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1

Measurement of MODIS optics effective focal length, distortion, and modulation transfer function  

NASA Astrophysics Data System (ADS)

A combination MODIS optics characteristics, short back focal length, and relatively distorting optics, has required major revisions in techniques used earlier to characterize effective focal length (EFL) and modulation transfer function (MTF) in the thematic mapper (TM) project. This paper compares measurement approaches used to characterize TM optics and revised methodology intended to characterize MODIS optics at an integration and assembly level.

Thurlow, Paul E.; Cline, Richard W.

1993-08-01

2

Variable focal length microlenses  

NASA Astrophysics Data System (ADS)

Refractive surface relief microlenses (150 ?m diameter) are immersed in nematic liquid crystal in a cell. Application of a variable voltage across the cell effectively varies the refractive index of the liquid crystal and results in a change of the focal length by the lensmakers formula (E. Hecht, Optics, 2nd edn., Addison-Wesley, Reading, Massachusetts, 1987, p. 138). We describe the cell design and construction and demonstrate a range of focal lengths from +490 to +1000 ?m for 2 to 12 V applied. A diverging lens results when the voltage is lower. Theoretical models are developed to account for some of the observed aberrations.

Commander, L. G.; Day, S. E.; Selviah, D. R.

2000-04-01

3

Design and improvement of long-focal-length space optical system  

NASA Astrophysics Data System (ADS)

According to technical requirements and the structure characteristics of long-focal-length optical system, the paper analyzes the advantages and shortcomings of reflective system and refractive system in details. By the aberration theory and ZEMAX optical design software, a long-focal-length space optical system which is characterized by the catadioptric configuration,with the spectrum band 500~ 800 nm is designed. And evaluations show that the image quality is close to the diffraction limit. After being manufactured, the optical transfer function (simplified MTF) of long-focal-length lens is tested, and it shows that the best focal planes of spectrum 500nm~800nm, 550 nm, 650nm are not in the same position and deviate greatly, which is chromatic aberration. Whereas, after remeasuring the long-focal-length lens, it is found that the MTF values of the three wavebands can meet the qualification requirements simultaneously if we defocus 57.7?m from the best focal plane of spectrum 500nm~800nm. Finally, the cause of chromatic aberration phenomenon in the measurement of catadioptric optical system is deeply discussed at the first time based on the structure characteristics of optical system, then the improvement is achieved correspondingly and the results show as below: the full-aperture spherochromatic aberration of improved optical system is reduced from 0.45?m to 0.25?m, and its MTF values are up to 0.6 plus. The technical requirements of high-precision, small size, light weight, good image quality are fulfilled.

Wei, Xiao-Xiao; Xu, Feng; Nie, Yun-Feng; Yu, Jian-Jun

2011-11-01

4

Rotating type miniature camera phone multi-focal-length optical system  

Microsoft Academic Search

We have designed a practical mass produced rotating type miniature camera phone multi-focal-length optical system. The compact\\u000a and short system, with 3× magnification, 1.3 megapixel sensor elements and total length of less than 10.7 mm, is described\\u000a and evaluated in detail. Using Zemax lens design software, we start the design with thin lenses first order layout, and then\\u000a spherical thick

Junewen Chen; Yao-Chen Tseng; Kai-Chun Chuang; Jung-Chao Chen; Shu-Yuan Lin

2009-01-01

5

Multi-focal length and multi-channel holographic optical element  

NASA Astrophysics Data System (ADS)

A new holographic optical element (HOE) consisting of the hololenses with different focal lengths and diffractional channels is described. The object space axes of all hololenses in the HOE are the same, while each optical axis in the image space is different. By the aid of such HOE, the object planes at different distances can be imaged into the corresponding channels. Therefore, a 3-D object field may be displayed by many 2-D images. The primary experimental results for sampling 3-D particles field are presented.

Ge, Zhou; Yimo, Zhang

1994-12-01

6

Compact optical imaging system for star tracker with long focal length and perfect thermal adaptability  

NASA Astrophysics Data System (ADS)

A star tracker optical imaging system is designed for Polaris detection. System parameters determination and its configuration chosen method are given. Based on Macsutov-Cassegrain configuration, the system is designed imagery tele-centric. It works at 0.6?m~1.1?m waveband and the view field is 0.5 degree. The tube length of the system is 80mm, which is only 8 percent of its focal length. Its MTF reaches diffraction limit and the spot diagrams are quit near a circle. About 80% of the energy is encircled in a CCD pixel. And the distortion is less than 1%. Moreover, it has a perfect thermal adaptability from -40° to 60°.

Ji, Yiqun; Shi, Rongbao; He, Hucheng; Xu, Li; Liu, Xuxia; Jin, Yangming; Shen, Weimin

2012-11-01

7

Variable focal length deformable mirror  

DOEpatents

A variable focal length deformable mirror has an inner ring and an outer ring that simply support and push axially on opposite sides of a mirror plate. The resulting variable clamping force deforms the mirror plate to provide a parabolic mirror shape. The rings are parallel planar sections of a single paraboloid and can provide an on-axis focus, if the rings are circular, or an off-axis focus, if the rings are elliptical. The focal length of the deformable mirror can be varied by changing the variable clamping force. The deformable mirror can generally be used in any application requiring the focusing or defocusing of light, including with both coherent and incoherent light sources.

Headley, Daniel (Albuquerque, NM); Ramsey, Marc (Albuquerque, NM); Schwarz, Jens (Albuquerque, NM)

2007-06-12

8

Focal length tunable fluidic adaptive lens  

Microsoft Academic Search

In this presentation, we demonstrate a fluidic adaptive lens inspired by animal eye's crystalline lens that can be deformed by muscles to adjust its focal length. Fluidic adaptive lenses, which can adjust their focal length by changing the shape or index without moving parts, are attractive. In summary, we have demonstrated a fluidic lens with an adjustable focal length over

Deying Zhang; Yu-Hwa Lo

2003-01-01

9

Microlenses with focal length controlled by chemical processes  

NASA Astrophysics Data System (ADS)

The influence of chemical processing on the optical properties of microlenses formed on a gelatin-sensitized layer was investigated. The gelatin is sensitized with tot'hema and eosin, irradiated with a Gaussian profile laser beam and subsequently chemically processed. Microlenses with a focal length of 400??m were obtained after alcohol processing. Additionally, focal lengths could be controlled by varying the alum concentration, and lenses with focal length up to 1.2?mm were obtained. The microlenses become stable after alum processing. Their optical properties remain unchanged.

Muric, B. D.; Panic, B. M.

2012-05-01

10

Crystal diffraction lens with variable focal length  

DOEpatents

A method and apparatus for altering the focal length of a focusing element of one of a plurality of pre-determined focal lengths by changing heat transfer within selected portions of the element by controlled quantities is disclosed. Control over heat transfer is accomplished by manipulating one or more of a number of variables, including: the amount of heat or cold applied to surfaces; type of fluids pumped through channels for heating and cooling; temperatures, directions of flow and rates of flow of fluids; and placement of channels. 19 figures.

Smither, R.K.

1991-04-02

11

Fast Focal Length Solution in Partial Panoramic Image Stitching  

Microsoft Academic Search

Accurate estimation of effective camera focal length is crucial to the success of panoramic image stitching. Fast techniques for estimating the focal length exist, but are de- pendent upon a close initial approximation or the existence of a full circle panoramic image sequence. Numerical so- lutions of the focal length demonstrate strong coupling be- tween the focal length and the

Kirk L. Duffin; William A. Barrett

2001-01-01

12

Variable-focal-length microelectromechanical lens  

Microsoft Academic Search

We discuss the characteristics of a novel microelectromechanical cylindrical focusing mirror having a focal length which is controlled by active and intrinsic stresses in the thin films composing it. The unactuated mechanical state of the mirror is determined by intrinsic stress levels in a SiN structural layer and a piezoelectric PZT actuator layer which are part of a doubly clamped

Mark J. Mescher; Michael L. Reed; Tuviah E. Schlesinger

1998-01-01

13

Variable-focal length lens using IPMC  

Microsoft Academic Search

We fabricated a liquid lens type variable-focal length lens(VFLL), which is composed of a container with a movable silicon plate having a pupil (diameter: 4 mm) covered by a thin polydimethylsiloxane (PDMS) film, a liquid enclosed in the container and a plural IPMCs fixed above the container for pushing the silicon plate downward. By applying a force to the silicon

Ippei SHIMIZU; Kunitomo KIKUCHI; Shigeki TSUCHITANI

2009-01-01

14

Design and fabrication of long focal length microlens arrays  

NASA Astrophysics Data System (ADS)

In this paper, we present microlens arrays (MLA) with long focal length (in millimeter range) based on thermal reflow process. The focal length of microlens is usually in the same order of lens diameter or several hundred microns. To extend focal length, we made a photoresist (SU-8) MLA covered by a Polydimethylsiloxane (PDMS) film on a glass substrate. Because the refractive index difference between PDMS and photoresist interface is lower than that of air and MLA interface, light is less bended when passing through MLA and is focused at longer distance. Microlenses of diameters from 50 ?m to 240 ?m were successfully fabricated. The longest focal length was 2.1 mm from the microlens of 240 ?m diameter. The numerical aperture (NA) was reduced 0.06, which is much lower than the smallest NA (~ 0.15) by regular thermal reflow processes. Cured PDMS has high transmittance and becomes parts of MLA without too much optical power loss. Besides, other focal lengths can be realized by modifying the refractive index different between two adjacent materials as described in this paper.

Hsieh, Hsin-Ta; Lin, Vinna; Hsieh, Jo-Lan; Su, Guo-Dung John

2011-10-01

15

Vibration isolation and damping for long focal length synchrotron radiation instruments  

Microsoft Academic Search

Vibrations of the optical elements in long focal length, high resolution monochromators and other long focal length optical systems used at synchrotron radiation facilities can lead to serious degradation of the performance of these systems. As higher resolution instruments with state-of-the-art spherical and plane elements come on line, vibration will become an increasingly serious problem. The vibrations excited in beamline

Roger W. C. Hansen; Eric Brodsky; Sherry Collier; Charles H. Pruett; Amir Salehzadeh; Dan Wallace; Fred Middleton

1988-01-01

16

Optical fibre tapers: focal reduction and magnification  

NASA Astrophysics Data System (ADS)

Optical fibre tapers show great promise as a simple and highly effective means of efficiently coupling broadband light into astronomical instruments. Fibre tapers can replace bulk optics systems such as focal plane reduction and magnification optics by controlling and manipulating image scale and beam angle in a small, robust and cost effective device. However, like any new photonic device fibre tapers must be thoroughly characterised before they can be applied to astronomy. The specific characteristics of importance are the device’s ability to maintain the etendue of the system and to transmit light over a broad wavelength range with minimal loss. In this paper we present the manufacturing technique and preliminary results for the first large taper transition prototype devices manufactured in-house intended for astronomy applications. Characteristics addressed include: beam angle, focal ratio degradation and throughput for devices with a conversion ratio of 5 (5 x focal reduction or magnification) for two taper transition lengths.

Haynes, Dionne M.; Haynes, Roger; Olaya, J. C.; Leon-Saval, Sergio G.

2012-09-01

17

Design and fabrication of long focal length microlens arrays  

Microsoft Academic Search

We present microlens array (MLA) with various structure and arrangement in long focal length (millimeter range) based on thermal reflow process. The microlens focal length is usually in the same order of lens diameter or several hundred microns. To extend the focal length, we made a photoresist MLA covered by Polydimethysiloxane (PDMS) film on a glass substrate. Because the refractive

Vinna Lin; Hsin-Ta Hsieh; Jo-Lan Hsieh; Guo-Dung John Su

2011-01-01

18

Design and fabrication of long focal length microlens arrays  

Microsoft Academic Search

In this paper, we present microlens arrays (MLA) with long focal length (in millimeter range) based on thermal reflow process. The focal length of microlens is usually in the same order of lens diameter or several hundred microns. To extend focal length, we made a photoresist (SU-8) MLA covered by a Polydimethylsiloxane (PDMS) film on a glass substrate. Because the

Hsin-Ta Hsieh; Vinna Lin; Jo-Lan Hsieh; Guo-Dung John Su

2011-01-01

19

Multilayer Laue Lenses with Focal Length of 10 mm  

NASA Astrophysics Data System (ADS)

Multilayer laue lenses are diffractive optics with a high potential for producing X-ray foci in the order of 10 nm or even below. Particularly for hard X-rays (E > 6 keV) these optics promise better resolution and higher efficiencies than currently available Fresnel zone plates. Magnetron sputter deposition has been used for the fabrication of multilayer laue lenses using the layer materials MoSi2 and Si. The lens design has been defined to get focal length in the order of 10 mm. One of the lenses with an aperture of about 20 ?m has been used as focusing optics in the nanoprobe beamline P06 at PETRA III. Ptychography has been applied to characterize the caustic of the focused beam and to determine the size of the X-ray focus. A spot size of about 39 nm could be obtained with a photon energy of 21 keV and a focal length of 9.9 mm.

Braun, S.; Kubec, A.; Menzel, M.; Niese, S.; Krüger, P.; Seiboth, F.; Patommel, J.; Schroer, C.

2013-03-01

20

Recursive Estimation of Motion, Structure, and Focal Length  

Microsoft Academic Search

We present a formulation for recursive recoveryof motion, pointwise structure, and focal length from featurecorrespondences tracked through an image sequence.In addition to adding focal length to the state vector, severalrepresentational improvements are made over earlierstructure from motion formulations, yielding a stable andaccurate estimation framework which applies uniformly toboth true perspective and orthographic projection. Resultson synthetic and real imagery illustrate the...

Ali Azarbayejani; Alex P. Pentland

1995-01-01

21

Design of a twenty-element long focal length zoom lens.  

National Technical Information Service (NTIS)

An optical lens system with varying magnification has been designed for a 70-mm image format. Twenty optical elements were needed to provide for the 345- to 1050-mm focal length zoom range as well as the proper color correction over the visible spectrum. ...

R. M. Malone B. C. Frogget D. A. Grafton F. R. Mitchell

1990-01-01

22

A micro optofluidic lens with short focal length  

NASA Astrophysics Data System (ADS)

A micro optofluidic lens is formed by laminar streams of immiscible liquids with different refractive indices. This paper reports modelling and characterization for a new design of a micro optofluidic lens. The lens has a circular chamber allowing the formation of interfaces with a perfect arc shape. The inlet and the outlet of the lens chamber are placed with an offset to the chamber axis to achieve a radius of curvature smaller than the limiting chamber radius. A model mathematically predicts the relationship between the flow rate ratio and the curvature of the interface and the resulting focal length. The device was fabricated and tested with laser light guided by optical fibres. Experiments were carried out to verify the analytical model. Benzyl alcohol and ethylene glycol were used as optical media to form the lens. Due to the small radius of curvature, better focusing ability than the previous symmetric design was achieved. On-chip focusing with fibre-to-fibre transmission was demonstrated with this micro optofluidic lens.

Song, Chaolong; Nguyen, Nam-Trung; Tan, Say-Hwa; Asundi, Anand Krishna

2009-08-01

23

Design of a twenty-element long focal length zoom lens  

Microsoft Academic Search

An optical lens system with varying magnification has been designed for a 70-mm image format. Twenty optical elements were needed to provide for the 345- to 1050-mm focal length zoom range as well as the proper color correction over the visible spectrum. A 4-in diameter port window limits the f\\/{number sign} of the optical lens system. Operation of the lens

Robert M. Malone; Brent C. Frogget; David A. Grafton; Frank R. Mitchell

1990-01-01

24

Four-group stabilized zoom lens design of two focal-length-variable elements.  

PubMed

We present a theoretical method for analyzing the first-order optics of stabilized zoom lenses with two focal-length-variable elements. The zoom equations are established through the use of the Gaussian brackets method. This is done because the optical power of the focal-length-variable elements varies during the zooming process. The first and second derivatives and the Hessian matrix of the zoom equations with respect to the Gaussian parameters are determined using the equations. These parameters could represent the sensitivity of the zoom ratio of the system to changes in the corresponding system variables. We select the initial values of these system variables, i.e. the magnification of the focal-length-variable element and the structure parameters of the fixed lens group, to be close to the steepest gradient direction. Here the sensitivity of the system focal length is high with respect to variations in the zoom variables. This process leads to an increase in the zoom ratio of the zoom system. The results show successful four-group stabilized zoom lens designs with 2:1 and 5:1 zoom ratios, using two deformable mirrors as focal-length-variable elements. This system, with the inherent characteristics of a steepest gradient, could miniaturize zoom systems. PMID:23546157

Hao, Qun; Cheng, Xuemin; Du, Ke

2013-03-25

25

Switchable fiber coupling using variable-focal-length microlenses  

Microsoft Academic Search

An array of microlenses, with focal lengths that can be electrically varied, can control the coupling of light into a single mode fiber using an applied voltage. We have examined this technology with a view to the design of a confocal microlens\\/image-fiber endoscope. Maximum coupling to the fiber was found to occur over a voltage range of ?1 V and

P. J. Smith; C. M. Taylor; E. M. McCabe; D. R. Selviah; S. E. Day; L. G. Commander

2001-01-01

26

Switchable fiber coupling using variable-focal-length microlenses  

Microsoft Academic Search

An array of microlenses, with focal lengths that can be electrically varied, can control the coupling of light into a single mode fiber using an applied voltage. We have examined this technology with a view to the design of a confocal microlens\\/image-fiber endoscope. Maximum coupling to the fiber was found to occur over a voltage range of ~1 V and

P. J. Smith; C. M. Taylor; E. M. McCabe; D. R. Selviah; S. E. Day; Commander L. G

2001-01-01

27

Refractive beryllium x-ray lens with variable focal length  

Microsoft Academic Search

A refractive lens for hard X-rays comprising two saw-tooth profiles is presented. This lens has the same focusing properties as a parabolic compound refractive lens. One advantage is the remarkably low fabrication cost, since curved surfaces are replaced by planar ones. In addition, the focal length of the lens can be easily varied by adjusting the angle between the two

Bjoern Cederstroem; Mats Danielsson; Mats Lundqvist

2001-01-01

28

Improvement in the measurement of focal length using spot patterns and spherical aberration.  

PubMed

Using an optical setup that includes a square array of 3×3 holes, we used nine meridional rays to measure the effective focal length of a lens. We observed the selected meridional rays as a spot pattern on a diffuse screen. First, we generated a regular square spot pattern (reference pattern) without a lens to test, and then we generated two spot patterns in two different axial positions when the lens being tested refracts the rays. By selecting two sets of four rays of each spot pattern, we were able to measure the difference of the longitudinal (primary) spherical aberration in two positions. With this difference we were able to improve the calculation of the effective focal length. To determine the method's precision, we first simulated the relative error in the effective focal length considering the error in the measurement of the ray heights. Then we determined the experimental relative error by means of the standard deviation of the focal lengths obtained for each spot (in the image of reference and for the images at the two different locations) for both sets of four spots. The experimental results agree very well with the simulation. The error analysis allows us to establish under what conditions it is possible to obtain relative errors of less than 1% in the effective focal length. PMID:23938404

Mejía, Yobani

2013-08-10

29

Alignment techniques required by precise measurement of effective focal length  

NASA Astrophysics Data System (ADS)

The characteristics of false color imagery produced by instrumentation on earth resource mapping satellites are examined. The spatial fidelity of the imagery is dependent upon the geometric accuracy (GA) and the band-to-band registration (BBR) with which the telescope instrument is assembled. BBR and GA require knowledge of telescope effective focal length (EFL) to one part in 10,000 in order that the next generation of earth mappers be able to carry out their missions. The basis for this level of precision is briefly considered, and a description is given of the means by which such precise EFL measurements have been carried out. Attention is given to accuracy requirements, the technique used to measure effective focal length, possible sources of error in the EFL measurement, approaches for eliminating errors, and the results of the efforts to control measurement errors in EFL determinations.

Wise, T. D.

1980-01-01

30

Polymer microlens with independent control of radius and focal length for an imaging fiber  

NASA Astrophysics Data System (ADS)

Fabrication of microlens array using polymer reflow is beginning to be a mainstream process, whether the polymer is directly used or whether the spherical profile is transferred by plasma etching to a glass substrate as, for example, in some handphone cameras. The focus so far has been on uniformity and obtaining lenses with equal radius and equal focal length. Actually it is easy to show using a phenomenological model that the focal length is depending on the lens radius, and not much on the contact angle, an effect that can be traced to the line tension force. For a biomedical application we need to terminate a 600um diameter imaging fiber with a group of lenses of different diameters - but with similar focal length. We have devised a microfabrication process on a silicon wafer to produce the lens with variable diameter and identical focal length, while etching the silicon wafer has helped us producing a sheath to insert the optical fiber and mount the lenses on the optical fiber.

Ashraf, Mohammed; Chollet, Franck; Matham, Murukeshan; Yang, Chun

2006-12-01

31

Optical interconnections to focal plane arrays  

SciTech Connect

The authors have successfully demonstrated an optical data interconnection from the output of a focal plane array to the downstream data acquisition electronics. The demonstrated approach included a continuous wave laser beam directed at a multiple quantum well reflectance modulator connected to the focal plane array analog output. The output waveform from the optical interconnect was observed on an oscilloscope to be a replica of the input signal. They fed the output of the optical data link to the same data acquisition system used to characterize focal plane array performance. Measurements of the signal to noise ratio at the input and output of the optical interconnection showed that the signal to noise ratio was reduced by a factor of 10 or more. Analysis of the noise and link gain showed that the primary contributors to the additional noise were laser intensity noise and photodetector receiver noise. Subsequent efforts should be able to reduce these noise sources considerably and should result in substantially improved signal to noise performance. They also observed significant photocurrent generation in the reflectance modulator that imposes a current load on the focal plane array output amplifier. This current loading is an issue with the demonstrated approach because it tends to negate the power saving feature of the reflectance modulator interconnection concept.

Rienstra, J.L.; Hinckley, M.K.

2000-11-01

32

Simple focal-length measurement technique with a circular Dammann grating  

NASA Astrophysics Data System (ADS)

A novel technique for focal-length measurements with a circular Dammann grating is presented. In the back focal plane of the lens under test, a one-order circular Dammann grating with limited aperture will produce double-humped radial rings. The separation between the two lobes varies with the displacement of the observed plane from the focal plane of the lens. By searching for the position at which the separation is minimal, the focal point of the lens can be located and hence the back focal length can be determined. Experimental results demonstrated that this method is efficient and can be used effectively for a quick check of focal length.

Zhao, Shuai; Fung Wen, Jacky; Sheun Chung, Po

2007-01-01

33

Microspot x-ray focusing using a short focal-length compound refractive lenses  

Microsoft Academic Search

We have fabricated and tested short focal-length compound refractive lenses (CRLs) composed of microbubbles embedded in epoxy encased in glass capillaries. The interface between the bubbles formed 90 to 350 spherical biconcave microlenses reducing the overall focal length inversely by the number of lenses or bubbles. When compared with CRLs manufactured using other methods, the microbubble lenses have shorter focal

Y. I. Dudchik; N. N. Kolchevsky; F. F. Komarov; M. A. Piestrup; J. T. Cremer; C. K. Gary; A. M. Khounsary

2004-01-01

34

Design of a twenty-element long focal length zoom lens  

SciTech Connect

An optical lens system with varying magnification has been designed for a 70-mm image format. Twenty optical elements were needed to provide for the 345- to 1050-mm focal length zoom range as well as the proper color correction over the visible spectrum. A 4-in diameter port window limits the f/{number sign} of the optical lens system. Operation of the lens system is done by actuating stepping motors through a MacPlus computer. This lens system was designed for Los Alamos National Laboratory Group M-8, because no commercial zoom lens existed that would change its reduction from 1/15 to 1/4 at a focusing range of 5 meters. Additionally, we required a larger, non-standard image size that could be recorded by a rotating mirror streak camera. A Nikkor lens sales manual does offer a long focal length, 35-mm lens only upon special order. The closest focusing range of this Nikkor lens is 6 meters. 2 refs., 4 figs., 1 tab.

Malone, R.M.; Frogget, B.C. (EG and G, Inc., Los Alamos, NM (USA)); Grafton, D.A. (Grafton (David A.), Santa Monica, CA (USA)); Mitchell, F.R. (Mitchell (Frank) and Associates, South Pasadena, CA (USA))

1990-01-01

35

Micro-optic integration with focal plane arrays  

NASA Astrophysics Data System (ADS)

The large detector size of conventional focal plane arrays (FPAs) often acts as a limiting source of noise currents and requires these devices to run at undesirably low temperatures. To reduce the detector size without reducing the detector's quantum efficiency (QE), we have developed efficient on-focal-plane collection optics consisting of arrays of thin-film binary-optics microlenses and photoresist-based refractive microlenses on the back surface of hybrid detector array structures. Photodiodes of p/n polarity, of an unusual planar-mesa geometry, were fabricated in epitaxial HgCdTe deposited by molecular beam epitaxy (MBE) on the front side of a CdZnTe substrate. Diffractive (8- to 16-phase-level) Ge microlenses were deposited on 48-micrometer centers in a registered fashion (using an IR mask aligner and appropriate marks on the front surface of the CdZnTe) on the back side of the substrate using a lifting process. The lifting circumvents some of the process limitations of the more conventional chemical etching methods on diffractive-microlens processing, allowing the microlenses to approach more closely their theoretical efficiency limit of greater than 95%. Photoresist microlenses were fabricated by reflow of photolithographically defined photoresist islands. Prior to microlens deposition, but after diode fabrication, the test structures were flip-chip bonded or 'hybridized' using indium interconnections to metallic striplines that had been photolithographically deposited on sapphire dice (a process equally compatible with a silicon-integrated-circuit readout). After hybridization, the CdZnTe was thinned to equal the focal length of the lenses in the CdZnTe material. Optical characterization has demonstrated that the microlenses combined with the detector mesas concentrate light sufficiently to increase the effective collection area. The optical size of the mesa detectors being larger than the theoretical diffraction limit of the microlenses precludes determining whether the lenses themselves produce the theoretical diffraction-limited gain, but they clearly decrease the required detector area by at least 3 to 6 times. To our knowledge, this is the first successful demonstration of IR detectors and binary optics and of photoresist refractive-microlens integration.

Motamedi, M. Edward; Tennant, William E.; Sankur, Haluk O.; Melendes, Robert; Gluck, Natalie S.; Park, Sangtae; Arias, Jose M.; Bajaj, Jagmohan; Pasko, John G.; McLevige, William V.; Zandian, Majid; Hall, Randolph L.; Steckbauer, Karla G.; Richardson, Patti D.

1997-05-01

36

Focal length hysteresis of a double-liquid lens based on electrowetting  

NASA Astrophysics Data System (ADS)

In this paper, an extended Young equation especially suited for an ideal cylindrical double-liquid variable-focus lens is derived by means of an energy minimization method. Based on the extended Young equation, a kind of focal length hysteresis effect is introduced into the double-liquid variable-focus lens. Such an effect can be explained theoretically by adding a force of friction to the tri-phase contact line. Theoretical analysis shows that the focal length at a particular voltage can be different depending on whether the applied voltage is increasing or decreasing, that is, there is a focal length hysteresis effect. Moreover, the focal length at a particular voltage must be larger when the voltage is rising than when it is dropping. These conclusions are also verified by experiments.

Peng, Runling; Wang, Dazhen; Hu, Zhiwei; Chen, Jiabi; Zhuang, Songlin

2013-02-01

37

Sensor for Radiometric Measurements with Pyroelectric Detector and Reflecting Objective of Long Focal Length.  

National Technical Information Service (NTIS)

A sensor which permits radiometric and pyrometric measurements is described. The sensor is equipped with a cassegrain reflecting objective of long focal length. Radiation measurements are made in a chopped radiation mode at chopping frequencies between 6 ...

