spectrum according to the experimenter's needs. In this paper, we present a method for creating metameric lights with an LED-based spectrally tunable illuminator. The equipment we use consists of six Gamma Scientific RS-5B lamps, each containing nine different LEDs and a 1 m integrating sphere. We provide a method for describing the (almost) entire set of illuminant metamers. It will be shown that the main difficulty in describing this set arises as the result of the intensity dependent peak-wavelength shift, which is manifested by the majority of the LEDs used by the illuminators of this type. We define the normalized metamer set describing all illuminator spectra that colorimetrically match a given chromaticity. Finally, we describe a method for choosing the smoothest or least smooth metamer from the entire set.

  1. Illumination invariance and shadow compensation via spectro-polarimetry technique

    NASA Astrophysics Data System (ADS)

    Ibrahim, Izzati; Yuen, Peter; Hong, Kan; Chen, Tong; Soori, Umair; Jackman, James; Richardson, Mark

    2012-10-01

    A major problem for obtaining target reflectance via hyperspectral imaging systems is the presence of illumination and shadow effects. These factors are common artefacts, especially when dealing with a hyperspectral imaging system that has sensors in the visible to near infrared region. This region is known to have highly scattered and diffuse radiance that can modify the energy recorded by the imaging system. A shadow effect will lower the target reflectance values due to the small radiant energy impinging on the target surface. Combined with illumination artefacts, such as diffuse scattering from the surrounding targets, background or environment, the shape of the shadowed target reflectance will be altered. We propose a new method to compensate for illumination and shadow effects on hyperspectral imageries by using a polarization technique. This technique, called spectro-polarimetry, estimates the direct and diffuse irradiance based on two images taken with and without a polarizer. The method is then evaluated using a spectral similarity measure, angle and distance metric. The results of indoor and outdoor tests have shown that using the spectro-polarimetry technique can improve the spectral constancy between shadow and full illumination spectra.

  2. Fully depleted back-illuminated p-channel CCD development

    SciTech Connect

    Bebek, Chris J.; Bercovitz, John H.; Groom, Donald E.; Holland, Stephen E.; Kadel, Richard W.; Karcher, Armin; Kolbe, William F.; Oluseyi, Hakeem M.; Palaio, Nicholas P.; Prasad, Val; Turko, Bojan T.; Wang, Guobin

    2003-07-08

    An overview of CCD development efforts at Lawrence Berkeley National Laboratory is presented. Operation of fully-depleted, back-illuminated CCD's fabricated on high resistivity silicon is described, along with results on the use of such CCD's at ground-based observatories. Radiation damage and point-spread function measurements are described, as well as discussion of CCD fabrication technologies.

  3. Uneven illumination removal and image enhancement using empirical mode decomposition

    NASA Astrophysics Data System (ADS)

    Pei, Soo-Chang; Hsiao, Yu-Zhe; Tzeng, Mary; Chang, Feng Ju

    2013-10-01

    Uneven light distribution problems often arise in poorly scanned text or text-photo images and natural images taken by digital camera. An innovative image-processing technique for uneven illumination removal using empirical mode decomposition (EMD) is proposed. The EMD is local, adaptive, and useful for analyzing nonlinear and nonstationary signals. In this method, we decompose images by EMD and get the background level locally and adaptively. This algorithm can enhance the local reflectance in the image while removing uneven illumination for black/white text images, text-photo images, and natural color/gray-level images. The proposed technique can be very helpful for image and text recognition. The EMD can also be applied to the three color channels (RGB) of color images separately to estimate the reflectances of the three color channels. After we relight these channels using white light and the estimated reflectances, a simple color constancy task can be performed to correct certain poorly lighted color images. Our technique is compared with recently proposed methods for correcting images with uneven illumination and the experimental results demonstrated that the proposed approach can effectively enhance natural color/gray-level images and make text and text-photo images more readable under uneven illumination.

  4. Energy Savings Forecast of SSL in General Illumination Report Summary

    SciTech Connect

    2016-09-30

    Summary of the DOE report Energy Savings Forecast of Solid-State Lighting in General Illumination Applications, a biannual report that models the adoption of LEDs in the U.S. general-lighting market, along with associated energy savings, based on the full potential DOE has determined to be technically feasible over time.

  5. Illuminating a Dialectical Transformative Activist Stance in Education

    ERIC Educational Resources Information Center

    Ritchie, Stephen M.

    2008-01-01

    In this essay I comment on Stetsenko's (2008) essay that draws together the work of Vygotsky, Piaget and Dewey, as she attempts to counter the "new" reductionist synthesis in public educational policy. While this theoretical work is helpful, it could be enhanced further by illuminating everyday practices of learners. I pose some questions that…

  6. Electrical Power and Illumination Systems. Energy Technology Series.

    ERIC Educational Resources Information Center

    Center for Occupational Research and Development, Inc., Waco, TX.

    This course in electrical power and illumination systems is one of 16 courses in the Energy Technology Series developed for an Energy Conservation-and-Use Technology curriculum. Intended for use in two-year postsecondary technical institutions to prepare technicians for employment, the courses are also useful in industry for updating employees in…

  7. Apparatus and method for generating partially coherent illumination for photolithography

    DOEpatents

    Sweatt, William C.

    2001-01-01

    The present invention introduces a novel scatter plate into the optical path of source light used for illuminating a replicated object. The scatter plate has been designed to interrupt a focused, incoming light beam by introducing between about 8 to 24 diffraction zones blazed onto the surface of the scatter plate which intercept the light and redirect it to a like number of different positions in the condenser entrance pupil each of which is determined by the relative orientation and the spatial frequency of the diffraction grating in each of the several zones. Light falling onto the scatter plate, therefore, generates a plurality of unphased sources of illumination as seen by the back half of the optical system. The system comprises a high brightness source, such as a laser, creating light which is taken up by a beam forming optic which focuses the incoming light into a condenser which in turn, focuses light into a field lens creating Kohler illumination image of the source in a camera entrance pupil. The light passing through the field lens illuminates a mask which interrupts the source light as either a positive or negative image of the object to be replicated. Light passing by the mask is focused into the entrance pupil of the lithographic camera creating an image of the mask onto a receptive media.

  8. 49. STREET LIGHTING & ILLUMINATED SIGNS, NORTH & SOUTH APPROACHES, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    49. STREET LIGHTING & ILLUMINATED SIGNS, NORTH & SOUTH APPROACHES, LAMP BRACKETS, POLES & DETAILS *Sheet 1 of 3 sheets), June 29, 1932 - West End-North Side Bridge, Spanning Ohio River, approximately 1 mile downstream from confluence of Monongahela & Allegheny rivers, Pittsburgh, Allegheny County, PA

  9. Illumination invariant face recognition using near-infrared images.

    PubMed

    Li, Stan Z; Chu, Rufeng; Liao, Shengcai; Zhang, Lun

    2007-04-01

    Most current face recognition systems are designed for indoor, cooperative-user applications. However, even in thus-constrained applications, most existing systems, academic and commercial, are compromised in accuracy by changes in environmental illumination. In this paper, we present a novel solution for illumination invariant face recognition for indoor, cooperative-user applications. First, we present an active near infrared (NIR) imaging system that is able to produce face images of good condition regardless of visible lights in the environment. Second, we show that the resulting face images encode intrinsic information of the face, subject only to a monotonic transform in the gray tone; based on this, we use local binary pattern (LBP) features to compensate for the monotonic transform, thus deriving an illumination invariant face representation. Then, we present methods for face recognition using NIR images; statistical learning algorithms are used to extract most discriminative features from a large pool of invariant LBP features and construct a highly accurate face matching engine. Finally, we present a system that is able to achieve accurate and fast face recognition in practice, in which a method is provided to deal with specular reflections of active NIR lights on eyeglasses, a critical issue in active NIR image-based face recognition. Extensive, comparative results are provided to evaluate the imaging hardware, the face and eye detection algorithms, and the face recognition algorithms and systems, with respect to various factors, including illumination, eyeglasses, time lapse, and ethnic groups.

  10. Lensless phase microscopy using phase retrieval with multiple illumination wavelengths.

    PubMed

    Bao, Peng; Situ, Guohai; Pedrini, Giancarlo; Osten, Wolfgang

    2012-08-01

    A phase retrieval method for microscopy using multiple illumination wavelengths is proposed. A fast algorithm suitable for calculations with high numerical aperture is used for the iterative retrieval of the object wavefront. The advantages and limitations of the technique are systematically analyzed and demonstrated by both simulation and experimental results.

  11. Soft-light overhead illumination systems improve laparoscopic task performance.

    PubMed

    Takai, Akihiro; Takada, Yasutsugu; Motomura, Hideki; Teramukai, Satoshi

    2014-02-01

    The aim of this study was to evaluate the impact of attached shadow cues for laparoscopic task performance. We developed a soft-light overhead illumination system (SOIS) that produced attached shadows on objects. We compared results using the SOIS with those using a conventional illumination system with regard to laparoscopic experience and laparoscope-to-target distances (LTDs). Forty-two medical students and 23 surgeons participated in the study. A peg transfer task (LTD, 120 mm) for students and surgeons, and a suture removal task (LTD, 30 mm) for students were performed. Illumination systems were randomly assigned to each task. Endpoints were: total number of peg transfers; percentage of peg-dropping errors; and total execution time for suture removal. After the task, participants filled out a questionnaire on their preference for a particular illumination system. Total number of peg transfers was greater with the SOIS for both students and surgeons. Percentage of peg-dropping errors for surgeons was lower with the SOIS. Total execution time for suture removal was shorter with the SOIS. Forty-five participants (69% in total) evaluated the SOIS for easier task performance. The present results confirm that the SOIS improves laparoscopic task performance, regardless of previous laparoscopic experience or LTD.

  12. Studies in Natural Illumination in Schoolrooms. Part III

    DTIC Science & Technology

    1929-11-01

    PI"C HEALTH BULLIN No. 188 STUDIESJIN ATURA ILUMINATION IN SCHOOLROOMSA f1-~7~PART III 20 U. 0 49990809 433 UngimED STATES ý-REASURY DE~PART1WENT... ilumination ratio of desk No. 14 for each month and hour of observation ---------------------------------------------- 55 29. Mean illumination ratio of desk

  13. View of OMS burn and illuminated orbiter stabilizer

    NASA Image and Video Library

    1997-05-16

    STS084-357-008 (15-24 May 1997) --- Photographed through the aft flight deck windows of the Earth-orbiting Space Shuttle Atlantis, this 35mm frame captures a firing of the Orbital Maneuvering System (OMS) engines to perform a necessary maneuver. The vertical stabilizer, flanked by the two OMS pods, is illuminated in the scene.

  14. Illumination Profile & Dispersion Variation Effects on Radial Velocity Measurements

    NASA Astrophysics Data System (ADS)

    Grieves, Nolan; Ge, Jian; Thomas, Neil B.; Ma, Bo; Li, Rui; SDSS-III

    2015-01-01

    The Multi-object APO Radial-Velocity Exoplanet Large-Area Survey (MARVELS) measures radial velocities using a fiber-fed dispersed fixed-delay interferometer (DFDI) with a moderate dispersion spectrograph. This setup allows a unique insight into the 2D illumination profile from the fiber on to the dispersion grating. Illumination profile investigations show large changes in the profile over time and fiber location. These profile changes are correlated with dispersion changes and long-term radial velocity offsets, a major problem within the MARVELS radial velocity data. Characterizing illumination profiles creates a method to both detect and correct radial velocity offsets, allowing for better planet detection. Here we report our early results from this study including improvement of radial velocity data points from detected giant planet candidates. We also report an illumination profile experiment conducted at the Kitt Peak National Observatory using the EXPERT instrument, which has a DFDI mode similar to MARVELS. Using profile controlling octagonal-shaped fibers, long term offsets over a 3 month time period were reduced from ~50 m/s to within the photon limit of ~4 m/s.

  15. Illuminating a Dialectical Transformative Activist Stance in Education

    ERIC Educational Resources Information Center

    Ritchie, Stephen M.

    2008-01-01

    In this essay I comment on Stetsenko's (2008) essay that draws together the work of Vygotsky, Piaget and Dewey, as she attempts to counter the "new" reductionist synthesis in public educational policy. While this theoretical work is helpful, it could be enhanced further by illuminating everyday practices of learners. I pose some questions that…

  16. 'Edge illumination' in X-ray Phase Contrast Imaging

    SciTech Connect

    Munro, Peter R. T.; Ignatyev, Konstantin; Diemoz, Paul C.; Szafraniec, Magdalena B.; Hagen, Charlotte K.; Millard, Thomas P.; Zapata, Cesar E.; Speller, Robert D.; Olivo, Alessandro

    2012-07-31

    In the late '90s, the concept of 'edge illumination' was developed at ELETTRA in Italy as an alternative method to increase the phase sensitivity of an imaging system. The main idea was to be able to reproduce the fine angular selection of 'analyzer' crystals without actually using a crystal, as this would allow employing the method with divergent and polychromatic (i.e. conventional) x-ray sources. It was observed that this could be achieved by illuminating only the edges of the detector pixels, and that the method's sensitivity could be progressively increased by illuminating smaller pixel fractions closer to its physical edge. A few years later the idea was adapted for use with a conventional source by means of two sets of x-ray masks ('coded aperture' masks), which enabled obtaining the same effect for each row (or column) of pixels of an area detector illuminated by a cone beam. This article reviews the method and presents recent examples of application.

  17. Novel technique for solar power illumination using plastic optical fibres

    NASA Astrophysics Data System (ADS)

    Munisami, J.; Kalymnios, D.

    2008-09-01

    Plastic Optical Fibres (POF) were developed almost 3 decades ago. They are mainly used for short haul data communications (up to 1 km with data rates up to 1 Gbps). Over the years, POF has found applications in many other areas including solar energy transport for illumination. In such an application, light is collected from the sun and is directed into a space which needs to be illuminated. The use of fibres and more specifically POF, in daylighting systems, started only a few years ago. Several approaches have been investigated and we have seen the development of a few commercial products. The market however, has not really taken off for these technologies simply because of their enormous price tags. It is important to note that the use of POF in these designs has been limited to the function of POF as the transmission medium only. We propose a novel solar illumination technique using POF as both the light collecting/concentrating mechanism and the transmission medium. By modifying the structure of the fibre, solar light can be directed into the fibre by using an analogous process to fibre side emission but, in the reverse. We shall report on the solar light capturing efficiency of POF as modified by several types of external imperfections introduced onto the fibre. One major advantage of our proposed approach lies in the fact that we aim to eliminate at least one of the two axes of sun tracking that is currently used in existing solar illumination systems.

  18. Illumination conditions of the lunar polar regions using LOLA topography

    NASA Astrophysics Data System (ADS)

    Mazarico, E.; Neumann, G. A.; Smith, D. E.; Zuber, M. T.; Torrence, M. H.