U. Mester W. Glockmann E. Pudelko

1980-01-01

38

Micro-optic integration with focal plane arrays  

Microsoft Academic Search

The large detector size of conventional focal plane arrays (FPAs) often acts as a limiting source of noise currents and requires these devices to run at undesirably low temperatures. To reduce the detector size without reducing the detector's quantum efficiency (QE), we have developed efficient on-focal-plane collection optics consisting of arrays of thin-film binary-optics microlenses and photoresist-based refractive microlenses on

M. Edward Motamedi; William E. Tennant; Haluk O. Sankur; Robert Melendes; Natalie S. Gluck; Sangtae Park; Jose M. Arias; Jagmohan Bajaj; John G. Pasko; William V. McLevige; Majid Zandian; Randolph L. Hall; Karla G. Steckbauer; Patti D. Richardson

1997-01-01

39

Simplified model of an O-ring-driven liquid-filled lens for calculating focal length  

Microsoft Academic Search

The purpose of this study was to develop a mathematical model that could be used to obtain the approximate focal length of O-ring-driven liquid-filled lenses. An O-ring-driven liquid-filled lens is composed of a base plate, a glass-covered liquid reservoir, a pliable membrane, an O-ring, a spring, and three actuators. The movement of the ring changes the focal length or the

Chih-Wei Lin; Dein Shaw

2009-01-01

40

Novel approach to optical profiler with gradient focal point methods.  

PubMed

Novel gradient focal point (GFP) methods by use of the gradient curvature cylindrical lens, the gradient thickness cylindrical lens and a tilted imaging sensor are proposed for the optical profiler. With the employed simple idea that the different divergence angle of an input beam to the lens generates the different focal position, the height information of one point can be obtained just in a single-shot by GFP approaches. The feasibility of the proposed system is demonstrated to be an alternative to optical profilers. PMID:23188270

Leeghim, Henzeh; Ahn, MyoungKi; Kim, Kwangsoo

2012-10-01

41

Multi-focal optical-resolution photoacoustic microscopy in vivo  

PubMed Central

Although ultrasound arrays were exploited in photoacoustic imaging to improve imaging speed, ultrasound-array-based optical-resolution photoacoustic microscopy (OR-PAM) has never been achieved previously. Here we present our development of multi-focal OR-PAM using a microlens array for optical illumination and an ultrasound array for photoacoustic detection. Our system is capable of imaging hemoglobin concentration and oxygenation in individual microvessels in vivo at high speed. Compared with a single focus, multiple foci reduce the scanning load and increase the imaging speed significantly. The current multi-focal system can acquire 1000 × 500 × 200 voxels at ~10-?m lateral resolution within 4 min.

Song, Liang; Maslov, Konstantin; Wang, Lihong V.

2011-01-01

42

Multi-mode fiber optically coupling a radiation source module to a multi-focal confocal microscope  

US Patent & Trademark Office Database

A multi-mode optical fiber delivers light from a radiation source to a multi-focal confocal microscope with reasonable efficiency. A core diameter of the multi-mode fiber is selected such that an etendue of light emitted from the fiber is not substantially greater than a total etendue of light passing through a plurality of pinholes in a pinhole array of the multi-focal confocal microscope. The core diameter may be selected taking into account a specific optical geometry of the multi-focal confocal microscope, including pinhole diameter and focal lengths of relevant optical elements. For coherent radiation sources, phase randomization may be included. A multi-mode fiber enables the use of a variety of radiation sources and wavelengths in a multi-focal confocal microscope, since the coupling of the radiation source to the multi-mode fiber is less sensitive to mechanical and temperature influences than coupling the radiation source to a single mode fiber.

Berman; Richard (King City, CA)

2012-09-25

43

Liquid Crystal Microlens Arrays With Switchable Positive and Negative Focal Lengths  

Microsoft Academic Search

A flat microlens array whose focal length can be switched from positive to negative by electric field is demonstrated experimentally and confirmed by computer simulations. To generate the required gradient refractive index, an inhomogeneous electric field is created by a spherical indium-tin-oxide (ITO) electrode which is imbedded in the top flat substrate. The bottom substrate has a planar ITO electrode

Yun-Hsing Fan; Hongwen Ren; Xiao Liang; Haiying Wang; Shin-Tson Wu

2005-01-01

44

Shack-Hartmann wavefront sensor with high sensitivity by using long focal length microlens array  

Microsoft Academic Search

The performance of Shack-Hartmann wavefront sensor (SHWFS) is mainly described by the accuracy, spatial resolution, dynamic range, and sensitivity of the measurement. These factors are particularly affected by the design of the microlens array (MLA). In order to provide a large dynamic range of wavefront measurement, most of the conventional and commercial SHWFS implemented a short focal length lenslet array,

Vinna Lin; Hsiang-Chun Wei; Guo-Dung J. Su

2011-01-01

45

Longwave IR focal-plane binary optics  

Microsoft Academic Search

In this paper we discuss a choice between the diffr active and refractive binary micro-lenses for the longwave IR FPA. To investigate diffraction on the micro-lenses we have used a numerical code based-on the rigorous electromagnetic theory, because neither ge ometrical optics nor thin element approach of scala r diffraction theory can correctly describe waveguide , shadowing and interference effects

Z. Sikorski; H. Polakowski

46

Shack-Hartmann wavefront sensor with high sensitivity by using long focal length microlens array  

NASA Astrophysics Data System (ADS)

The performance of Shack-Hartmann wavefront sensor (SHWFS) is mainly described by the accuracy, spatial resolution, dynamic range, and sensitivity of the measurement. These factors are particularly affected by the design of the microlens array (MLA). In order to provide a large dynamic range of wavefront measurement, most of the conventional and commercial SHWFS implemented a short focal length lenslet array, which means that the measurement sensitivity is being sacrificed and the accuracy of the wavefront sensor will be degraded. However, it is also critical to detect very small displacement of SHWFS spot in order to reconstruct it into a fine wavefront variation. We fabricated long focal length MLA with various structure arrangement by thermal reflow process with Polydimethysiloxane (PDMS) cover on the glass substrate and implemented them on the image system. A longer focal length will provide high sensitivity in determining the average slope across each lenslet under a given wavefront, and the spatial resolution of the wavefront sensor is increased by the number of lenslets across the detector. The experimental setup consists of the fabricated 245 ?m diameter MLA which provides a 5.2 mm long focal distance and is paired with the CMOS as the detector. The observable smallest sensitivity is around wavelength/20 (?=630nm).

Lin, Vinna; Wei, Hsiang-Chun; Su, Guo-Dung J.

2011-09-01

47

Intensity distribution near focal point of high aperture optical system formed by partly polarized light  

NASA Astrophysics Data System (ADS)

The paper presents the mathematical technique for calculation of three dimensional intensity distribution near a focal point of a high aperture optical system in case of quasi monochromatic partly polarized light. This technique is extension of the vector diffraction theory for high aperture optical systems. It is based on Huygens-Fresnel principle: spherical wave at an exit pupil is considered as a numerous set of elementary secondary partly polarized light sources. The total intensity is calculated as superposition of complex wave amplitudes taking into account polarization orientation, degree of polarization defined by Stokes parameters, orientation of detector aperture and coherence length of quasi-monochromatic light.

Borovytsky, Volodymyr; Chorna, Viktoriia

2009-08-01

48

Hard X-ray microbeam lithography using a Fresnel zone plate with a long focal length.  

PubMed

Focused hard X-ray microbeams for use in X-ray nanolithography have been investigated. A 7.5?keV X-ray beam generated at an undulator was focused to about 3?µm using a Fresnel zone plate fabricated on silicon. The focused X-ray beam retains a high degree of collimation owing to the long focal length of the zone plate, which greatly facilitates hard X-ray nanoscale lithography. The focused X-ray microbeam was successfully utilized to fabricate patterns with features as small as 100?nm on a photoresist. PMID:21335899

Lee, S Y; Cho, I H; Kim, J M; Kang, H C; Noh, D Y

2010-12-02

49

Low voltage adaptive 128×128 element liquid crystal micro lens array with electric tunable focal length  

NASA Astrophysics Data System (ADS)

A new LC micro-lens array of 128×128 elements circular hole top electrode is proposed, which is fabricated by both the lithography and HCL etching methods. Some valuable results are got in tests. The focal length of LC micro-lens array is 50?m~400?m under operating voltage from 0.2VRMS to 5.0VRMS. The lowest operating voltage of LC micro-lens array is 0.2VRMS. The size of focus is about 10?m. And the PSF of LC micro-lens array is close to the theory values. The optical multiple images which are got by LC micro-lens array are clear.

Li, Hui; Liu, Kan; Zhang, Xinyu; Zhang, Tianxu; Shen, Xubang

2009-08-01

50

Scaling of the generation of high-order harmonics in large gas media with focal length  

NASA Astrophysics Data System (ADS)

We present theoretical and experimental results on high-order harmonic generation in a low-density few-centimeter-long gas medium (Lmed? 10 cm). We study the dependence with focal length of harmonic efficiency. Theoretically, we consider in detail the generation of the 25th harmonic of a short pulse Ti:sapphire laser in argon. Within the strong-field approximation for the atomic dipole, and a complete account of the macroscopic propagation, we compute the number of photons produced as a function of the medium parameters and the focusing conditions. The simulations show that, at constant intensity, the emission of the 25th harmonic scales with the focal length as ˜f4 at low pressure (P=2 Torr) and as ˜f6 at higher pressure (P=5 Torr). At constant laser energy, we find that the harmonic signal scales approximately as f2 at low pressure and as f4 at higher pressure. Those numerical results are compared with experimental data.

Boutu, W.; Auguste, T.; Caumes, J. P.; Merdji, H.; Carré, B.

2011-11-01

51

Materials for intraocular lenses enabling photo-controlled tuning of focal length in vivo  

NASA Astrophysics Data System (ADS)

Typical postoperative complications in cataract surgery are that refractive power and curvature of the implanted intraocular lens (IOL) do not have optimum values, requiring the patient to wear viewing aids. This is mainly because biometric data relevant for calculation of the IOL's shape cannot be determined with the required precision. Hence, there is a need for methods to tune the focal length postoperatively in a non-invasive manner. We have developed polymers where we can induce a change in refractive index by linking or cleaving bonds between a su.ciently large number of side groups of the polymer main chain in a photoinduced cycloaddition or cycloreversion reaction, respectively. These photoreactions lead to a change in refractive index great enough to be interesting for the concept of in vivo tunable IOL's. The photochemical reaction can be triggered by a two-photon process (TPA) using a pulsed laser system, i.e. the energy required for bond breaking is provided by two photons in the visible range. This is important because light in the UV cannot induce undesired changes of the refractive index owing to the strong UV-absorption of the cornea. Undesired changes due to light in the visible range of the spectrum are unlikely to happen because photon density of sun light is much too low for TPA. Due to the excellent spatial resolution that can be achieved with two-photon processes one cannot only modify the refractive index of the entire lens but also selectively in well defined areas enabling to correct for aberrations such as astigmatism. Here, we present new polymers that do not only exhibit a photo induced change of refractive index great enough to induce a change of focal length of more than two diopters in a standard IOL. These new polymers have also significantly improved material properties with respect to the fabrication of the IOL and the TPA-sensitivities and the light energy required to induce the refractive index change.

Träger, Jens; Heinzer, Jasmin; Kim, Hee-Cheol; Hampp, Norbert

2007-06-01

52

Brain SPECT with short focal-length cone-beam collimation  

SciTech Connect

Single-photon emission-computed tomography (SPECT) imaging of deep brain structures is compromised by loss of photons due to attenuation. We have previously shown that a centrally peaked collimator sensitivity function can compensate for this phenomenon, increasing sensitivity over most of the brain. For dual-head instruments, parallel-hole collimators cannot provide variable sensitivity without simultaneously degrading spatial resolution near the center of the brain; this suggests the use of converging collimators. We have designed collimator pairs for dual-head SPECT systems to increase sensitivity, particularly in the center of the brain, and compared the new collimation approach to existing approaches on the basis of performance in estimating activity concentration of small structures at various locations in the brain. The collimator pairs we evaluated included a cone-beam collimator, for increased sensitivity, and a fan-beam collimator, for data sufficiency. We calculated projections of an ellipsoidal uniform background, with 0.9-cm-radius spherical lesions at several locations in the background. From these, we determined ideal signal-to-noise ratios (SNR{sub CRB}) for estimation of activity concentration within the spheres, based on the Cramer-Rao lower bound on variance. We also reconstructed, by an ordered-subset expectation-maximization (OS-EM) procedure, images of this phantom, as well as of the Zubal brain phantom, to allow visual assessment and to ensure that they were free of artifacts. The best of the collimator pairs evaluated comprised a cone-beam collimator with 20 cm focal length, for which the focal point is inside the brain, and a fan-beam collimator with 40 cm focal length. This pair yielded increased SNR{sub CRB}, compared to the parallel-parallel pair, throughout the imaging volume. The factor by which SNR{sub CRB} increased ranged from 1.1 at the most axially extreme location to 3.5 at the center. The gains in SNR{sub CRB} were relatively robust to mismatches between the center of the brain and the center of the imaging volume. Artifact-free reconstructions of simulated data acquired using this pair were obtained. Combining fan-beam and short-focusing cone-beam collimation should greatly improve dual-head brain SPECT imaging, especially for centrally located structures.

Park, Mi-Ae; Moore, Stephen C.; Kijewski, Marie Foley [Department of Radiology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115 (United States)

2005-07-15

53

Focal Plane Wavefront Sensing Using Residual Adaptive Optics Speckles  

NASA Astrophysics Data System (ADS)

Optical imperfections, misalignments, aberrations, and even dust can significantly limit sensitivity in high-contrast imaging systems such as coronagraphs. An upstream deformable mirror (DM) in the pupil can be used to correct or compensate for these flaws, either to enhance the Strehl ratio or suppress the residual coronagraphic halo. Measurement of the phase and amplitude of the starlight halo at the science camera is essential for determining the DM shape that compensates for any non-common-path (NCP) wavefront errors. Using DM displacement ripples to create a series of probe and anti-halo speckles in the focal plane has been proposed for space-based coronagraphs and successfully demonstrated in the lab. We present the theory and first on-sky demonstration of a technique to measure the complex halo using the rapidly changing residual atmospheric speckles at the 6.5 m MMT telescope using the Clio mid-IR camera. The AO system's wavefront sensor measurements are used to estimate the residual wavefront, allowing us to approximately compute the rapidly evolving phase and amplitude of speckle halo. When combined with relatively short, synchronized science camera images, the complex speckle estimates can be used to interferometrically analyze the images, leading to an estimate of the static diffraction halo with NCP effects included. In an operational system, this information could be collected continuously and used to iteratively correct quasi-static NCP errors or suppress imperfect coronagraphic halos.

Codona, Johanan L.; Kenworthy, Matthew

2013-04-01

54

Direct photofabrication of focal-length-controlled microlens array using photoinduced migration mechanisms of photosensitive sol-gel hybrid materials  

Microsoft Academic Search

Photosensitive sol-gel hybrid (SGH) materials exhibited the peculiar photoinduced migration behavior of unreacted molecules from unexposed areas to exposed areas by selective UV exposure. Using the photoinduced migration mechanism of the photosensitive SGH materials, the microlens array (MLA) with a smooth surface was directly photofabricated, and the focal length was controlled by changing the photoinduced migration parameters. The higher photoactive

Dong Jun Kang; Jong-Pil Jeong; Byeong-Soo Bae

2006-01-01

55

X-ray imaging inside the focal spot of polycapillary optics using the coded aperture concept.  

PubMed

We present a method for x-ray imaging of objects inside the focal spot of polycapillary optics that resolves details smaller than the focal spot dimensions. This method employs coded aperture imaging, in which the micro-structure of polycapillary optics is treated as the coding pattern. Projection of the object is decoded from a magnified x-ray image of the polycapillary structure which is specifically sharpened by the object. Field of view can be extended by scanning the object across the focal spot. PMID:23481750

D?browski, K M; Dul, D T; Korecki, P

2013-02-11

56

Path-length-resolved optical Doppler perfusion monitoring.  

PubMed

We report the first path-length-resolved perfusion measurements on human skin measured with a phase-modulated low-coherence Mach-Zehnder interferometer with spatially separated fibers for illumination and detection. Optical path lengths of Doppler shifted and unshifted light and path-length-dependent Doppler broadening of multiply scattered light from skin are measured from the Doppler broadened interference peaks appearing in the power spectrum. Perfusion and its variations during occlusion are measured in real time for a given optical path length, and the results are compared with the perfusion signal obtained with a conventional laser Doppler perfusion monitor. PMID:18163803

Varghese, Babu; Rajan, Vinayakrishnan; Van Leeuwen, Ton G; Steenbergen, Wiendelt

57

Polarization-dependent optical tuning of focal intensity of liquid crystal polymer microlens array  

Microsoft Academic Search

This work demonstrates the feasibility of a microlens array (MLA) with a focal intensity that can be optically tuned by controlling the polarization of incident light. The proposed MLA has a focusing unit based on birefringent liquid crystalline polymer (LCP) and a tuning unit with a photo-alignment layer for controlling the polarization state of incident laser light. The optically variable

S.-Y. Huang; T.-C. Tung; C.-L. Ting; H.-C. Jau; M.-S. Li; H.-K. Hsu; A. Y.-G. Fuh

2011-01-01

58

Fabrication of a focal length variable microlens array based on a nematic liquid crystal  

Microsoft Academic Search

We fabricated a two-dimensional liquid crystal microlens array using a surface relief structure of ultraviolet (UV) curable polymer. The surface relief structure is produced by the spatially modulated UV exposure of the polymer through a photomask. Application of a voltage to the microlens changes the effective refractive index of the liquid crystal layer, which gives the change of a focal

Yoonseuk Choi; Jae-Hong Park; Jae-Hoon Kim; Sin-Doo Lee

2003-01-01

59

Spot size and effective focal length measurements for a fast axial flow CO{sub 2} laser  

SciTech Connect

An evaluation of the variation in focal plane position and spot size for a 1,650 W fast axial flow CO{sub 2} laser was performed. Multiple measurements of the focused beam were taken at stepped intervals along the beam axis to create a composite representation of the focus region. Measurements were made at several power levels from low to full power for each of five nominally identical lenses. It was found that as laser output power increases, the minimum focused spot radius increases, and the position of minimum focus shifts toward the laser resonator. These effects were attributed to observed variations in the diameter of the beam entering the focusing lens. For the ZnSe (f = 127 mm) lenses examined, variations in spot radius and focal plane position were seen. Lenses with high rated absorption had a larger variation in spot size and effective focal length than those with low absorption. Lenses that had previously been degraded by welding had the greatest variation.

Steele, R.J. [Naval Air Warfare Center, China Lake, CA (United States); Fuerschbach, P.W.; MacCallum, D.O. [Sandia National Labs., Albuquerque, NM (United States)

1997-12-31

60

Polarization-dependent optical tuning of focal intensity of liquid crystal polymer microlens array  

NASA Astrophysics Data System (ADS)

This work demonstrates the feasibility of a microlens array (MLA) with a focal intensity that can be optically tuned by controlling the polarization of incident light. The proposed MLA has a focusing unit based on birefringent liquid crystalline polymer (LCP) and a tuning unit with a photo-alignment layer for controlling the polarization state of incident laser light. The optically variable refractive indices of LCP allow a positive or negative MLA to be realized by controlling the polarization of the incident light.

Huang, S.-Y.; Tung, T.-C.; Ting, C.-L.; Jau, H.-C.; Li, M.-S.; Hsu, H.-K.; Fuh, A. Y.-G.

2011-07-01

61

Polarization-dependent optical tuning of focal intensity of liquid crystal polymer microlens array  

Microsoft Academic Search

This work demonstrates the feasibility of a microlens array (MLA) with a focal intensity that can be optically tuned by controlling\\u000a the polarization of incident light. The proposed MLA has a focusing unit based on birefringent liquid crystalline polymer\\u000a (LCP) and a tuning unit with a photo-alignment layer for controlling the polarization state of incident laser light. The optically\\u000a variable

S.-Y. Huang; T.-C. Tung; C.-L. Ting; H.-C. Jau; M.-S. Li; H.-K. Hsu; A. Y.-G. Fuh

2011-01-01

62

Fiber optic acoustic hydrophone with double Mach–Zehnder interferometers for optical path length compensation  

Microsoft Academic Search

We report on the development of a fiber optic acoustic hydrophone which consists of a sensing Mach–Zehnder (MZ) interferometer and a compensating MZ interferometer for optical path length compensation. This double-interferometer configuration has the following advantages: the hydrophone is a true heterodyne device; a laser source with a short coherence length can be used; the sensing interferometer is completely passive;

T. K Lim; Y Zhou; Y Lin; Y. M Yip; Y. L Lam

1999-01-01

63

[Laser optic measurements of the axial length of the eye].  

PubMed

A new method has been developed for determining the axial length of the human eye. This method is based on laser interferometry with partially coherent light emitted by a multimode semiconductor laser diode. The measurement procedure is as follows. The subject looks into the laser beam (wavelength approximately equal to 780 nm, power approximately equal to 100 microW), which appears as a red spot. Hence the laser beam acts as a fixation target and measuring beam. This beam passes a Fabry-Perot interferometer in front of the eye. Reflected beams are generated at the cornea and retina. Since the coherence length of the laser used (approximately equal to 25 microns) is less than the difference in path length of the two reflected beams, they will usually not interfere with each other. However, if the distance between the interferometer plates is equal to the optical length of the eye, an interference pattern can be observed. (This is due to a second illuminating beam, which is generated by the interferometer and delayed by two times the interferometer plate distance.) During measurement, the plates are displaced relative to each other until the interference pattern is observed. At this point the plate distance, which can readily be measured, is equal to the optical eye length. This method has several advantages in comparison with the usual ultrasonic technique: it is a non-contact method; no anesthesia is needed; the optical eye length is determined directly; no assumptions need be made about sound velocities in the different eye media. High longitudinal and transversal resolution is achieved (10 microns or better possible). The first measurements obtained with the optical method were compared with the results yielded by the ultrasound technique.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2737574

Hitzenberger, C; Mengedoht, K; Fercher, A F

1989-01-01

64

Simultaneous angular multiplexing optical projection tomography at shifted focal planes.  

PubMed

We describe an angular multiplexing technique for optical projection tomography that improves resolution, signal-to-noise ratio, and imaging speed by ameliorating the trade-off between spatial resolution and depth of field and improving the light collection efficiency. Here we demonstrate that imaging at two orthogonal angular projections simultaneously, focused on shifted planes in the sample, improves the average spatial resolution by ~20% and the light collection efficiency by a factor of ~4, thereby enabling increased acquisition speed and reduced light dose. PMID:23503237

Chen, Lingling; Andrews, Natalie; Kumar, Sunil; Frankel, Paul; McGinty, James; French, Paul M W

2013-03-15

65

All-optical controlling of the focal intensity of a liquid crystal polymer microlens array.  

PubMed

The current work demonstrates a liquid crystalline polymer microlens array (LCP MLA) with an all-optically tunable and multistable focal intensity through photochemical phase transition. The operational mechanism of the optical tuning is associated with the photoisomerization effect. The proposed LCP MLA device has a focusing unit based on a birefringence LCP and a tuning unit with a light responsive material to control the polarization state of the incident probe beam. The optically variable refractive indices of LCP enable a positive or negative MLA that can control the polarization of incident light to be realized. PMID:22015416

Huang, San-Yi; Tung, Tung-Chen; Jau, Hung-Chang; Liu, Jui-Hsiang; Fuh, Andy Ying-Guey

2011-10-20

66

Localization method of fiber optics defects on short length of optical cable  

Microsoft Academic Search

Physical simulation of optical fiber cladding defects and experimental investigation results are described in present paper. By these results it is confirmed that assumption about fiber light-guide cladding defects localization on short length of optical fiber by comparison polarization backscattering characteristic with sliding correlation test is correct. Samples of defects localization on less then 2 km optical fiber with less

Eugeniy V. Dmitriev

2010-01-01

67

Smart polymers containing substituted coumarin side groups enable photo-induced tuning of focal length of intraocular lenses  

NASA Astrophysics Data System (ADS)

Over the past 100 years medicine evolved continuously, which can clearly be seen in the rising average of life expectancy. But as the population becomes older and older the number of old age diseases increases. Cataract is such an old age disease and worldwide the number one reason for blindness. Implantation of IOL's is up-to-date the only possibility to restore vision. In this study we present novel polymers containing derivatized coumarins in the side chains as smart materials for IOL manufacturing. These materials enable tuning of the focal length of an already implanted IOL by 2 diopters via photo induced dimerization and cleavage of the coumarin side groups respectively. The advantages of these new polymers are increased dimerization rates while decreasing the energy dose needed for photochemical dimerization of the coumarin side groups.

Schraub, Martin; Hampp, Norbert

2011-02-01

68

Double peacock eye optical element for extended focal depth imaging with ophthalmic applications  

NASA Astrophysics Data System (ADS)

The aged human eye is commonly affected by presbyopia, and therefore, it gradually loses its capability to form images of objects placed at different distances. Extended depth of focus (EDOF) imaging elements can overcome this inability, despite the introduction of a certain amount of aberration. This paper evaluates the EDOF imaging performance of the so-called peacock eye phase diffractive element, which focuses an incident plane wave into a segment of the optical axis and explores the element's potential use for ophthalmic presbyopia compensation optics. Two designs of the element are analyzed: the single peacock eye, which produces one focal segment along the axis, and the double peacock eye, which is a spatially multiplexed element that produces two focal segments with partial overlapping along the axis. The performances of the peacock eye elements are compared with those of multifocal lenses through numerical simulations as well as optical experiments in the image space. The results demonstrate that the peacock eye elements form sharper images along the focal segment than the multifocal lenses and, therefore, are more suitable for presbyopia compensation. The extreme points of the depth of field in the object space, which represent the remote and the near object points, have been experimentally obtained for both the single and the double peacock eye optical elements. The double peacock eye element has better imaging quality for relatively short and intermediate distances than the single peacock eye, whereas the latter seems better for far distance vision.

Romero, Lenny A.; Millán, María S.; Jaroszewicz, Zbigniew; Kolodziejczyk, Andrzej

2012-04-01

69

Double peacock eye optical element for extended focal depth imaging with ophthalmic applications.  

PubMed

The aged human eye is commonly affected by presbyopia, and therefore, it gradually loses its capability to form images of objects placed at different distances. Extended depth of focus (EDOF) imaging elements can overcome this inability, despite the introduction of a certain amount of aberration. This paper evaluates the EDOF imaging performance of the so-called peacock eye phase diffractive element, which focuses an incident plane wave into a segment of the optical axis and explores the element's potential use for ophthalmic presbyopia compensation optics. Two designs of the element are analyzed: the single peacock eye, which produces one focal segment along the axis, and the double peacock eye, which is a spatially multiplexed element that produces two focal segments with partial overlapping along the axis. The performances of the peacock eye elements are compared with those of multifocal lenses through numerical simulations as well as optical experiments in the image space. The results demonstrate that the peacock eye elements form sharper images along the focal segment than the multifocal lenses and, therefore, are more suitable for presbyopia compensation. The extreme points of the depth of field in the object space, which represent the remote and the near object points, have been experimentally obtained for both the single and the double peacock eye optical elements. The double peacock eye element has better imaging quality for relatively short and intermediate distances than the single peacock eye, whereas the latter seems better for far distance vision. PMID:22559691

Romero, Lenny A; Millán, María S; Jaroszewicz, Zbigniew; Kolodziejczyk, Andrzej

2012-04-01

70

On the use of clessidra prism arrays in long-focal-length X-ray focusing.  

PubMed

Clessidra (hour-glass) X-ray lenses have an overall shape of an old hour glass, in which two opposing larger triangular prisms are formed of smaller identical prisms or prism-like objects. In these lenses, absorbing and otherwise optically inactive material was removed with a material-removal strategy similar to that used by Fresnel in the lighthouse lens construction. It is verified that when the single prism rows are incoherently illuminated they can be operated as independent micro-lenses with coinciding image positions for efficient X-ray beam concentration. Experimental data for the line width and the refraction efficiency in one-dimensional focusing are consistent with the expectations. Imperfections in the structures produced by state-of-the-art deep X-ray lithography directed only 35% of the incident intensity away from the image and widened it by just 10% to 125 microm. An array of micro-lenses with easily feasible prism sizes is proposed as an efficient retrofit for the refocusing optics in an existing beamline, where it would provide seven-fold flux enhancement. PMID:18552435

Jark, Werner; Matteucci, Marco; Menk, Ralf Hendrik

2008-05-15

71

All-optical payload envelope detection for variable length 40-gb\\/s optically labeled packets  

Microsoft Academic Search

We demonstrate a new technique to all-optically identify the precise temporal locations and durations of the payloads of optical packets consisting of a variable length 40-Gb\\/s return-to-zero payload and 10-Gb\\/s nonreturn-to-zero label. The all-optically generated payload envelope signal can be used to erase the original optical label and rewrite a new label. The recovered payload envelope has 300-ps rise time

Brian R. Koch; Zhaoyang Hu; John E. Bowers; Daniel J. Blumenthal

2006-01-01

72

Wide-Field Infrared Explorer (WIRE) instrument description: focal planes, optics, and electronics  

Microsoft Academic Search

An elegantly simple cryogenic instrument has been proposed to measure far infrared radiation from starburst galaxies. The experiment-known as WIRE- employs a Cassegrain telescope with diamond-turned mirrors to provide a light- weight optical system for photon collection. A dichroic beamsplitter and filter separate the light into two broad, well-defined bands of interest. Two 128- X 128-pixel arsenic-doped silicon focal plane

John C. Kemp; Harry O. Ames; Roy W. Esplin; Glenn D. Allred

1994-01-01

73

Evaluation the development of focal cerebral ischemia in rats by optical imaging based on the spreading depression signals  

Microsoft Academic Search

Spreading depression (SD) has been found involved in focal cerebral ischemia which may result in severe or lethal neurological deficits. Electrical recording of SD has been used for acute and long term monitoring of focal cerebral ischemia but with an inherently low resolution. Here, we presented optical intrinsic signal imaging (OISI) to characterize the spontaneous SD waves following permanent middle

Shangbin Chen; Zhe Feng; Shaoqun Zeng; Qingming Luo; Pengcheng Li

2007-01-01

74

Extended-length fiber optic carbon dioxide monitoring  

NASA Astrophysics Data System (ADS)

This paper discusses the design and performance of fiber optic distributed intrinsic sensors for dissolved carbon dioxide, based on the use optical fibers fabricated so that their entire lengths are chemically sensitive. These fibers use a polymer-clad, silica-core structure where the cladding undergoes a large, reversible, change in optical absorbance in the presence of CO2. The local "cladding loss" induced by this change is thus a direct indication of the carbon dioxide concentration in any section of the fiber. To create these fibers, have developed a carbon dioxide-permeable polymer material that adheres well to glass, is physically robust, has a refractive index lower than fused silica, and acts as excellent hosts for a unique colorimetric indicator system that respond to CO2. We have used this proprietary material to produce carbon-dioxide sensitive fibers up to 50 meters long, using commercial optical fiber fabrication techniques. The sensors have shown a measurement range of dissolved CO2 of 0 to 1,450 mg/l (0 to 100% CO2 saturation), limit of detection of 0.3 mg/l and precision of 1.0 mg/l in the 0 to 50 mg/l dissolved CO2 range, when a 5 meter-long sensor fiber segment is used. Maximum fiber length, minimum detectable concentration, and spatial resolution can be adjusted by adjusting indicator concentration and fiber design.

Delgado-Alonso, Jesus; Lieberman, Robert A.

2013-05-01

75

Water absorption length measurement with the ANTARES optical beacon system  

NASA Astrophysics Data System (ADS)

ANTARES is a neutrino telescope located in the Mediterranean Sea with the aim of detecting high energy neutrinos of extra-terrestrial origin. It consists of a three dimensional array on 12 detection lines of photomultiplier tubes (PMTs) able to detect the Cherenkov light induced by muons produced in the interaction of neutrinos with the surrounding water and seabed. To reach the best angular resolution, good time and positioning calibrations are required. The propagation of Cherenkov photons strongly depends on the optical properties of the sea water, which has an impact on the reconstruction efficiency. The determination of the optical parameters, as the absorption and scattering lengths, is crucial to calculate properly the effective area and the angular resolution of the detector. The ANTARES optical beacon system consists of pulsed and fast, well controlled light sources distributed throughout the detector to carry out in situ the relative time calibration of the detector components. In this contribution we show some results on the sea water optical properties and their stability measured with the optical beacon system.

Yepes-Ramirez, Harold; ANTARES Collaboration

2011-01-01

76

Thermal lens determination of the temperature coefficient of optical path length in optical materials  

NASA Astrophysics Data System (ADS)

In this work thermal lens spectrometry is applied to determine the temperature coefficient of optical path length in several optical materials. Polymer, fluoride and low silica calcium aluminosilicate glasses and YAG, YVO4, YLF, LiSAF, and LiSGaF crystals were analyzed. The results showed the ability of the thermal lens method to obtain the absolute values of this so important optical parameter, which is crucial for those who work in the designing of solid state laser cavity.

Andrade, A. A.; Catunda, T.; Bodnar, I.; Mura, J.; Baesso, M. L.

2003-01-01

77

Thermal lens determination of the temperature coefficient of optical path length in optical materials  

Microsoft Academic Search

In this work thermal lens spectrometry is applied to determine the temperature coefficient of optical path length in several optical materials. Polymer, fluoride and low silica calcium aluminosilicate glasses and YAG, YVO4, YLF, LiSAF, and LiSGaF crystals were analyzed. The results showed the ability of the thermal lens method to obtain the absolute values of this so important optical parameter,

A. A. Andrade; T. Catunda; I. Bodnar; J. Mura; M. L. Baesso

2003-01-01

78

Optical scattering lengths in large liquid-scintillator neutrino detectors  

SciTech Connect

For liquid-scintillator neutrino detectors of kiloton scale, the transparency of the organic solvent is of central importance. The present paper reports on laboratory measurements of the optical scattering lengths of the organic solvents phenylxylylethane, linear alkylbenzene (LAB), and dodecane, which are under discussion for next-generation experiments such as SNO+ (Sudbury Neutrino Observatory), HanoHano, or LENA (Low Energy Neutrino Astronomy). Results comprise the wavelength range of 415-440 nm. The contributions from Rayleigh and Mie scattering as well as from absorption/re-emission processes are discussed. Based on the present results, LAB seems to be the preferred solvent for a large-volume detector.

Wurm, M.; Feilitzsch, F. von; Goeger-Neff, M.; Hofmann, M.; Lewke, T.; Meindl, Q.; Moellenberg, R.; Oberauer, L.; Potzel, W.; Tippmann, M.; Todor, S.; Winter, J. [Physik-Department E15, Technische Universitaet Muenchen, James-Franck-Str., D-85748 Garching (Germany); Lachenmaier, T.; Traunsteiner, C. [Excellence Cluster Universe, Technische Universitaet Muenchen, Boltzmannstr. 2, D-85748 Garching (Germany); Undagoitia, T. Marrodan [Physik-Department E15, Technische Universitaet Muenchen, James-Franck-Str., D-85748 Garching (Germany); Physik-Institut, Universitaet Zuerich, Winterthurstr. 189, CH-8057 Zuerich (Switzerland)

2010-05-15

79

Optical design of the focal adjustable flashlight based on a power white-LED  

NASA Astrophysics Data System (ADS)

In the paper, we design a focal adjustable flashlight, which can provide the spotlight and the wide-angle illumination in different modes. For most users, they two request two illumination modes. In such two modes, one is high density energy of the light pattern and the other is the uniform light pattern in a wide view field. In designing the focal adjustable flashlight, we first build a precise optical model for the high-power LED produced by CREE Inc. in mid-field verification to make sure the accuracy of our simulation. Typically, the lens is useful to be the key component of the adjustable flashlight, but the optical efficiency is low. Here, we introduce a concept of so-called total internal refraction (TIR) lens into the design of flashlight. By defocusing the TIR lens, the flashlight can quickly change the beam size and energy density to various applications. We design two segments of the side of the TIR lens so that they can be applied to the two modes, and the flashlight provides a high optical efficiency for each mode. The illuminance of the center of light pattern at a distance of 2 m from the lamp is also higher than using the lens in the spotlight and wide-angle illumination. It provides good lighting functions for users.

Cai, Jhih-You; Lo, Yi-Chien; Sun, Ching-Cherng

2011-09-01

80

Polymers for refractive index change in intraocular lenses: a novel approach for photoinduced tuning of focal length  

NASA Astrophysics Data System (ADS)

Before an intraocular lens (IOL) is implanted during cataract surgery, biometric data of the patient's eye have to be determined to calculate the thickness and shape of the IOL. In particular the postoperative anterior chamber depth is an important parameter to predict the correct shape of the IOL. This value, however, cannot be measured without significant uncertainities. We present a solution to this problem, describe novel polymers suitable for IOLs which refractive indices can be changed non-invasively in a photo-induced process. The focal length can be modified by about 2 D, which is sufficient to achive ideal acuteness of vision for almost all patients with implanted IOLs. The change in refractive index is accomplished by linking or cleaving bonds between a sufficiently large number of side groups of the polymer main chain in a photoinduced cyloaddition or cycloreversion, respectively. The photochemical reaction can also be triggered by a two-photon process (TPA) using a pulsed laser system, i.e. the energy required for bond breaking is provided by two photons in the visible range. Light in the UV as well as the visible range of the spectrum cannot induce undesired changes of the refractive index owing to the strong UV-absorption of the cornea and photon densities much too low for TPA, respectively. Due to the excellent spatial resolution that can be achieved with two-photon processes not only modification of the refractive index of the entire lens but also selectively in well defined areas is possible enabling the correction for aberrations such as astigmatism.

Träger, Jens; Kim, Hee-Cheol; Hampp, Norbert

2006-03-01

81

Measuring integrated cellular mechanical stress response at focal adhesions by optical tweezers  

NASA Astrophysics Data System (ADS)

The ability of cells to sustain mechanical stress is largely modulated by the cytoskeleton. We present a new application of optical tweezers to study cell's mechanical properties. We trap a fibronectin-coated bead attached to an adherent H4II-EC3 rat hepatoma cell in order to apply the force to the cell surface membrane. The bead position corresponding to the cell's local mechanical response at focal adhesions is measured with a quadrant detector. We assessed the cell response by tracking the evolution of the equilibrium force for 40 cells selected at random and selected a temporal window to assess the cell initial force expression at focal adhesions. The mean value of the force within this time window over 40 randomly selected bead/cell bounds was 52.3 pN. Then, we assessed the responses of the cells with modulation of the cytoskeletons, namely the ubiquitous actin-microfilaments and microtubules, plus the differentiation-dependent keratin intermediate filaments. Notably, a destabilization of the first two networks led to around 50 and 30% reductions in the mean equilibrium forces, respectively, relative to untreated cells, whereas a loss of the third one yielded a 25% increase. The differences in the forces from untreated and treated cells are resolved by the optical tweezers experiment.

Bordeleau, François; Bessard, Judicael; Marceau, Normand; Sheng, Yunlong

2011-09-01

82

Design of a dual field-of-view optical system for infrared focal-plane arrays  

NASA Astrophysics Data System (ADS)

In this paper, the design of a dual field-of-view optical system for 3-5 ?m infra-red focal-plane arrays is described. Preliminary calculations are done to determine the first-order parameters of the narrow and the wide-field modes. To achieve a switchable dual field-of-view system, two different optical configurations, one based on the axial motion of a lens group and the other based on a roate-in motion of two separated lens groups, are studied and compared. Diffractive and conic surfaces are used to control the color and the monochromatic aberrations with less number of total lenses used. Paraxial and real-ray modelling of the Narcissus effect is described. It is shown that the rotate-in scheme achieves better optical performance in both the narrow and the wide-fifeld modes. The axial-motion scheme suffers from poor lateral color in the wide-angle mode. The final optical designs along with the aberrations curves and MTF plots are presented showing excellent performance.

Akram, Muhammad N.

2002-09-01

83

Investigation of Radiation Collection by InSb Infrared Focal-Plane Arrays with Micro-optic Structures  

NASA Astrophysics Data System (ADS)

Three designs of micro-optic structures have been analyzed by two-dimensional simulation. Compared with traditional spherical microlenses, the micro-optic structures have the same ability to collect radiation and do not have the disadvantages of traditional microlenses. In our analysis the micro-optic structures are simple grooved notches above the space between two adjacent mesas. We also investigate the characteristics of InSb focal-plane arrays with both spherical microlenses and micro-optic structures under oblique incident radiation. Empirical formulas were derived to describe the response and crosstalk as a function of incident radiation angle. Our results show that the micro-optic structures can be effectively used in radiation collection for InSb infrared focal-plane arrays.

Guo, N.; Hu, W. D.; Chen, X. S.; Lei, W.; Lv, Y. Q.; Zhang, X. L.; Si, J. J.; Lu, W.

2013-08-01

84

A superconducting focal plane array for ultraviolet, optical, and near-infrared astrophysics.  

PubMed

Microwave Kinetic Inductance Detectors, or MKIDs, have proven to be a powerful cryogenic detector technology due to their sensitivity and the ease with which they can be multiplexed into large arrays. A MKID is an energy sensor based on a photon-variable superconducting inductance in a lithographed microresonator, and is capable of functioning as a photon detector across the electromagnetic spectrum as well as a particle detector. Here we describe the first successful effort to create a photon-counting, energy-resolving ultraviolet, optical, and near infrared MKID focal plane array. These new Optical Lumped Element (OLE) MKID arrays have significant advantages over semiconductor detectors like charge coupled devices (CCDs). They can count individual photons with essentially no false counts and determine the energy and arrival time of every photon with good quantum efficiency. Their physical pixel size and maximum count rate is well matched with large telescopes. These capabilities enable powerful new astrophysical instruments usable from the ground and space. MKIDs could eventually supplant semiconductor detectors for most astronomical instrumentation, and will be useful for other disciplines such as quantum optics and biological imaging. PMID:22274494

Mazin, Benjamin A; Bumble, Bruce; Meeker, Seth R; O'Brien, Kieran; McHugh, Sean; Langman, Eric

2012-01-16

85

X-ray optics: Imaging at arm's length  

Microsoft Academic Search

With continuing improvements in X-ray optics, conventional techniques for measuring their performance are finding it hard to keep up. Iterative phase-retrieval algorithms for reconstructing an optical field at the focus of an optical element could not only solve this problem, but remove the need for such optics altogether.

Chris Jacobsen

2006-01-01

86

Angstrom-Range Optical Path-Length Measurement with a High-Speed Scanning Heterodyne Optical Interferometer  

NASA Astrophysics Data System (ADS)

A highly accurate method of optical path-length measurement is introduced by use of a scanning heterodyne optical interferometer with no moving parts. The instrument has demonstrated the potential to measure optical path length at angstrom resolution over continuous thickness in the micrometer range. This optical path length can be used to calculate the thickness of any material if the refractive index is known or to measure the refractive index of the material if the thickness is known. The instrument uses a single acousto-optic device in an in-line ultra-stable reflective geometry to implement rapid scanning in the microsecond domain for thickness measurements of the test medium.

Riza, Nabeel A.; Arain, Muzammil A.

2003-05-01

87

OPTICAL FIELD PARAMETERS: Estimate of the minimal coherence length of probe optical radiation in interferometry  

NASA Astrophysics Data System (ADS)

The minimal coherence length of probe optical radiation sufficient for formation of a homogeneous interference structure is estimated. The estimate is based on the analysis of the interference structure in the intensity distribution of the field scattered by rough surfaces and point objects and also formed in interferometers. Analysis was performed for the field intensity detected for the time T > 10?c (under the condition that the coherence time of the probe radiation is ?c > 3/?0, where ?0 is the central frequency of the emission spectrum). It is shown that the minimal coherence length Lc of the probe radiation, at which the homogeneous stratified interference structure of the scattered field can be still formed, is 8? (? is the central wavelength). The possibility of using this result for determining the maximal information content of the method of low-coherence optical tomography is analysed.

Bakut, P. A.; Mandrosov, V. I.

2007-01-01

88

In vivo optical reflectance imaging of spreading depression waves in rat brain with and without focal cerebral ischemia  

Microsoft Academic Search

Spreading depression SD waves occur in focal cerebral ischemia of the brain. Optical reflectance imaging at 550±10-nm wavelength using a charge-coupled device CCD camera, called op- tical intrinsic signal imaging OISI in the neuroscience community, provides high resolution imaging of SD waves based on changes in blood perfusion. We present optical images of SD waves in normal rat brain induced

Shangbin Chen; Zhe Feng; Pengcheng Li; Steven L. Jacques; Shaoqun Zeng; Qingming Luo

2006-01-01

89

Calibration of optical tweezers with positional detection in the back focal plane  

SciTech Connect

We explain and demonstrate a new method of force and position calibrations for optical tweezers with back-focal-plane photodetection. The method combines power spectral measurements of thermal motion and the response to a sinusoidal motion of a translation stage. It consequently does not use the drag coefficient of the trapped object as an input. Thus, neither the viscosity, nor the size of the trapped object, nor its distance to nearby surfaces needs to be known. The method requires only a low level of instrumentation and can be applied in situ in all spatial dimensions. It is both accurate and precise: true values are returned, with small error bars. We tested this experimentally, near and far from surfaces in the lateral directions. Both position and force calibrations were accurate to within 3%. To calibrate, we moved the sample with a piezoelectric translation stage, but the laser beam could be moved instead, e.g., by acousto-optic deflectors. Near surfaces, this precision requires an improved formula for the hydrodynamical interaction between an infinite plane and a microsphere in nonconstant motion parallel to it. We give such a formula.

Tolic-Noerrelykke, Simon F.; Schaeffer, Erik; Howard, Jonathon; Pavone, Francesco S.; Juelicher, Frank; Flyvbjerg, Henrik [Max Planck Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, 01187 Dresden (Germany) and European Laboratory for Non-linear Spectroscopy, via Nello Carrara 1, 50019 Sesto Fiorentino, Florence (Italy) and Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden (Germany); European Laboratory for Non-linear Spectroscopy, via Nello Carrara 1, 50019 Sesto Fiorentino, Florence (Italy); Max Planck Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, 01187 Dresden (Germany); Isaac Newton Institute for Mathematical Sciences, Cambridge CB3 0EH (United Kingdom); Biosystems Department, Risoe National Laboratory, DK-4000 Roskilde (Denmark) and Danish Polymer Centre, Risoe National Laboratory, DK-4000 Roskilde (Denmark)

2006-10-15

90

Multispectral Thermal Imager optical assembly performance and integration of the flight focal plane assembly  

NASA Astrophysics Data System (ADS)

The Multispectral Thermal Imager Optical Assembly (OA) has been fabricated, assembled, successfully performance tested, and integrated into the flight payload structure with the flight Focal Plane Assembly (FPA) integrated and aligned to it. This represents a major milestone achieved towards completion of this earth observing E-O imaging sensor that is to be operated in low earth orbit. The OA consists of an off- axis three mirror anastigmatic (TMA) telescope with a 36 cm unobscured clear aperture, a wide-field-of-view (WFOV) of 1.82 degrees along the direction of spacecraft motion and 1.38 degree across the direction of spacecraft motion. It also contains a comprehensive on-board radiometric calibration system. The OA is part of a multispectral pushbroom imaging sensor which employs a single mechanically cooled focal plane with 15 spectral bands covering a wavelength range from 0.45 to 10.7 micrometer. The OA achieves near diffraction-limited performance from visible to the long-wave infrared (LWIR) wavelengths. The two major design drivers for the OA are 80% enpixeled energy in the visible bands and radiometric stability. Enpixeled energy in the visible bands also drove the alignment of the FPA detectors to the OA image plane to a requirement of less than plus or minus 20 micrometer over the entire visible detector field of view (FOV). Radiometric stability requirements mandated a cold Lyot stop for stray light rejection and thermal background reduction. The Lyot stop is part of the FPA assembly and acts as the aperture stop for the imaging system. The alignment of the Lyot stop to the OA drove the centering and to some extent the tilt alignment requirements of the FPA to the OA.

Henson, Tammy D.; Krumel, Leslie; Blake, Richard J.; Bender, Steven C.; Byrd, Donald A.; Christensen, R. Wynn; Rappoport, William M.; Shen, GonYen

1999-10-01

91

Active optical zoom system  

NASA Astrophysics Data System (ADS)

In order to optically vary the magnification of an imaging system, continuous mechanical zoom lenses require multiple optical elements and use fine mechanical motion to precisely adjust the separations between individual or groups of lenses. By incorporating active elements into the optical design, we have designed and demonstrated imaging systems that are capable of variable optical magnification with no macroscopic moving parts. Changing the effective focal length and magnification of an imaging system can be accomplished by adeptly positioning two or more active optics in the optical design and appropriately adjusting the optical power of those elements. In this application, the active optics (e.g. liquid crystal spatial light modulators or deformable mirrors) serve as variable focal-length lenses. Unfortunately, the range over which currently available devices can operate (i.e. their dynamic range) is relatively small. Therefore, the key to this concept is to create large changes in the effective focal length of the system with very small changes in the focal lengths of individual elements by leveraging the optical power of conventional optical elements surrounding the active optics. By appropriately designing the optical system, these variable focal-length lenses can provide the flexibility necessary to change the overall system focal length, and therefore magnification, that is normally accomplished with mechanical motion in conventional zoom lenses.

Wick, David V.; Martinez, Ty; Payne, Don M.; Sweatt, William C.; Restaino, Sergio R.

2005-05-01

92

Adaptive optical zoom sensor.  

SciTech Connect

In order to optically vary the magnification of an imaging system, continuous mechanical zoom lenses require multiple optical elements and use fine mechanical motion to precisely adjust the separations between individual or groups of lenses. By incorporating active elements into the optical design, we have designed and demonstrated imaging systems that are capable of variable optical magnification with no macroscopic moving parts. Changing the effective focal length and magnification of an imaging system can be accomplished by adeptly positioning two or more active optics in the optical design and appropriately adjusting the optical power of those elements. In this application, the active optics (e.g. liquid crystal spatial light modulators or deformable mirrors) serve as variable focal-length lenses. Unfortunately, the range over which currently available devices can operate (i.e. their dynamic range) is relatively small. Therefore, the key to this concept is to create large changes in the effective focal length of the system with very small changes in the focal lengths of individual elements by leveraging the optical power of conventional optical elements surrounding the active optics. By appropriately designing the optical system, these variable focal-length lenses can provide the flexibility necessary to change the overall system focal length, and therefore magnification, that is normally accomplished with mechanical motion in conventional zoom lenses.

Sweatt, William C.; Bagwell, Brett E.; Wick, David Victor

2005-11-01

93

New optical modalities utilizing curved focal plane imaging detector devices and large arrays for terrestrial and spaceborne telescopes  

NASA Astrophysics Data System (ADS)

As terrestrial and spaceborne astronomical telescopes advance in multi-functional design sophistication, incorporating greater spectral resolutions, the utilization of curved focal plane ccd and cmos imaging detectors, contoured to match the telescope's Petzval field of curvature, provides a fundamental and novel optical simplicity facilitating new imaging frontiers in astronomical research. For space based telescopes, curved focal plane detector devices require significantly fewer optics than their flat counterparts, which require field flattening optics, in achieving maximum imaging resolutions for adjoining spectrometers or imaging cameras. consequently, with fewer optics comes greater room to place other optics within the same space to accomplish other tasks, providing much greater diversification of observing functions and techniques reserved simultaneously for the telescope. Included within this is the operational capability of producing multi-wavelength spectrometers gathering data concurrently at a multitude of selected wavelengths, with greater sensitivity, reliability, size reduction, and operational longevity of the restructured optical system. Specialized applications involving optical interferometry are also achievable with further enhancements when the curved detectors are applied specifically to refine or maximize detection of fringes, and when employing occulting mask algorithms for existing light paths. for planetary surface mapping space probes, curved focal plane detection provides real-time 3D multi-perspective image acquisition for streaming 3D data sets, replacing onboard or remote computationally intensive 3D reconstructions used for examining terrestrial surface features performed with corresponding flat detectors. For earth based telescopes, where mass of the telescope's optics are not so constrained, more degrees of freedom are also part of the benefits introduced by curved focal plane detector device optimization. Associated with the very large Petzval radii of curvature for very large and extreme telescopes within this class are wide field spatial distortions which are instantaneously corrected when arrays of curved CCD's or CMOS devices are joined homogeneously and precisely together along the converging field of curvature, without field flattening optics, insuring complete full field detection superior to flat facet detectors which compromise the telescope's imaging field curvature detection abilities.

Mark, David

2010-07-01

94

Optimizing the Elemental Sensitivity and Focal Spot Size of a Monolithic Polycapillary Optic Using Micro-X-Ray Fluorescence  

Microsoft Academic Search

A commercial micro-X-ray fluorescence (MXRF) instrument with an aperture X-ray guide was used to compare elemental sensitivities and focal spot sizes with those obtained by focusing the source with a monolithic polycapillary optic retrofitted into the system. The capillary provided an intensity gain of 125 at 4 keV vs. using a pinhole beam collimator; however, this gain advantage declined with

C. Worley; G. Havrilla; N. Gao; Q.-F. Xia

1998-01-01

95

The free electron laser interaction with a short-Rayleigh-length optical mode  

Microsoft Academic Search

High-power, short-wavelength free electron lasers (FELs) can make use of a short-Rayleigh-length (SRL) optical mode in order to reduce the intensity on resonator mirrors. The conventional FEL interaction attempts to optimize the coupling between the electron beam and optical mode by minimizing the optical mode volume around the electron beam. In contrast, the SRL FEL focuses optical power in a

W. B. Colson; J. Blau; R. L. Armstead

2003-01-01

96

Precise cavity length control in fiber optic extrinsic Fabry-Perot interferometers  

Microsoft Academic Search

A technique to precisely control the cavity length in fiber optic extrinsic Fabry-Perot interferometric structures by CO2 laser is described. The white light monitored laser bonding system can achieve a 3 nm cavity control resolution.

Juncheng Xu; G. R. Pickrell; K. L. Cooper; Po Zhang; Anbo Wang

2005-01-01

97

Joint statistics of photon path length and cloud optical depth: Case studies  

NASA Astrophysics Data System (ADS)

We show the joint statistics of photon path length and cloud optical depth for cloudy sky cases observed at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site between September and December 1997. The photon path lengths are retrieved from moderate resolution oxygen A-band observations taken by a rotating shadow band spectroradiometer (RSS). For high optical depth cloud cases, two different populations in the scattergram of the path length versus cloud optical depth are apparent. One population is a result of single-layer cloud cases that exhibit a small variation of path length enhancement over a large optical depth range, together with a strong correlation between the radiation field and the cloud liquid water path, while the second population is attributed to multiple-layer cloud cases with large variability of enhanced photon path lengths. When the optical depth is less than 5, the population of cases appears to bifurcate as the solar air mass increases, with the lower branch exhibiting pressure-weighted path lengths shorter than the direct beam path lengths at these larger solar zenith angles. Using information from a millimeter-wave cloud radar, together with lidar and balloon-borne sonde data to further analyze these cases demonstrates that this bifurcation is caused by the altitude of the scattering; thin clouds aloft produce the lower branch and low-level aerosols produce the upper branch.

Min, Qilong; Harrison, Lee C.; Clothiaux, Eugene E.