    2011-02-01

    We use high-resolution altimetry data obtained by the Lunar Orbiter Laser Altimeter instrument onboard the Lunar Reconnaissance Orbiter to characterize present illumination conditions in the polar regions of the Moon. Compared to previous studies, both the spatial and temporal extent of the simulations are increased significantly, as well as the coverage (fill ratio) of the topographic maps used, thanks to the 28 Hz firing rate of the five-beam instrument. We determine the horizon elevation in a number of directions based on 240 m-resolution polar digital elevation models reaching down to ˜75° latitude. The illumination of both polar regions extending to ˜80° can be calculated for any geometry from those horizon longitudinal profiles. We validated our modeling with recent Lunar Reconnaissance Orbiter Wide-Angle Camera images. We assessed the extent of permanently shadowed regions (PSRs, defined as areas that never receive direct solar illumination), and obtained total areas generally larger than previous studies (12,866 and 16,055 km 2, in the north and south respectively). We extended our direct illumination model to account for singly-scattered light, and found that every PSR does receive some amount of scattered light during the year. We conducted simulations over long periods (several 18.6-years lunar precession cycles) with a high temporal resolution (6 h), and identified the most illuminated locations in the vicinity of both poles. Because of the importance of those sites for exploration and engineering considerations, we characterized their illumination more precisely over the near future. Every year, a location near the Shackleton crater rim in the south polar region is sunlit continuously for 240 days, and its longest continuous period in total darkness is about 1.5 days. For some locations small height gains (˜10 m) can dramatically improve their average illumination and reduce the night duration, rendering some of those particularly attractive

  19. Colour constancy and conscious perception of changes of illuminant.

    PubMed

    Barbur, John L; Spang, Karoline

    2008-02-12

    A sudden change in illuminant (e.g., the outcome of turning on a tungsten light in a room illuminated with dim, natural daylight) causes a "global" change in perceived colour which subjects often recognise as a change of illuminant. In spite of this distinct, global change in the perceptual appearance of the scene caused by significant changes in the wavelength composition of the light reflected from different objects under the new illuminant, the perceived colour of the objects remains largely unchanged and this cornerstone property of human vision is often described as instantaneous colour constancy (ICC). ICC mechanisms are often difficult to study. The generation of appropriate stimuli to isolate ICC mechanisms remains a difficult task since the extraction of colour signals is also confounded in the processing of spatial chromatic context that leads to ICC. The extraction of differences in chromaticity that describe spatial changes in the wavelength composition of the light on the retina is a necessary operation that must precede colour constancy computations. A change of illuminant or changes in the spectral reflectance of the elements that make up the scene under a constant illuminant cause spatial changes in chromatic context and are likely to drive colour constancy mechanisms, but not exclusively. The same stimulus changes also cause differences in local luminance contrast and overall light flux changes, stimulus attributes that can activate different areas of the visual cortex. In order to address this problem we carried out a series of dichoptic experiments designed to investigate how the colour signals from the two eyes are combined in dichoptically viewed Mondrians and the extent to which the processing of chromatic context in monocularly driven neurons contributes to ICC. The psychophysical findings show that normal levels of ICC can be achieved in dichoptic experiments, even when the subject remains unaware of any changes of illuminant. Functional MRI

  20. Effects of optical illumination on superconducting quantum devices

    NASA Astrophysics Data System (ADS)

    Budoyo, Rangga Perdana

    I report measurements of two different types of superconducting devices illuminated by 780 nm light, one of the wavelengths needed in a proposed atom-superconductor hybrid quantum system. I illuminated a thin-film Al lumped-element resonator and observed the resonator quality factor and resonance frequency as a function of illumination intensity, microwave power, and temperature. The resonator was mounted in a 3d aluminum cavity. The variation in optically-induced loss due to microwave power was similar to the behavior expected for loss from a distribution of two-level systems. Although this behavior may suggest the presence of optically activated two-level systems, I found that the loss is better explained by the presence of nonequilibrium quasiparticles generated by the illumination and excited by the microwave drive. I described a model of the system where optical absorption creates an effective source of phonons and solved the coupled quasiparticle-phonon rate equations. I found good agreement between the simulation and the measured resonator quality factor and frequency shift as a function of temperature, microwave power, and optical illumination. I fabricated a transmon qubit and studied the qubit transition frequency and relaxation time as a function of illumination intensity and temperature. The qubit was mounted in a 3d aluminum cavity and coupled to the cavity forming a Jaynes-Cummings system. Qubit relaxation showed non-exponential behavior that I fit to a quasiparticle fluctuation model with two characteristic times. The transition frequency and both characteristic times decreased with increasing illumination intensity. For comparison, I described a nonequilibrium quasiparticle model for the expected frequency shift and relaxation time due to quasiparticle tunneling through the Josephson junction. While the quasiparticle simulation predicted the general qualitative behavior of the frequency shift and relaxation time, there were some significant

  1. Transillumination spatially modulated illumination microscopy for human chromosome imaging

    NASA Astrophysics Data System (ADS)

    Pitris, Costas; Heracleous, Peter; Patsalis, Philippos

    2005-03-01

    Human chromosome analysis is an essential task in cytogenetics, especially in prenatal screening, genetic syndrome diagnosis, cancer pathology research and mutagen dosimetry. Chromosomal analysis begins with the creation of a karyotype, which is a layout of chromosome images organized by decreasing size in pairs. Both manual and automatic classification of chromosomes are limited by the resolution of the microscope and imaging system used. One way to improve the results of classification and even detect subtleties now remaining undetected, is to enhance the resolution of the images. It is possible to achieve lateral resolution beyond the classical limit, by using spatially modulated illumination (SMI) in a wide-field, non-confocal microscope. In this case, the sample is illuminated with spatially modulated light, which makes normally inaccessible high-resolution information visible in the observed image by shifting higher frequencies within the OTF limits of the microscope. Although, SMI microscopes have been reported in the past, this manuscript reports the development of a transillumination microscope for opaque, non-fluorescent samples. The illumination path consisted of a light source illuminating a ruled grating which was subsequently imaged on the sample. The grating was mounted on a rotating and translating stage so that the magnification and rotation of the pattern could be adjusted. The imaging lens was a 1.25 NA oil immersion objective. Test samples showed resolution improvement, as judged from a comparison of the experimentally obtained FWHM. Further studies using smaller fringe distance or laser interference pattern illumination will be evaluated to further optimize the SMI results.

  2. Formation of Singlet Molecular Oxygen on Illuminated Ice and Snow

    NASA Astrophysics Data System (ADS)

    McKellar, S. R.; Anastasio, C.

    2005-12-01

    Pollutants and other trace compounds on snow and ice are transformed both by direct photolysis as well as indirect photoreactions mediated by oxidants such as hydroxyl radical (OH). These reactions likely play a major role in the fate of environmental contaminants in regions with permanent or seasonal snow cover, but we know relatively little about which reactions are important and at what rates they transform trace pollutants. The indirect photodegradation of organics is most likely caused by oxidants such as OH and singlet molecular oxygen (1O2* ), which can be formed in the snowpack by illumination from the sun. While some recent work has characterized the formation of OH in snow, the presence of 1O2* on illuminated snow or ice has not been studied previously. In this study, our goal is to determine the steady state concentrations of singlet molecular oxygen in illuminated snow samples collected from Summit, Greenland during the summer of 2005. We add furfuryl alcohol (FFA), which acts as a chemical probe of singlet molecular oxygen, to ice pellets made from Greenland snow samples and monitor the rate of loss of FFA during illumination. Our initial results indicate that 1O2* is formed in illuminated Summit samples and that the steady-state concentration of 1O2* is much larger on ice (-10 °C) than in liquid solution (°C) using the same prepared sample. We will present our measured steady-state concentrations of 1O2* as well as the impacts of this oxidant on the lifetimes of trace organics such as PAHs and biogenic phenols in Greenland snow.

  3. Apparatus and method for generating partially coherent illumination for photolithography

    DOEpatents

    Sweatt, W.C.

    1999-07-06

    The present invention relates an apparatus and method for creating a bright, uniform source of partially coherent radiation for illuminating a pattern, in order to replicate an image of said pattern with a high degree of acuity. The present invention introduces a novel scatter plate into the optical path of source light used for illuminating a replicated object. The scatter plate has been designed to interrupt a focused, incoming light beam by introducing between about 8 to 24 diffraction zones blazed onto the surface of the scatter plate which intercept the light and redirect it to a like number of different positions in the condenser entrance pupil each of which is determined by the relative orientation and the spatial frequency of the diffraction grating in each of the several zones. Light falling onto the scatter plate, therefore, generates a plurality of unphased sources of illumination as seen by the back half of the optical system. The system includes a high brightness source, such as a laser, creating light which is taken up by a beam forming optic which focuses the incoming light into a condenser which in turn, focuses light into a field lens creating Kohler illumination image of the source in a camera entrance pupil. The light passing through the field lens illuminates a mask which interrupts the source light as either a positive or negative image of the object to be replicated. Light passing by the mask is focused into the entrance pupil of the lithographic camera creating an image of the mask onto a receptive media. 7 figs.

  4. Apparatus and method for generating partially coherent illumination for photolithography

    DOEpatents

    Sweatt, William C.

    1999-01-01

    The present invention relates an apparatus and method for creating a bright, uniform source of partially coherent radiation for illuminating a pattern, in order to replicate an image of said pattern with a high degree of acuity. The present invention introduces a novel scatter plate into the optical path of source light used for illuminating a replicated object. The scatter plate has been designed to interrupt a focused, incoming light beam by introducing between about 8 to 24 diffraction zones blazed onto the surface of the scatter plate which intercept the light and redirect it to a like number of different positions in the condenser entrance pupil each of which is determined by the relative orientation and the spatial frequency of the diffraction grating in each of the several zones. Light falling onto the scatter plate, therefore, generates a plurality of unphased sources of illumination as seen by the back half of the optical system. The system includes a high brightness source, such as a laser, creating light which is taken up by a beam forming optic which focuses the incoming light into a condenser which in turn, focuses light into a field lens creating Kohler illumination image of the source in a camera entrance pupil. The light passing through the field lens illuminates a mask which interrupts the source light as either a positive or negative image of the object to be replicated. Light passing by the mask is focused into the entrance pupil of the lithographic camera creating an image of the mask onto a receptive media.

  5. An overview of LED applications for general illumination

    NASA Astrophysics Data System (ADS)

    Pelka, David G.; Patel, Kavita

    2003-11-01

    This paper begins by reviewing the current state of development of LEDs, their existing markets as well as their potential for energy conservation and their potential for gaining market share in the general illumination market. It discusses LED metrics such as chip size, lumens per watt, thermal resistance, and the recommended maximum current rating. The paper then goes on to consider the importance of non-imaging optics for both optically efficient and extremely compact LED lighting systems. Finally, microstructures useful for controlling the fields-of-view of LED lighting systems are considered and described in some detail. An extremely efficient and cost effective microstructure, called kinoform diffusers, is shown to have very unique properties that make this technology almost ideal for shaping the output beams of LED lighting systems. It concludes by illustrating some general illumination LED lighting systems

  6. Virtual fringe projection system with nonparallel illumination based on iteration

    NASA Astrophysics Data System (ADS)

    Zhou, Duo; Wang, Zhangying; Gao, Nan; Zhang, Zonghua; Jiang, Xiangqian

    2017-06-01

    Fringe projection profilometry has been widely applied in many fields. To set up an ideal measuring system, a virtual fringe projection technique has been studied to assist in the design of hardware configurations. However, existing virtual fringe projection systems use parallel illumination and have a fixed optical framework. This paper presents a virtual fringe projection system with nonparallel illumination. Using an iterative method to calculate intersection points between rays and reference planes or object surfaces, the proposed system can simulate projected fringe patterns and captured images. A new explicit calibration method has been presented to validate the precision of the system. Simulated results indicate that the proposed iterative method outperforms previous systems. Our virtual system can be applied to error analysis, algorithm optimization, and help operators to find ideal system parameter settings for actual measurements.

  7. Bright afterglow illuminator made of phosphorescent material and fluorescent fibers.

    PubMed

    Saito, M; Yamamoto, K

    2000-08-20

    Phosphorescent oxides and fluorescent dyes were used together to create a fiber-type illuminator that glows in the dark without the need for electric power. Dye-doped polymer fibers, which were bundled at one end, were linearly arrayed in a polysiloxane resin that contained phosphorescent oxide particles. The phosphorescent resin continued to glow for a long time even after the excitation light was removed. Organic dyes in a polymer fiber were excited by the phosphorescence and emitted fluorescence toward the fiber end. Fluorescence from a number of dyes was combined in the long fiber, and, consequently a bright light beam emerged from the fiber end. Useful performance, i.e., high power density, narrow beam divergence, and long afterglow, is demonstrated by the prototype fiber illuminator.

  8. Countermeasure against tailored bright illumination attack for DPS-QKD.

    PubMed

    Honjo, Toshimori; Fujiwara, Mikio; Shimizu, Kaoru; Tamaki, Kiyoshi; Miki, Shigehito; Yamashita, Taro; Terai, Hirotaka; Wang, Zhen; Sasaki, Masahide

    2013-02-11

    We propose a countermeasure against the so-called tailored bright illumination attack for differential-phase-shift QKD (DPS-QKD). By monitoring a rate of coincidence detection at a pair of superconducting nanowire single-photon detectors (SSPDs) which is connected at each of the output ports of Bob's Mach-Zehnder interferometer, Alice and Bob can detect and defeat this kind of attack. We also experimentally confirmed the feasibility of this countermeasure using our 1 GHz-clocked DPS-QKD system. In the emulation of the attack, we achieved much lower power of the bright illumination light compared with the original demonstration by using a pulse stream instead of broad pulses.

  9. Optical Fiber Illumination System for visual flight simulation

    NASA Technical Reports Server (NTRS)

    Hollow, R. H.

    1981-01-01

    An electronically controlled lighting system simulating runway, aircraft carrier, and landing aid lights for flight simulations is described. The various colored lights that would be visible to a pilot by day, at dusk, or at night are duplicated at the distances the lights would normally become visible. Plastic optical fiber illuminators using tungsten halogen lights are distributed behind the model. The tips of the fibers of illuminators simulating runway lights are bevelled in order that they may be seen from long distances and at low angles. Fibers representing taxiway lights are pointed and polished for omni-directional visibility. The electronic intensity controls, which can be operated either manually or remotely, regulate the intensity of the lights to simulate changes in distance. A dichronic mirror, infrared filter system is used to maintain color integrity.

  10. Array illumination of a Fresnel-Dammann zone plate.

    PubMed

    Ma, Yayao; Ye, Chaochao; Ke, Jie; Zhang, Junyong; Zhu, Jianqiang; Ling, Zunqing

    2016-09-10

    The traditional Dammann grating is a phase-only modulation, and its theoretical foundation is based on far-field diffraction. Here we extend the traditional Fresnel zone plate (FZP) into a Fresnel-Dammann zone plate (FDZP), which is, in essence, considered as a FZP with Dammann modulation. Different from the Dammann grating, a single FDZP can generate array illumination from the near field to the far field by means of amplitude-only modulation in the absence of phase modulation. We then give some array illuminations operated in a water window to validate the feasibility and validity. This kind of wave-front modulation technology can be applied to array focusing and imaging from the x-ray to the EUV region.