2001-04-01

98

Lessons learned from the optics and focal plane alignment of a wide field of view RC telescope  

NASA Astrophysics Data System (ADS)

Medium-sized Aperture Camera (MAC) is the main payload for Earth observation satellite RazakSAT to be launched at the end of 2005. The flight model has been recently assembled and tested. The 300 mm diameter Cassegrain telescope optics and the focal plane assembly for a space camera have been aligned. Topics discussed in this paper include the lessons learned from the optics alignment and assembly of the telescope and the focal plane. A computer-aided alignment method was used for the alignment of the relatively wide field of view (+/-1 deg) telescope. RMS wavefront error measurement environment was found to be more critical than previously experienced, and the importance of the initial alignment is discussed. System modulation transfer function (MTF) was used as the figure-of-merit for the alignment of the focal plane assembly with linear CCD detectors. MTF was measured by a knife-edge scanning technique using a dedicated 450 mm diameter collimator with diffraction-limited performance.

Kim, Eugene D.; Choi, Young-Wan; Kang, Myung-Seok; Kim, Ee-Eul; Yang, Ho-Soon; Bin Ismail, Ad. Mohd. Afiq; Sabirin Arshad, Ahmad

2005-08-01

99

Length dependence of the saturation characteristics in 1.5-?m multiple quantum well optical amplifiers  

Microsoft Academic Search

The dependence on amplifier length of gain and gain saturation characteristics in 1.5-?m multiple-quantum-well optical amplifiers is reported. Gain measurements are presented for amplifiers with lengths of 200 ?m to 1 mm, and a simple model is introduced which relates gain and saturation characteristics to the amplifier length. The 1-mm-long device has superb properties, with a gain of 25.2 dB

G. Eisenstein; N. Tessler; U. Koren; J. M. Wiesenfeld; G. Raybon; C. A. Burrus

1990-01-01

100

Study of temperature dependence of the optical path length in ion doped solids  

NASA Astrophysics Data System (ADS)

The aim of this work is to use Thermal Lens (TL) technique to measure the absolute value of the temperature coefficient of optical path length (ds/dT) in several optical materials. We studied fluoride, calcium aluminate glasses and YAG, YVO4, YLF, LiSAF, LiSGaF laser crystals.

Andrade, A. A.; Catunda, Tomaz; Mura, J.; Baesso, Mauro L.

2003-11-01

101

Study of temperature dependence of the optical path length in ion doped solids  

Microsoft Academic Search

The aim of this work is to use Thermal Lens (TL) technique to measure the absolute value of the temperature coefficient of optical path length (ds\\/dT) in several optical materials. We studied fluoride, calcium aluminate glasses and YAG, YVO4, YLF, LiSAF, LiSGaF laser crystals.

A. A. Andrade; Tomaz Catunda; J. Mura; Mauro L. Baesso

2003-01-01

102

High accuracy length measuring set up for optical encoder calibration  

NASA Astrophysics Data System (ADS)

Regarding nano-sciences and nano-technologies there is a permanent confusion between resolution and accuracy. Many sophisticated devices (APM, AFM, SNOM, confocal microscopes) characterized by their resolution, are used to observe at the nano-scale but they are far from being metrological devices, i.e. they do not measure. A metrological instrument must be traceable to the internationally accepted unit: meter in our case. We present an optical setup able to measure in micrometer range with nanometer resolution and ten nanometers accuracy. Its utility for MEMS geometrical parameter is obvious. The setup is working on a passive vibration-isolated table and contains a SIOS laser interferometer which assures the traceability of the measurement, a high resolution translation table, and a long working distance microscope. Few hundred measurements were done to a linear grating to measure the micrometric range pitch with nanometer accuracy. A 2 10-4 relative error was obtained.

Iordache, Iuliana; Iancu, O.; Schiopu, P.; Apostol, D.

2009-01-01

103

The Focal Plane Package for the Solar Optical Telescope on Solar-B  

NASA Astrophysics Data System (ADS)

Solar-B is a Japanese space science mission of the Institute of Space and Astronautical Sciences (ISAS), with major participation of US and UK research groups. The mission includes the 50-cm aperture Solar Optical Telescope (SOT), with its Focal Plane Package (FPP) designed for high resolution photospheric and chromospheric imaging and spectro-polarimetry. There are also two coronal instruments, the X-Ray Telescope and Extreme-ultraviolet Imaging Spectrometer. Solar-B will be launched into a Sun-synchronous polar orbit in August, 2005. The SOT is provided by ISAS and is being built by the National Astronomical Observatory of Japan (NAOJ) and Mitsubishi Electric Co. A team of Lockheed Martin, High Altitude Observatory (HAO), and NAOJ scientists and engineers are designing the FPP instrument. This talk gives an overview of the science goals of the FPP as well as the current instrument design and performance characteristics. The primary goal is to understand the coupling between the fine magnetic structures in the photosphere and dynamic processes and heating in the chromosphere and corona. The FPP consists of a narrow-band tunable birefringent filter imager, broad-band interference filter imager, and spectro-polarimeter (SP), essentially a space version of the HAO Advanced Stokes Polarimeter. The image is stabilized by a correlation tracker and active tilt mirror. The SP makes vector magnetic measurements from Stokes spectra of the Fe I lines 630.1 and 630.2 nm, with 0.16 arcsec pixels and field of view up to 164 x 328 arcsec. The broad-band system takes diffraction-limited images (0.05 arcsec pixels) in the Ca II H line, CN and G bandheads, and continuum bands. The narrow-band system makes filtergrams, magnetograms, Dopplergrams, and Stokes images in several photospheric lines, Mg b, and H-alpha. It has 0.08 arcsec pixels and field-of-view same as that of the SP. The SP and filter imagers will usually observe simultaneously on the same target region. High-level observing sequences and coordination with the other instruments will be managed by FPP science planners, similar to those of SXT and TRACE. The FPP project is supported by NASA (NAS8-01002).

Tarbell, T.

2001-05-01

104

The Focal Plane Package for the Solar Optical Telescope on Solar-B  

NASA Astrophysics Data System (ADS)

Solar-B is a space science mission of the Japanese Aerospace Exploration Agency (JAXA) and a NASA Solar Terrestrial Probes mission. It includes the 50-cm aperture Solar Optical Telescope (SOT), with its Focal Plane Package (FPP) designed for high resolution photospheric and chromospheric imaging and spectro-polarimetry. There are also two coronal instruments, the X-Ray Telescope and Extreme-ultraviolet Imaging Spectrometer. Solar-B will be launched into a Sun-synchronous polar orbit in August, 2006. The SOT is provided by JAXA and is being built by the National Astronomical Observatory of Japan (NAOJ) and Mitsubishi Electric Co. A team of Lockheed Martin, High Altitude Observatory (HAO), and NAOJ scientists and engineers have built the FPP instrument. This paper gives an overview of the science goals of the FPP as well as the instrument performance characteristics. The primary goal is to understand the coupling between the fine magnetic structures in the photosphere and dynamic processes and heating in the chromosphere and corona. The FPP consists of a narrow-band tunable birefringent filter imager, broad-band interference filter imager, and spectro-polarimeter (SP), essentially a space version of the HAO Advanced Stokes Polarimeter. The image is stabilized by a correlation tracker and active tilt mirror. The SP makes vector magnetic measurements from Stokes spectra of the Fe I lines 630.1 and 630.2 nm, with 0.16 arcsec pixels and field of view up to 164 x 328 arcsec. The broad-band system takes diffraction-limited images (0.05 arcsec pixels) in the Ca II H line, CN and G bandheads, and continuum bands. The narrow-band system makes filtergrams, magnetograms, Dopplergrams, and Stokes images in several photospheric lines, Mg b, Na D, and H-alpha, similar to the SOUP filter at La Palma. It has 0.08 arcsec pixels and field-of-view same as that of the SP. SOT and FPP have been calibrated in great detail and have observed the sun in two end-to-end tests at NAOJ. Sample results of these observations will be shown. Observing programs and coordination with the other instruments and observatories during the mission will be managed by SOT/FPP science planners, similar to those of SOHO and TRACE. The FPP project is supported by NASA (NAS8-01002).

Tarbell, T. D.

2005-05-01

105

FIBER OPTICS: Distribution of the intensity of surface optical waves in the focal region of a geodesic lens made of LiNbO3:Ti  

NASA Astrophysics Data System (ADS)

An experimental investigation was made of a redistribution of the intensity in the transverse cross section of a surface optical wave focused by a spherical geodesic lens in a Ti-diffused waveguide formed in a Y-cut LiNbO3 crystal. A wave theory of geodesic waveguide lenses was used to calculate the optical field in the focal and several other transverse cross sections for a spherical lens with parameters found experimentally. The results of these calculations were in good agreement with the experimental data.

Kiselev, A. V.; Prokhorov, A. M.; Shcherbakov, E. A.

1988-02-01

106

Effective optical path length investigation for cubic diffuse cavity as gas absorption cell  

NASA Astrophysics Data System (ADS)

A simple cubic-shaped cavity with a high-diffuse-reflectivity inner coating as a novel gas detection cell was developed. The effective optical path length (EOPL) was evaluated by comparing the oxygen absorption signal in the cavity and in air based on tunable diode laser absorption spectroscopy. The law for a spherical cavity was applied and modified to a cubic cavity as a function of reflectivity ?, port fraction f, and the side length. Single-pass average path length of the cubic cavity was 0.723(7) times the side length. EOPL can be modified conveniently by adjusting the parameters of the cavity.

Yu, Jia; Zheng, Fu; Gao, Qiang; Li, Yinjie; Zhang, Yungang; Zhang, Zhiguo; Wu, Shaohua

2013-10-01

107

Precision Fiber Optic Links for Transporting Signals Off Cryogenic Infrared Focal Planes.  

National Technical Information Service (NTIS)

The high performance Infrared Focal Plane Array (IRFPA) detectors used by surveillance sensors for data acquisition, discrimination and track and on hit to kill interceptors produce vast amounts of data of wide dynamic range (> 80 dB) and high bandwidth (...

G. Wyntjes A. Newburgh A. Ducharme R. Rieder

1998-01-01

108

An optical see-through head mounted display with addressable focal planes  

Microsoft Academic Search

Most existing stereoscopic head mounted displays (HMDs), presenting a pair of stereoscopic images at a fixed focal distance, lack the ability to correctly render the naturally coupled accommodation and convergence cues. Psychophysical studies have shown that such displays may cause many adverse consequences such as visual fatigue, diplopic vision, degraded oculomotor response, and depth perception errors. In this paper, we

Sheng Liu; Dewen Cheng; Hong Hua

2008-01-01

109

Evaluation the development of focal cerebral ischemia in rats by optical imaging based on the spreading depression signals  

NASA Astrophysics Data System (ADS)

Spreading depression (SD) has been found involved in focal cerebral ischemia which may result in severe or lethal neurological deficits. Electrical recording of SD has been used for acute and long term monitoring of focal cerebral ischemia but with an inherently low resolution. Here, we presented optical intrinsic signal imaging (OISI) to characterize the spontaneous SD waves following permanent middle cerebral artery occlusion (MCAO) in rats with high spatial resolution. During each SD episode, the measured optical reflectance varied regionally: decreased (-12.5+/-2.8%) in the area near the midline, remained flat (3.1+/-2.5%) in the lateral region, and increased (12.1+/-3.6%) in the intermediate cortex. The three types of changes yielded identifications for three biological relevant zones: nonischemic cortex, penumbra and infarct core. Accompanying recurrent SD waves, the suggested penumbral area reduced by about 6.4+/-2.5% of the whole imaged area per SD event, indicating a growth of the infracted area. Staining with 2% 2,3,5-triphenyltetrazolium chloride (TTC) 4 h post-occlusion proved the infarct cortex to be consistent with the lateral region where the final SD wave did not invade (r=0.86+/-0.10). The results suggest that OISI based on SD can effectively used to distinguish nonischemic cortex, penumbra and infarct core in the ischemic hemisphere and monitor the development of ischemia with high spatial resolution.

Chen, Shangbin; Feng, Zhe; Zeng, Shaoqun; Luo, Qingming; Li, Pengcheng

2007-03-01

110

An inversion formula for the exponential Radon transform in spatial domain with variable focal-length fan-beam collimation geometry  

SciTech Connect

Inverting the exponential Radon transform has a potential use for SPECT (single photon emission computed tomography) imaging in cases where a uniform attenuation can be approximated, such as in brain and abdominal imaging. Tretiak and Metz derived in the frequency domain an explicit inversion formula for the exponential Radon transform in two dimensions for parallel-beam collimator geometry. Progress has been made to extend the inversion formula for fan-beam and varying focal-length fan-beam (VFF) collimator geometries. These previous fan-beam and VFF inversion formulas require a spatially variant filtering operation, which complicates the implementation and imposes a heavy computing burden. In this paper, we present an explicit inversion formula, in which a spatially invariant filter is involved. The formula is derived and implemented in the spatial domain for VFF geometry (where parallel-beam and fan-beam geometries are two special cases). Phantom simulations mimicking SPECT studies demonstrate its accuracy in reconstructing the phantom images and efficiency in computation for the considered collimator geometries.

Wen Junhai; Liang Zhengrong [Department of Biomedical Engineering, Beijing Institute of Technology, Beijing, 100081 (China) and Department of Radiology, State University of New York, Stony Brook, New York 11794 (United States); Department of Radiology, State University of New York, Stony Brook, New York 11794 (United States)

2006-03-15

111

Beamlet focal plane diagnostic  

SciTech Connect

This paper describes the major optical and mechanical design features of the Beamlet Focal Plane Diagnostic system as well as measurements of the system performance, and typical data obtained to date. We also discuss the NIF requirements on the focal spot that we are interested in measuring, and some of our plans for future work using this system.

Caird, J.A.; Nielsen, N.D.; Patton, H.G.; Seppala, L.G.; Thompson, C.E.; Wegner, P.J.

1996-12-01

112

Design of multiplexed phase diffractive optical elements for focal depth extension.  

PubMed

A more computationally tractable method to design a multiplexed phase diffractive optical element with optical design software to extend the depth of focus is proposed, through which the intensity distribution of the output beams can also be controlled with great flexibility. The design principle is explained in detail. And the feasibility of this design method is illustrated through a design example followed by computer simulation verification. PMID:20588408

Liu, Hua; Lu, Zhenwu; Sun, Qiang; Zhang, Hu

2010-06-01

113

Effect of discrete scatterers in CSF layer on optical path length in the brain  

NASA Astrophysics Data System (ADS)

Adequate modeling of light propagation in the complex and heterogeneous tissue of the human head is very important for quantitative near infrared spectroscopy and optical imaging. The presence of a clear and non-scattering CSF layer around the brain has been previously shown to strongly affect light propagation in the head. However the CSF layer is not totally filled with a non-scattering fluid and quite a few fine arachnoid trabeculae are actually present in the layer. In this study light propagation in an adult head model with discrete scatterers distributed within the CSF layer has been predicted by Monte Carlo simulation in order to investigate the effect of scattering caused by the arachnoid trabecula in the CSF layer. Results show that the presence of the arachnoid trabeculae affect the total optical path length, a parameter which can be directly measured by time-resolved measurement. However, the partial optical path length in the brain tissue, which relates the sensitivity of the near infrared spectroscopy signal to absorption changes in the brain is strongly affected by the CSF layer even in the presence of the arachnoid trabeculae. The increased partial optical path length results from an increased lateral spreading of the NIR light within the gray matter of the cortex.

Okada, Eiji; Delpy, David T.

2000-11-01

114

Study of the polarization maintaining optical fiber beat length variation with external force  

NASA Astrophysics Data System (ADS)

The polarization maintaining fiber has been playing an important role in the fields of optical fiber sensing, communication, and so on. The beat length is one of the main parameters of polarization maintaining fiber, and it usually represents its polarization maintaining performance. In this paper, the beat length variation of Panda fiber with external force is investigated. The simulation results indicate that the beat length variation was determined both by the external force value F and the angle ? between the external force direction and the slow axis of Panda fiber. When F is a constant, the beat length of polarization maintaining fiber is changed in sinusoidal form whose various cycle is ? with the variation of ?. Meanwhile, the minimum and maximum values of beat length will be obtained when the angles are even multiple of ?/2 or odd multiple of ?/2, respectively. When ? is a constant, the beat length is changed in linear form with the increasing of external force value. Finally, the experimental system of beat length measurement based on Sagnac interferometer loop is illustrated, and the result shows an excellent agreement with the theoretical analysis.

Ou, Zhonghua; Sun, Ping; Chen, Yu; Li, Jian-feng; Liu, Yong; Yue, Huimin; Dai, Zhiyong; Zhang, Lixun

2013-08-01

115

Length-dependent optical properties of single-walled carbon nanotube samples  

NASA Astrophysics Data System (ADS)

Contradictory findings have been reported on the length dependence of optical absorption cross sections and fluorescence quantum yields in single-walled carbon nanotubes (SWCNTs). To clarify these points, studies have been made on bulk SWCNT dispersions subjected to length fractionation by electrophoretic separation or by ultrasonication-induced scission. Fractions ranged from ca. 120 to 760 nm in mean length. Samples prepared by shear-assisted dispersion were subsequently shortened by ultrasonic processing. After accounting for processing-induced changes in the surfactant absorption background, SWCNT absorption was found constant within ±11% as average nanotube length changed by a factor of 3.8. This indicates that the absorption cross-section per carbon atom is not length dependent. By contrast, in length fractions prepared by both methods, the bulk fluorescence efficiency or average quantum yield increased with SWCNT average length and approached an apparent asymptotic limit near 1 ?m. This result is interpreted as reflecting the combined contributions of exciton quenching by sidewall defects and by the ends of shorter nanotubes.

Naumov, Anton V.; Tsyboulski, Dmitri A.; Bachilo, Sergei M.; Weisman, R. Bruce

2013-08-01

116

Focal-Plane Image and Beam Quality Sensors for Adaptive Optics  

Microsoft Academic Search

Control of adaptive optical elements for real-time wavefront phase distortion compen- sation is a rapidly growing field of research and technology development. Wavefront cor- rection is essential for reliable long distance, near-ground laser communication as well as for imaging extended objects over large distances. Crucial to adaptively correcting the wavefront is a performance metric that can be directly evaluated from

Marc Cohent; Gert Cauwenberghst; Mikhail Vorontsovt; Gary Carhart

2001-01-01

117

Electron bunch length monitors using spatially encoded electro-optical technique in an orthogonal configuration  

SciTech Connect

A single-shot, nondestructive, electro-optical, electron bunch length monitor is experimentally verified by encoding the Coulomb field of the bunch profile on the spatial intensity distribution of an unchirped femtosecond laser pulse in an orthogonal geometry, hence a temporal-to-spatial transformation. This electron bunch measurement scheme can simultaneously measure large timing jitter (approximately in picoseconds) with a wide measurement time span covering picosecond to subpicosecond ranges.

Yang, X.; Murphy, J. B.; Shen, Y.; Wang, X. J. [National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973 (United States); Tsang, T.; Rao, T. [Instrumentation Division, Brookhaven National Laboratory, Upton, New York 11973 (United States)

2009-12-07

118

Electron Bunch Length Monitors using Spatially Encoded Electro-optical Technique  

SciTech Connect

A single-shot, nondestructive, electro-optical, electron bunch length monitor is experimentally verified by encoding the Coulomb field of the bunch profile on the spatial intensity distribution of an unchirped femtosecond laser pulse in an orthogonal geometry (hence, a temporal-to-spatial transformation). This electron bunch measurement scheme can simultaneously measure large timing jitter (?ps) with a wide measurement timespan covering picosecond to subpicosecond ranges.

X Yang; T Tsang; J Murphy; Y Shen; X Wang

2011-12-31

119

Transcranial optical path length in infants by near-infrared phase-shift spectroscopy  

Microsoft Academic Search

Background. Near-infrared spectroscopy (NIRS) is an emerging technique for noninvasive, bedside monitoring of cerebral oxygenation and\\u000a blood flow. Traditionally, it has relied on the Beer's Law relationship in which the concentration of light-absorbing oxygen-carrying\\u000a pigments is proportional to their light absorbance, and inversely proportional to an optical path length (a measure of the\\u000a distance traveled by photons passing through the

David A. Benaron; C. Dean Kurth; James M. Steven; Maria Delivoria-Papadopoulos; Britton Chance

1995-01-01

120

6-micron interaction length electro-optic modulation based on lithium niobate photonic crystal cavity.  

PubMed

We report on electro-optic modulation using a Lithium Niobate (LN) Photonic Crystal (PC) cavity structure. The compact device (6 ?m in length) consists of a 2D photonic crystal cavity made on an Annealed Proton Exchange (APE) LN waveguide with vertical deposited electrodes. Experimental results show a tunability of 0.6 nm/V. This compact design opens a way towards micro and nano-scale tunable photonic devices with low driving electrical power. PMID:23037212

Lu, H; Sadani, B; Ulliac, G; Courjal, N; Guyot, C; Merolla, J-M; Collet, M; Baida, F I; Bernal, M-P

2012-09-10

121

Decreasing the optical path length in an optoelectronic module using silicon micromachining  

NASA Astrophysics Data System (ADS)

In order to decrease the optical path length of an optoelectronic module, two ways of achieving 0960-1317/9/2/006/img1 silicon mirrors with trenches defining the mirror size are presented: dicing, and dry etching. The dicing was performed with a Disco DAD 361 dicing machine. To define the dry etched trench UV-lithography on electrodeposited resist was used. The electrodeposition was performed using commercially available positive photoresist PEPR 2400 from Shipley Ltd.

Richard, Åse; Rangsten, Pelle; Strandman, Carola; Bäcklund, Ylva

1999-06-01

122

Single-shot electron bunch length measurements using a spatial electro-optical autocorrelation interferometer  

SciTech Connect

A spatial, electro-optical autocorrelation (EOA) interferometer using the vertically polarized lobes of coherent transition radiation (CTR) has been developed as a single-shot electron bunch length monitor at an optical beam port downstream the 100 MeV preinjector LINAC of the Swiss Light Source. This EOA monitor combines the advantages of step-scan interferometers (high temporal resolution) [D. Mihalcea et al., Phys. Rev. ST Accel. Beams 9, 082801 (2006) and T. Takahashi and K. Takami, Infrared Phys. Technol. 51, 363 (2008)] and terahertz-gating technologies [U. Schmidhammer et al., Appl. Phys. B: Lasers Opt. 94, 95 (2009) and B. Steffen et al., Phys. Rev. ST Accel. Beams 12, 032802 (2009)] (fast response), providing the possibility to tune the accelerator with an online bunch length diagnostics. While a proof of principle of the spatial interferometer was achieved by step-scan measurements with far-infrared detectors, the single-shot capability of the monitor has been demonstrated by electro-optical correlation of the spatial CTR interference pattern with fairly long (500 ps) neodymium-doped yttrium aluminum garnet (Nd:YAG) laser pulses in a ZnTe crystal. In single-shot operation, variations of the bunch length between 1.5 and 4 ps due to different phase settings of the LINAC bunching cavities have been measured with subpicosecond time resolution.

Suetterlin, Daniel [PUBLICA Swiss Federal Pension Fund, CH-3000 Berne (Switzerland); Paul Scherrer Institute, CH-5232 Villigen (Switzerland); Erni, Daniel [General and Theoretical Electrical Engineering (ATE), Faculty of Engineering, University of Duisburg-Essen, D-47048 Duisburg (Germany); Schlott, Volker [Department of Large Research Facilities, Paul Scherrer Institute, CH- 5232 Villigen (Switzerland); Sigg, Hans [Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, CH- 5232 Villigen (Switzerland); Jaeckel, Heinz [Department of Information Technology and Electrical Engineering, Electronics Laboratory, ETHZ, CH-8092 Zurich (Switzerland); Murk, Axel [Department of Microwave Physics, Institute of Applied Physics, University of Berne, CH-3012 Berne (Switzerland)

2010-10-15

123

Effects of Conformational Disorder on the Conjugation Length and non Linear Optical Properties of Conjugated Polymers  

NASA Astrophysics Data System (ADS)

Conjugated polymers are of special interest due to the technological relevance of their nonlinear optical properties for photonic applications. The large non linear responses are in this case associated with the large one dimensional conjugation lengths of the delocalized p-electrons. Recent work has concentrated on the nature of conjugation lengths. We study the effect of conformational disorder on the electronic and optical properties of polymers. By taking both steric and conjugation interactions into account, we find that, even if deviations from planar configurations are small, the large angular breaks, although rare are determinative. This leads to a model for the conjugated chain that can be described as relatively long, almost planar segments separated by abrupt breaks in planarity ("flips"). It is the flips that dominate the optical properties. The obtained probability distribution for the segments agrees with results from numerical simulations. We also compare our predictions to recent experiments on long conjugated molecules, and find that our theory provides better agreement over previous models.

Yaliraki, Sophia N.; Silbey, Robert J.

1997-01-01

124

Long gage-length fiber optic sensors for monitoring pipeline integrity  

NASA Astrophysics Data System (ADS)

This paper describes the use of FOX-TEK's long gage-length FT fiber optic sensors (FOS) for monitoring the integrity of pipelines and refinery components. Site assessment protocols and installation methods are described, in addition to the different FOS configurations required to monitor component integrity. It is shown how sensor information can also be used for process control, involving the monitoring of line temperature, pressure, and pipe wall thinning. Models are described that allow the operator to interpret field data to detect corrosion rates, pipe bending, movement and buckling.

Tennyson, R. C.; Morison, W. D.

2006-04-01

125

Transit time of optical pulses propagating through a finite length medium.  

PubMed

We present experimental and theoretical results on the transit time of optical pulses propagating through bulk media of finite length, specifically GaAs and silica. The transit time of the peak of the pulse varies with the central wavelength due to the étalon effects caused by the reflectivity at the air/medium boundaries. For transform limited optical pulses, the transit time as a function of wavelength follows the transmittance spectrum, that is, the longest transit time occurs at the transmittance maxima where the cavity dwell time is the longest and the shortest transit time occurs at the transmittance minima. The results are dramatically different for chirped pulses obtained by modulating the injection current of a diode laser. The range in the transit times for chirped pulses is a factor of four times larger compared with transform limited pulses. In addition, the transit time for chirped pulses propagating through the GaAs sample is negative at certain wavelengths. Also, the transmitted pulse is not distorted. Although modulating the injection current of a diode laser is the most common method for generating optical pulses, to our knowledge this is the first reported observation of the transit time of these chirped optical pulses propagating through a simple étalon structure. PMID:12059739

Bloemer, Mark; Myneni, Krishna; Centini, Marco; Scalora, Michael; D'Aguanno, Giuseppe

2002-05-20

126

Common path endoscopic optical coherence tomography with outside path length compensation  

NASA Astrophysics Data System (ADS)

Endoscopic optical coherence tomography (OCT) allowing high-resolution imaging of internal tissue is attractive for medical imaging. Fibre, fibre bundle or GRIN lens rod acting as endoscopic probe is placed in the sample arm of a Michelson interferometer in current endoscopic OCT systems, this arrangement has to be carefully configured to avoid dispersion and polarization fading. In this study, a common path OCT system with outside path length compensation is presented. The system based on Fizeau configuration requires a Michelson interferometer to compensate the optical path difference between the reference and signal light in the Fizeau sensing interferometer. Experiments of path length compensation and vibration are conducted, and the results demonstrate that this outside compensation method is feasible and the system is immune to the vibration which occurs at the Fizeau sensing interferometer. This OCT imaging approach is very suitable for endoscopic imaging and detailed endoscopic OCT system is also presented. Several samples were imaged to demonstrate the performance of the proposed OCT system.

Yang, Yaliang; Ding, Zhihua; Meng, Jie; Wu, Lan; He, Zi"ang; Wu, Tong; Chen, Minghui

2007-10-01

127

Design and implementation of multi-layer and multi-bit micro holographic optical data storage employing blue lasers  

NASA Astrophysics Data System (ADS)

A zoom objective lens for a multi-layer optical recording has been designed. A newly proposed optical power arrangement enables varying back focal length while focal length invariant by a linear movement of single zooming component. The zoom lens is implemented into multi-layer and multi-bit holographic recording system employing 405 nm blue lasers.

Takashima, Yuzuru; Hesselink, Lambertus

2012-10-01

128

Influence of core diameter and length of polymer optical fiber on Brillouin scattering properties  

NASA Astrophysics Data System (ADS)

Brillouin scattering in perfluorinated graded-index polymer optical fibers (PFGI-POFs) is potentially useful in developing high-accuracy distributed temperature sensors with reduced strain sensitivity. In this study, we investigate, both experimentally and theoretically, the influence of the fiber core diameter and length on the Brillouin gain spectra (BGS) in PFGI-POFs. First, we show that smaller core diameter drastically enhances the Stokes power using PFGI-POFs with 62.5-?m and 120-?m core diameters, and discuss the Brillouin threshold power. Then, we demonstrate that the PFGI-POF length has little influence on the BGS when the length is longer than 50 m. We also predict that, at 1.55-?m wavelength, it is difficult to reduce the Brillouin threshold power of PFGI-POFs below that of long silica single-mode fibers even if their core diameter is sufficiently reduced to satisfy the single-mode condition. Finally, making use of the enhanced Stokes signal, we confirm the Brillouin linewidth narrowing effect.

Mizuno, Yosuke; Ishigure, Takaaki; Nakamura, Kentaro

2012-01-01

129

Experimental determination of the effect of temperature on refractive index and optical path length of glass.  

PubMed

With the Fizeau interferometer method, the change in optical path length with temperature is measured at six wavelengths for twenty new Corning optical glasses. The sample, a polished block with a few seconds of wedge, is held in a double-walled chamber with temperature control provided over the range -20 degrees C to +80 degrees C by a circulating water-glycol mixture. A Gaertner interferometer viewing apparatus is modified by addition of a monitor head that permits simultaneous photoelectric fringe detecting and viewing. Measurement of thermal expansion with the Plummer-Hagy high precision dilatometer permits the extraction of the temperature coefficient of absolute refractive index from the optical path measurement. The coefficient of refractive index relative to standard air at the temperature of the glass is found by further data reduction using Edlén's equations. The experimental values of the index change as a function of temperature are curve-fitted by a FORTRAN program, and the slopes are computed to give instantaneous values of the coefficients. The average residual for the fit is about 1.0 x 10(-6). The precision of the absolute coefficient values is estimated to be +/-0.05 x 10(-6). Representative data for one glass are presented to illustrate the results available from this work. PMID:20111284

Parker, C J; Popov, W A

1971-09-01

130

Scintillators for fiber optics: system sensitivity and bandwidth as a function of fiber length. [Nuclear explosions  

SciTech Connect

Scintillators have been employed for several years as ionizing radiation-to-light converters in plasma diagnostic experiments that utilize fiber optics. Until recently, nanosecond and subnanosecond scintillators were available only in the near ultraviolet. However, the bandwidth and transmission properties of fiber optics both strongly favor operation at longer wavelengths. More recently, nanosecond and subnanosecond scintillators with emission peaks around 480 nm have been reported. A time-resolved plasma-imaging experiment using one of these scintillators and 100 channels of graded-index fiber, each 500 m long, has been successfully tested on a nuclear event at the Nevada Test Site. During the past year we have developed several new scintillator systems with emission wavelengths more compatible with fiber optics and with response times in the nanosecond and subnanosecond time region. One scintillator, based on Kodak dye 14567 (DCM), has an emission maximum at 650 nm and a response time (FWHM) of 1.2 ns. Experimental data on system sensitivity and bandwidth versus fiber length are presented for three fluor-fiber systems. Data on fluor formulation, response time, and linearity-of-response are given, and a model for scintillator nonlinearity, based on solvent, radiation-induced, transient absorption, is presented.

Lutz, S.S.; Franks, L.A.; Fluornoy, J.M.; Lyons, P.B.

1981-01-01

131

Individual sarcomere length determination from isolated cardiac cells using high-resolution optical microscopy and digital image processing.  

PubMed Central

Discrete sarcomere lengths have been determined from dynamically contracting isolated cardiac cells with a high-speed, high-resolution direct optical imaging system. Calcium-tolerant cardiac cells from the rat are isolated by perfusion with collagenase and hyaluronidase. Individual sarcomere lengths can be determined by directly imaging the cell's striation pattern onto a solid-state charge-coupled device (CCD) detector interfaced with a digital computer. The precision of detection in a real light microscopic optical system is discussed in relation to the type of image detector, optical contract enhancement techniques, and digital image processing. The optical performance of the direct striation pattern image apparatus has been determined empirically with test grids under standard bright-field and Nomarski-differential interference contrast (DIC) conditions for application to real muscle imaging. Discrete striation positions of isolated cells have been detected and followed with high precision during phasic contraction-relaxation cycles down to average sarcomere lengths as short as 1.43 +/- 0.053 microns. The maximum rates of contraction and relaxation are rapid and synchronous in time course along the length of the cell. These results indicate that direct optical imaging can provide an accurate means to monitor discrete striations and sarcomere lengths along the length of Ca2+-tolerant heart cells. Images FIGURE 1 FIGURE 4

Roos, K P; Brady, A J

1982-01-01

132

Influence of the word length and input power on nonlinear crosstalk induced by hybrid optical amplifiers  

NASA Astrophysics Data System (ADS)

In this paper, the influence of the word length (WL) of a pseudo-random bit sequence (PRBS) and the input laser power on nonlinear crosstalk induced by the different hybrid optical amplifiers (HOAs) has been examined. It is found that the crosstalk is strongly dependent on the WL and very sensitive to the relative powers of the input signals at 0.2 nm and 0.4 nm of the channel spacing. It is shown that the proposed hybrid Raman–EDFA induces lesser crosstalk as compared to other HOAs. The performance of Raman–EDFA HOA is also investigated for 16 × 10 Gbps dense wavelength division multiplexed (DWDM) system at 0.2 nm of channel spacing.

Singh, Simranjit; Kaler, R. S.

2013-10-01

133

High-speed simulation of skin spectral reflectance based on an optical path-length matrix method and its application  

NASA Astrophysics Data System (ADS)

In this paper, we propose optical path-length matrix method for high-speed simulation of photon migration in human skin. The optical path-length matrix is defined as the probability density distribution of optical pathlength in the skin. Generally, Monte Carlo simulation is used to simulate a skin reflectance, since it can simulate the reflectance accurately. However, it requires a huge computation time, thus this is not easily applicable in practical imaging system with large number of pixels. On the other hand, the proposed optical path-length matrix method achieves the simulation in shorter time. The skin model was assumed to be two-layered media of the epidermal and dermal layers. For obtaining the path-length matrix, photon migration in the model without any absorption was simulated only once by Monte Carlo simulation for each wavelength, and the probabilistic density histograms of the optical path-length at each layer were acquired and stored in the optical path-length matrix. Skin spectral reflectance for arbitrary absorption can be calculated easily by accumulating all combination of an element in the above pre-recomputed path-length matrix and absorption coefficient based on the Beer-Lambert law. Our proposed method was compared with the conventional Monte Carlo simulation. Computational time of the proposed method was approximately two minutes; while that of the conventional method was 15 hours. In addition, error margin of the proposed method was approximately less than 1.6%. This method would applied to skin spectral image analysis for skin chromophore quantification.

Fujiwara, Izumi; Yamamoto, Satoshi; Yamauchi, Midori; Ogawa-Ochiai, Keiko; Nakaguchi, Toshiya; Tsumura, Norimichi

2011-02-01

134

Novel method for laser focal point positioning on the cover slip for TPP-based microfabrication and detection of the cured structure under optical microscope  

NASA Astrophysics Data System (ADS)

Detection of a single cured structure in two-photon photopolymerization (TPP) based microstructure fabrication requires the laser focal spot to be exactly positioned on the cover slip. This is due to the fact that if the laser focal position is not exactly on the cover slip, the structure may not stick to the cover slip and flow away with the liquid during the washing and developing stages. In this paper, we report a scheme of laser spot positioning for the implementation of TPP process and the detection of a single cured microstructure under an optical microscope. For this, a novel yet very simple approach is devised and an uncomplicated procedure is developed. Experimental results are also included to prove the worthiness of the devised method.

Najam, Muhammad Tallal Bin; Arif, Khalid Mahmood; Lee, Yong-Gu

2013-04-01

135

Evaluation of a multimode fiber optic low coherence interferometer for path length resolved Doppler measurements of diffuse light.  

PubMed

The performance of a graded index multimode fiber optic low coherence Mach-Zehnder interferometer with phase modulation is analyzed. Investigated aspects were its ability to measure path length distributions and to perform path length resolved Doppler measurements of multiple scattered photons in a turbid suspension of particles undergoing Brownian and translational motion. The path length resolution of this instrument is compared with a system using single mode fibers for illumination and detection. The optical path lengths are determined from the zero order moment of the phase modulation peak in the power spectrum. The weighted first moment, which is equal to the average Doppler shift, shows a linear response for different mean flow velocities within the physiological range. PMID:18163752

Varghese, Babu; Rajan, Vinayakrishnan; Van Leeuwen, Ton G; Steenbergen, Wiendelt

2007-12-01

136

Design and fabrication of fluid controlled dynamic optical lens system  

NASA Astrophysics Data System (ADS)

A novel small fluid controlled optical lens system that is capable of displaying dynamic variation of its focal length and field-of-view (FOV) is designed and fabricated. In this active lens system, appropriate volume of the optical fluid can be pumped into or out of the lens chamber to provide double-convex (DCX) or double-concave (DCV) lens effect. Simple optical imaging experiments were performed using different sets of glass lenses with fixed focal lengths to determine the optimum lens configuration required for designing a dynamic optical lens system. The experimental results obtained from the glass lenses demonstrate that a combination of a single DCX lens with three DCV lenses provides a wider FOV. The flexible membranes for fluid controlled lenses were fabricated using polydimethylsiloxane polymer material, which has good optical transparency and elasticity. A simple fluid injection system is used to vary the radius of curvature of the lenses, and thereby to change the focal length. A dynamic optical lens system with a combination of one DCX and multiple variable focal length DCV lenses as designed here can image an object with a wide range of focal length and FOV. With this fluid controlled optical system, the FOV and focal length could be continuously varied and a maximum FOV of 118.3° could be achieved. The smallest f-number (f/#) for this fluid controlled single lens system was found to be 1.3, which corresponds to the numerical aperture value of 0.35.

Gunasekaran, R. A.; Agarwal, M.; Singh, A.; Dubasi, P.; Coane, P.; Varahramyan, K.

2005-06-01

137

Optical design of GAIA  

NASA Astrophysics Data System (ADS)

The optical design is discussed for the GAIA astrometric satellite project of the European Space Agency. A Gregory-type telescope with a focal length of 60 m is presented, and the usefulness of dispersed interferometric fringes is discussed. A payload with four interferometers is proposed and presently called GAIA95C. It contains two Hipparcos-type beam combiners and telescopes with 2 m diameter giving direct imaging onto a focal plane assembly of CCDs suited for astrometry and 10-colour photometry.

Hoeg, E.; Bastian, U.; Seifert, W.

1997-08-01

138

OPTICAL SYSTEMS: Calculation of the illuminance distribution in the focal spot of a focusing system taking into account aberrations in this system and divergence of a focused laser beam  

NASA Astrophysics Data System (ADS)

The dependence of the focal-spot size of a 'deep' parabolic mirror reflector on the laser-beam divergence is analysed by the method of elementary reflections. The dependence of the focal-beam diameter of an ideal focusing optical system on the laser-beam parameters is described. The expression is obtained for calculating the illumination distribution in the focal spot of a 'deep' mirror reflector which takes into account both aberrations and light-gathering power of the reflector and the divergence of a focused laser beam.

Gitin, Andrey V.

2007-03-01

139

Active optical zoom for laser communication  

NASA Astrophysics Data System (ADS)

Changing the field-of-view of a laser communication system in real-time without mechanical motion could significantly improve signal strength and reduce drop out rates. By incorporating active elements into the optical design, we have designed and demonstrated imaging systems that are capable of variable effective focal lengths with no macroscopic moving parts (i.e. active optical zoom). This technique, in which the active optics serve as variable focal-length lenses, could easily be applied to laser communication systems to improve capability. The key to this concept is to create relatively large changes in the field-of-view of the system with very small changes in the focal lengths of individual elements by leveraging the optical power of conventional optical elements surrounding the active optics. By appropriately designing the optical system, these variable focal-length lenses can provide the flexibility necessary to change the overall system focal length, and therefore field-of-view, that is normally accomplished with mechanical motion in conventional zoom systems.

Martinez, Ty; Wick, David V.; Payne, Don M.; Restaino, Sergio R.

2005-05-01

140

Properties of Optical Design Modules.  

National Technical Information Service (NTIS)

Optical design modules are defined as a class of two-surface optical systems with fixed focal lengths and having the property that, relative to a pair of conjugate planes, one finite and the other infinite, the third-order spherical aberration is zero. It...

R. I. Mercado

1972-01-01

141

Influence of nanotube length on the optical and conductivity properties of thin single-wall carbon nanotube networks.  

PubMed

We study the optical and electrical properties of transparent conducting films made from length-sorted single-wall carbon nanotubes (SWCNT). Thin films of length-sorted SWCNTs, formed through filtration from a dispersing solvent onto a filter substrate ("buckypaper"), exhibit sharp changes in their optical properties and conductivity (sigma) with increasing SWCNT surface concentration. At a given surface concentration, tubes longer than 200 nm are found to form networks that are more transparent and conducting. We show that changes of sigma with SWCNT concentration can be quantitatively described by the generalized effective medium (GEM) theory. The scaling universal exponents describing the "percolation" transition from an insulating to a conducting state with increasing concentration are consistent with the two-dimensional (2D) percolation model. Shorter tubes and mixed length tubes form 3D networks. Furthermore, we demonstrate that the conductivity percolation threshold (x(c)) varies with the aspect ratio L as, x(c) approximately 1/L, a result that is also in accordance with the percolation theory. These findings provide a framework for engineering the optical and electrical properties of SWCNT networks for technological applications where flexibility, transparency, and conductivity are required. PMID:19206428

Simien, Daneesh; Fagan, Jeffrey A; Luo, Wei; Douglas, Jack F; Migler, Kalman; Obrzut, Jan

2008-09-23

142

Direct measurement of DNA molecular length in solution using optical tweezers: detection of looping due to binding protein interactions.  

PubMed

DNA looping is caused by the interaction between DNA binding proteins located at separate positions on a DNA molecule and may play an important role in transcription regulation. We have developed a system to stretch single DNA molecules and to measure changes in molecular length. DNA molecules were prepared and 5' end-labeled by PCR amplification. Two beads and the intervening DNA molecule were trapped and manipulated independently with dual trap optical tweezers. The trapped DNA molecule was then stretched and the extension (the distance between the two beads) was measured. The extension at the specific tension force of 30 pN was calculated and used as a molecular length. The molecular length was found to be proportional to the base pair number. The rise per residue was calculated to be 3.31 +/- 0.05 A. The length measurement was applied to DNA fragments containing GC box sequences at two different locations separated by a distance of 2.428 kbp. The addition of GC box binding transcription factor Sp1 shortened the molecular length, suggesting DNA looping forms as a result of interaction between transcription factors. PMID:9463890

Sakata-Sogawa, K; Kurachi, M; Sogawa, K; Fujii-Kuriyama, Y; Tashiro, H

1998-01-01

143

CO[sub 2] laser beam propagation with ZnSe optics  

SciTech Connect

Beam propagation characteristics of ZnSe optics used in kiloWatt power CO[sub 2] laser aided material processing applications are determined using the Prometec Laser Beam Analyzer. The laser used was a Rofin Sinar RS6000 CO[sub 2] laser with mode aperturing. Beam power varied from 500W to 6300W and beam modes used were TEM[sub 00], TEM[sub 01], TEM[sub 10] and TEM[sub 20]. Both transmissive and reflective optics were examined. The ZnSe lenses tested included meniscus, diffractive and cylindrical lenses of 5in focal length and a 10in focal length integrading lens. Reflective optics included an integrator and a 5in focal length parabolic mirror for welding. Parameters obtained included beam propagation profiles, intensity profiles, depth of focus, spot size and back focal length. A subset of the data obtained is presented here. Details of the work will appear in a full length paper.

Leong, K.H.; Liu, Yi; Holdridge, D.J.

1992-01-01

144

CO{sub 2} laser beam propagation with ZnSe optics  

SciTech Connect

Beam propagation characteristics of ZnSe optics used in kiloWatt power CO{sub 2} laser aided material processing applications are determined using the Prometec Laser Beam Analyzer. The laser used was a Rofin Sinar RS6000 CO{sub 2} laser with mode aperturing. Beam power varied from 500W to 6300W and beam modes used were TEM{sub 00}, TEM{sub 01}, TEM{sub 10} and TEM{sub 20}. Both transmissive and reflective optics were examined. The ZnSe lenses tested included meniscus, diffractive and cylindrical lenses of 5in focal length and a 10in focal length integrading lens. Reflective optics included an integrator and a 5in focal length parabolic mirror for welding. Parameters obtained included beam propagation profiles, intensity profiles, depth of focus, spot size and back focal length. A subset of the data obtained is presented here. Details of the work will appear in a full length paper.

Leong, K.H.; Liu, Yi; Holdridge, D.J.

1992-11-01

145

Variable Focal Length High Speed Lens.  

National Technical Information Service (NTIS)

This report describes the development and prototype manufacture of a high speed (f/2.4) zoom lens to work in the near infra-red (0.7 to 0.9mm) in conjunction with an image tube night viewing system. The development or design effort covered a period of 32 ...

A. L. Shawcross

1972-01-01

146

Short-Length Raptor Codes for Free-Space Optical Communications  

Microsoft Academic Search

Free-space optical (FSO) links are competitive wireless links offering high data rate,security and low system complexity. Compared to radio-frequency (RF) links, FSOlinks offer high rates at gigabit-per-second (Gbps) level and relatively low cost. However, atmospheric scintillation and misalignment between optical transmitter and receiver impair data rates of FSO links. Scintillation and misalignment are slow fadingprocesses with a fading interval of

Wenzhe Zhang

2009-01-01

147

Passive thermal compensation of the optical bench of the Galaxy Evolution Explorer  

Microsoft Academic Search

The Galaxy Evolution Explorer is an orbiting space telescope that will collect information on star formation by observing galaxies and stars in ultraviolet wavelengths. The optical bench supporting detectors and related optical components used an interesting and unusual passive thermal compensation technique to accommodate thermally-induced focal length changes in the optical system. The proposed paper will describe the optical bench

Virginia G. Ford; Richard Parks; Michelle Coleman

2004-01-01

148

A New Optical Configurations Proposed for GAIA  

NASA Astrophysics Data System (ADS)

The baseline optical configurations proposed for the Global Astrometric Interferometer for Astrophysics (GAIA) have an effective focal length of ~12 m (Perryman & Lindegren 1994, Shacklan & Loiseau 1995) appropriate for image location on the focal plane via a modulating grid. To allow direct fringe detection, an effective focal length of 25-30 m is required to sample properly the white interferometric fringes with improved state of the art CCDs. Alternative optical configurations of the GAIA interferometer subject to the requirement above and therefore suitable for direct fringedetection were investigated. In particular, a 4-mirror and 4-reflection (4M/4R) configuration was designed and analysed. This configuration realizes an effective focal length of 25 m due to the introduction of one aspheric surface; this appears sufficient to match the sampling requirement of the fringes which calls for ~2.5 micrometer pixels.

Cecconi, M.; Gai, M.; Lattanzi, M. G.

1997-08-01

149

The effect of collimator lenses on the performance of an optical coherence tomography system  

NASA Astrophysics Data System (ADS)

The effect of using collimator lenses with different focal lengths on the performance of a spectral-domain adaptive optics optical coherence tomography (AO-OCT) system has been studied. In vivo OCT scans of a healthy human retina were taken separately with different collimator lenses. Although shorter focal length lenses provide a smaller beam diameter at the pupil of the eye, and therefore a larger diffraction-limited spot size, on the return path the shorter focal length collimators demonstrate a better performance focusing the sinc-function-like intensity distribution returning from the eye on the fiber tip. The results might have applications in the OCT imaging of challenging cases.

Fält, Pauli; Zawadzki, Robert J.; Cense, Barry

2011-02-01

150

Influence of substituents and chain length on the optical properties of poly(p-phenylenevinylene) oligomers  

SciTech Connect

Electronic-structure calculations based upon the Pariser-Parr-Pople semiempirical Hamiltonian were applied to short-chain oligomers of the conducting polymer poly(p-phenylenevinylene) (PPV) to study the effects of appending methoxy groups along the backbone as well as push-pull nitro and amino groups at the ends of the oligomers. Optical absorption spectra were calculated utilizing configuration interaction methods at the single-excitation level, and the nonlinear optical properties of the push-pull oligomers were studied using the sum-over-states approach. In short-chain oligomers, the calculated electronic and optical properties are controlled by the nature of the pendant groups. However, in the longest oligomers studied, these molecular properties are relatively insensitive to any of the studied modifications.

Davis, W.B.; Ratner, M.A. [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Wasielewski, M.R. [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry]|[Argonne National Lab., IL (United States). Chemistry Div.

1999-04-15

151

Electro Optic Bunch Length Measurements at the VUV-FEL at DESY  

Microsoft Academic Search

For the operation of a SASE FEL, the longitudinal bunch profile is one of the most critical parameters. At the superconducting linac of the VUV-FEL at DESY, an electro optic sampling (EOS) experiment was installed to probe the time structure of the electric field of the bunches to better than 100 fs rms. The field induced birefringence of a ZnTe

B. Steffen; S. Casalbuoni; E.-A. Knabbe; H. Schlarb; B. Schmidt; P. Schmuser; A. Winter

2005-01-01

152

Short length of single walled-carbon nano tubes for application to optical devices  

Microsoft Academic Search

Carbon nano tubes (CNT) attracts attention in the field of optical communication. However, CNT is too long as it is compared with the wavelength of communication wavelength and causes the scattering. So we could make CNT short and fat, and our devise showed saturable absorption.

S. Kato; Y. Miyazaki; T. Takashima; K. Utaka

2010-01-01

153

Imaging and full-length biometry of the eye during accommodation using spectral domain OCT with an optical switch  

PubMed Central

Abstract: An optical switch was implemented in the reference arm of an extended depth SD-OCT system to sequentially acquire OCT images at different depths into the eye ranging from the cornea to the retina. A custom-made accommodation module was coupled with the delivery of the OCT system to provide controlled step stimuli of accommodation and disaccommodation that preserve ocular alignment. The changes in the lens shape were imaged and ocular distances were dynamically measured during accommodation and disaccommodation. The system is capable of dynamic in vivo imaging of the entire anterior segment and eye-length measurement during accommodation in real-time.

Ruggeri, Marco; Uhlhorn, Stephen R.; De Freitas, Carolina; Ho, Arthur; Manns, Fabrice; Parel, Jean-Marie

2012-01-01

154

Synthesis and optical properties of triangular gold nanoplates with controllable edge length  

Microsoft Academic Search

Gold triangular nanoplates with a uniform size were synthesized by a simple seeds-growth method in a lamellar lyotropic liquid\\u000a crystal (LLC) medium consisting of F127, n-C4H9OH and H2O. The edge length of gold nanoplates can be adjusted from tens to several hundreds nanometers (and even a few micrometers)\\u000a by varying the concentration of Au3+ and the seeds solution volume. The

JianHua Sun; MingYun Guan; TongMing Shang; CuiLing Gao; Zheng Xu

2010-01-01

155

Effect of the side chain length on the optical and electrical properties of soluble PPV derivatives  

Microsoft Academic Search

2-Alkoxy-5-methoxy poly(1,4-phenylenevinylene) derivatives with different lengths of the alkoxy side chain have been synthesized via a modified Gilch polymerization. Their number-average molecular weights are in the range of 10,000–14,000. 1H NMR, 13C NMR, FT-IR spectroscopies have shown that the polymer structures are the expected ones and were free from defects. The polymers are amorphous and show good thermal stability up

H. Trad; A. Ltaief; M. Majdoub; A. Bouazizi; J. Davenas

2006-01-01

156

On the path length of an excess electron interacted with optical phonons in a molecular chain  

NASA Astrophysics Data System (ADS)

We show that in a molecular chain with dispersionless phonons at zero temperature, a “quasistationary” moving soliton state of an excess electron is possible. As the soliton velocity vanishes, the path length of the excess electron exponentially tends to infinity. It is demonstrated that in the presence of dispersion, when the soliton initial velocity exceeds the maximum group velocity of the chain, the soliton slows down until it reaches the maximum group velocity and then moves stationarily at this maximum group velocity. A conclusion is made of the fallacy of some works were the existence of moving polarons in a dispersionless medium is considered infeasible.

Lakhno, V. D.

2008-08-01

157

Application of maximum likelihood estimator in nano-scale optical path length measurement using spectral-domain optical coherence phase microscopy  

PubMed Central

Spectral-domain optical coherence phase microscopy (SD-OCPM) measures minute phase changes in transparent biological specimens using a common path interferometer and a spectrometer based optical coherence tomography system. The Fourier transform of the acquired interference spectrum in spectral-domain optical coherence tomography (SD-OCT) is complex and the phase is affected by contributions from inherent random noise. To reduce this phase noise, knowledge of the probability density function (PDF) of data becomes essential. In the present work, the intensity and phase PDFs of the complex interference signal are theoretically derived and the optical path length (OPL) PDF is experimentally validated. The full knowledge of the PDFs is exploited for optimal estimation (Maximum Likelihood estimation) of the intensity, phase, and signal-to-noise ratio (SNR) in SD-OCPM. Maximum likelihood (ML) estimates of the intensity, SNR, and OPL images are presented for two different scan modes using Bovine Pulmonary Artery Endothelial (BPAE) cells. To investigate the phase accuracy of SD-OCPM, we experimentally calculate and compare the cumulative distribution functions (CDFs) of the OPL standard deviation and the square root of the Cramér-Rao lower bound (1/2SNR) over 100 BPAE images for two different scan modes. The correction to the OPL measurement by applying ML estimation to SD-OCPM for BPAE cells is demonstrated.

Motaghian Nezam, S. M. R.; Joo, C; Tearney, G. J.; de Boer, J. F.

2009-01-01

158

X-ray Pulse Length Characterization using the Surface Magneto Optic Kerr Effect  

SciTech Connect

It will be challenging to measure the temporal profile of the hard X-ray SASE beam independently from the electron beam in the LCLS and other 4th generation light sources. A fast interaction mechanism is needed that can be probed by an ultrafast laser pulse in a pump-probe experiment. It is proposed to exploit the rotation in polarization of light reflected from a thin magnetized film, known as the surface magneto optic Kerr effect (SMOKE), to witness the absorption of the x-ray pulse in the thin film. The change in spin orbit coupling induced by the x-ray pulse occurs on the subfemtosecond time scale and changes the polarization of the probe beam. The limitation to the technique lies with the bandwidth of the probe laser pulse and how short the optical pulse can be made. The SMOKE mechanism will be described and the choices of materials for use with 1.5 {angstrom} x-rays. A schematic description of the pump-probe geometry for x-ray diagnosis is also described.