  11. TIR optics for non-rotationally symmetric illumination design

    NASA Astrophysics Data System (ADS)

    Domhardt, André; Weingaertner, Simon; Rohlfing, Udo; Lemmer, Uli

    2008-09-01

    High-Power-LEDs have reached a development stage that affords their reasonable application to general illumination. Nonimaging total internal reflection optics (TIR optics) that generate non-rotationally symmetric light distributions are proper components to preserve the advantages associated with this type of light source. Thus, high efficiency has to be reconciled, e.g., with the use of freeform surfaces. This contribution investigates the development of TIR optics for LED-based illumination applications. First, we consider rotationally symmetric TIR optics in order to illustrate their functional principle and demonstrate some special design criteria. Second, we apply them to non-rotationally cases using the tailoring technique. Finally, we illustrate various aspects of the design process with selected examples.

  12. Tip Enhanced Raman Spectroscopy and Imaging: an Apical Illumination Geometry

    PubMed Central

    Schultz, Zachary D.; Stranick, Stephan J.; Levin, Ira W.

    2009-01-01

    Results are presented illustrating the use of tip enhanced Raman spectroscopy and imaging in a top-illumination geometry. A radially polarized beam is used to generate an electric field component in the direction of beam propagation, normal to the surface, resulting in a 5× increased enhancement compared to a linearly polarized beam. This multiplicative enhancement facilitates a discrimination of the near field signal from the far field Raman background. The top illumination configuration facilitates the application of TERS for investigating molecules on a variety of surfaces, such as Au, glass, and Si. The near field Raman spectrum is presented of Si(100), rhodamine B, brilliant cresyl blue, and single wall carbon nanotubes. Sufficient enhancement is obtained to permit a sub-diffraction limited resolution Raman imaging of the surface distribution of large bundles of carbon nanotubes of various diameters. PMID:19007457

  13. Parallel phase-shifting dual-illumination phase unwrapping

    NASA Astrophysics Data System (ADS)

    Tahara, Tatsuki; Maeda, Akifumi; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2012-11-01

    We propose a single-shot phase unwrapping technique using a single wavelength and parallel phase-shifting interferometry. In the proposed technique, an object is illuminated by two laser beams, which are emitted from the same laser, and have different illumination angles and polarizations. Two types of object waves generated by the two beams are separately and simultaneously recorded by a polarization-imaging camera. In the path of the reference wave, an array of phase retarders is placed to implement the parallel phase-shifting technique. A highly accurate three-dimensional shape is reconstructed from a single hologram. We numerically simulated the proposed technique and conducted a preliminary experiment to verify its effectiveness. It was confirmed that millimeter-order height, which was several thousand times the wavelength of the laser, can be reconstructed by the proposed technique without wrapping.

  14. Combining near-infrared illuminants to optimize venous imaging

    SciTech Connect

    Paquit, Vincent C; Price, Jeffery R; Meriaudeau, Fabrice; Tobin Jr, Kenneth William; Ferrell, Thomas L

    2007-01-01

    The first and perhaps most important phase of a surgical procedure is the insertion of an intravenous (IV) catheter. Currently, this is performed manually by trained personnel. In some visions of future operating rooms, however, this process is to be replaced by an automated system. We previously presented work for localizing near-surface veins via near-infrared (NIR) imaging in combination with structured light ranging for surface mapping and robotic guidance. In this paper, we describe experiments to determine the best NIR wavelengths to optimize vein contrast for physiological differences such as skin tone and/or the presence of hair on the arm or wrist surface. For illumination, we employ an array of NIR LEDs comprising six different wavelength centers from 740nm to 910nm. We capture imagery of each subject under every possible combination of illuminants and determine the optimal combination of wavelengths for a given subject to maximize vein contrast using linear discriminant analysis.

  15. 3D endoscopic imaging using structured illumination technique (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Le, Hanh N. D.; Nguyen, Hieu; Wang, Zhaoyang; Kang, Jin U.

    2017-02-01

    Surgeons have been increasingly relying on minimally invasive surgical guidance techniques not only to reduce surgical trauma but also to achieve accurate and objective surgical risk evaluations. A typical minimally invasive surgical guidance system provides visual assistance in two-dimensional anatomy and pathology of internal organ within a limited field of view. In this work, we propose and implement a structure illumination endoscope to provide a simple, inexpensive 3D endoscopic imaging to conduct high resolution 3D imagery for use in surgical guidance system. The system is calibrated and validated for quantitative depth measurement in both calibrated target and human subject. The system exhibits a depth of field of 20 mm, depth resolution of 0.2mm and a relative accuracy of 0.1%. The demonstrated setup affirms the feasibility of using the structured illumination endoscope for depth quantization and assisting medical diagnostic assessments

  16. Fault Tolerant Algorithm for Structured Illumination Microscopy with Incoherent Light

    NASA Astrophysics Data System (ADS)

    Wang, Kun; Heidingsfelder, Philipp; Gao, Jun; Yu, Liandong; Ott, Peter

    2015-04-01

    In this contribution we present a new algorithm for structured illumination microscopy with incoherent light. Existing algorithms for determining the contrast values of the focal depth response require a high accurate phase shift of the fringe pattern illumination. The presented algorithm, which is robust against inaccurate phase shift of the fringe pattern, reduces significantly the requirements for the phase shift and consequently the costs of the microscope. The new algorithm was tested by a preliminary experiment, whereby the grating was shifted by an elastic guided micro-motion mechanism employing a low-cost stepper motor replacing the conventional expensive piezo drive. The determined focal depth response is very smooth and corresponds very well to the theoretical focal depth response.

  17. Face verification and rejection with illumination variations using MINACE filters

    NASA Astrophysics Data System (ADS)

    Patnaik, Rohit; Casasent, David P.

    2004-04-01

    A face verification system based on the use of a minimum noise and average correlation energy (MINACE) filter for each person is presented that functions with illumination variations present. A separate filter is used for each person; it is a combination of different training images of only that person. The system is tested using both unregistered and registered images from the CMU Pose, Illumination and Expression (PIE) database. The number of correct (PC) and the number of false alarm (PFA) scores are compared for the two cases. Rather than using the same parameters for the filter of each person, an automated iterative filter training and synthesis method is used. A validation set of several other faces is used to achieve parameter selection for good rejection performance. For filter-evaluation, all filters are tested against all images, but the same peak threshold is used for each filter to determine verification and rejection.

  18. Quantitative sectioning and noise analysis for structured illumination microscopy

    PubMed Central

    Hagen, Nathan; Gao, Liang; Tkaczyk, Tomasz S.

    2011-01-01

    Structured illumination (SI) has long been regarded as a nonquantitative technique for obtaining sectioned microscopic images. Its lack of quantitative results has restricted the use of SI sectioning to qualitative imaging experiments, and has also limited researchers’ ability to compare SI against competing sectioning methods such as confocal microscopy. We show how to modify the standard SI sectioning algorithm to make the technique quantitative, and provide formulas for calculating the noise in the sectioned images. The results indicate that, for an illumination source providing the same spatially-integrated photon flux at the object plane, and for the same effective slice thicknesses, SI sectioning can provide higher SNR images than confocal microscopy for an equivalent setup when the modulation contrast exceeds about 0.09. PMID:22274364

  19. 3D fluorescence anisotropy imaging using selective plane illumination microscopy

    PubMed Central

    Hedde, Per Niklas; Ranjit, Suman; Gratton, Enrico

    2015-01-01

    Fluorescence anisotropy imaging is a popular method to visualize changes in organization and conformation of biomolecules within cells and tissues. In such an experiment, depolarization effects resulting from differences in orientation, proximity and rotational mobility of fluorescently labeled molecules are probed with high spatial resolution. Fluorescence anisotropy is typically imaged using laser scanning and epifluorescence-based approaches. Unfortunately, those techniques are limited in either axial resolution, image acquisition speed, or by photobleaching. In the last decade, however, selective plane illumination microscopy has emerged as the preferred choice for three-dimensional time lapse imaging combining axial sectioning capability with fast, camera-based image acquisition, and minimal light exposure. We demonstrate how selective plane illumination microscopy can be utilized for three-dimensional fluorescence anisotropy imaging of live cells. We further examined the formation of focal adhesions by three-dimensional time lapse anisotropy imaging of CHO-K1 cells expressing an EGFP-paxillin fusion protein. PMID:26368202

  20. High-speed compressive range imaging based on active illumination.

    PubMed

    Sun, Yangyang; Yuan, Xin; Pang, Shuo

    2016-10-03

    We report a compressive imaging method based on active illumination, which reconstructs a 3D scene at a frame rate beyond the acquisition speed limit of the camera. We have built an imaging prototype that projects temporally varying illumination pattern and demonstrated a joint reconstruction algorithm that iteratively retrieves both the range and high-temporal-frequency information from the 2D low-frame rate measurement. The reflectance and depth-map videos have been reconstructed at 1000 frames per second (fps) from the measurement captured at 200 fps. The range resolution is in agreement with the resolution calculated from the triangulation methods based on the same system geometry. We expect such an imaging method could become a simple solution to a wide range of applications, including industrial metrology, 3D printing, and vehicle navigations.

  1. Excimer laser processing of backside-illuminated CCDS

    NASA Technical Reports Server (NTRS)

    Russell, S. D.

    1993-01-01

    An excimer laser is used to activate previously implanted dopants on the backside of a backside-illuminated CCD. The controlled ion implantation of the backside and subsequent thin layer heating and recrystallization by the short wavelength pulsed excimer laser simultaneously activates the dopant and anneals out implant damage. This improves the dark current response, repairs defective pixels and improves spectral response. This process heats a very thin layer of the material to high temperatures on a nanosecond time scale while the bulk of the delicate CCD substrate remains at low temperature. Excimer laser processing backside-illuminated CCD's enables salvage and utilization of otherwise nonfunctional components by bringing their dark current response to within an acceptable range. This process is particularly useful for solid state imaging detectors used in commercial, scientific and government applications requiring a wide spectral response and low light level detection.

  2. Combining near-infrared illuminants to optimize venous imaging

    NASA Astrophysics Data System (ADS)

    Paquit, Vincent; Price, Jeffery R.; Mériaudeau, Fabrice; Tobin, Kenneth W., Jr.; Ferrell, Thomas L.

    2007-03-01

    The first and perhaps most important phase of a surgical procedure is the insertion of an intravenous (IV) catheter. Currently, this is performed manually by trained personnel. In some visions of future operating rooms, however, this process is to be replaced by an automated system. We previously presented work for localizing near-surface veins via near-infrared (NIR) imaging in combination with structured light ranging for surface mapping and robotic guidance. In this paper, we describe experiments to determine the best NIR wavelengths to optimize vein contrast for physiological differences such as skin tone and/or the presence of hair on the arm or wrist surface. For illumination, we employ an array of NIR LEDs comprising six different wavelength centers from 740nm to 910nm. We capture imagery of each subject under every possible combination of illuminants and determine the optimal combination of wavelengths for a given subject to maximize vein contrast using linear discriminant analysis.

  3. Sensitivity of an illumination system to lamp flicker

    NASA Astrophysics Data System (ADS)

    Rehn, H.

    2008-09-01

    Discharge lamps serve a wide variety of applications and outperform novel light sources such as LEDs in terms of luminous flux and luminance. Unfortunately, such lamps occasionally show arc movements (flicker) which change the amount of light that is coupled into an optical system. A variety of measures in lamp design can suppress flicker tendencies of a lamp but arc movement cannot be totally avoided. In our contribution, we show that the way how the light is collected considerably influences the impact of flicker on the collected luminous flux. We investigate light collection sensitivity of an illumination system as a function of the etendue and of the particular realization of the illumination system. As a result, flicker sensitivity can be substantially reduced at the expense of collection efficiency.

  4. Optical photon reassignment with increased axial resolution by structured illumination

    NASA Astrophysics Data System (ADS)

    Roth, Stephan; Heintzmann, Rainer

    2016-12-01

    Fluorescent microscopy methods linked to the reassignment principle as image scanning microscopy (ISM), re-scan confocal (RSC), optical photon reassignment (OPRA) and instant structured illumination microscopy (iSIM) have the potential to replace confocal microscopy as the standard microscopy technique. Photon reassignment methods are known to link the most important properties in biological imaging as resolution, sensitivity, imaging speed and combinability with fluorophores in an elegant way. On the example of OPRA, we show how this method could be easily extended to the third dimension. If OPRA is used in combination with a structured illumination pattern the sectioning ability can be improved while maintaining the very high signal intensity. We present a detailed analysis about the imaging properties of OPRA in three dimensions and show experimental results on biological samples.

  5. Charged domain walls under super-band-gap illumination

    NASA Astrophysics Data System (ADS)

    Sturman, B.; Podivilov, E.

    2017-03-01

    Charged domain walls (CDWs), which possess metallic-type conductivity and can be created and controlled in the bulk of wide-band-gap ferroelectrics, attract nowadays a strong research interest. The most advanced method for production of stable CDWs involves weak super-band-gap illumination. Here, we investigate theoretically the impact of this illumination on the major wall properties including the energy and the spatial profiles of the polarization, of the electrostatic potential, and of the compensating charge carriers. The key material parameters determining the effect of light are the zero-field polarization strength, the dielectric permittivity, and the trap concentration. The main predictions are substantial reduction of the wall energies and decrease of the electric wall potential under light. These features facilitate creation of dense CDWs patterns and accessibility of the metallic-type wall conductivity.

  6. Broadband seismic illumination and resolution analyses based on staining algorithm

    NASA Astrophysics Data System (ADS)

    Chen, Bo; Jia, Xiao-Feng; Xie, Xiao-Bi

    2016-09-01

    Seismic migration moves reflections to their true subsurface positions and yields seismic images of subsurface areas. However, due to limited acquisition aperture, complex overburden structure and target dipping angle, the migration often generates a distorted image of the actual subsurface structure. Seismic illumination and resolution analyses provide a quantitative description of how the above-mentioned factors distort the image. The point spread function (PSF) gives the resolution of the depth image and carries full information about the factors affecting the quality of the image. The staining algorithm establishes a correspondence between a certain structure and its relevant wavefield and reflected data. In this paper, we use the staining algorithm to calculate the PSFs, then use these PSFs for extracting the acquisition dip response and correcting the original depth image by deconvolution. We present relevant results of the SEG salt model. The staining algorithm provides an efficient tool for calculating the PSF and for conducting broadband seismic illumination and resolution analyses.

  7. The importance of pulsing illumination parameters in LLLT

    NASA Astrophysics Data System (ADS)

    Barolet, D.

    2010-02-01

    The influence of emission parameters in Low Level Light Therapy (LLLT) on cellular responses is not yet fully understood. This study assessed the impact of various light delivery modes on collagen production in human primary fibroblast cultured in monolayers after three treatments with red light emitting diode illumination (630 nm, 8 J/cm2). Human type I collagen was measured in cell culture supernatants with procollagen Type I C-Peptide enzyme immunoassay. Results from this study demonstrated that specific μsec pulsing patterns had a more favorable impact on the ability of fibroblasts to produce collagen de novo than comparator conditions of continuous wave, pulsed 50% duty cycle, and millisecond pulsing domain (72 hours post baseline). The cascade of events leading to collagen production by red illumination may be explained by the photodissociation of nitric oxide from cytochrome c oxidase. Short and intermittent light delivery might enhance this cellular strategy.