Krejcik, P.; /SLAC

2006-10-04

159

160 Gb\\/s variable length packet\\/10 Gb\\/s-label all-optical label switching with wavelength conversion and unicast\\/multicast operation  

Microsoft Academic Search

We report on the first demonstration of all-optical label switching (AOLS) with 160 Gb\\/s variable length packets and 10 Gb\\/s optical labels. This result demonstrates the transparency of AOLS techniques from previously demonstrated 2.5 Gb\\/s to this 160 Gb\\/s demonstration using a common routing and packet lookup framework. Packet forwarding\\/conversion, optical label erasure\\/re-write and signal regeneration at 160 Gb\\/s is

Wei Wang; Lavanya G. Rau; Daniel J. Blumenthal

2005-01-01

160

Bunch Length Monitoring at the A0 Photoinjector Using a Quasi-Optical Schottky Detector  

SciTech Connect

Noninvasive bunch duration monitoring has a crucial importance for modern accelerators intended for short wavelength FEL's, colliders and in some beam dynamics experiments. Monitoring of the bunch compression in the Emittance Exchange Experiment at the A0 Photoinjector was done using a parametric presentation of the bunch duration via Coherent Synchrotron Radiation (CSR) emitted in a dipole magnet and measured with a wideband quasi-optical Schottky Barrier Detector (SBD). The monitoring resulted in a mapping of the quadrupole parameters allowing a determination of the region of highest compression of the bunch in the sub-picosecond range. The obtained data were compared with those measured using the streak camera. A description of the technique and the results of simulations and measurements are presented and discussed in this report.

Kazakevich, G.; Davidsaver, M.; Edwards, H.; Fliller, R.; Koeth, T.; Lumpkin, A.; Nagaitsev, S.; Ruan, J.; Thurman-Keup, R.; /Fermilab; Jeong, Y.U.; /KAERI, Taejon; Kubarev, V.; /Novosibirsk, IYF

2009-05-01

161

Primary extranodal marginal zone lymphoma of the uvea associated with massive diffuse epibulbar extension and focal infiltration of the optic nerve and meninges, clinically presented as uveitis masquerade syndrome: a case report  

Microsoft Academic Search

To report a clinical, histopathological and immunohistochemical findings in a case of primary extranodal marginal zone lymphoma\\u000a of the uvea associated with massive diffuse extraocular episcleral extension and focal infiltration of the optic nerve and\\u000a meninges, clinically presented as longstanding uveitis masquerade syndrome. Interventional case reports with histopathological\\u000a correlation. We describe a 80-year-old male patient with a 3-year history of

D. M. Raši?; Z. Stankovi?; T. Terzi?; D. Kova?evi?; Z. Koturovi?; V. Markovi?

2010-01-01

162

Optical Design of a Broadband Infrared Spectrometer for Bunch Length Measurement at the Linac Coherent Light Source  

SciTech Connect

The electron pulses generated by the Linac Coherent Light Source at the SLAC National Accelerator Laboratory occur on the order of tens of femtoseconds and cannot be directly measured by conventional means. The length of the pulses can instead be reconstructed by measuring the spectrum of optical transition radiation emitted by the electrons as they move toward a conducting foil. Because the emitted radiation occurs in the mid-infrared from 0.6 to 30 microns a novel optical layout is required. Using a helium-neon laser with wavelength 633 nm, a series of gold-coated off-axis parabolic mirrors were positioned to direct a beam through a zinc selenide prism and to a focus at a CCD camera for imaging. Constructing this layout revealed a number of novel techniques for reducing the aberrations introduced into the system by the off-axis parabolic mirrors. The beam had a recorded radius of less than a millimeter at its final focus on the CCD imager. This preliminary setup serves as a model for the spectrometer that will ultimately measure the LCLS electron pulse duration.

Williams, Kiel; /SLAC

2012-09-07

163

Herschel Space Telescope: Optical test and model correlation  

Microsoft Academic Search

Subsequent to the cyrogenic optical testing of the 3.5 m silicon carbide ESA Herschel Space Telescope, a discrepancy between the prediction and measurement of the telescope back focal length was identified. Efforts to resolve this discrepancy involved both improvements to modeling and more thorough examination of the optical test techniques. The most significant input to modeling was the use of

B. Catanzaro; Dominic Doyle

2009-01-01

164

Optical considerations for the Long Trace Profiler: Required camera resolution  

Microsoft Academic Search

As requirements for measuring mirrors with more accuracy become more demanding, knowledge of the Long Trace Profiler's (LTP's) ability to measure small slope differences between adjacent locations on a mirror becomes more important. This presentation shows what kind of slope resolution one can expect of a measurement, given the optical system parameters. The optical system parameters are focal length of

Irick

2000-01-01

165

Defocus compensation system of long focal aerial camera based on auto-collimation  

NASA Astrophysics Data System (ADS)

Nowadays, novel aerial reconnaissance camera emphasizes on the shooting performance in high altitude or in long distance of oblique photography. In order to obtain the larger scale pictures which are easier for image interpretation, we need the camera has long focal length. But long focal length camera is easier to be influenced by environmental condition and lead to great change of lens' back focus which can result in the lens' resolution decreased greatly. So, we should do precise defocusing compensation to long focal aerial camera system. In order to realize defocusing compensation, a defocusing compensation system based on autocollimation is designed. Firstly, the reason which can lead to long focal camera's defocusing was discussed, then the factors such as changes of atmospheric pressure and temperature and oblique photographic distance were pointed out, and mathematical equation which could compute camera's defocusing amount was presented. Secondly, after camera's defocusing was analyzed, electro-optical autocollimation of higher automation and intelligent was adopted in the system. Before shooting , focal surface was located by electro-optical autocollimation focal detection mechanism, the data of airplane's height was imported through electronic control system. Defocusing amount was corrected by computing defocusing amount and the signal was send to focusing control motor. And an efficient improved mountain climb-searching algorithm was adopted for focal surface locating in the correction process. When confirming the direction of curve, the improved algorithm considered both twice focusing results and four points. If four points continue raised, the curve would be confirmed as rising direction. On the other hand, if four points continue decreased, the curve would be confirmed as decrease direction. In this way, we could avoid the local peak value appeared in two focusing steps. The defocusing compensation system consists of optical component and precise control system and precise driver component. Based on FPGA hardware system, hardware function is realized by VHDL. It has been using on some kinds of long focal CCD cameras and film cameras. It not only has good dimensional stability and structural stability in harsh environment, but also has ability of focal surface precision detection and accurate focusing.

Zhang, Yu-Ye; Zhao, Yu-Liang; Xu, Zhao-Lin

2010-05-01

166

Focal segmental glomerulosclerosis  

MedlinePLUS

Focal segmental glomerulosclerosis is scar tissue that forms in parts of the kidney called glomeruli. The glomeruli serve as ... The cause of focal segmental glomerulosclerosis is usually ... and adults. Men and boys are affected slightly more often than ...

167

A CMOS image sensor method of focal spot size measurement.  

PubMed

A phosphor opto-coupled monochrome CMOS image sensor with a slit diaphragm was used to investigate focal spot characteristics. Images were captured during x-ray exposure with a triggered frame grabber and subsequently enhanced. Dimensions of the focal spot width (1.39mm) and length (1.92mm) were determined from the focal spot intensity profiles and their corresponding Full Width at Half Maxima (FWHM) in two orthogonal orientations. The CMOS image sensor measurements demonstrated differences in the measured width and length dimensions when compared to film measurements. The obtained nominal focal spot values however showed that image-sensor determined focal spot dimensions agreed with the direct film and film-screen methods when based on the AS/NZS defined nominal focal spot values. The CMOS image sensor tested appears to lack the measurement accuracy required for the measurement of small focal spot sizes due in part to its limited camera sensitivity. PMID:15462588

Tuchyna, T; Paix, D

2004-06-01

168

Herschel Space Telescope: Impact of new material strain data on optical test and model correlation  

Microsoft Academic Search

Successful launch and imagery from the Herschel Space Telescope has demonstrated a nominally in focus telescope. There still remains a discrepancy between the prediction and measurement of the telescope back focal length prior to launch. New material strain data has been applied to the structural\\/optical model of the telescope. The new data significantly closed the gap between the previous optical

Brian Catanzaro; Dominic Doyle; E. J. Cohen

2010-01-01

169

Herschel Space Telescope: impact of new material strain data on optical test and model correlation  

Microsoft Academic Search

Successful launch and imagery from the Herschel Space Telescope has demonstrated a nominally in focus telescope. There still remains a discrepancy between the prediction and measurement of the telescope back focal length prior to launch. New material strain data has been applied to the structural\\/optical model of the telescope. The new data significantly closed the gap between the previous optical

Brian Catanzaro; Dominic Doyle; Eri Cohen

2010-01-01

170

An electron-optical phase-shift element for high-speed electron beam testing  

Microsoft Academic Search

An electron-optical element has been developed which delays electron pulses with continuous phase-shift resolution over a 200 ps delay span. The method relies on changing the beam potential, and hence electron flight time, in an axisymmetric electrostatic lens system over a defined section of the optical path. Changes in the focal length of the electrostatic lens are compensated for by

J. T. L. Thong; W. C. Nixon

1990-01-01

171

Decibels versus dollars: long-range atmospheric optical communications on a tight budget  

Microsoft Academic Search

Three decades of experiment by the authors have shown that the combination of high intensity light emitting diodes, silicon photodiodes, and large aperture moulded Fresnel lens collimators of moderate focal length provide effective and economical long distance atmospheric optical communications. While the use of larger transmitter and receiver lenses increases optical flux at the detector, their greatest advantage is in

Christopher Long; Michael Groth; Clinton Turner

2008-01-01

172

Mosaic Focal Plane Development  

NASA Astrophysics Data System (ADS)

Advances in systems engineering, applied sciences, and manufacturing technologies have enabled the development of large ground based and spaced based astronomical instruments having a large Field of View (FOV) to capture a large portion of the universe in a single image. A larger FOV can be accomplished using light weighted optical elements, improved support structures, and the development of mosaic Focal Plane Assemblies (mFPA). A mFPA designed for astronomy can use multiple Charged Coupled Devices (CCD) mounted onto a single camera baseplate integrated at the instrument plane of focus. Examples of current, or proposed, missions utilizing mFPA technology include FAME, GEST, Kepler, GAIA, LSST, and SNAP. The development of a mFPA mandates tighter control on the design trades, component development, CCD characterization, component integration, and performance verification testing. This paper addresses the capability Lockheed Martin Space Systems Company's (LMSSC) Advanced Technology Center (ATC) has developed to perform CCD characterization, mFPA assembly and alignment, and mFPA system level testing.

Mason, David L.; Horner, Scott D.; Aamodt, Earl K.

2002-12-01

173

Mosaic Focal Plane Development  

NASA Astrophysics Data System (ADS)

Advances in manufacturing and applied sciences have enabled the development of large ground and spaced based astronomical instruments having a Field of View (FOV) large enough to capture a large portion of the universe in a single image. A large FOV can be accomplished using light weighted optics, improved structures, and the development of mosaic Focal Plane Assemblies (mFPAs). A mFPA comprises multiple Charged Coupled Devices (CCD) mounted onto a single baseplate integrated at the focus plane of the instrument. Examples of current, or proposed, missions utilizing mFPA technology include FAME, GEST, Kepler, GAIA, LSST, and SNAP. The development of a mFPA mandates tight control on the design trades of component development, CCD definition and characterization, component integration, and performance verification testing. This paper addresses the results of the Lockheed Martin Space Systems Company (LMSSC), Advanced Technology Center (ATC) developed mFPA. The design trades and performance characterization are services provided by the LMSSC ATC but not detailed in this paper.

Mason, D.; Horner, S.; Aamodt, E.

174

Flux density distribution in the focal region of a solar concentrator system  

SciTech Connect

In high temperature solar energy applications highly concentration optical systems, such as, e.g., parabolic dishes, achieve typical tradition flux densities {gt}2 MW/M{sup 2}. In order to investigate thermo and photochemical reactions at temperatures {gt}1500 K and radiation flux densities {gt}2 MW/m{sup 2} a solar furnace was built at Paul Scherrer Institute (PSI). This furnace is a two-stage concentrator. The first stage is a prefocusing glass heliostat with a focal length of 100 m. The second stage is an highly concentrating parabolic dish with a focal length of 1.93 m. To design experiments to be carried out in the focal region of the parabolic dish, the radiation flux as well as its density distribution have to be known. This distribution is usually measured by radiometric methods. However, these methods are generally rather troublesome because of the high temperatures involved. In this paper the authors present a simple method to estimate the characteristic features of the radiation flux density distribution in the focal region of the concentrator system.

Schubnell, M.; Keller, J.; Imhof, A. (Paul Scherrer Inst., CH-5232 Villigen-PSI (CH))

1991-05-01

175

A unique, accurate LWIR optics measurement system  

NASA Astrophysics Data System (ADS)

A compact low-cost LWIR test station has been developed that provides real time MTF testing of IR optical systems and EO imaging systems. The test station is intended to be operated by a technician and can be used to measure the focal length, blur spot size, distortion, and other metrics of system performance. The challenges and tradeoffs incorporated into this instrumentation will be presented. The test station performs the measurement of an IR lens or optical system's first order quantities (focal length, back focal length) including on and off-axis imaging performance (e.g., MTF, resolution, spot size) under actual test conditions to enable the simulation of their actual use. Also described is the method of attaining the needed accuracies so that derived calculations like focal length (EFL = image shift/tan(theta)) can be performed to the requisite accuracy. The station incorporates a patented video capture technology and measures MTF and blur characteristics using newly available lowcost LWIR cameras. This allows real time determination of the optical system performance enabling faster measurements, higher throughput and lower cost results than scanning systems. Multiple spectral filters are also accommodated within the test stations which facilitate performance evaluation under various spectral conditions.

Fantone, Stephen D.; Orband, Daniel G.

2011-05-01

176

Lateral compliance and elastic stability of a dual-coated optical fiber of finite length, with application to nano-rods embedded into low-modulus elastic media  

Microsoft Academic Search

We address the lateral compliance and elastic stability of a dual-coated fiber of finite length (such as, e.g., an optical fiber interconnect) and apply the obtained solution to a nano-rod (nano-wire, nano-fiber, carbon nano-tube) embedded into a low-modulus elastic medium. The latter situation is encountered in nano-composites, as well as in some advanced heat-spreaders employing nano-rod-arrays. Both the photonic (dual-coated

E. Suhir

2009-01-01

177

Influence of Axial Length on Peripapillary Retinal Nerve Fiber Layer Thickness in Children: A Study by RTVue Spectral-Domain Optical Coherence Tomography.  

PubMed

Abstract Purpose: To evaluate the influence of axial length on peripapillary retinal nerve fiber layer (RNFL) thickness in myopic, hyperopic and emmetropic children eyes by RTVue optical coherence tomography (OCT). Methods: One hundred twenty eyes of 120 children including 40 myopic, 40 emmetropic and 40 hyperopic eyes were enrolled in the study. Peripapillary RNFL thickness measurements were performed using spectral-domain RTVue OCT (Optovue, Fremont, CA). RNFL thickness parameters were obtained from all octametric sections: upper temporal (TU), superotemporal (ST), superonasal (SN), upper nasal (NU), lower nasal (NL), inferonasal (IN), inferotemporal (IT) and lower temporal (TL). Spherical equivalent refractive error was determined via cycloplegic auto-refraction (Topcon, Tokyo, Japan). The axial length was measured using IOLMaster (Carl Zeiss MEDITEC). Littmann formula was used for correction of axial length-related ocular magnification effect. Results: Peripapillary RNFL thicknesses were significantly different among the three groups in all sectors except for NU and IT sectors. RNFL thicknesses in all sectors except for TU and TL sectors had significant negative correlations with axial length. However, these differences (excluding TU and TL sectors) and correlations disappeared after correction of magnification effect. Conclusion: In conclusion, axial length influences peripapillary RNFL thickness as measured by RTVue OCT. However, this appears to be due to the ocular magnification effects associated with axial length and can be corrected for with the application of the Littman formula. PMID:23972028

Aykut, Veysel; Oner, Veysi; Ta?, Mehmet; I?can, Yalç?n; A?açhan, Ahmet

2013-08-23

178

Combining Single-Molecule Optical Trapping and Small-Angle X-Ray Scattering Measurements to Compute the Persistence Length of a Protein ER/K ?-Helix  

PubMed Central

Abstract A relatively unknown protein structure motif forms stable isolated single ?-helices, termed ER/K ?-helices, in a wide variety of proteins and has been shown to be essential for the function of some molecular motors. The flexibility of the ER/K ?-helix determines whether it behaves as a force transducer, rigid spacer, or flexible linker in proteins. In this study, we quantify this flexibility in terms of persistence length, namely the length scale over which it is rigid. We use single-molecule optical trapping and small-angle x-ray scattering, combined with Monte Carlo simulations to demonstrate that the Kelch ER/K ?-helix behaves as a wormlike chain with a persistence length of ?15 nm or ?28 turns of ?-helix. The ER/K ?-helix length in proteins varies from 3 to 60 nm, with a median length of ?5 nm. Knowledge of its persistence length enables us to define its function as a rigid spacer in a translation initiation factor, as a force transducer in the mechanoenzyme myosin VI, and as a flexible spacer in the Kelch-motif-containing protein.

Sivaramakrishnan, S.; Sung, J.; Ali, M.; Doniach, S.; Flyvbjerg, H.; Spudich, J.A.

2009-01-01

179

Profile reconstruction of grazing-incidence x-ray mirrors from intra-focal x-ray full imaging  

NASA Astrophysics Data System (ADS)

The optics of a number of future X-ray telescopes will have very long focal lengths (10 - 20 m), and will consist of a number of nested/stacked thin, grazing-incidence mirrors. The optical quality characterization of a real mirror can be obtained via profile metrology, and the Point Spread Function of the mirror can be derived via one of the standard computation methods. However, in practical cases it can be difficult to access the optical surfaces of densely stacked mirror shells, after they have been assembled, using the widespread metrological tools. For this reason, the assessment of the imaging resolution of a system of mirrors is better obtained via a direct, full-illumination test in X-rays. If the focus cannot be reached, an intra-focus test can be performed, and the image can be compared with the simulation results based on the metrology, if available. However, until today no quantitative information was extracted from a full-illumination, intra-focal exposure. In this work we show that, if the detector is located at an optimal distance from the mirror, the intensity variations of the intra-focal, full-illumination image in single reflection can be used to reconstruct the profile of the mirror surface, without the need of a wavefront sensor. The Point Spread Function can be subsequently computed from the reconstructed mirror shape. We show the application of this method to an intra-focal (8 m distance from mirror) test performed at PANTER on an optical module prototype made of hot-slumped glass foils with a 20 m focal length, from which we could derive an expected imaging quality near 16 arcsec HEW.

Spiga, D.; Basso, S.; Bavdaz, M.; Burwitz, V.; Civitani, M.; Citterio, O.; Ghigo, M.; Hartner, G.; Menz, B.; Pareschi, G.; Proserpio, Laura; Salmaso, B.; Tagliaferri, G.; Wille, E.

2013-09-01

180

Focal paroxysmal kinesigenic choreoathetosis  

PubMed Central

Three cases of paroxysmal kinesigenic choreoathetosis are described in whom unilateral attacks were focally induced, together with a case in whom bilateral attacks only occured. Treatment with phenytoin was effective in all cases. The aspects of the literature relating to focal and generalised attacks in paroxysmal kinesigenic choreoathetosis are reviewed.

Plant, Gordon

1983-01-01

181

Focal dystonia in musicians.  

PubMed

In conclusion, musicians' focal dystonia is a significant and potentially career-ending neurological condition of which physiatrists and other performing arts medicine clinicians should be aware. Pathology has been identified in the somatosensory cortex, and in the motor cortex and basal ganglia. Although advances have been made in the elucidating some of the pathologic changes in focal dystonia, better understanding is needed. Current treatments such as retraining, splinting, oral medications, and botulinum toxin injections are limited. Therefore, the ultimate goal for focal dystonia is to prevent this disabling disorder of instrumental musicians. PMID:17097479

Lie-Nemeth, Theresa J

2006-11-01

182

Analysis of sensitivity and optical path-length in non-invasive measurement of glucose with near infrared spectroscopy  

NASA Astrophysics Data System (ADS)

Non-invasive glucose monitoring with optical methods has obtained increasing interest, in that the methods have shown great benefit for diabetes. Nevertheless, low sensitivity and signal to noise ratio (ratio of effective photons) are two major difficulties in non-invasively NIR spectral monitoring of blood glucose concentration. Designing the optical probe properly is one of the effective ways to improve measuring sensitivity and ratio of effective photons. In this paper, definition about ratio of effective photons in measurement of glucose is introduced. And then effect of glucose on optical properties of human skin is analyzed, based on this, two kind of sensitivities for diffuse reflectance, namely sensitivity to absorption and that to scattering, is derived. To investigate the ratio of effective photons and sensitivities, Monte Carlo simulations have been performed on a three-layered media with optical parameters similar to those of human skin. The results have shown that (1) high ratio of effective photons, even as high as 60%, can be obtained by choosing proper the separation between source and detector; (2) sensitivity of diffuse reflectance to absorption and scattering has different dependence on source-detector separation, which enables one can have different options by making use of different effect from glucose level changing. In the end, some suggestions have been put forward to improve precision of measurement of blood glucose.

Luo, Yunhan; Liu, Rong; Chen, Wenliang; Cui, Houxin; Xu, Kexin

2005-03-01

183

Electromagnetic field calculations for microlens optical systems  

NASA Astrophysics Data System (ADS)

Microlenses are becoming more widely used in modern optical equipment. When the microlens diameter is comparable with the incident electromagnetic illumination wavelength, diffraction effects through the microlens aperture dominate and significantly affect the microlens optical properties leading to differences from that predicted by ordinary geometrical optics theory. In this work, the continuous-profile symmetrical biconvex microlens is selected for investigation. Its optical properties, with both monochromatic plane wave and TEM00 mode Gaussian beam illumination, are studied using the full-field Separation-of-Variables method (SVM) in the oblate spheroidal coordinate system by calculating the electromagnetic field distributions inside of and adjacent to the microlens. The microlens optical properties are also compared with the corresponding geometrical optics theory. The investigations and discussions include the focusing properties of a single microlens with monochromatic plane wave illumination, the beam transformation properties of a single microlens with monochromatic TEM00 mode Gaussian beam illumination, the axial combination properties of dual microlenses with monochromatic plane wave and TEM00 mode Gaussian beam illumination, the interference properties between dual parallel-arranged microlenses with monochromatic plane wave illumination, and the imaging properties of a single microlens with monochromatic plane wave and TEM00 mode Gaussian beam illumination. The optical properties of microlens optical systems are found to be similar to that given by the geometrical optics theory. The microlens actual focal length is measured for different profile and diameter microlenses and is compared with its corresponding geometrical focal length. It is shown that the microlens actual focal length is an important parameter and can be used to describe and approximately formulate the microlens optical properties. The transmitted beam waist position through a microlens calculated using the Rayleigh Range method (RRM) with the microlens actual focal length closely matches the exact value determined using the Separation-of-Variables method in the oblate spheroidal coordinate system. The axial combination properties of dual microlenses with monochromatic plane wave illumination and the imaging properties of a single microlens can also be described using the geometrical imaging formula with the microlens actual focal length.

Wang, Jian

184

About focal tolerances of the segments of Deutsches Grossteleskop  

NASA Astrophysics Data System (ADS)

In order to address the variance in the focal lengths of the segments for the Deutsches Grossteleskop (DGT), a method is delineated to calculate permissible focal tolerances. Sets of arbitrarily distributed delta-f (differences in focal lengths), where for each the average is zero and the standard deviation is normalized to 1 mm, are used to calculate the permissible tolerance. The DGT's correlation function provides the criteria for the analysis, and the results demonstrate that the two types of segmentation considered should have a delta-f of 0.072 for the four-quadrant configuration and of 0.360 for the 13-piece configuration.

Kuehne, Christoph

1990-08-01

185

MTI Focal Plane Assembly Design and Performance  

SciTech Connect

The focal plane assembly for the Multispectral Thermal Imager (MTI) consists of sensor chip assemblies, optical filters, and a vacuum enclosure. Sensor chip assemblies, composed of linear detector arrays and readout integrated circuits, provide spatial resolution in the cross-track direction for the pushbroom imager. Optical filters define 15 spectral bands in a range from 0.45 {micro}m to 10.7 {micro}m. All the detector arrays are mounted on a single focal plane and are designed to operate at 75 K. Three pairs of sensor chip assemblies (SCAs) are required to provide cross-track coverage in all 15 spectral bands. Each pair of SCAs includes detector arrays made from silicon, iridium antimonide, and mercury cadmium telluride. Read out integrated circuits multiplex the signals from the detectors to 18 separate video channels. Optical filter assemblies defining the spectral bands are mounted over the linear detector arrays. Each filter assembly consists of several filter strips bonded together side-by-side. The MTI focal plane assembly has been integrated with the rest of the payload and has undergone detailed testing and calibration. This paper includes representative test data for the various spectral bands and the overall performance of the focal plane assembly.

Ballard, M.; Rienstra, J.L.

1999-06-17

186

A conceptual midwave infrared remote sensor based on an uncooled focal plane array  

NASA Astrophysics Data System (ADS)

The 3-5?m wave length region has been recognized as an effective mid infrared spectral range for the detection of high temperature events on Earth surface with remote sensing camera. Most of current mid infrared remote sensors relied on cooled detectors. Although they have high radiometric sensitivity, they inevitably are large size and weight, high power consumption, short life-time, and high cost. With the advent of uncooled thermal detectors, the miniaturization of mid infrared imagers suitable for microsatellite is being investigated widely. Based on uncooled focal plane array, a conceptual compact midwave infrared sensor has been put forward. It is designed for hot spot detection. First, working environments and requirements of the sensor for hot spot detection is introduced. Then the characteristic of its main constituent parts including selected uncooled focal plane array and the designed optical system is presented. Because uncooled focal plane array has lower radiometric sensitivity than the cooled, we are more concerned about the thermal resolution of the system. And its performance including sub-pixel hot spot detection capabilities and spatial resolution is evaluated. It shows that the suggested compact sensor with uncooeld focal plane array can not meet the requirement.

Liu, Lin; Shen, Weimin; Chen, Yuheng

2008-12-01

187

Theoretical and experimental analysis of basic parameters of two-element optical systems.  

PubMed

Our work presents detailed theoretical analysis of two-element optical systems of telephoto lenses and objectives of anallactic telescopes with internal focusing. The first element of such systems has positive optical power and the second element has negative optical power. This type of optical system is widespread in practice mainly in the field of photographic lenses and in surveying instruments (theodolites, leveling instruments, etc.) where the anallactic telescope with internal focusing is being used. In our work we propose methods to determine the basic parameters of such objectives, i.e., the focal lengths of both the elements of the objective lens and their mutual axial separation. Furthermore, the detailed analysis of aberration properties of such optical systems is performed and methods for measuring the focal lengths of individual elements and their mutual distance without the need for disassembling the investigated optical system are presented. PMID:23089783

Mikš, Antonín; Novák, Pavel

2012-10-20

188

Comparative analysis of doublets versus single-layer diffractive optical elements in eyepiece or magnifier design.  

PubMed

We quantify the impact of eye clearance requirement on the performance of eyepieces utilizing doublets versus diffractive optical elements on aspheric substrates. In this study, the doublets were designed to be cemented on-axis elements. Specifically, four different values of eye clearance were implemented: 17, 20, 23, and 26 mm. For each value, axial and lateral color, spherical aberration, coma, astigmatism, field curvature, and distortion were compared. Each system under comparison was optimized for the same focal length, a 9 mm exit pupil, photopic wavelengths (513-608 nm), and a 40 degrees full field of view. We demonstrate that the single-layer diffractive optical element supports an eye clearance value of approximately 80% of the effective focal length, while the doublet drops below desired specifications at approximately 65% of the effective focal length. PMID:18026553

Cakmakci, Ozan; Rolland, Jannick

2007-11-20

189

Analysis and application of refractive variable-focus lenses in optical microscopy  

NASA Astrophysics Data System (ADS)

We present an approach to an analysis of the third order monochromatic and chromatic aberrations of refractive fluid lenses with a variable focal length. A detailed theoretical analysis is performed for a simple variable-focus lens and formulas are derived for an optical design of such lenses. The advantage of these active lenses is their capability to change continuously the focal length within a certain range. These lenses give a possibility to design non-conventional optical systems which change their parameters (focal length, magnification, etc.) in a continuous way without a need for mechanical movements of lenses. Such lenses with a variable focal length make possible to design optical systems with functions that are difficult or even impossible to combine using conventional approaches. We perform an analysis of optical design of such lenses. The experimental analysis and calculations are provided for Varioptic lens Arctic-416. Potential applications of variable-focus liquid lenses in optical microscopy are analyzed and simulated. We also investigate a possibility of increasing the depth of focus using such lenses and the influence of a variable-focus lens on the image quality.

Novak, Pavel; Novak, Jiri; Miks, Antonin

2011-05-01

190

SNAP focal plane  

SciTech Connect

The proposed SuperNova/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square-degree field sensitive in the visible and near-infrared wavelength regime. We describe the requirements for the instrument suite and the evolution of the focal plane design to the present concept in which all the instrumentation--visible and near-infrared imagers, spectrograph, and star guiders--share one common focal plane.

Lampton, Michael L.; Kim, A.; Akerlof, C.W.; Aldering, G.; Amanullah, R.; Astier, P.; Barrelet, E.; Bebek, C.; Bergstrom, L.; Berkovitz, J.; Bernstein, G.; Bester, M.; Bonissent, A.; Bower, C.; Carithers Jr., W.C.; Commins, E.D.; Day, C.; Deustua, S.E.; DiGennaro,R.; Ealet, A.; Ellis, R.S.; Eriksson, M.; Fruchter, A.; Genat, J.-F.; Goldhaber, G.; Goobar, A.; Groom, D.; Harris, S.E.; Harvey, P.R.; Heetderks, H.D.; Holland, S.E.; Huterer, D.; Karcher, A.; Kolbe, W.; Krieger, B.; Lafever, R.; Lamoureux, J.; Levi, M.E.; Levin, D.S.; Linder,E.V.; Loken, S.C.; Malina, R.; Massey, R.; McKay, T.; McKee, S.P.; Miquel, R.; Mortsell, E.; Mostek, N.; Mufson, S.; Musser, J.; Nugent, P.; Oluseyi, H.; Pain, R.; Palaio, N.; Pankow, D.; Perlmutter, S.; Pratt, R.; Prieto, E.; Refregier, A.; Rhodes, J.; Robinson, K.; Roe, N.; Sholl, M.; Schubnell, M.; Smadja, G.; Smoot, G.; Spadafora, A.; Tarle, G.; Tomasch,A.; von der Lippe, H.; Vincent, R.; Walder, J.-P.; Wang, G.

2002-07-29

191

Idiopathic focal segmental glomerulosclerosis.  

PubMed

This study was conducted to determine the prognostic value of some clinical, laboratory, histopathologic and therapeutic factors in 62 children with focal segmental glomerulosclerosis. There were no significant differences between the factors studied, except for severe interstitial fibrosis, which was more frequent in patients with chronic kidney disease (P=0.03). The prevalence of chronic kidney disease in nonresponder groups was significantly higher (P <0.05). We found therapy with cyclophosphamide to be promising in patients with focal segmental glomerulosclerosis. PMID:19736363

Naseri, Mitra; Madani, Abbas; Attaii, Nematolah; Naseri, Homa

2009-09-03

192

MWIR and LWIR megapixel QWIP focal plane arrays  

NASA Astrophysics Data System (ADS)

A mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 1024x1024 pixel quantum well infrared photodetector (QWIP) focal plane array has been demonstrated with excellent imagery. MWIR focal plane has given noise equivalent differential temperature (NETD) of 19 mK at 95K operating temperature with f/2.5 optics at 300K background and LWIR focal plane has given NEDT of 13 mK at 70K operating temperature with same optical and background conditions as MWIR array. Both of these focal plane arrays have shown background limited performance (BLIP) at 90K and 70K operating temperatures with the same optics and background conditions. In this paper, we will discuss their performance in quantum efficiency, NETD, uniformity, and operability.

Gunapala, Sarath D.; Bandara, Sumith V.; Liu, John K.; Hill, Cory J.; Rafol, B., Sir; Mumolo, Jason M.; Thang, J.; Tidrow, Meimei Z.; LeVan, Paul D.

2004-10-01

193

Focal Plane Metrology for the LSST Camera  

SciTech Connect

Meeting the science goals for the Large Synoptic Survey Telescope (LSST) translates into a demanding set of imaging performance requirements for the optical system over a wide (3.5{sup o}) field of view. In turn, meeting those imaging requirements necessitates maintaining precise control of the focal plane surface (10 {micro}m P-V) over the entire field of view (640 mm diameter) at the operating temperature (T {approx} -100 C) and over the operational elevation angle range. We briefly describe the hierarchical design approach for the LSST Camera focal plane and the baseline design for assembling the flat focal plane at room temperature. Preliminary results of gravity load and thermal distortion calculations are provided, and early metrological verification of candidate materials under cold thermal conditions are presented. A detailed, generalized method for stitching together sparse metrology data originating from differential, non-contact metrological data acquisition spanning multiple (non-continuous) sensor surfaces making up the focal plane, is described and demonstrated. Finally, we describe some in situ alignment verification alternatives, some of which may be integrated into the camera's focal plane.

A Rasmussen, Andrew P.; Hale, Layton; Kim, Peter; Lee, Eric; Perl, Martin; Schindler, Rafe; Takacs, Peter; Thurston, Timothy; /SLAC

2007-01-10

194

Length-dependent change of optical, magnetic, and vibrational properties of vanadate (V(IV)O3(2-)) quantum wire embedded in AM-6 vanadosilicate.  

PubMed

AM-6 and VSH-1 are vanadosilicates containing VO(3)(2-) quantum wires and oxovanadate [O?VO(4)](2-) quantum dots, respectively. We developed methods to synthesize pure, highly crystalline, monodisperse, and all-V(IV) AM-6 and VSH-1 crystals with sizes between 0.2-0.3 and 10 ?m. On the basis of their optical, magnetic susceptibility, vibrational, and electron spin resonance (ESR) properties, we have elucidated the following interesting phenomena. The length of the VO(3)(2-) quantum wire (l) linearly increases as the length along the [110] direction {L([110])} increases. The band gap energy (E(g)) of the VO(3)(2-) quantum wire progressively decreases with increasing l even when it reaches ~210 nm, indicating that the Bohr length (the length at which the quantum confinement effect no longer appears) is longer than 200 nm. The deduced ?(z) and ?(xy) are 0.0005m(e) and 15.7m(e), respectively. Per-V(IV)-ion oscillator strength of the d-d transition increases by 7-9 times and that of CT transition increases by 1.5-1.9 times with increasing l from ~50 to 210 nm (by ~4 times). The longitudinal vibration frequency ? of the VO(3)(2-) quantum wire decreases and the intensity of the vibrational band increases as l increases. The ESR intensity increases while the peak-to-peak width decreases as l increases, indicating that the spin-spin relaxation rate (R(ssr)) decreases as l increases. The magnetic susceptibility ? decreases as l increases, especially at T > 125 K, indicating that the tendency of the d(1) electron spins to orient to the external magnetic field decreases with increasing l. PMID:23009119

Datta, Shuvo Jit; Yoon, Kyung Byung

2012-10-05

195

Reproducibility of coronary optical coherence tomography for lumen and length measurements in humans (The CLI-VAR [Centro per la Lotta contro l'Infarto-VARiability] study).  

PubMed

Frequency-domain optical coherence tomography (FD-OCT) is becoming a useful diagnostic tool for coronary imaging for quantitative coronary analysis. Second-generation FD-OCT produces detailed coronary lumen images. However, the reproducibility of coronary measurements using FD-OCT in humans has not been thoroughly explored. Our goal was to determine the intraobserver, interobserver, and interpullback reproducibility of the in vivo FD-OCT measurements of the lumen area and/or lesion length. Twenty-five patients undergoing coronary angioplasty were included. In all subjects, FD-OCT pullbacks (20 mm/s) were acquired twice from the same coronary segment different from the target lesion, at an interval of 5 minutes, with no other intervention. A total of 9,396 cross-sectional lumen area frames and the relative coronary lesion length of each pullback were analyzed off-line with dedicated software by 2 independent expert readers (A and B). We compared the lumen area and length measurements as follows: pullback 1, read by reader A twice at an interval of 7 days (intraobserver analysis); pullback 1, independently read by readers A and B (interobserver comparison); and pullback 1 versus pullback 2, read by reader A (interpullback comparison). The per-segment and per-frame analyses showed very high and significant correlation coefficients for the interobserver, intraobserver, and interpullback comparisons for the lumen area and lesion length (R ?0.95 and p <0.001 in all cases). Accordingly, the Bland-Altman estimates of bias showed nonsignificant differences in the interobserver, intraobserver, and interpullback comparisons at all levels, with average biases never >0.150 mm(2) for the lumen area or 0.200 mm for the lesion length. In conclusion, coronary imaging using FD-OCT showed excellent reproducibility, with low intraobserver, interobserver, and interpullback variability for both lumen area and lesion length measurements in humans. Thus, FD-OCT can be proposed for precise analysis in the catheterization laboratory to guide decision making and in clinical trials focusing on imaging end points. PMID:22748353

Fedele, Silvio; Biondi-Zoccai, Giuseppe; Kwiatkowski, Piotr; Di Vito, Luca; Occhipinti, Michele; Cremonesi, Alberto; Albertucci, Mario; Materia, Laura; Paoletti, Giulia; Prati, Francesco

2012-06-28

196

Focal Cardiac Myocytolysis.  

National Technical Information Service (NTIS)

During the course of a clinical pathologic study of cardiac lesions observed in 375 autopsies at ABCC, focal cardiac myocytolysis (FCM) was found in 21 hearts. There was no evidence that FCM was related to prior exposure at the time of the bomb. Myocardia...

A. Steer T. Kawashima T. Nakashima D. S. Dock K. K. Lee

1975-01-01

197

Focal-Plane Polarimeter  

NASA Astrophysics Data System (ADS)

The preferential spin orientation of a particle in the final state of a nuclear reaction is an observable which carries information about the underlying reaction mechanism. In this introductory lecture I will discuss the basic principles of polarimetry of spin 1/2 particles, focal-plane proton polarimeter and the extraction of the proton recoil polarization.

Strauch, Steffen

2004-03-01

198

Laser Focal Shift Monitor.  

National Technical Information Service (NTIS)

A change in the collimation angle (describing the overall beam divergence or convergence) causes a corresponding change in the laser focal position. The collimation angle of a ray can be expressed in terms of the ratio alpha of its position to slope at th...

J. A. Stamper

1976-01-01

199

Epistemic Focal Bias  

Microsoft Academic Search

This paper defends strict invariantism against some philosophical and empirical data that have been taken to compromise it. The defence involves a combination of a priori philosophical arguments and empirically informed theorizing. The positive account of the data is an epistemic focal bias account that draws on cognitive psychology. It involves the assumption that, owing to limitations of the involved

Mikkel Gerken

2011-01-01

200

Geometric Optics  

NSDL National Science Digital Library

This interactive simulation adapted from the University of Colorado's Physics Education Technology project illustrates how lenses refract light to form images. Manipulate the object, screen, lens, and focal length and observe how the image adjusts.

Foundation, Wgbh E.

2007-08-09

201

Electro-optically actuated liquid-lens zoom  

NASA Astrophysics Data System (ADS)

Progressive miniaturization and mass market orientation denote a challenge to the design of dynamic optical systems such as zoom-lenses. Two working principles can be identified: mechanical actuation and application of active optical components. Mechanical actuation changes the focal length of a zoom-lens system by varying the axial positions of optical elements. These systems are limited in speed and often require complex coupled movements. However, well established optical design approaches can be applied. In contrast, active optical components change their optical properties by varying their physical structure by means of applying external electric signals. An example are liquidlenses which vary their curvatures to change the refractive power. Zoom-lenses benefit from active optical components in two ways: first, no moveable structures are required and second, fast response characteristics can be realized. The precommercial development of zoom-lenses demands simplified and cost-effective system designs. However the number of efficient optical designs for electro-optically actuated zoom-lenses is limited. In this paper, the systematic development of an electro-optically actuated zoom-lens will be discussed. The application of aberration polynomials enables a better comprehension of the primary monochromatic aberrations at the lens elements during a change in magnification. This enables an enhanced synthesis of the system behavior and leads to a simplified zoom-lens design with no moving elements. The change of focal length is achieved only by varying curvatures of targeted integrated electro-optically actuated lenses.

Pütsch, O.; Loosen, P.

2012-05-01

202

The Effect of Side-Chain Length on the Solid-State Structure and Optical Properties of F8BT: A DFT Study  

NASA Astrophysics Data System (ADS)

Using the long-range corrected hybrid density functional theory (DFT/B97D) approach, we have performed bulk solid state calculations to investigate the influence of side-chain length on the molecular packing and optical properties of poly (9,9-di-n-octylfluorene-alt-benzothiadiazole) or F8BT. Two different packing structures, the lamellar and nearly hexagonal, were obtained corresponding to longer and shorter side-chains respectively. This behavior can be attributed to the micro-phase separations between the flexible side-chains and the rigid backbones and is in agreement with previous investigations for other hairy-rod polymers. In addition, as a result of the efficient inter-chain interactions for the lamellar structure, the dihedral angle between the F8 and BT units is reduced providing a more planar configuration for the backbone which leads to the decreased band gap (by 0.2-0.3 eV) in comparison to the hexagonal phase and the gas phase with no side-chain. Time-dependent DFT (TDDFT/B3LYP) was also used to study the excited states of the monomer of F8BT optimized in solid-state structures with different side-chain lengths. It is found that the absorption spectrum is red shifted for the polymers with lamellar structure relative to the polymers in hexagonal and gas phases.

Javad Eslamibidgoli, Mohammad; Lagowski, Jolanta B.

2012-02-01

203

Precision evaluation of lens systems using a nodal slide/MTF optical bench  

NASA Astrophysics Data System (ADS)

A compact, self-contained production instrument designed to permit the rapid and precise performance characterization of a wide variety of lenses and optical systems has been developed by Eidolon Corporation. The Eidolon Production Nodal Slide/MTF Measurement System can be used to measure effective focal length (EFL), distortion, field curvature, chromatic aberration, spot size, and modulation transfer function (MTF).

Doherty, Victor J.; Chapnik, Philip D.

1992-01-01

204

Highly efficient coupling between LD array and optical fiber array using Si microlens array  

Microsoft Academic Search

By using a Si microlens array, highly efficient coupling is realized between laser diode (LD) and optical-fiber arrays. The Si microlens is fabricated by transferring the lens shape of photoresist onto the Si surface using an etching process. For an optimal coupling scheme, a high-NA microlens with a diameter of 240 ?m and focal length of 190 ?m is designed

Gohji Nakagawa; Kazunori Miura; Masao Makiuchi; Mitsuhiro Yano

1993-01-01

205

Optically recorded tunable microlenses based on dye-doped liquid crystal cells  

NASA Astrophysics Data System (ADS)

We report on optically recorded microlenses in conventional liquid crystal cells doped with the azo-dye methyl-red. The focal length can be tuned electrically and changed in a wide range with just a small variation of the applied dc voltage. No patterned electrodes, built-in polymeric lens, or patterned molecular reorientation are required.

Lucchetti, Liana; Tasseva, Jordanka

2012-04-01

206

Focal mechanism of deep moonquakes  

Microsoft Academic Search

To elucidate the focal mechanism of deep moonquakes, S-wave polarizations of deep moonquake signals from the A(1) source region are analyzed. At station 12, where the available data are of the highest quality, the variation of polarization angle with the anomalistic phase of the moon indicates agreement with that expected from the focal mechanism model of Nakamura (1978). Focal mechanism

J. Koyama; Y. Nakamura

1980-01-01

207

Focal cortical dysplasia.  

PubMed

Focal cortical dysplasias are among the most common causes of intractable epilepsy in children. As the neuropathology of these conditions has been better clarified, the nomenclature has undergone numerous revisions. Their recognition has grown with the use of neuroimaging, and recent advances in imaging technology will further improve detection. Clinical, electroencephalographic, and imaging findings are often diagnostic, so it is imperative for the clinician to recognize the characteristic patterns. Treatment for developmental and behavioral disability remains largely symptomatic, and epilepsy medications are often ineffective. Epilepsy surgery, however, can be successful in selected patients. The basic science underlying the development of focal cortical dysplasias may lead to novel therapeutic approaches in the future. PMID:23859852

Gaitanis, John N; Donahue, John

2013-08-01

208

Focal cortical dysplasia - review  

PubMed Central

Summary Focal cortical dysplasia is a malformation of cortical development, which is the most common cause of medically refractory epilepsy in the pediatric population and the second/third most common etiology of medically intractable seizures in adults. Both genetic and acquired factors are involved in the pathogenesis of cortical dysplasia. Numerous classifications of the complex structural abnormalities of focal cortical dysplasia have been proposed – from Taylor et al. in 1971 to the last modification of Palmini classification made by Blumcke in 2011. In general, three types of cortical dysplasia are recognized. Type I focal cortical dysplasia with mild symptomatic expression and late onset, is more often seen in adults, with changes present in the temporal lobe. Clinical symptoms are more severe in type II of cortical dysplasia usually seen in children. In this type, more extensive changes occur outside the temporal lobe with predilection for the frontal lobes. New type III is one of the above dysplasias with associated another principal lesion as hippocampal sclerosis, tumor, vascular malformation or acquired pathology during early life. Brain MRI imaging shows abnormalities in the majority of type II dysplasias and in only some of type I cortical dysplasias. The most common findings on MRI imaging include: focal cortical thickening or thinning, areas of focal brain atrophy, blurring of the gray-white junction, increased signal on T2- and FLAIR-weighted images in the gray and subcortical white matter often tapering toward the ventricle. On the basis of the MRI findings, it is possible to differentiate between type I and type II cortical dysplasia. A complete resection of the epileptogenic zone is required for seizure-free life. MRI imaging is very helpful to identify those patients who are likely to benefit from surgical treatment in a group of patients with drug-resistant epilepsy. However, in type I cortical dysplasia, MR imaging is often normal, and also in both types the lesion seen on MRI may be smaller than the seizure-generating region seen in the EEG. The abnormalities may also involve vital for life brain parts, where curative surgery will not be an option. Therefore, other diagnostic imaging techniques such as FDG PET, MEG, DTI and intra-cranial EEG are widely used to establish the diagnosis and to decide on management. With advances in both genetics and neuroimaging, we may develop a better understanding of patients with drug-resistant epilepsy, which will help us to provide more successful pharmacological and/or surgical treatment in the future.

Kabat, Joanna; Krol, Przemyslaw

2012-01-01

209

Ladybug Lengths  

NSDL National Science Digital Library

This lesson introduces students to the measurable attribute of length and provides practice in measuring length using non-standard units. The lesson is launched using the story Ladybug on the Move by Richard Fowler. Lesson objectives, teaching ideas, and handouts are included.

2012-01-01

210

Ladybug Lengths  

NSDL National Science Digital Library

This experience focuses studentâs attention on the attributes of length and gives students the opportunity to develop knowledge of and skills in using nonstandard units of measurement. The lesson begins with a connection to children's literature. As students practice measuring length, they do so using nonstandard units.

Math, Illuminations N.

2009-01-28

211

Alterable focal shift of concentric piecewise cylindrical vector beam  

NASA Astrophysics Data System (ADS)

Focal shift plays an important in many optical fusing systems. In this article, focal shift of concentric piecewise cylindrical vector beam is investigated by means of vector diffraction theory in detail. The section of the beam consists of three concentric zones. The center circle zone and outer annular zone are radial polarized, and the inner annular zone is generalized polarized. In addition the wavefront phase distribution of the vector beam is linear function to radial coordinate. It is found that the parameter in phase distribution induces focal shift and can alter focal shift considerably. However, radii of the inner annular zone and polarization angle do affect focal shift very slightly. So the phase parameter can be used to alter big focal shift while the radii and polarization angle may be employed to adjust intensity distribution. In focusing system, the focal shift and intensity distribution may be controlled separately, which improves the application freedom of this kind of technique. Focal shift direction can also be altered by change the phase parameter.

Zhan, Qiufang; Li, Jinsong; Gao, Xiumin

2009-10-01

212

Payload-envelope detection and label-detection integrated photonic circuit for asynchronous variable-length optical-packet switching with 40-gb\\/s RZ payloads and 10-gb\\/s NRZ labels  

Microsoft Academic Search

A photonic integrated circuit that performs 40-Gb\\/s payload-envelope detection (PED) and 10-Gb\\/s label detection for asynchronous variable-length optical-packet switching is demonstrated. The circuit consists of an InP photonic integrated device combined with electronic GaAs and InP devices on a carrier. Asynchronous variable-length optical packets with 40-Gb\\/s return-to-zero (RZ) payloads and 10-Gb\\/s non-RZ (NRZ) labels are processed by the circuit. The

Brian R. Koch; Zhaoyang Hu; John E. Bowers; Daniel J. Blumenthal

2006-01-01

213

Focal adhesions in osteoneogenesis  

PubMed Central

As materials technology and the field of tissue engineering advances, the role of cellular adhesive mechanisms, in particular the interactions with implantable devices, becomes more relevant in both research and clinical practice. A key tenet of medical device technology is to use the exquisite ability of biological systems to respond to the material surface or chemical stimuli in order to help develop next-generation biomaterials. The focus of this review is on recent studies and developments concerning focal adhesion formation in osteoneogenesis, with an emphasis on the influence of synthetic constructs on integrin mediated cellular adhesion and function.

Biggs, M.J.P; Dalby, M.J

2010-01-01

214

Idiopathic focal segmental glomerulosclerosis.  

PubMed

Idiopathic focal segmental glomerulosclerosis (FSGS) is a primary glomerular disease that essentially represents a form of chronic, progressive renal fibrosis for which there is no discernible cause. Often presenting with or eventually manifesting the nephrotic syndrome, this disease is increasing in incidence in both children and adults. Therapy continues to be a challenge, although some patients clearly respond to corticosteroids or cyclosporine with a decrease in, or remission of, proteinuria. A favorable response is associated with a decreased likelihood of progression to kidney failure. Given our clinical experience and recent advances in understanding the genetics of FSGS, a stochastic model of disease pathogenesis can be proposed. PMID:12704578

Schnaper, H William

2003-03-01

215

Optical system design of visible camera for space debris  

NASA Astrophysics Data System (ADS)

In order to detect the space debris, a visible camera for space debris was proposed.The visible camera was mainly consisted of primary mirror , secondary mirror.In order to balance aberration, six correcting lens were used in the optical system. To reduce the visible camera system size, two mirrors were joined,which could fold the system and shorten the overall length.The focal length was 12000 mm ,field of view was 1. 0 and the f-number was 10.0.The imaging quafity of the optical system in visible camera approached to diffraction limit.

Wang, Hu; Luo, Jianjun

2013-08-01

216

Graphite-epoxy optical systems: lessons learned on the way to Mars  

Microsoft Academic Search

The Mars Orbiter Camera (MOC) narrow angle system is a 3.5 m focal length camera that has operated for the last five years as part of the Mars Global Surveyor (MGS) Mission. Folded into a total package (including electronics) of less than 1 m length and weighing just over 20 kg, MOC's Ritchey-Chretien optical design is extremely sensitive to primary-to-secondary

Michael A. Ravine; Eddy A. Derby; G. Edward Danielson; Michael C. Malin; John Richer; Thomas A. Soulanille; Arthur R. Telkamp

2003-01-01

217

Long wavelength infrared dual field-of-view optical system  

NASA Astrophysics Data System (ADS)

For cooled 320×240 staring focal plane array (FPA), a novel long wavelength infrared dual field-of-view optical system is presented in the paper. The optical system is composed of re-imaging part and zooming part. The parameters of the system are 1.96 f/number, 100% cold shield efficiency, 180mm/60mm effective focal length (EFL) and 8-10 ?m spectrum region. The optical system is analyzed from two modes of narrow field of view (NFOV) and wide field of view (WFOV). The system can be used in the temperature range from-30°Cand 60°C without significant degradation of optical performance. The final test results prove the designed performance is good..

Xiong, Tao; Yang, Chang-cheng

2007-12-01

218

Design of microlens illuminated aperture array fabricated by aligned ultraviolet imprinting process for optical read only memory card system  

Microsoft Academic Search

A microlens illuminated aperture array (MLIAA) was designed for the multiprobe optical read only memory card system. As a method to integrate the microlens array (MLA) with the aperture array containing 1000×1000 apertures, an aligned ultraviolet imprinting process was used to satisfy the system objectives of reduced focal length and reduced spot size. An analysis using diffraction theory was performed

Hongmin Kim; Jeeseung Lee; Jiseok Lim; Seok-Min Kim; Shinill Kang; Young-Joo Kim; Christopher Busch

2006-01-01

219

Determination of the refractive index of highly scattering human tissue by optical coherence tomography  

NASA Astrophysics Data System (ADS)

We describe two new techniques, based on optical coherence tomography (OCT), for determining the refractive index of highly scattering human tissue. We obtained refractive indices of in vitro human tissue, using OCT to measure the physical and optical path lengths of the sample. We obtained measurements of the refractive index of in vitro and in vivo human tissue, using OCT to track the focal length shift that results from translating the focus along the optic axis within the tissue. The refractive indices of human skin, adipose, and muscle were measured and compared with previously published estimates.

Tearney, G. J.; Brezinski, M. E.; Southern, J. F.; Bouma, B. E.; Hee, M. R.; Fujimoto, J. G.

1995-11-01

220

Systematic study of the focal shift effect in planar plasmonic slit lenses.  

PubMed

In this paper, we systematically studied the focal shift effect in planar plasmonic slit lenses. Through theoretical derivations and numerical simulations, we found that there is a focal length shift between the traditional design model and the finite-difference time-domain simulations. The shift is not only dependent on the Fresnel number (FN) of the lens, like traditional dielectric lenses, determined by the lens width and the designed focal length, but also on the surface plasmon polariton (SPPs) interaction on the lens surfaces, dependent on the slit numbers. We also found that the FN-induced focal shift is predominant when FN < 1. However, the SPP interaction-induced focal shift plays a major role when FN > 1. An approximated theoretical model is presented to estimate the focal shift of plasmonic slit lens with FN < 1. PMID:23079867

Hu, Bin; Wang, Qi Jie; Zhang, Ying

2012-10-18

221

Illustrative EDOF topics in Fourier optics  

NASA Astrophysics Data System (ADS)

In this talk we present a series of illustrative topics in Fourier Optics that are proving valuable in the design of EDOF camera systems. They are at the level of final examination problems that have been made solvable by a student or professoi having studied from one of Joseph W. Goodman's books---our tribute for his 75fr year. As time permits, four illustrative topics are l) Electromagnetic waves and Fourier optics;2) The perfect lens; 3) Connection between phase delay and radially varying focal length in an asphere and 4) tailored EDOF designs.

George, Nicholas; Chen, Xi; Chi, Wanli

2011-09-01

222

Finger Length  

NSDL National Science Digital Library

Although life experience plays a huge role in shaping who we are, the foundations of our personality begin in the womb. This Science Update describes a recent study that looks to finger length for signs of a man's pre-natal exposure to testosterone.