  8. Selective plane illumination microscopy techniques in developmental biology

    PubMed Central

    Huisken, Jan; Stainier, Didier Y. R.

    2009-01-01

    Summary Selective plane illumination microscopy (SPIM) and other fluorescence microscopy techniques in which a focused sheet of light serves to illuminate the sample have become increasingly popular in developmental studies. Fluorescence light-sheet microscopy bridges the gap in image quality between fluorescence stereomicroscopy and high-resolution imaging of fixed tissue sections. In addition, high depth penetration, low bleaching and high acquisition speeds make light-sheet microscopy ideally suited for extended time-lapse experiments in live embryos. This review compares the benefits and challenges of light-sheet microscopy with established fluorescence microscopy techniques such as confocal microscopy and discusses the different implementations and applications of this easily adaptable technology. PMID:19465594

  9. Interferometric homogeneity test using adaptive frequency comb illumination.

    PubMed

    Mantel, Klaus; Schwider, Johannes

    2013-03-20

    The homogeneity test of glass plates in a Fizeau interferometer requires the measurement of the glass sample in reflected as well as in transmitted light. For the measurement in transmitted light, the sample has to be inserted into the ray path of a Fizeau or Twyman-Green interferometer, which leads to a nested cavity setup. To separate the interference signals from the different cavities, we illuminate a Fizeau interferometer with an adaptive frequency comb. In this way, rigid glass plates can be measured, and linear variations in the homogeneity can also be detected. The adaptive frequency comb is provided by a variable Fabry-Perot filter under broadband illumination from a superluminescence diode. Compared to approaches using a two-beam interferometer as a filter for the broadband light source, the visibility of the fringe system is considerably higher.

  10. Temporal focusing microscopy combined with three-dimensional structured illumination

    NASA Astrophysics Data System (ADS)

    Isobe, Keisuke; Toda, Keisuke; Song, Qiyuan; Kannari, Fumihiko; Kawano, Hiroyuki; Miyawaki, Atsushi; Midorikawa, Katsumi

    2017-05-01

    Temporal focusing microscopy provides the optical sectioning capability in wide-field two-photon fluorescence imaging. Here, we demonstrate temporal focusing microscopy combined with three-dimensional structured illumination, which enables us to enhance the three-dimensional spatial resolution and reject the background fluorescence. Experimentally, the periodic pattern of the illumination was produced not only in the lateral direction but also in the axial direction by the interference between three temporal focusing pulses, which were easily generated using a digital micromirror device. The lateral resolution and optical sectioning capability were successfully enhanced by factors of 1.6 and 3.6, respectively, compared with those of temporal focusing microscopy. In the two-photon fluorescence imaging of a tissue-like phantom, the out-of-focus background fluorescence and the scattered background fluorescence could also be rejected.

  11. Illumination system having a plurality of movable sources

    DOEpatents

    Sweatt, William C.; Kubiak, Glenn D.

    2002-01-01

    An illumination system includes several discharge sources that are multiplexed together to reduce the amount of debris generated. The system includes: (a) a first electromagnetic radiation source array that includes a plurality of first activatable radiation source elements that are positioned on a first movable carriage; (b) a second electromagnetic radiation source array that includes a plurality of second activatable radiation source elements that are positioned on a second movable carriage; (c) means for directing electromagnetic radiation from the first electromagnetic radiation source array and electromagnetic radiation from the second electromagnetic radiation source array toward a common optical path; (d) means for synchronizing (i) the movements of the first movable carriage and of the second movable carriage and (ii) the activation of the first electromagnetic radiation source array and of the second electromagnetic radiation source array to provide an essentially continuous illumination of electromagnetic radiation along the common optical path.

  12. Quasi-Bessel beams from asymmetric and astigmatic illumination sources.

    PubMed

    Müller, Angelina; Wapler, Matthias C; Schwarz, Ulrich T; Reisacher, Markus; Holc, Katarzyna; Ambacher, Oliver; Wallrabe, Ulrike

    2016-07-25

    We study the spatial intensity distribution and the self-reconstruction of quasi-Bessel beams produced from refractive axicon lenses with edge emitting laser diodes as asymmetric and astigmatic illumination sources. Comparing these to a symmetric mono-mode fiber source, we find that the asymmetry results in a transition of a quasi-Bessel beam into a bow-tie shaped pattern and eventually to a line shaped profile at a larger distance along the optical axis. Furthermore, we analytically estimate and discuss the effects of astigmatism, substrate modes and non-perfect axicons. We find a good agreement between experiment, simulation and analytic considerations. Results include the derivation of a maximal axicon angle related to astigmatism of the illuminating beam, impact of laser diode beam profile imperfections like substrate modes and a longitudinal oscillation of the core intensity and radius caused by a rounded axicon tip.

  13. Illumination of dense urban areas by light redirecting panels.

    PubMed

    El-Henawy, Sally I; Mohamed, Mohamed W N; Mashaly, Islam A; Mohamed, Osama N; Galal, Ola; Taha, Iman; Nassar, Khaled; Safwat, Amr M E

    2014-05-05

    With the high population growth rate, especially in developing countries, and the scarcity of land resources, buildings are becoming so close to each other, depriving the lower floors and the alleys from sunlight and consequently causing health problems. Therefore, there is an urgent need for cost-effective efficient light redirecting panels that guide sun rays into those dim places. In this paper, we address this problem. A novel sine wave based panel is presented to redirect/diverge light downward and enhance the illumination level in those dark places. Simulation results show that the proposed panel improves the illuminance values by more than 200% and 400% in autumn and winter respectively, operates over wide solar altitude ranges, and redirects light efficiently. Experimental and simulation results are in good agreement.

  14. Response of silicon solar cell to pulsed laser illumination

    NASA Technical Reports Server (NTRS)

    Willowby, D.; Alexander, D.; Edge, T.; Herren, K.

    1993-01-01

    The response of silicon solar cell(s) to pulsed laser illumination is discussed. The motivation was due to the interest of Earth to space/Moon power beaming applications. When this work began, it was not known if solar cells would respond to laser light with pulse lengths in the nanosecond range and a repetition frequency in the kHz range. This is because the laser pulse would be shorter than the minority carrier lifetime of silicon. A 20-nanosecond (ns) full width half max (FWHM) pulse from an aluminum-gallium/arsenide (Al-Ga-As) diode laser was used to illuminate silicon solar cells at a wavelength of 885 nanometers (nm). Using a high-speed digital oscilloscope, the response of the solar cells to individual pulses across various resistive loads was observed and recorded.

  15. Is White Light the Best Illumination for Palmprint Recognition?

    NASA Astrophysics Data System (ADS)

    Guo, Zhenhua; Zhang, David; Zhang, Lei

    Palmprint as a new biometric has received great research attention in the past decades. It owns many merits, such as robustness, low cost, user friendliness, and high accuracy. Most of the current palmprint recognition systems use an active light to acquire clear palmprint images. Thus, light source is a key component in the system to capture enough of discriminant information for palmprint recognition. To the best of our knowledge, white light is the most widely used light source. However, little work has been done on investigating whether white light is the best illumination for palmprint recognition. In this study, we empirically compared palmprint recognition accuracy using white light and other six different color lights. The experiments on a large database show that white light is not the optimal illumination for palmprint recognition. This finding will be useful to future palmprint recognition system design.

  16. Structured illumination microscopy for vibrational molecular imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Watanabe, Kozue; Palonpon, Almar F.; Smith, Nicholas I.; Chiu, Liang-da; Kasai, Atsushi; Hashimoto, Hitoshi; Kawata, Satoshi; Fujita, Katsumasa

    2016-09-01

    Raman microscopy is a powerful tool for analytical imaging. The wavelength shift of Raman scattering corresponds to molecular vibrational energy. Therefore, we can access rich chemical information, such as distribution, concentration, and chemical environment of sample molecules. Despite these strengths of Raman microscopy, the spatial resolution has been a limiting factor for many practical applications. In this study, we developed a large-area, high-resolution Raman microscope by utilizing structured illumination microscopy (SIM) to overcome the spatial resolution limit. A structured line-illumination (SLI) Raman microscope was constructed. The structured illumination is introduced along the line direction by the interference of two line-shaped beams. In SIM, the spatial frequency mixing between structured illumination and Raman scattering from the sample allows access to the high spatial frequency information beyond the conventional cut-off. As a result, the FWHM of 40-nm fluorescence particle images showed a clear resolution enhancement in the line direction: 366 nm in LI and 199 nm in SLI microscope. Using the developed microscope, we successfully demonstrated high-resolution Raman imaging of various kinds of specimens, such as few-layer graphene, graphite, mouse brain tissue, and polymer nanoparticles. The high resolution Raman images showed the capability to extract original spectral features from the mixed Raman spectra of a multi-component sample because of the enhanced spatial resolution, which is advantageous in observing complex spectral features. The Raman microscopy technique reported here enables us to see the detailed chemical structures of chemical, biological, and medical samples with a spatial resolution smaller than 200 nm.

  17. Understanding and Recreating Visual Appearance Under Natural Illumination

    DTIC Science & Technology

    2011-01-01

    a time-lapse Eiffel Tower clip art object which, when inserted into a new scene, will automatically become correctly lit. 63 4.2 Overview Illuminant...skyscrapers from Tokyo are placed into an image sequence in Berkeley, CA (Fig. 4.5a); 2) the Eiffel Tower in Paris is composited into the Berlin skyline (Fig...building) (b) Object transfer ( Eiffel tower) (c) Sky transfer Figure 4.5: Appearance transfer between webcams. The first column shows example frames

  18. Multimode tapered optical light pipe for illumination systems

    NASA Astrophysics Data System (ADS)

    Romańczuk, Patryk; Pietrzycki, Marcin; Źmojda, Jacek; Kochanowicz, Marcin; Dorosz, Dominik

    2015-09-01

    In the article the multimode tapered optical light pipe for illumination systems was investigated. Based on tree light emitting diodes at the wavelength of 460 nm (blue), 528 nm (green) and 631 nm (red) possibility of white light emission on the output surface of the tapered light pipe was submitted. Influence of optical power of LEDs on the colour coordinates (CIE-1931) has been investigated.

  19. Even Illumination from Fiber-Optic-Coupled Laser Diodes

    NASA Technical Reports Server (NTRS)

    Howard, Richard T.

    2006-01-01

    A method of equipping fiber-optic-coupled laser diodes to evenly illuminate specified fields of view has been proposed. The essence of the method is to shape the tips of the optical fibers into suitably designed diffractive optical elements. One of the main benefits afforded by the method would be more nearly complete utilization of the available light. Diffractive optics is a relatively new field of optics in which laser beams are shaped by use of diffraction instead of refraction.

  20. MONIM: the new Met Office Night Illumination Model

    NASA Astrophysics Data System (ADS)

    Revell, S. J.; Hignett, P.

    2004-09-01

    This paper describes a new model developed by the Met Office to predict night-time light levels. The Met Office Night Illumination Model (MONIM) predicts light levels both in the visible (photopic) range and in the waveband to which night vision goggles (NVGs) are sensitive. The model will be used operationally for support of night-time flying operations. The model is described in detail and its light-level forecasts are compared with observations.

  1. Illuminating a dialectical transformative activist stance in education

    NASA Astrophysics Data System (ADS)

    Ritchie, Stephen M.

    2008-07-01

    In this essay I comment on Stetsenko's (2008) essay that draws together the work of Vygotsky, Piaget and Dewey, as she attempts to counter the `new' reductionist synthesis in public educational policy. While this theoretical work is helpful, it could be enhanced further by illuminating everyday practices of learners. I pose some questions that might provoke ongoing discussions by researchers as they transform collaboratively cultural-historical activity theory.

  2. Structured white-light illumination for diagnostic investigations

    NASA Astrophysics Data System (ADS)

    Schau, P.; Brandes, A.; Frenner, K.; Kienle, A.; Osten, W.

    2013-04-01

    The optical coherence tomography (OCT) is an important technology for non-invasive, in vivo medical diagnostics. It enables the high-resolution recording of two-dimensional tomograms or three-dimensional volumes of biological tissue. Two mechanisms help separating the signal from the scattering background. First, reflected or backscattered light from outside the focal spot is suppressed by confocal discrimination. Additionally, the signal modulation is enhanced due to identical optical path lengths of both branches of the white light interferometry setup. Since the OCT relies on the interference between reference light and scattered light, this method cannot be readily extended for fluorescence measurements. An alternative approach is the confocal fluorescence microscopy, which uses confocal microscopy to suppress the fluorescent light from outside the focal spot. Hence, only the fluorescent light in the focal plane, which is 3 to 4 magnitudes lower in intensity than the excitation light, is detected. However, the surrounding area is illuminated with full intensity, which might cause photo-bleaching. There are also other promising approaches such as the two-photon excitation microscopy or fluorescence lifetime microscopy, which we will not cover in more detail. For fluorescence measurements of strongly-scattering samples such as biological tissue but also for technical surfaces, we propose a structured white-light illumination. We present two different approaches for the sample illumination utilizing a white light laser or a white light LED, respectively. We show first simulations of the individual illumination setups and their impact on the scattering within the sample. Furthermore, we investigated the distribution of the fluorescent light that reaches the detection part of the device when excited within a scattering medium, for this purpose we implemented a novel fast-converging algorithm for conditional fluence rate in our Monte Carlo algorithm.

  3. A new radiometric unit of measure to characterize SWIR illumination

    NASA Astrophysics Data System (ADS)

    Richards, A.; Hübner, M.

    2017-05-01

    We propose a new radiometric unit of measure we call the `swux' to unambiguously characterize scene illumination in the SWIR spectral band between 0.8μm-1.8μm, where most of the ever-increasing numbers of deployed SWIR cameras (based on standard InGaAs focal plane arrays) are sensitive. Both military and surveillance applications in the SWIR currently suffer from a lack of a standardized SWIR radiometric unit of measure that can be used to definitively compare or predict SWIR camera performance with respect to SNR and range metrics. We propose a unit comparable to the photometric illuminance lux unit; see Ref. [1]. The lack of a SWIR radiometric unit becomes even more critical if one uses lux levels to describe SWIR sensor performance at twilight or even low light condition, since in clear, no-moon conditions in rural areas, the naturally-occurring SWIR radiation from nightglow produces a much higher irradiance than visible starlight. Thus, even well-intentioned efforts to characterize a test site's ambient illumination levels in the SWIR band may fail based on photometric instruments that only measure visible light. A study of this by one of the authors in Ref. [2] showed that the correspondence between lux values and total SWIR irradiance in typical illumination conditions can vary by more than two orders of magnitude, depending on the spectrum of the ambient background. In analogy to the photometric lux definition, we propose the SWIR irradiance equivalent `swux' level, derived by integration over the scene SWIR spectral irradiance weighted by a spectral sensitivity function S(λ), a SWIR analog of the V(λ) photopic response function.

  4. Light pollution: the possible consequences of excessive illumination on retina

    PubMed Central

    Contín, M A; Benedetto, M M; Quinteros-Quintana, M L; Guido, M E

    2016-01-01

    Light is the visible part of the electromagnetic radiation within a range of 380–780 nm; (400–700 on primates retina). In vertebrates, the retina is adapted to capturing light photons and transmitting this information to other structures in the central nervous system. In mammals, light acts directly on the retina to fulfill two important roles: (1) the visual function through rod and cone photoreceptor cells and (2) non-image forming tasks, such as the synchronization of circadian rhythms to a 24 h solar cycle, pineal melatonin suppression and pupil light reflexes. However, the excess of illumination may cause retinal degeneration or accelerate genetic retinal diseases. In the last century human society has increased its exposure to artificial illumination, producing changes in the Light/Dark cycle, as well as in light wavelengths and intensities. Although, the consequences of unnatural illumination or light pollution have been underestimated by modern society in its way of life, light pollution may have a strong impact on people's health. The effects of artificial light sources could have direct consequences on retinal health. Constant exposure to different wavelengths and intensities of light promoted by light pollution may produce retinal degeneration as a consequence of photoreceptor or retinal pigment epithelium cells death. In this review we summarize the different mechanisms of retinal damage related to the light exposure, which generates light pollution. PMID:26541085

  5. Light pollution: the possible consequences of excessive illumination on retina.

    PubMed

    Contín, M A; Benedetto, M M; Quinteros-Quintana, M L; Guido, M E

    2016-02-01

    Light is the visible part of the electromagnetic radiation within a range of 380-780 nm; (400-700 on primates retina). In vertebrates, the retina is adapted to capturing light photons and transmitting this information to other structures in the central nervous system. In mammals, light acts directly on the retina to fulfill two important roles: (1) the visual function through rod and cone photoreceptor cells and (2) non-image forming tasks, such as the synchronization of circadian rhythms to a 24 h solar cycle, pineal melatonin suppression and pupil light reflexes. However, the excess of illumination may cause retinal degeneration or accelerate genetic retinal diseases. In the last century human society has increased its exposure to artificial illumination, producing changes in the Light/Dark cycle, as well as in light wavelengths and intensities. Although, the consequences of unnatural illumination or light pollution have been underestimated by modern society in its way of life, light pollution may have a strong impact on people's health. The effects of artificial light sources could have direct consequences on retinal health. Constant exposure to different wavelengths and intensities of light promoted by light pollution may produce retinal degeneration as a consequence of photoreceptor or retinal pigment epithelium cells death. In this review we summarize the different mechanisms of retinal damage related to the light exposure, which generates light pollution.

  6. Optical super resolution using tilted illumination coupled with object rotation

    NASA Astrophysics Data System (ADS)

    Hussain, Anwar; Mudassar, Asloob A.

    2015-03-01

    In conventional imaging systems, the resolution of the final image is mainly distorted due to diffraction of higher spatial frequencies of the target object. To overcome the diffraction limit, imaging techniques which synthetically enlarge the aperture of the system are used. In this paper, synthesized aperture is produced by means of a three fiber illumination assembly coupled with an in-plane object rotation. The high order diffracted spatial frequencies of the object are brought into the pass band of optical system by illuminating the object with tilted beams. The tilt produced at the fiber assembly plane is related to the dimension of the aperture, placed at the Fourier plane of the system. To span the 2D object spectrum at the Fourier plane, an in-plane object rotation procedure is applied at the object plane. The spectrum of the object is rotated as the object is rotated and illuminated with tilted beams. The corresponding object beam is interfered with a reference beam from the same source to record interferograms. All the recorded interferograms are stored in computer and de-convolution algorithm is applied to recover the synthesized spectrum. The image of the synthesized spectrum has three times improved resolution compared to the conventional image.

  7. 3D digitising using structured illumination: application to mould redesign

    NASA Astrophysics Data System (ADS)

    Granero, L.; Sánchez, J.; Micó, V.; Esteve, J. J.; Hervás, J.; Simón, S.; Pérez, E.

    2007-06-01

    Conventional techniques applied to three dimensional (3D) acquisition of information has significant limitations depending on the features of the piece under test. Thus, complex curvatures, deeper concavities and higher volumes are some examples of critical factors in which contact digitising systems are not suitable to undertake such kind of task. In these cases, the usage of optical 3D digitization systems implies a more appropriate way to obtain 3D information about the sample. In particular, structured illumination by means of white light provides point-to-point object acquisition with accuracy and resolution that are always below the manufactured tolerances. Moreover, when the object under test is too large, structured illumination can be mixed with photogrammetrical techniques in order to avoid errors by means of the delimitation of the overall working volume. This proceeding presents several real cases applied to mould industry in which 3D shape measurement using white light structured illumination is combined with finite element method (FEM) and laser cladding techniques to allow the repair of the mould.

  8. Wide-field Fourier ptychographic microscopy using laser illumination source

    PubMed Central

    Chung, Jaebum; Lu, Hangwen; Ou, Xiaoze; Zhou, Haojiang; Yang, Changhuei

    2016-01-01

    Fourier ptychographic (FP) microscopy is a coherent imaging method that can synthesize an image with a higher bandwidth using multiple low-bandwidth images captured at different spatial frequency regions. The method’s demand for multiple images drives the need for a brighter illumination scheme and a high-frame-rate camera for a faster acquisition. We report the use of a guided laser beam as an illumination source for an FP microscope. It uses a mirror array and a 2-dimensional scanning Galvo mirror system to provide a sample with plane-wave illuminations at diverse incidence angles. The use of a laser presents speckles in the image capturing process due to reflections between glass surfaces in the system. They appear as slowly varying background fluctuations in the final reconstructed image. We are able to mitigate these artifacts by including a phase image obtained by differential phase contrast (DPC) deconvolution in the FP algorithm. We use a 1-Watt laser configured to provide a collimated beam with 150 mW of power and beam diameter of 1 cm to allow for the total capturing time of 0.96 seconds for 96 raw FPM input images in our system, with the camera sensor’s frame rate being the bottleneck for speed. We demonstrate a factor of 4 resolution improvement using a 0.1 NA objective lens over the full camera field-of-view of 2.7 mm by 1.5 mm. PMID:27896016

  9. Effect of distorted illumination waves on coherent diffraction microscopy

    SciTech Connect

    Kohmura, Yoshiki; Nishino, Yoshinori; Ishikawa, Tetsuya; Miao Jianwei

    2005-12-15

    Coherent diffraction microscopy requires a well-defined illumination wave such as a plane wave on a specimen. Experimentally, a small pinhole or a focused beam is often used to reduce the illumination area but they unavoidably distort the waves. The distortion of the illumination wave causes artifacts in the phase retrieval of oversampled diffraction patterns. Using computer simulations, we searched for the conditions where strong artifacts arise by changing the Fresnel number, pinhole size, alignment error and photon statistics. The experimental setup with Fresnel number of around 1 and smaller than 1 realized a small reconstruction error when the pinhole radius is larger than a few times the specimen size. These conditions are suitable for the rotation of specimens for the three-dimensional (3D) observations. Such investigation will have an impact in the design of coherent diffraction microscopes for the 3D characterization of nanoscale materials and biological systems using the third generation synchrotron radiation and future x-ray free-electron lasers.

  10. Köhler integrators embedded into illumination optics add functionality

    NASA Astrophysics Data System (ADS)

    Dross, O.; Mohedano, R.; Hernández, M.; Cvetkovic, A.; Miñano, J. C.; Benítez, P.

    2008-09-01

    The Köhler illumination concept was originally invented to achieve uniform illumination in microscopy1. Köhler integrators can also be formed by arrays of lenticulations that can be any combination of reflective and/or refractive surfaces, organized in corresponding pairs. Arrays of integrating facets can be arranged not only on flat surfaces but on rotationally symmetric and even freeform surfaces6. Currently flat lenslet arrays are widely applied as homogenizing optics2 for lithography, machine vision illumination, and projection. Adding Köhler facets onto already designed surfaces can improve the optical system performance, while respecting its original function. In general, the optics output can be made somewhat independent of the source characteristics, although at the expense of a slight ètendue dilution or efficiency losses. This work revises the Köhler concept and its application to different kind of optics, ranging from photovoltaic concentrators to automotive LED headlights. In the former, irradiance peaks on the solar cell can be avoided, while preserving high aiming tolerance (acceptance) of the solar concentrator. In the latter, LEDs drawbacks like large source image sizes, source misalignments, ill defined source edges, and low source radiance can be compensated.

  11. Detector Based Realisation of Illuminance Scale at NML-SIRIM

    NASA Astrophysics Data System (ADS)

    Abdullah, Mohd Nizam; Abidin, Mohd Nasir Zainal; Abidin, Abdul Rashid Zainal; Shaari, Sahbudin

    2009-07-01

    Illuminance scale is one of the fundamentals in the realisation of candela in optical radiation. The en route of the realisation is based on the fundamental process from the unbroken chain of traceability which includes from the primary standard disseminated to working standard and lastly the end user. There are many variations towards this realisation even though some of the national metrology institutes (NMI) does not have the primary standard but their traceability still valid. The realisation of National Metrology Laboratory SIRIM (NML-SIRIM), Malaysia illuminance scale is based on detector. The scale is traceable to National Physical Labortaory (NPL), United Kingdom (UK) by annually calibrating photometers and luminous intensity lamp. This paper describes measurement method and the system set-up was previously crosschecked with Korea Research Institute Standards and Science (KRISS), Republic of Korea. The agreement between both laboratories is within 0.5% the uncertainty maintained at NML-SIRIM. Furthermore, the basic measurement equation for illuminance realisation is also derived.

  12. Random laser illumination: an ideal source for biomedical polarization imaging?

    NASA Astrophysics Data System (ADS)

    Carvalho, Mariana T.; Lotay, Amrit S.; Kenny, Fiona M.; Girkin, John M.; Gomes, Anderson S. L.

    2016-03-01

    Imaging applications increasingly require light sources with high spectral density (power over spectral bandwidth. This has led in many cases to the replacement of conventional thermal light sources with bright light-emitting diodes (LEDs), lasers and superluminescent diodes. Although lasers and superluminescent diodes appear to be ideal light sources due to their narrow bandwidth and power, however, in the case of full-field imaging, their spatial coherence leads to coherent artefacts, such as speckle, that corrupt the image. LEDs, in contrast, have lower spatial coherence and thus seem the natural choice, but they have low spectral density. Random Lasers are an unconventional type of laser that can be engineered to provide low spatial coherence with high spectral density. These characteristics makes them potential sources for biological imaging applications where specific absorption and reflection are the characteristics required for state of the art imaging. In this work, a Random Laser (RL) is used to demonstrate speckle-free full-field imaging for polarization-dependent imaging in an epi-illumination configuration. We compare LED and RL illumination analysing the resulting images demonstrating that the RL illumination produces an imaging system with higher performance (image quality and spectral density) than that provided by LEDs.

  13. Small angle x-ray scattering with edge-illumination

    NASA Astrophysics Data System (ADS)

    Modregger, Peter; Cremona, Tiziana P.; Benarafa, Charaf; Schittny, Johannes C.; Olivo, Alessandro; Endrizzi, Marco

    2016-08-01

    Sensitivity to sub-pixel sample features has been demonstrated as a valuable capability of phase contrast x-ray imaging. Here, we report on a method to obtain angular-resolved small angle x-ray scattering distributions with edge-illumination- based imaging utilizing incoherent illumination from an x-ray tube. Our approach provides both the three established image modalities (absorption, differential phase and scatter strength), plus a number of additional contrasts related to unresolved sample features. The complementarity of these contrasts is experimentally validated by using different materials in powder form. As a significant application example we show that the extended complementary contrasts could allow the diagnosis of pulmonary emphysema in a murine model. In support of this, we demonstrate that the properties of the retrieved scattering distributions are consistent with the expectation of increased feature sizes related to pulmonary emphysema. Combined with the simplicity of implementation of edge-illumination, these findings suggest a high potential for exploiting extended sub-pixel contrasts in the diagnosis of lung diseases and beyond.

  14. Improved Starting Materials for Back-Illuminated Imagers

    NASA Technical Reports Server (NTRS)

    Pain, Bedabrata

    2009-01-01

    An improved type of starting materials for the fabrication of silicon-based imaging integrated circuits that include back-illuminated photodetectors has been conceived, and a process for making these starting materials is undergoing development. These materials are intended to enable reductions in dark currents and increases in quantum efficiencies, relative to those of comparable imagers made from prior silicon-on-insulator (SOI) starting materials. Some background information is prerequisite to a meaningful description of the improved starting materials and process. A prior SOI starting material, depicted in the upper part the figure, includes: a) A device layer on the front side, typically between 2 and 20 m thick, made of p-doped silicon (that is, silicon lightly doped with an electron acceptor, which is typically boron); b) A buried oxide (BOX) layer (that is, a buried layer of oxidized silicon) between 0.2 and 0.5 m thick; and c) A silicon handle layer (also known as a handle wafer) on the back side, between about 600 and 650 m thick. After fabrication of the imager circuitry in and on the device layer, the handle wafer is etched away, the BOX layer acting as an etch stop. In subsequent operation of the imager, light enters from the back, through the BOX layer. The advantages of back illumination over front illumination have been discussed in prior NASA Tech Briefs articles.

  15. Skin image illumination modeling and chromophore identification for melanoma diagnosis

    NASA Astrophysics Data System (ADS)

    Liu, Zhao; Zerubia, Josiane

    2015-05-01

    The presence of illumination variation in dermatological images has a negative impact on the automatic detection and analysis of cutaneous lesions. This paper proposes a new illumination modeling and chromophore identification method to correct lighting variation in skin lesion images, as well as to extract melanin and hemoglobin concentrations of human skin, based on an adaptive bilateral decomposition and a weighted polynomial curve fitting, with the knowledge of a multi-layered skin model. Different from state-of-the-art approaches based on the Lambert law, the proposed method, considering both specular reflection and diffuse reflection of the skin, enables us to address highlight and strong shading effects usually existing in skin color images captured in an uncontrolled environment. The derived melanin and hemoglobin indices, directly relating to the pathological tissue conditions, tend to be less influenced by external imaging factors and are more efficient in describing pigmentation distributions. Experiments show that the proposed method gave better visual results and superior lesion segmentation, when compared to two other illumination correction algorithms, both designed specifically for dermatological images. For computer-aided diagnosis of melanoma, sensitivity achieves 85.52% when using our chromophore descriptors, which is 8~20% higher than those derived from other color descriptors. This demonstrates the benefit of the proposed method for automatic skin disease analysis.

  16. PSM design for inverse lithography with partially coherent illumination.

    PubMed

    Ma, Xu; Arce, Gonzalo R

    2008-11-24

    Phase-shifting masks (PSM) are resolution enhancement techniques (RET) used extensively in the semiconductor industry to improve the resolution and pattern fidelity of optical lithography. Recently, a set of gradient-based PSM optimization methods have been developed to solve for the inverse lithography problem under coherent illumination. Most practical lithography systems, however, use partially coherent illumination due to non-zero width and off-axis light sources, which introduce partial coherence factors that must be accounted for in the optimization of PSMs. This paper thus focuses on developing a framework for gradient-based PSM optimization methods which account for the inherent nonlinearities of partially coherent illumination. In particular, the singular value decomposition (SVD) is used to expand the partially coherent imaging equation by eigenfunctions into a sum of coherent systems (SOCS). The first order coherent approximation corresponding to the largest eigenvalue is used in the PSM optimization. In order to influence the solution patterns to have more desirable manufacturability properties and higher fidelity, a post-processing of the mask pattern based on the 2D discrete cosine transformation (DCT) is introduced. Furthermore, a photoresist tone reversing technique is exploited in the design of PSMs to project extremely sparse patterns.

  17. Robust Crop and Weed Segmentation under Uncontrolled Outdoor Illumination

    PubMed Central

    Jeon, Hong Y.; Tian, Lei F.; Zhu, Heping

    2011-01-01

    An image processing algorithm for detecting individual weeds was developed and evaluated. Weed detection processes included were normalized excessive green conversion, statistical threshold value estimation, adaptive image segmentation, median filter, morphological feature calculation and Artificial Neural Network (ANN). The developed algorithm was validated for its ability to identify and detect weeds and crop plants under uncontrolled outdoor illuminations. A machine vision implementing field robot captured field images under outdoor illuminations and the image processing algorithm automatically processed them without manual adjustment. The errors of the algorithm, when processing 666 field images, ranged from 2.1 to 2.9%. The ANN correctly detected 72.6% of crop plants from the identified plants, and considered the rest as weeds. However, the ANN identification rates for crop plants were improved up to 95.1% by addressing the error sources in the algorithm. The developed weed detection and image processing algorithm provides a novel method to identify plants against soil background under the uncontrolled outdoor illuminations, and to differentiate weeds from crop plants. Thus, the proposed new machine vision and processing algorithm may be useful for outdoor applications including plant specific direct applications (PSDA). PMID:22163954

  18. Automated illumination control for use in ophthalmic endoscopy

    NASA Astrophysics Data System (ADS)

    Blessing, Patrick; Niederer, Peter F.; Rol, Pascal O.; Hafliger, J.

    2000-05-01

    In endoscopic ophthalmic procedures care has to be exercised that the retina is protected from overexposure. Accordingly, it is advantageous if the endoscope is equipped with a stable and reliable automatic illumination control. To this end, an illumination control system has been devised, which consists of a mechanical iris and a digital control algorithm. The iris is designed such that it influences neither the spectral composition of the lightsource nor its aperture. It is furthermore linear with respect to the light intensity such that a fast control algorithm based on the data of a digital video camera used for observation purposes can be implemented. In order that no false signals are induced from specular reflections caused, e.g., by operating tools held in front of the camera, the control algorithm is designed such that reflections and true overexposure are distinguished from each other. For this purpose, the field of view is subdivided into small sectors and a statistical evaluation is made. The application under realistic conditions shows that the unit provides the user with a well illuminated image while the retina is reliably protected from overexposure.

  19. Laser scanning saturated structured illumination microscopy based on phase modulation

    NASA Astrophysics Data System (ADS)

    Huang, Yujia; Zhu, Dazhao; Jin, Luhong; Kuang, Cuifang; Xu, Yingke; Liu, Xu

    2017-08-01

    Wide-field saturated structured illumination microscopy has not been widely used due to the requirement of high laser power. We propose a novel method called laser scanning saturated structured illumination microscopy (LS-SSIM), which introduces high order of harmonics frequency and greatly reduces the required laser power for SSIM imaging. To accomplish that, an excitation PSF with two peaks is generated and scanned along different directions on the sample. Raw images are recorded cumulatively by a CCD detector and then reconstructed to form a high-resolution image with extended optical transfer function (OTF). Our theoretical analysis and simulation results show that LS-SSIM method reaches a resolution of 0.16 λ, equivalent to 2.7-fold resolution than conventional wide-field microscopy. In addition, LS-SSIM greatly improves the optical sectioning capability of conventional wide-field illumination system by diminishing our-of-focus light. Furthermore, this modality has the advantage of implementation in multi-photon microscopy with point scanning excitation to image samples in greater depths.

  20. Image recombination transform algorithm for superresolution structured illumination microscopy

    NASA Astrophysics Data System (ADS)

    Zhou, Xing; Lei, Ming; Dan, Dan; Yao, Baoli; Yang, Yanlong; Qian, Jia; Chen, Guangde; Bianco, Piero R.

    2016-09-01

    Structured illumination microscopy (SIM) is an attractive choice for fast superresolution imaging. The generation of structured illumination patterns made by interference of laser beams is broadly employed to obtain high modulation depth of patterns, while the polarizations of the laser beams must be elaborately controlled to guarantee the high contrast of interference intensity, which brings a more complex configuration for the polarization control. The emerging pattern projection strategy is much more compact, but the modulation depth of patterns is deteriorated by the optical transfer function of the optical system, especially in high spatial frequency near the diffraction limit. Therefore, the traditional superresolution reconstruction algorithm for interference-based SIM will suffer from many artifacts in the case of projection-based SIM that possesses a low modulation depth. Here, we propose an alternative reconstruction algorithm based on image recombination transform, which provides an alternative solution to address this problem even in a weak modulation depth. We demonstrated the effectiveness of this algorithm in the multicolor superresolution imaging of bovine pulmonary arterial endothelial cells in our developed projection-based SIM system, which applies a computer controlled digital micromirror device for fast fringe generation and multicolor light-emitting diodes for illumination. The merit of the system incorporated with the proposed algorithm allows for a low excitation intensity fluorescence imaging even less than 1 W/cm2, which is beneficial for the long-term, in vivo superresolved imaging of live cells and tissues.

  1. Process window study with various illuminations for EUV lithography applications

    NASA Astrophysics Data System (ADS)

    Lee, Sang Hun; Zhang, Zhiyu

    2007-03-01

    EUV lithography has the ability to support 22 nm logic manufacturing and beyond. Similar to the DUV lithographic systems, partial coherence on EUV lithographic systems can have a big impact on process latitude for critical layers. Thus, it is important to understand the effect of partial coherence on EUV imaging systems. In this paper, process windows with various illumination settings are investigated. The experiments are conducted using the MET station at the Advance Light Source (ALS). In addition to the annular and dipole illuminations which reported in our last paper1, C-quad and Quad illuminations are used to explore the impact of the partial coherence on the process window. Even though the MET system has resolutions below 30nm dense lines, the exposures are targeted for 60nm, 50nm, and 45nm dense features due to the resist limitation. The experimental results are compared with simulation results using Intel's lithography modeling tool, I-Photo. Resist and aerial image threshold models are used for the comparison study. The experimental results correlate well with the resist based simulation results, but some discrepancies are observed for the aerial image threshold cases. We believe the discrepancies are due to the resist limitations. We found that the dipole shows the largest Depth of Focus for dense lines and spaces.

  2. Root planing with interdental papilla reflection and fiber optic illumination.

    PubMed

    Reinhardt, R A; Johnson, G K; Tussing, G J

    1985-12-01

    The complete removal of accretions during closed scaling and root planing in moderate-deep pockets is difficult, presumably due to inadequate mechanical and visual access. The purpose of this study was to evaluate the effect of minimal papilla reflection and illumination with a prototype fiber optic unit on root planing efficiency. Nonmolar teeth with moderate-deep interproximal pockets (greater than 3 mm) in four patients scheduled to receive immediate complete dentures were randomly divided into groups for treatment: Group I--interproximal root planing augmented by papilla reflection and fiber optic illumination (n = 26 surfaces); Group II--interproximal root planing with papilla reflection only (n = 24); Group III--untreated controls (n = 23). Immediately after treatment, the experimental teeth were extracted, stained with toluidine blue and interproximal areas were evaluated for remaining accretions with a microscope-digitizing pad-computer system. Significantly less (P less than 0.01) root surface was covered by deposits in Group I than Group II (0.57 +/- 0.29% vs. 2.42 +/- 0.63%), and both treatment groups had fewer (P less than 0.0005) accretions than untreated controls (57.72 +/- 3.40%). These results suggest that root planing with papilla reflection produces an interproximal surface with few remaining deposits, and fiber optic illumination and transillumination further enhance this effect.

  3. Wavefront sensing in a partially illuminated, rotating pupil

    NASA Astrophysics Data System (ADS)

    Bertram, Thomas; Kumar Radhakrishnan Santhakumari, Kalyan; Marafatto, Luca; Arcidiacono, Carmelo; Berwein, Jürgen; Ragazzoni, Roberto; Herbst, Thomas M.

    2014-08-01

    LINC-NIRVANA is the near-infrared interferometric imaging camera for the Large Binocular Telescope. Once operational, it will provide an unprecedented combination of angular resolution, sensitivity, and field of view. Its pyramid-based layer-oriented MCAO systems are conjugated to the ground layer and to an additional layer in the upper atmosphere. The Groundlayer Wavefront Sensor optically coadds the light of up to 12 reference stars in the pupil, the Highlayer Wavefront Sensor optically combines the light of up to 8 reference stars in its metapupil. Each Wavefront Sensor has its own associated field derotator. It introduces a dependency of the sensor-actuator relation on the angle of the field derotator, which requires regular updates of the reconstructor in closed loop. In addition, the Highlayer Wavefront Sensor has to be able to reconstruct the incoming wavefronts by analyzing an only partially illuminated metapupil. The distribution of illuminated subapertures depends on the distribution of reference stars. For each pointing, a specific reconstruction matrix has to be generated, which only considers the illuminated subapertures. In this contribution we will present the concept of LINC-NIRVANA's wavefront reconstruction mechanism and report on laboratory and on-sky tests.

  4. Color digital lensless holographic microscopy: laser versus LED illumination.

    PubMed

    Garcia-Sucerquia, Jorge

    2016-08-20

    A comparison of the performance of color digital lensless holographic microscopy (CDLHM) as utilized for illumination of RGB lasers or a super-bright white-light LED with a set of spectral filters is presented. As the use of lasers in CDLHM conceals the possibility of having a compact, lightweight, portable, and low cost microscope, and additionally the limited available laser radiation wavelengths limit a real multispectral imaging microscope, here we present the use of super-bright white-light LED and spectral filters for illuminating the sample. The performance of RGB laser-CDLHM and LED-CDLHM is evaluated on imaging a section of the head of a Drosophila melanogaster fly. This comparison shows that there is trade-off between the spatial resolution of the microscope and the light sources utilized, which can be understood with regard to the coherence properties of the illuminating light. Despite the smaller spatial coherence features of LED-CDLHM in comparison with laser-CDLHM, the former shows promise as a portable RGB digital lensless holographic microscope that could be extended to other wavelengths by the use of different spectral filters.

  5. Standards for illumination of digital prints and photographs

    NASA Astrophysics Data System (ADS)

    Green, Phil

    2010-06-01

    Standards for illuminating digital prints and photographs have a number of quite different applications. In the graphic arts industry, the main applications are defined as appraisal and critical comparison, for which 500lux and 2000lux are specified in ISO 3664. In the museum world much lower levels of illumination are imposed when artefacts are considered to be prone to damage from such exposure. For display and storage of photographic prints, BS 5454:2000 is applicable and specifies maximum levels of 50 lux and 200 lux respectively. While these standards provide recommendations for exposure to radiant energy with the goal of limiting damage to materials and maximising visual discrimination, there is a need for more data on the radiative damage spectrum for the materials used in digital prints and photographs and other artefacts, and on the viewing conditions which can maximise visual performance for specific tasks. It is recommended that radiative exposure is measured in watts per square metre instead of lux to give a better indication of the propensity for radiative damage of a given illumination source.

  6. Characterization of photoacoustic tomography system with dual illumination

    NASA Astrophysics Data System (ADS)

    Fukutani, Kazuhiko; Someda, Yasuhiro; Taku, Masakazu; Asao, Yasufumi; Kobayashi, Shuichi; Yagi, Takayuki; Yamakawa, Makoto; Shiina, Tsuyoshi; Sugie, Tomoharu; Toi, Masakazu

    2011-03-01

    In this study, we characterized a newly developed imaging system, "dual illumination mode photoacoustic tomography (PAT) system". The PAT system can simultaneously or separately illuminate biological tissues from a forward and backward direction toward an array transducer. The shape of the custom-made transducer is rectangular, which allows direct illumination of tissue surfaces in front of the array transducer through a holding plate from the backward direction. The transducer frequency was designed at 1 MHz by considering the trade-off relationship between ultrasound attenuation and image resolution. A Ti:Sa laser optically pumped with a Q-switched Nd:YAG laser, having a tunable wavelength of 700 to 900 nm, was chosen for deep light penetration in tissues. The laser light was sufficiently expanded and homogenized to keep the level of laser-pulse fluence on the sample surface under the ANSI safety limit. System performance was tested with phantoms. The results of our study showed that the system visualized all the absorbers embedded in a 50-mm-thick tissue-mimicking phantom with a lateral resolution of 2{3 mm.

  7. The effect of illuminant position on perceived curvature.

    PubMed

    Curran, W; Johnston, A

    1996-05-01

    In shaded scenes surface features can appear either concave or convex, depending upon the viewer's judgement about the direction of the prevailing illumination. If other curvature cues are added to the image this ambiguity can be removed. However, it is not clear to what extent, if any, illuminant position exerts an influence on the perceived magnitude of surface curvature. Subjects were presented with pairs of spherical surface patches in a curvature matching task. The patches were defined by shading and texture cues. The perceived curvature of a standard patch was measured as a function of light source position. We found a clear effect of light source position on apparent curvature. Perceived curvature decreased as light source tilt increased and as light source slant decreased. We also found that the strength of this effect is determined partly by a surface's reflectance function and partly by the relative weight of the texture cue. When a specular component was added to the stimuli, the effect of light source orientation was weakened. The weight of the texture cue was manipulated by disrupting the regular distribution of texture elements. We found an inverse relationship between the strength of the effect and the weight of the texture cue: lowering the texture cue weight resulted in an enhancement of the illuminant position effect.

  8. LED uniform illumination system for DMD-based confocal microscopy

    NASA Astrophysics Data System (ADS)

    Xiao, Kaimin; Hou, Wenmei; Xu, Qixin; Peng, Bofang

    2013-10-01

    Due to the coherence of laser light source it could produce coherent noise in parallel confocal microscopy based on Digital Micromirror Device (DMD) and thus affect the resolution. LED light source instead of the laser light source can give full play because of its incoherence characterization. In this paper, free-form surface lens is used for LED secondary optics design. According to the LED characteristics and the law of refraction, we have established differential equations of free-form surface. We solved equations with the method of Runge-Kutta by Matlab and the model was built in Tracepro for optical simulation. The results show that the uniformity on the DMD is better than 90% and the lighting efficiency is higher than before. The measured data show us a much more uniform illumination on DMD and LED uniform illumination system successfully avoided the gray error which was caused by the uneven illumination. The LED driver circuit using DC power supply provides us a more stable light source. The axial optical tomography is more accurate and the reconstruction of three-dimensional image is more clearer.

  9. Smoothing of Diamond-Turned Substrates for Extreme Ultraviolet Illuminators

    SciTech Connect

    Soufli, R; Spiller, E; Schmidt, M A; Robinson, J C; Baker, S L; Ratti, S; Johnson, M A; Gullikson, E M

    2003-11-13

    Condenser optics in extreme ultraviolet lithography (EUVL) systems are subjected to frequent replacement as they are positioned close to the illumination source, where increased heating and contamination occur. In the case of aspherical condenser elements made by optical figuring/finishing, their replacement can be very expensive (several hundred thousand dollars). One approach to this problem would be to manufacture inexpensive illuminator optics that meet all required specifications and could be replaced at no substantial cost. Diamond-turned metal substrates are a factor of 100 less expensive than conventional aspherical substrates but have insufficient finish, leading to unacceptably low EUV reflectance after multilayer coating. In this work it is shown that, by applying a smoothing film prior to multilayer coating, the high spatial frequency roughness of a diamond-turned metal substrate is reduced from 1.76 to 0.27 nm rms while the figure slope error is maintained at acceptable levels. Metrology tests performed at various stages of the fabrication of the element demonstrated that it satisfied all critical figure and finish specifications as illuminator. Initial experimental results on the stability and performance of the optic under a real EUVL plasma source environment show no accelerated degradation when compared to conventional substrates.

  10. Plasmonic Au nano-needle fabricated by optical vortex laser illumination

    NASA Astrophysics Data System (ADS)

    Izumisawa, Kai; Sugimoto, Tatsuyuki; Nakamura, Yuri; Miyamoto, Katsuhiko; Torimoto, Tsukasa; Morita, Ryuji; Omatsu, Takashige

    2017-04-01

    We reported on a plasmonic metal Au nano-needle by nanosecond optical vortex pulse illumination. The Au nano-needle with a tip-diameter of <100 nm was structured by illumination of a single vortex pulse.

  11. Implementation of pattern-specific illumination pupil optimization on Step & Scan systems

    NASA Astrophysics Data System (ADS)

    Engelen, Andre; Socha, Robert J.; Hendrickx, Eric; Scheepers, Wieger; Nowak, Frank; Van Dam, Marco; Liebchen, Armin; Faas, Denis A.

    2004-05-01

    Step&Scan systems are pushed towards low k1 applications. Contrast enhancement techniques are crucial for successful implementation of these applications in a production environment. A NA - sigma - illumination mode optimizer and a contrast-based optimization algorithm are implemented in LithoCruiser in order to optimize illumination setting and illumination pupil for a specific repetitive pattern. Calculated illumination pupils have been realized using Diffractive Optical Elements (DOE), which are supported by ASML's AERIAL II illuminator. The qualification of the illumination pupil is done using inline metrology on the ASML Step & Scan system. This paper describes the process of pattern specific illumination optimization for a given mask. Multiple examples will be used to demonstrate the advantage of using non-standard illumination pupils.

  12. Gram-Schmidt orthonormalization for retrieval of amplitude images under sinusoidal patterns of illumination

    USDA-ARS?s Scientific Manuscript database

    Structured illumination using sinusoidal patterns has been utilized for optical imaging of biological tissues in biomedical research and, of horticultural products. Implementation of structured-illumination imaging relies on retrieval of amplitude images, which is conventionally achieved by a phase-...

  13. 77 FR 57083 - American Illuminating Company, LLC; Supplemental Notice that Initial Market-Based Rate Filing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-17

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission American Illuminating Company, LLC; Supplemental Notice that Initial Market... in the above-referenced proceeding, of American Illuminating Company, LLC's application for...

  14. Solving the MCAO partial illumination issue and laboratory results

    NASA Astrophysics Data System (ADS)

    Santhakumari, K. K. R.; Arcidiacono, C.; Bertram, T.; Berwein, J.; Herbst, T. M.; Ragazzoni, R.

    2016-07-01

    Telescopes or instruments equipped with Multi-Conjugate Adaptive Optics (MCAO) provide uniform turbulence correction over a wide Field of View (FoV), thereby overcoming the problems of isoplanatism and enabling previously challenging science. LINC-NIRVANA (LN), the German-Italian near-infrared high-resolution imager for the Large Binocular Telescope (LBT), has an advanced and unique MCAO module, which uses the Optical Co-addition of Layer- Oriented Multiple-FoV Natural Guide Star approach to MCAO with pyramid wavefront sensing. The layer-oriented wavefront correction can be performed by conjugating the Deformable Mirrors (DM) and the respective Wavefront Sensors (WFS) to the corresponding atmospheric layers. LN corrects for the aberrations in two different layers. The ground layer, conjugated to the telescope pupil 100m above LBT, is corrected by the Ground-layer Wavefront Sensors (GWS) driving the LBT adaptive secondary mirrors, and a higher layer 7.1km above the telescope is corrected by the High-layer Wavefront Sensors (HWS) driving a pair of Xinetics DMs on the LN bench. At the ground layer, the footprints of the stars overlap completely and every star footprint illuminates the entire pupil-plane. However, for a higher layer, the footprints do not overlap completely and each star illuminates a different region of the conjugated plane. Lack of stars, therefore, results in some regions in this "meta-pupil"-plane not being illuminated, implying no information regarding the aberrations in these areas. The optimum way of correcting the high layer, given this limited information, is the crux of the "partial illumination issue". In this paper, we propose a solution for this issue and discuss laboratory results from the aligned LN bench in the lab. Currently, LN has completed the re-integration and re-alignment at LBT. In early June 2016, we tested our partial illumination algorithm in the instrument's final configuration in the LBT mountain lab, using simulated stars

  15. Side-illuminating LED luminaires with accurate projection in high uniformity and high optical utilization factor for large-area field illumination.

    PubMed

    Lo, Yi-Chien; Cai, Jhih-You; Tasi, Ming-Shiou; Tasi, Zheng-Yu; Sun, Ching-Cherng

    2014-03-10

    A novel light luminaire is proposed and experimentally analyzed, which accurately projects light into a large rectangular area to achieve uniform illumination and a high optical utilization factor at the target. Side-illuminating luminaires for large-scale illuminated area are typically set with an elevated tilt angle to enlarge the illuminated area. However, the light pattern is bent thereby reducing the uniformity and optical utilization factor at the target. In this paper, we propose an efficient and useful approach with a rotationally symmetric projection lens that is trimmed to adjust the bending effect and to form a rectangular illumination light pattern on the ground. The design concept is demonstrated and verified. Several potential applications such as highly uniform illumination with fitting shapes for sport courts are analyzed and discussed.

  16. Studies in Illumination. 1. The Hygienic Conditions of Illumination in Certain Post Offices, Especially Relating to Visual Defects and Efficiency

    DTIC Science & Technology

    1924-07-01

    entrance examination for post office work . Since there was no such record available, the Civil Service Commission kindly furnished the visual findings of...and lighting codes published dur- ing the last 10 years. For instance, Bell,’ in 1912, said, "Nearly all classes of clerical and office work can be...OF ILLUMINATION IN CERTAIN POST OFFICES, ESPECIALLY RELATING TO VISUAL DEFECTS AND EFFICIENCY BY LEWIS R. THOMPSON, Surgeon, U. S. P. H. S. LOUIS

  17. Applying local Gabor ternary pattern for video-based illumination variable face recognition

    NASA Astrophysics Data System (ADS)

    Wang, Huafeng; Han, Yong; Zhang, Zhaoxiang

    2011-12-01

    The illumination variation problem is one of the well-known problems in face recognition in uncontrolled environment. Due to that both Gabor feature and LTP(local ternary pattern) are testified to be robust to illumination variations, we proposed a new approach which achieved illumination variable face recognition by combining Gabor filters with LTP operator. The experimental results compared with the published results on Yale-B and CMU PIE face database of changing illumination verify the validity of the proposed method.

  18. Applying local Gabor ternary pattern for video-based illumination variable face recognition

    NASA Astrophysics Data System (ADS)

    Wang, Huafeng; Han, Yong; Zhang, Zhaoxiang

    2012-01-01

    The illumination variation problem is one of the well-known problems in face recognition in uncontrolled environment. Due to that both Gabor feature and LTP(local ternary pattern) are testified to be robust to illumination variations, we proposed a new approach which achieved illumination variable face recognition by combining Gabor filters with LTP operator. The experimental results compared with the published results on Yale-B and CMU PIE face database of changing illumination verify the validity of the proposed method.

  19. Inclined selective plane illumination microscopy adaptor for conventional microscopes.

    PubMed

    Cutrale, Francesco; Gratton, Enrico

    2012-11-01

    Driven by the biological sciences, there is an increased need for imaging modalities capable of live cell imaging with high spatial and temporal resolution. To achieve this goal in a comprehensive manner, three-dimensional acquisitions are necessary. Ideal features of a modern microscope system should include high imaging speed, high contrast ratio, low photo-bleaching and photo-toxicity, good resolution in a 3D context, and mosaic acquisition for large samples. Given the importance of collecting data in live sample further increases the technical challenges required to solve these issues. This work presents a practical version of a microscopy method, Selective Plane Illumination Microscopy re-introduced by Huisken et al. (Science2004,305,1007-1009). This method is gaining importance in the biomedical field, but its use is limited by difficulties associated with unconventional microscope design which employs two objectives and a particular kind of sample preparation needed to insert the sample between the objectives. Based on the selective plane illumination principle but with a design similar to the Total Internal Reflection Fluorescence microscope, Dunsby (Dunsby, Opt Express 2008,16,20306-20316) demonstrated the oblique plane microscope (OPM) using a single objective which uses conventional sample preparation protocols. However, the Dunsby instrument was not intended to be part of a commercial microscope. In this work, we describe a system with the advantages of OPM and that can be used as an adaptor to commonly used microscopes, such as IX-71 Olympus, simplifying the construction of the OPM and increasing performance of a conventional microscope. We named our design inclined selective plane illumination microscope (iSPIM).

  20. Acoustic-resolution photoacoustic imaging system with simple fiber illumination

    NASA Astrophysics Data System (ADS)

    Tsunoi, Yasuyuki; Sato, Shunichi; Watanabe, Ryota; Kawauchi, Satoko; Ashida, Hiroshi; Terakawa, Mitsuhiro

    2013-03-01

    Acoustic-resolution photoacoustic microscopy (AR-PAM) with dark-field confocal illumination enables unique high-resolution visualization of chromophores in tissue, such as microvasculatures, within depths of a few millimeters. However, most current systems are bulky and use complex optical components for illumination, thus requiring highly sensitive alignment. In this study, we developed a compact alignment-free acoustic-resolution photoacoustic imaging system with simple fiber illumination. Four optical fibers were placed in four directions around a high-frequency (30-MHz) ultrasound sensor attached with the high-numerical-aperture acoustic lens. The setting angle of the fibers were determined to form a dark field on the tissue surface under the acoustic lens and for the four light beams from the fibers to be combined near the focal point of the acoustic lens, i.e., at a depth of around 1.2 mm in the tissue. The acoustic lens and output ends of the fibers were capped with an acoustically and optically transparent engineering plastic sheet, whose surface can be directly placed and scanned on the tissue surface with ultrasound gel. The diameter and height of this imaging head were as small as 32 mm and 27 mm respectively. The phantom study showed that the lateral signal spreading was 120 μm, which agreed well with the theoretical value of 112 μm. With the system, we attempted to image vasculatures in the rat skin, demonstrating high-contrast visualization of the blood vessels of a few hundred micrometers in diameter in the tissue.

  1. Multispectral lensless digital in-line holographic microscope: LED illumination

    NASA Astrophysics Data System (ADS)

    Ryle, James P.; McDonnell, Susan; Sheridan, John T.

    2010-05-01

    Holography is the process where two coherent wavefields interfere resulting in an interference pattern from which whole field information can be retrieved. Digital holography is the process where the intensity of the superposition of the two waves is recorded using a light sensitive opto-electronic detector array such as a CCD or CMOS camera. From this recorded hologram it is possible to numerically reconstruct the object wavefield. When an optical beam is focused on a pinhole whose diameter is of the order of a few times the wavelength of the illumination beam, a spherically divergent wavefield is emitted. We use the emitted optical beam to illuminate weakly scattering objects resulting in a geometrically magnified diffraction pattern at the camera face. Scattered light from the object is the called the object wavefield, while unscattered light acts as the reference wavefield. The hologram is captured digitally before numerical reconstruction is applied to yield whole field information about the object. It is possible to reconstruct the objects wavefield using this method from coherent laser or incoherent LED illumination. The emitted light from the pinhole acts a pointsource of spatially coherent light enabling holography. This, in combination with the use of multiple wavelength LED's multispectral amplitude images can be reconstructed. The multispectral lensless DIHM described here can be used to holographically image biological specimens such as cells grown for use in the biopharmaceutical industry or for research purposes. In analysing cell viability based on the trypan blue assay, the outer membrane of non-viable cells is penetrated by violet blue dye. Using such a Digital In-line Holographic Microscope as described here, automatic classification of viable and non-viable cells could be performed.

  2. Illumination system development using design and analysis of computer experiments

    NASA Astrophysics Data System (ADS)

    Keresztes, Janos C.; De Ketelaere, Bart; Audenaert, Jan; Koshel, R. J.; Saeys, Wouter

    2015-09-01

    Computer assisted optimal illumination design is crucial when developing cost-effective machine vision systems. Standard local optimization methods, such as downhill simplex optimization (DHSO), often result in an optimal solution that is influenced by the starting point by converging to a local minimum, especially when dealing with high dimensional illumination designs or nonlinear merit spaces. This work presents a novel nonlinear optimization approach, based on design and analysis of computer experiments (DACE). The methodology is first illustrated with a 2D case study of four light sources symmetrically positioned along a fixed arc in order to obtain optimal irradiance uniformity on a flat Lambertian reflecting target at the arc center. The first step consists of choosing angular positions with no overlap between sources using a fast, flexible space filling design. Ray-tracing simulations are then performed at the design points and a merit function is used for each configuration to quantify the homogeneity of the irradiance at the target. The obtained homogeneities at the design points are further used as input to a Gaussian Process (GP), which develops a preliminary distribution for the expected merit space. Global optimization is then performed on the GP more likely providing optimal parameters. Next, the light positioning case study is further investigated by varying the radius of the arc, and by adding two spots symmetrically positioned along an arc diametrically opposed to the first one. The added value of using DACE with regard to the performance in convergence is 6 times faster than the standard simplex method for equal uniformity of 97%. The obtained results were successfully validated experimentally using a short-wavelength infrared (SWIR) hyperspectral imager monitoring a Spectralon panel illuminated by tungsten halogen sources with 10% of relative error.

  3. Unsupervised defect segmentation of patterned materials under NIR illumination

    NASA Astrophysics Data System (ADS)

    Millán, María S.; Escofet, Jaume; Ralló, Miquel

    2011-01-01

    An unsupervised detection method for automatic flaw segmentation in patterned materials (textile, non-woven, paper) that has no need of any defect-free references or a training stage is presented in this paper. Printed materials having a pattern of colored squares, bands, etc. superimposed to the background texture can be advantageously analyzed using NIR illumination and a camera with enough sensitivity to this region of the spectrum. The contrast reduction of the pattern in the NIR image facilitates material inspection and defect segmentation. Underdetection and misdetection errors can be reduced in comparison with the inspection performed under visible illumination. For woven fabrics, with periodic structure, the algorithm is based on the structural feature extraction of the weave repeat from the Fourier transform of the sample image. These features are used to define a set of multiresolution bandpass filters adapted to the fabric structure that operate in the Fourier domain. Inverse Fourier transformation, binarization and merging of the information obtained at different scales lead to the output image that contains flaws segmented from the fabric background. For non-woven and random textured materials, the algorithm combines the multiresolution Gabor analysis of the sample image with a statistical analysis of the wavelet coefficients corresponding to each detail. The information of all the channels is merged in a single binary output image where the defect appears segmented from the background. The method is applicable to random, non-periodic, and periodic textures. Since all the information to inspect a sample is obtained from the sample itself, the method is proof against heterogeneities between different samples of the material, in-plane positioning errors, scale variations and lack of homogeneous illumination. Experimental results are presented for a variety of materials and defects.

  4. Coherent x-ray wavefront reconstruction of a partially illuminated Fresnel zone plate.

    PubMed

    Mastropietro, F; Carbone, D; Diaz, A; Eymery, J; Sentenac, A; Metzger, T H; Chamard, V; Favre-Nicolin, V

    2011-09-26

    A detailed characterization of the coherent x-ray wavefront produced by a partially illuminated Fresnel zone plate is presented. We show, by numerical and experimental approaches, how the beam size and the focal depth are strongly influenced by the illumination conditions, while the phase of the focal spot remains constant. These results confirm that the partial illumination can be used for coherent diffraction experiments. Finally, we demonstrate the possibility of reconstructing the complex-valued illumination function by simple measurement of the far field intensity in the specific case of partial illumination.

  5. Redundant information from thermal illumination: quantum Darwinism in scattered photons

    NASA Astrophysics Data System (ADS)

    Jess Riedel, C.; Zurek, Wojciech H.

    2011-07-01

    We study quantum Darwinism, the redundant recording of information about the preferred states of a decohering system by its environment, for an object illuminated by a blackbody. We calculate the quantum mutual information between the object and its photon environment for blackbodies that cover an arbitrary section of the sky. In particular, we demonstrate that more extended sources have a reduced ability to create redundant information about the system, in agreement with previous evidence that initial mixedness of an environment slows—but does not stop—the production of records. We also show that the qualitative results are robust for more general initial states of the system.

  6. Structured IR illumination for relative depth sensing in virtual interfaces

    NASA Astrophysics Data System (ADS)

    Kress, Bernard; Raulot, Victorien; Grossman, Michel

    2012-06-01

    Depth mapping or depth sensing has become a popular field, applied not only to automotive sensing for collision avoidance (radar) but also to gesture sensing for gaming and virtual interfaces (optical). Popular gesture sensing devices such as the Kinect from Microsoft's Xbox gaming device produce a full absolute depth map, which is in most cases not adapted to the task on hand (relative gesture sensing). We propose in this paper a new gesture sensing technique through structured IR illumination to provide a relative depth mapping rather than an absolute one, and this reducing the requirements on computing power and therefore enabling this technology for wearable computing such as see through display.

  7. Light induced modulation instability of surfaces under intense illumination

    SciTech Connect

    Burlakov, V. M. Goriely, A.; Foulds, I.

    2013-12-16

    We show that a flat surface of a polymer in rubber state illuminated with intense electromagnetic radiation is unstable with respect to periodic modulation. Initial periodic perturbation is amplified due to periodic thermal expansion of the material heated by radiation. Periodic heating is due to focusing-defocusing effects caused by the initial surface modulation. The surface modulation has a period longer than the excitation wavelength and does not require coherent light source. Therefore, it is not related to the well-known laser induced periodic structures on polymer surfaces but may contribute to their formation and to other phenomena of light-matter interaction.

  8. Pathogens and polymers: Microbe–host interactions illuminate the cytoskeleton

    PubMed Central

    Haglund, Cat M.

    2011-01-01

    Intracellular pathogens subvert the host cell cytoskeleton to promote their own survival, replication, and dissemination. Study of these microbes has led to many discoveries about host cell biology, including the identification of cytoskeletal proteins, regulatory pathways, and mechanisms of cytoskeletal function. Actin is a common target of bacterial pathogens, but recent work also highlights the use of microtubules, cytoskeletal motors, intermediate filaments, and septins. The study of pathogen interactions with the cytoskeleton has illuminated key cellular processes such as phagocytosis, macropinocytosis, membrane trafficking, motility, autophagy, and signal transduction. PMID:21969466

  9. Vertically illuminated TW-UTC photodiodes for terahertz generation

    NASA Astrophysics Data System (ADS)

    Barrientos Z., Claudio; Calle, Victor; Diaz, Marcos; Mena, F. Patricio; Vukusic, Josip; Stake, Jan; Michael, Ernest A.

    2010-07-01

    More efficient continuous-wave photonic nearinfrared mixers as terahertz sources are investigated with the motivation to develop a universal photonic local oscillator for astronomical submillimeter/terahertz receiver systems. For this, we develop new concepts for vertically illuminated traveling-wave (TW) photomixers, TW Uni-Travelling Carrier (UTC) photodiodes. Device simulation/modeling and optical/terahertz testing is being done in the new terahertz photonics laboratory at the Electrical Engineering Department of the University of Chile, whereas device fabrication is performed at the MC2 cleanroom facility at Chalmers Technical University. We report on first progress in this direction.

  10. Vertically Illuminated TW-UTC Photodiodes for Terahertz Generation

    NASA Astrophysics Data System (ADS)

    Barrientos, C.; Calle, V.; Diaz, M.; Mena, F. P.; Vukusic, J.; Stake, J.; Michael, E. A.

    2010-03-01

    More efficient continuous-wave photonic near-infrared mixers as terahertz sources are investigated with the motivation to develop a universal photonic local oscillator for astronomical submillimeter/terahertz receiver systems. For this, our group has developed new concepts for vertically illuminated traveling-wave (TW) photomixers. The new device called TW-Uni-Travelling Carrier photodiodes (TW-UTC PD) was simulated, modeled and shall be optical/terahertz tested at the Electrical Engineering Department of the University of Chile, whereas device fabrication is performed at the MC2 cleanroom facility at Chalmers University of technology. We are reporting on first progresses in this direction.

  11. Near spherical illumination of ion-beam and laser targets

    SciTech Connect

    Mark, J.W.K.

    1985-12-12

    A procedure is developed for reducing energy-deposition asymmetry in spherical targets driven directly by ion or laser beams. This work is part of a strategy for achieving illumination symmetry in such targets, which is proposed as an alternative to those in the literature. This strategy allows an axially symmetric placement of beamlets, which would be convenient for some driven or reactor scenarios. It also allows the use of beam currents or energy fluxes and beam transverse profiles to help reduce deposition asymmetry with fewer beamlets. In the ideal limit of thin deposition layers and controlled beam profiles, at most six beamlets are needed for target symmetry.

  12. Contrast- and illumination-invariant object recognition from active sensation.

    PubMed

    Rentschler, Ingo; Osman, Erol; Jüttner, Martin

    2009-01-01

    It has been suggested that the deleterious effect of contrast reversal on visual recognition is unique to faces, not objects. Here we show from priming, supervised category learning, and generalization that there is no such thing as general invariance of recognition of non-face objects against contrast reversal and, likewise, changes in direction of illumination. However, when recognition varies with rendering conditions, invariance may be restored and effects of continuous learning may be reduced by providing prior object knowledge from active sensation. Our findings suggest that the degree of contrast invariance achieved reflects functional characteristics of object representations learned in a task-dependent fashion.

  13. Twin removal in digital holography using diffuse illumination.

    PubMed

    Monaghan, David S; Kelly, Damien P; Pandey, Nitesh; Hennelly, Bryan M

    2009-12-01

    A method to numerically remove the twin image for inline digital holography, using multiple digital holograms, is discussed. Each individual hologram is recorded by using a statistically independent speckle field to illuminate the object. If the holograms are recorded in this manner and then numerically reconstructed, the twin image appears as a different speckle pattern in each of the reconstructions. By performing speckle-reduction techniques the presence of the twin image can be greatly reduced. A theoretical model is developed, and experimental results are presented that validate this approach. We show experimentally that the dc object intensity term can also be removed by using this technique.

  14. Augmented tracking and acquisition system for GBL satellite illumination

    NASA Astrophysics Data System (ADS)

    Brodsky, Aaron; Goodrich, Alan; Lawson, David G.; Holm, Richard W.

    1991-08-01

    The Augmented Tracking and Acquisition System (ATAS) provides the tracking acquisition aids, line-of-sight stabilization, and active closed-loop beam centering functions at two ground-based laser tracking sites for the Relay Mirror Experiment (RME). Simultaneous, steady illumination of the RME spacecraft with both ground beacons allows for successful beam relay between the two sites off of the orbiting mirror. Described in this paper is an overview of the functions, control system architectures, major subsystem components (steering mirrors and sensors), and mission operation of the ATAS subsystems. A brief discussion of ATAS evolution is included to show that versatility is needed for success.

  15. Restoration of uneven illumination in light sheet microscopy images.

    PubMed

    Uddin, Mohammad Shorif; Lee, Hwee Kuan; Preibisch, Stephan; Tomancak, Pavel

    2011-08-01

    Light microscopy images suffer from poor contrast due to light absorption and scattering by the media. The resulting decay in contrast varies exponentially across the image along the incident light path. Classical space invariant deconvolution approaches, while very effective in deblurring, are not designed for the restoration of uneven illumination in microscopy images. In this article, we present a modified radiative transfer theory approach to solve the contrast degradation problem of light sheet microscopy (LSM) images. We confirmed the effectiveness of our approach through simulation as well as real LSM images.

  16. Light-beam evolution in slant illumination of turbid medium

    NASA Astrophysics Data System (ADS)

    Aistov, A. V.; Gavrilenko, V. G.

    1993-08-01

    The space and angle distributions of the radiation intensity in an absorbing anisotropically scattering medium are examined for slant illumination of the boundary by a limited beam. An analytic solution of the transport equation in a small-angle approximation is compared with Monte Carlo modeling of light propagation in sea water. The existence of a depth region in which the variances of the space and angle intensity distributions rise anomalously rapidly due to the presence of absorption and the asymmetry of the problem is pointed out.

  17. Directed energy active illumination for near-Earth object detection

    NASA Astrophysics Data System (ADS)

    Riley, Jordan; Lubin, Philip; Hughes, Gary B.; O'Neill, Hugh; Meinhold, Peter; Suen, Jonathan; Bible, Johanna; Johansson, Isabella E.; Griswold, Janelle; Cook, Brianna

    2014-09-01

    On 15 February 2013, a previously unknown ~20 m asteroid struck Earth near Chelyabinsk, Russia, releasing kinetic energy equivalent to ~570 kt TNT. Detecting objects like the Chelyabinsk impactor that are orbiting near Earth is a difficult task, in part because such objects spend much of their own orbits in the direction of the Sun when viewed from Earth. Efforts aimed at protecting Earth from future impacts will rely heavily on continued discovery. Ground-based optical observatory networks and Earth-orbiting spacecraft with infrared sensors have dramatically increased the pace of discovery. Still, less than 5% of near-Earth objects (NEOs) >=100 m/~100 Mt TNT have been identified, and the proportion of known objects decreases rapidly for smaller sizes. Low emissivity of some objects also makes detection by passive sensors difficult. A proposed orbiting laser phased array directed energy system could be used for active illumination of NEOs, enhancing discovery particularly for smaller and lower emissivity objects. Laser fiber amplifiers emit very narrow-band energy, simplifying detection. Results of simulated illumination scenarios are presented based on an orbiting emitter array with specified characteristics. Simulations indicate that return signals from small and low emissivity objects is strong enough to detect. The possibility for both directed and full sky blind surveys is discussed, and the resulting diameter and mass limits for objects in different observational scenarios. The ability to determine both position and speed of detected objects is also discussed.

  18. Exomoon Habitability Constrained by Illumination and Tidal Heating

    PubMed Central

    2013-01-01

    Abstract The detection of moons orbiting extrasolar planets (“exomoons”) has now become feasible. Once they are discovered in the circumstellar habitable zone, questions about their habitability will emerge. Exomoons are likely to be tidally locked to their planet and hence experience days much shorter than their orbital period around the star and have seasons, all of which works in favor of habitability. These satellites can receive more illumination per area than their host planets, as the planet reflects stellar light and emits thermal photons. On the contrary, eclipses can significantly alter local climates on exomoons by reducing stellar illumination. In addition to radiative heating, tidal heating can be very large on exomoons, possibly even large enough for sterilization. We identify combinations of physical and orbital parameters for which radiative and tidal heating are strong enough to trigger a runaway greenhouse. By analogy with the circumstellar habitable zone, these constraints define a circumplanetary “habitable edge.” We apply our model to hypothetical moons around the recently discovered exoplanet Kepler-22b and the giant planet candidate KOI211.01 and describe, for the first time, the orbits of habitable exomoons. If either planet hosted a satellite at a distance greater than 10 planetary radii, then this could indicate the presence of a habitable moon. Key Words: Astrobiology—Extrasolar planets—Habitability—Habitable zone—Tides. Astrobiology 13, 18–46. PMID:23305357

  19. Adaptive display luminance for viewing smartphones under low illuminance.

    PubMed

    Na, Nooree; Suk, Hyeon-Jeong

    2015-06-29

    The study investigates the optimal display luminance for viewing smartphones in conditions of low illuminance. This proposes a model of adaptive display in that display luminance changes gradually with the passage of watching time. It starts at a fairly low display luminance of 10 cd/m2, and after 10 seconds, the luminance increases slowly until it reaches 40 cd/m2 for 20 seconds and maintains the luminance. For the development of the model, an experiment was conducted to identify the optimal luminance for initial viewing and that for continuous viewing, as well as the change speed of display luminance. In order to validate the model, users' subjective judgments and activation of alpha rhythm were observed, and the result confirmed the superiority of the adaptive display luminance compared to the current display luminance in terms of physiological comfort and psychological satisfaction. It is expected that this study contributes to the pleasing use of displays at night under low illuminance by applying to diverse types of display devices.

  20. Fast rendering of forest ecosystems with dynamic global illumination

    NASA Astrophysics Data System (ADS)

    Steele, Jay Edward

    Real-time rendering of large-scale, forest ecosystems remains a challenging problem, in that important global illumination effects, such as leaf transparency and inter-object light scattering, are difficult to capture, given tight timing constraints and scenes that typically contain hundreds of millions of primitives. We propose a new lighting model, adapted from a model previously used to light convective clouds and other participating media, together with GPU ray tracing, in order to achieve these global illumination effects while maintaining near real-time performance. The lighting model is based on a lattice-Boltzmann method in which reflectance, transmittance, and absorption parameters are taken from measurements of real plants. The lighting model is solved as a preprocessing step, requires only seconds on a single GPU, and allows dynamic lighting changes at run-time. The ray tracing engine, which runs on one or multiple GPUs, combines multiple acceleration structures to achieve near real-time performance for large, complex scenes. Both the preprocessing step and the ray tracing engine make extensive use of NVIDIA's Compute Unified Device Architecture (CUDA).