Science Update;

2005-03-28

223

High resolution wavefront measurement of aspheric optics  

NASA Astrophysics Data System (ADS)

With the recently emerged large volume production of miniature aspheric lenses for a wide range of applications, a new fast fully automatic high resolution wavefront measurement instrument has been developed. The Shack-Hartmann based system with reproducibility better than 0.05 waves is able to measure highly aspheric optics and allows for real time comparison with design data. Integrated advanced analysis tools such as calculation of Zernike coefficients, 2D-Modulation Transfer Function (MTF), Point Spread Function (PSF), Strehl-Ratio and the measurement of effective focal length (EFL) as well as flange focal length (FFL) allow for the direct verification of lens properties and can be used in a development as well as in a production environment.

Erichsen, I.; Krey, S.; Heinisch, J.; Ruprecht, A.; Dumitrescu, E.

2008-08-01

224

Smart focal plane technologies for ELT instruments  

NASA Astrophysics Data System (ADS)

Smart Focal Planes are devices that enable the efficient sampling of a telescope's focal plane to feed spectroscopic and imaging instruments. Examples are integral field units (fiber and image slicers), cryogenic beam manipulators, and MOEMS (micro-opto-electromechanical systems) such as miniature slit shutters. These technologies are critical in making best use of the current 8m class telescopes for key science goals such as spectroscopic surveys of high redshift galaxies, and will be even more important for Extremely Large Telescope (ELT) instruments. In fact, the density of pixels in an ELT focal plane with several milliarcsecond resolution will mean that sub-sampling of the field will be needed even for imaging. We have proposed a joint European project to develop these technologies, building on expertise from partners in the UK, France, the Netherlands, Spain, Germany and others, and led by the UK. We describe the current status of these technologies, showing how they will contribute to the feasibility and performance of proposed instruments for ELTs, and concentrating on capabilities within Europe. We then outline the proposed future developments, highlighting the technical challenges, such as the difficulties of manufacturing and verifying complex image slicers with thousands of optical surfaces, and building highly reliable cryogenic mechanisms such as pick-off arms, beam steering mirrors and reconfigurble slit mechanisms.

Cunningham, Colin R.; Ramsay-Howat, Suzanne K.; Garzon, Francisco; Parry, Ian R.; Prieto, Eric; Robertson, David J.; Zamkotsian, Frederic

2004-07-01

225

An optical wavefront sensor based on a double layer microlens array.  

PubMed

In order to determine light aberrations, Shack-Hartmann optical wavefront sensors make use of microlens arrays (MLA) to divide the incident light into small parts and focus them onto image planes. In this paper, we present the design and fabrication of long focal length MLA with various shapes and arrangements based on a double layer structure for optical wavefront sensing applications. A longer focal length MLA could provide high sensitivity in determining the average slope across each microlens under a given wavefront, and spatial resolution of a wavefront sensor is increased by numbers of microlenses across a detector. In order to extend focal length, we used polydimethysiloxane (PDMS) above MLA on a glass substrate. Because of small refractive index difference between PDMS and MLA interface (UV-resin), the incident light is less refracted and focused in further distance. Other specific focal lengths could also be realized by modifying the refractive index difference without changing the MLA size. Thus, the wavefront sensor could be improved with better sensitivity and higher spatial resolution. PMID:22346643

Lin, Vinna; Wei, Hsiang-Chun; Hsieh, Hsin-Ta; Su, Guo-Dung John

2011-10-31

226

Integrated Focal Plane Star Sensor.  

National Technical Information Service (NTIS)

A theoretical analysis on the detectors suitable for the Infrared Space Observer (ISO) Integrated Focal Plane Star Sensor (IFPSS) design are presented, together with system configuration concepts. A simplified configuration with respect to the electronic ...

G. Borghi M. Carboncini M. Stagi

1987-01-01

227

Electrically controllable ionic polymeric gels as adaptive optical lenses  

NASA Astrophysics Data System (ADS)

Reversible change in optical properties of ionic polymeric gels, 2-acrylamido-2-methylpropane sulfonic acid (PAMPS) and polyacrylic acid plus sodium acrylate cross-linked with bisacrylamide (PAAM), under the effect of an electric field is reported. The shape of a cylindrical piece of the gel, with flat top and bottom surfaces, changed when affected by an electric field. The top surface became curved and the sense of the curvature (whether concave or convex) depended on the polarity of the applied electric field. The curvature of the surface changed from concave to convex and vice versa by changing the polarity of the electric field. By the use of an optical apparatus, focusing capability of the curved surface was verified and the focal length of the deformed gel was measured. The effect of the intensity of the applied electric field on the surface curvature and thus, on the focal length of the gel are tested. Different mechanisms are discussed; either of them or their combination may explain the surface deformation and curvature. Practical difficulties in the test procedure and the future potential of the electrically adaptive and active optical lenses are also discussed. These adaptive lenses may be considered as smart adaptive lenses for contact lens or other optical applications requiring focal point undulation.

Salehpoor, Karim; Shahinpoor, Mohsen; Mojarrad, Mehran

1996-02-01

228

Polymer microlens array with tunable focal intensity by the polarization control of the incident light  

NASA Astrophysics Data System (ADS)

This paper proposes an optically tunable focal intensity microlens array (MLA) by using a focusing unit with birefringent liquid crystalline polymer (LCP) and a tuning unit with photoalignment for controlling the polarization state of the incident light. Due to the different refractive indices of LCP, it acts as a positive or negative microlens with respect to the polarization state. The resultant tunable focal intensity MLA shows the fast optical switching time without voltage and the multi-stable characteristics.

Huang, San-Yi; Tung, Tung-Chen; Ko, Shin-Wei; Ting, Chi-Lun; Jau, Hung-Chang; Li, Ming-Shian; Lin, Hui-Chi; Fuh, Andy Ying-Guey

2010-02-01

229

An expert system for preliminary optical design.  

NASA Astrophysics Data System (ADS)

An expert system has been developed which will undertake the preliminary design of optical systems. During the preliminary design the optical designer considers the specification of an optical system and derives parameters such as lens type, focal length, etc. These parameters are then converted into power group layouts with curvatures, thicknesses, etc ready for optimisation by lens design software. The preliminary design will have been arrived at by utilising previous design knowledge and 'rules of thumb' acquired through experience. It is this stage of the design process which has been implemented by an expert system, and will hopefully prove a valuable aid to the optical designer during the important creative stage of the design process.

Moss, G. H.

1989-04-01

230

Limits for reduction of effective focal volume in multiple-beam light microscopy.  

PubMed

Employing interference patterns for illumination has been shown to reduce the focal volume in fluorescence microscopy. For example, the 4Pi technique employs two interfering laser beams and significantly decreases the focal volume, as compared to conventional microscopy. We study theoretically the effect of using multiple interfering laser beams on the focal volume. In realistic setups with three or four beams, the focal volume is about half of that from the 4Pi case. This improvement reaches a limit quickly as more beams are added, and for the idealized case of an infinite number of beams the focal volume is rather close to the three- or four-beam cases. Thus, our study suggests a limit for the possible reduction of the focal volume in a purely optical far-field setup. PMID:19219190

Arkhipov, Anton; Schulten, Klaus

2009-02-16

231

Microlens array based LCD projection display with software-only focal distance control  

NASA Astrophysics Data System (ADS)

State of the art LED pico-projectors using single-channeled optical layouts are always constricted by a trade-off between achievable flux and minimum system size. Furthermore, their limited depth of focus require additional mechanically moving components for focusing if variable projection distances are essential for their specific application. We present a novel microlens-array based LCD projector breaking these constraints of conventional LED illuminated systems, thus enabling a super compact, robust and bright module while offering new features for electronic focal distance control without additional mechanical components. While the short focal length of each contributing channel maintains a certain system slimness, the superposition of all individual projections on a screen done by image-preprocessing leads to dramatic flux enhancement without blurring effects. Starting with a description of the working principle of array projection we focus on key properties regarding depth of focus for examining novel image-preprocessing algorithms that enable for only software-controlled focal distance. Further improved program code enables sharp images even onto freeform screen geometries. The realized prototype utilizes a transmissive LCD microdisplay along with a monolithic array of 45 microlenses actively aligned to the top of the display coverglass. While the display is illuminated by a collimated white LED; each channel is assigned to one primary color by applying a color filter array buried below the microlenses to obtain a full color image on the screen. The displayed image content is controlled via PC by a novel software tool, whose correct operation is verified by experimental results.

Sieler, Marcel; Schreiber, Peter; Bräuer, Andreas

2013-03-01

232

Sex prevalence of focal dystonias.  

PubMed Central

The sex prevalence of idiopathic focal dystonia is reported from a data base review of all patients seen at the National Hospital of Neurology, Queen Square and King's College, London up to 1993. There was a higher prevalence of females to males in all categories of focal dystonia involving the craniocervical region. The female to male ratio for cranial dystonia was 1.92:1 (P < 0.01) and 1.6:1 (P < 0.001) for spasmodic torticollis. On the other hand, twice as many men than women had writer's cramp (M:F = 2.0:1, P < 0.01). At present, there is no clear explanation to account for this differences in the sex prevalence of different types of focal dystonia.

Soland, V L; Bhatia, K P; Marsden, C D

1996-01-01

233

Focal segmental glomerulosclerosis in children.  

PubMed

Idiopathic focal segmental glomerulosclerosis is a histologic diagnosis that usually presents as the nephrotic syndrome but, unlike minimal change disease, often leads to renal failure in children. Standard therapies used to treat the proteinuria are often futile, and thus patients are at risk for the multiple complications resulting from persistent, severe proteinuria. Eventually, end-stage renal failure ensues, and the possibility of the disease recurring in the transplanted renal allograft is worrisome. This report reviews the clinical features and outcomes of idiopathic focal segmental glomerulosclerosis in children, the response to newer treatment options, and new insights into understanding what factors may be involved in causing the disorder. PMID:7787934

Ingulli, E; Tejani, A

1995-04-01

234

Novel adaptive laser processing system for flying optics  

NASA Astrophysics Data System (ADS)

The focusing characteristics of higher-order mode Gaussian beams in flying optics were investigated in detail. On the basis, a novel adaptive laser processing system for flying optics was developed. In the system, a lens with long focal length and two adaptive deformable mirrors controlled by hydraulic were employed. The lens was near the laser source for some distance and the two adaptive mirrors were integrated together with parabolic focusing mirror. The system has the advantages of compact structure and easy control. The system can keep the focus position and the focus radius constant for long distance laser processing.

Zhao, Quanzhong; Cheng, Zhaogu; Gao, Haijun; Huang, Huijie

2003-03-01

235

Modeling anamorphic optical surfaces in the MOEMS-based zoom lens  

NASA Astrophysics Data System (ADS)

MOEMS (Micro-opto-electromechanical systems) based zoom lens is a kind of optical system combining the off-axis reflective DM (deformable mirrors) and the on-axis refractive elements. It usually has two deformable mirrors. The magnification of one DM would be variable while its surface profile is changed by controlling the actuators, which results in a focal shift in the image space of the zoom lens. To compensate the variation of the focal plane position, the surface profile of another DM is varied. Therefore the focal length of the whole optical system would be varied and have a stabilized image position. In this paper, modeling anamorphic optical surfaces in the MOEMS-based zoom lens is described. The anamorphic profile of the DM is designed to satisfy the following requirements. First, the aberration coefficients of the DMs and the refractive surfaces are composed in the vector space to achieve the coefficients of the system. And the initial configuration of the refractive elements is determined to fulfill the system requirements and specifications at the wide angle and long focal length positions. Then the anamorphic profile of the DM is designed to compensate the off axis aberrations by creating two zeros of low order astigmatism, achieved a reasonable result.

Cheng, Xuemin; Hao, Qun

2010-11-01

236

Optical signal multiplexer and demultiplexer.  

National Technical Information Service (NTIS)

This invention pertains to an optical signal multiplexer and demultiplexer with the following characteristics: A single optical receptor or emission diode is positioned facing the lens surface of a condenser lens at the focal point of said lens. Multiple ...

H. Tsubata N. Oharu K. Sashida

1990-01-01

237

Development of compact optical zoom lenses with extended-depth-of-field  

NASA Astrophysics Data System (ADS)

Development of compact optical zoom lenses for integration in mobile phones is the goal of many companies. Optical zoom lenses change their focal length by the movement of lens elements or change in surface curvature or refractive index and this complicates the zoom lens design. Extended depth-of- field (EDOF) techniques provides the mean to simplify and miniaturize zoom lens designs with moving lens elements and a new EDOF optimization technique is presented. Finally, the starting point and an example of a compact optical zoom lens design with EDOF is also described.

Demenikov, Mads

2012-10-01

238

Diffractive-refractive optics for high energy astronomy. II. Variations on the theme  

NASA Astrophysics Data System (ADS)

In a companion paper diffractive-refractive optics components such as Fresnel Zone Plates and their derivatives have been proposed as a basis for telescope systems for X-ray and gamma-ray astronomy with high sensitivity and superb angular resolution. A wide family of configurations is possible and the first paper concentrated on simple systems for gamma-ray energies. The main problems arise from the very long focal lengths involved ( ~ 106 km) and from chromatic aberration in the focussing system. Ideas are presented here that could in some circumstances allow the focal length to be reduced by many orders of magnitude. In addition it is shown how lenses which are to first order achromatic might be constructed. Finally, the possibility of using similar optical components for X-ray and gamma-ray interferometry is discussed.

Skinner, G. K.

2002-01-01

239

Fish Tank Optics.  

ERIC Educational Resources Information Center

|Describes procedures for a demonstration of the focal length of spherical lenses and mirrors using an aquarium, a flashlight, and nondairy creamer. Enables nonquantitative three-dimensional observation of these phenomena. (DDR)|

McCausland, Stuart; Allard, Brian

1997-01-01

240

Research on reflective optical telescope system's wavefront aberration compensation method  

NASA Astrophysics Data System (ADS)

Wavefront aberration measurement of the image quality of reflective telescope system which has a large aperture and long focal length is one of the frequently-used methods of high-precision test and alignment. It was widely used during the large aperture telescope manufacturing process. The influences of surface shape error of the reflective optical telescope system components were simulated and analyst by input the actual measuring data into the optical design software CODE V in this article. According to the test results compared to the alignment process, the accuracy of the simulation method was indicated. At the same time, the wavefront aberration optical compensation principle of the reflective optical telescope system was proved by the simulation of alignment. And in this article, the feasibility of the application of optical phase compensation alignment method was investigated.

Duan, Xueting

241

1.06-micron laser damage of thin film optical coatings - A round-robin experiment involving various pulse lengths and beam diameters  

Microsoft Academic Search

In the round-robin experiment reported here, commercially available optical coatings, both antireflective and high reflective, were evaluated with respect to their laser-induced damage threshold. The results obtained are discussed with particular emphasis on the experimental approaches used at the various laboratories and their compatibility. It is noted that despite the very different conditions of the experiments, it is still possible

K. H. Guenther; E. Casparis; T. W. Humpherys; J. R. Bettis; J. Balmer; J. Ebert; E. Kiesel; M. Eichner; A. H. Guenther; R. Kuehnel; D. Milam; W. Ryseck; S. C. Seitel; A. F. Stewart; H. Weber; G. R. Wirtenson; R. M. Wood

1984-01-01

242

Optical design of evanescently coupled, waveguide-fed photodiodes for ultrawide-band applications  

Microsoft Academic Search

Beam propagation method simulation shows that evanescently coupled waveguide\\/photodiodes can be optimized to have absorption lengths as short as butt-coupled photodiodes. Efficient focalization of optical power in the absorber is achievable by appropriate choice of layer geometry and refractive index. Two AlGaInAs-GaInAs structures have been designed for ultrawide-band operation at 60 and 100 GHz: these devices exhibit internal quantum efficiency

L. Giraudet; F. Banfi; S. Demiguel; G. Herve-Gruyer

1999-01-01

243

Fast electrically switchable holographic optical elements in LiNbO3  

NASA Astrophysics Data System (ADS)

We present here the realization of fast electrically switchable holographic optical elements based on electric field multiplexing of volume holograms in lithium niobate crystals. We demonstrate the electrical control of holographic lenses and holographic mirrors for fast switching of the focal length and the direction of the reconstructed light beam, respectively. The switching time in the range of few hundred microseconds has been demonstrated using this technique.

Arora, P.; Petrov, V. M.; Petter, J.; Tschudi, T.

2008-03-01

244

Embossing of optical document security devices  

NASA Astrophysics Data System (ADS)

Embossing in the transparent window area of polymer banknotes, such as those seen on the Australian, New Zealand and Romanian currencies, have enormous potential for the development of novel optical security devices. The intaglio printing process can provide an efficient means for embossing of optical security structures such as micro lenses. Embossed micro lens arrays in the transparent window of a polymer banknote can be folded over a corresponding printed image array elsewhere on the note to reveal a series of moire magnified images. Analysis of samples of embossed micro lenses showed that the engraving side and impression side had a similar embossed profile. The embossed micro lens profiles were modelled using Optalix-LX commercial optical ray tracing software in order to determine the focal length of the lenses and compare with the focal length of desired embossed lenses. A fundamental understanding of how the polymer deforms during the embossing process is critical towards developing a micro lens embossing tool which can achieve the desired embossed micro lenses. This work also looks at extending the early research of the Intaglio Research Group (IRG) to better understand the embossibility of polymer substrates such as biaxially oriented polypropylene (BOPP).

Muke, Sani

2004-06-01

245

Optical passive athermalization for infrared zoom system  

NASA Astrophysics Data System (ADS)

In an infrared zoom system, it is difficult to obtain the best thermal compensation for all effective focal length (EFL) simultaneously by moving a single lens group. According to the principle of optical passive athermalization, the equations of focal length, achromatization and athermalization of both long and short EFL are established respectively. By analyzing the thermal aberration value relations between long EFL and short EFL, the thermal aberration values of the switching groups for short EFL athermalization are calculated. Firstly, the athermalization of long EFL is designed. Then through reasonable optical materials matching of the switching groups, the short EFL achieves athermalization as well. In this paper, a re-imaging switching zoom system is designed. It has a relative aperture of f/4.0, 100% cold shield efficiency, the EFL of 180mm/30mm at 3.7-4.8?m. The long EFL includes four refractive elements and one hybrid refractive/diffractive element. The switching groups of short EFL have two types, one is composed of four refractive elements, and the other is composed of two refractive elements and one hybrid refractive/diffractive element. Both of the short EFL achieve athermalization. With the aluminum materials of system structures, the zoom system achieves optical passive athermalization. It has the diffraction limited image quality and stable image plane from -30°C to 70°C.

Li, Shenghui; Yang, Changcheng; Zheng, Jia; Lan, Ning; Xiong, Tao; Li, Yong

2007-12-01

246

A combined electron beam\\/optical lithography process step for the fabrication of sub-half-micron-gate-length MMIC chips  

Microsoft Academic Search

Advanced radar and communication systems rely heavily on state-of-the-art microelectronics. Systems such as the phased-array radar require many transmit\\/receive (T\\/R) modules which are made up of many millimeter wave - microwave integrated circuits (MMIC's). The heart of a MMIC chip is the Gallium Arsenide (GaAs) field-effect transistor (FET). The transistor gate length is the critical feature that determines the operating

James S. Sewell; Christopher A. Bozada

1994-01-01

247

Seed-Mediated Synthesis of Ag Nanocubes with Controllable Edge Lengths in the Range of 30-200 nm and Comparison of Their Optical Properties  

PubMed Central

Silver nanocubes with edge lengths controllable in the range of 30–200 nm were synthesized using an approach based on seeded growth. The key to the success of this synthesis is the use of single-crystal Ag seeds to direct the growth and the use of AgNO3 as a precursor to elemental Ag where the by-product HNO3 can block both the homogeneous nucleation and evolution of single-crystal seeds into twinned nanoparticles. Either spherical (in the shape of cubooctahedron) or cubic seeds could be employed for this growth process. The edge length of resultant Ag nanocubes can be readily controlled by varying the amount of Ag seeds used, the amount of AgNO3 added, or both. For the first time, we could obtain Ag nanocubes with uniform edge lengths controllable in the range of 30–200 nm and then compare their localized surface plasmon resonance and surface-enhanced Raman scattering properties.

Zhang, Qiang; Li, Weiyang; Moran, Christine; Zeng, Jie; Chen, Jingyi; Wen, Long-Ping; Xia, Younan

2010-01-01

248

Gated fiber optic transmission  

Microsoft Academic Search

A gated fiber optic sensor system is disclosed for increasing the effective optical path of a length of optical fiber cable. A pulse of polarized light having a known optical wavelength is directed into a length of optical fiber cable for propagation therethrough in a cyclic path. A planar semiconductor member is mounted in the path of the polarized light

L. C. Bobb

1984-01-01

249

Development of a cable reel development system using a rotary joint for kilometer lengths of two-fiber multi-mode fiber optic cable  

SciTech Connect

Brookhaven National Laboratory (BNL) recently developed a two-component system for use during remote inspections. The system consists of a mobile unit with television cameras and other equipment and a stationary base station. A variety of signals must be continually transmitted between the two system components as the mobile unit is moved from the location to another. Two channels of broadband (10MHz) NTSC video are transmitted from the mobile unit to the base station, and a bi-directional ``talk set`` provides audio communication between personnel at each location. In addition, several channels of RS-232 are required to support present and future instruments used at the mobile unit and controlled by personnel at the base station. Brookhaven developed a mobile unit which communicated with a base station over a 2-fiber multimode fiber optic cable. One of the design requirements was maintaining constant communication with the base station during the time the mobile unit was moved about. To provide uninterrupted communications, deployment of the 1-km long fiber optic cable was initially performed with a ``spinning reel`` mechanism. The spinning reel mechanism proved to be mechanically unsuitable, and so the cable deployment mechanism was redesigned to spool the cable off the reel. The requirement for uninterrupted communications required a two-channel fiber optic rotary joint in the design. Incorporation of the rotary joint into the design is described, and appropriate reference material is included.

Curtiss, J.A.; Jahelka, J.R.

1995-08-11

250

The formation of optical membrane reflector surfaces using uniform pressure loading  

SciTech Connect

Potentially high quality optical reflector surfaces are attainable with the use of pressure formed membranes. Such reflector surfaces offer the prospect of very low weight and low cost. The formation of such surfaces, using initially flat circular membranes with uniform pressure loading, is studied in this paper. Finite axisymmetric deformations, along with both linear and nonlinear material response is considered. A wide range of focal-length-to-diameter ratios (above 0.6) are addressed and the structural/optical response mechanisms that lead to optical distortions relative to ideal parabolic reflector shapes are also considered. Results show that elastic material response can often lead to a significantly larger deviation from the ideal shape than will inelastic material response. This results primarily from the ability to limit stress nonuniformities when inelastic material response is operative. Furthermore, when under pressure loading the membrane focal length decreases monotonically with increasing radius for both linear and nonlinear material response. Further, the predicted focal length variation is increasingly nonlinear near the membrane support.

Murphy, L.M.; Tuan, C.

1987-08-01

251

Development of a Long-Focal-Range Annular Array Ultrasonic Transducer  

NASA Astrophysics Data System (ADS)

Conventional annular array transducers designed with Fresnel divided elements have a limited maximum size of the aperture of the transducer. In this study, we designed and fabricated a prototype of a large-aperture annular array transducer to inspect next-generation semiconductors. A new annular array pattern was designed with a wide focal range and a large focal length using equal areas for the inner elements and equal stroke widths for the outer elements. The prototype was fabricated by epoxy bonding with a patterned metal electrode on a flexible printed circuit and a piezoelectric copolymer. As a result of evaluation, we obtained a fine spatial resolution below 100 ?m and a narrow relative sensitivity variation of 6.5 dB for a large focal length and a wide focal range from 10 to 30 mm.

Korai, Yusuke; Baba, Atsushi

2012-07-01

252

Characterization and simulation of optical sensors.  

PubMed

Numerical simulation is gradually becoming an advantage in active safety. This is why the development of realistic numerical models enabling to substitute real truth by simulated truth is primordial. In order to provide an accurate and cost effective solution to simulate real optical sensor behavior, the software Pro-SiVIC™ has been developed. Simulations with the software Pro-SiVIC™ can replace real tests with optical sensors and hence allow substantial cost and time savings during the development of solutions for driver assistance systems. An optical platform has been developed by IFSTTAR (French Institute of Science and Technology for Transport, Development and Networks) to characterize and validate any existing camera, in order to measure their characteristics as distortion, vignetting, focal length, etc. By comparing real and simulated sensors with this platform, this paper demonstrates that Pro-SiVIC™ accurately reproduces real sensors' behavior. PMID:23735581

Grapinet, M; De Souza, Ph; Smal, J-C; Blosseville, J-M

2013-04-30

253

Multispectral Focal Plane Assembly for Satellite Remote Sensing  

SciTech Connect

Sandia National Laboratories and several subsystem contractors are developing technologies applicable to multispectral remote sensing from space. A proof of concept multispectral sensor system is under development. The objective of building this sensor is to demonstrate and evaluate multispectral imaging technologies for various applications. The three major subsystems making up the sensor are the focal plane assembly (FPA), the cryocooler, and the telescope. This paper covers the focal plane assembly, which is the basis of the sensor system. The focal plane assembly includes sensor chip assemblies, optical filters, and a vacuum enclosure with cold shielding. Linear detector arrays provide spatial resolution in the cross-track direction for a pushbroom imager configuration. The optical filters define 15 spectral bands in a range from 0.45 microns to 10.7 microns. All the detector arrays are mounted on a single focal plane and are designed to operate at 75 K. No beam splitters are used. The four spectral bands covering the visible to near infrared have roughly 2400 pixels each, and the remaining 11 spectral bands have roughly 600 pixels each. The average total rate of multispectral data from the FPA is approximately 15.4 megapixels per second. At the time this paper is being written, the multispectral focal plane assembly is in the fabrication phase. A thermal/mechanical mockup has been built and tested for the vibration environment and to determine the thermal load. Some of the sensor chip assemblies and filters have been built and tested. Several notable features of the design are covered in the paper as well as preliminary test data.

Rienstra, J. [Sandia National Labs., Albuquerque, NM (United States); Ballard, M. [Santa Barbara Research Center, Goleta, CA (United States)

1997-12-31

254

Genetics of focal segmental glomerulosclerosis  

Microsoft Academic Search

The recent advances in understanding the pathophysiology of focal segmental glomerulosclerosis (FSGS) and molecular function\\u000a of glomerular filtration barrier come directly from genetic linkage and positional cloning studies. The exact role and function\\u000a of the newly discovered genes and proteins are being investigated by in vitro and in vivo mechanistic studies. Those genes\\u000a and proteins interactions seem to change susceptibility

Robert P. Woroniecki; Jeffrey B. Kopp

2007-01-01

255

Analytical approximations for the focal properties of the plane?grid and cylinder electrostatic lens system  

Microsoft Academic Search

Analytical expressions are derived for the paraxial focal properties of the unsymmetrical lens system formed by adjacent planar?grid and cylindrical conductors. Resulting focal lengths and principal plane positions are shown to be in good agreement with existing ray?tracing calculations, especially in the converging lens region of voltage ratios 0.1 ? V2\\/V1 ? 1. Modifications applicable in the strongly diverging lens

C. E. Young

1975-01-01

256

Analytical approximations for the focal properties of the plane-grid and cylinder electrostatic lens system  

Microsoft Academic Search

Analytical expressions are derived for the paraxial focal properties of the unsymmetrical lens system formed by adjacent planar-grid and cylindrical conductors. Resulting focal lengths and principal plane positions are shown to be in good agreement with existing ray-tracing calculations, especially in the converging lens region of voltage ratios 0.1 ? V2\\/V1 ? 1. Modifications applicable in the strongly diverging lens

C. E. Young

1975-01-01

257

1.06-micron laser damage of thin film optical coatings - A round-robin experiment involving various pulse lengths and beam diameters  

NASA Astrophysics Data System (ADS)

In the round-robin experiment reported here, commercially available optical coatings, both antireflective and high reflective, were evaluated with respect to their laser-induced damage threshold. The results obtained are discussed with particular emphasis on the experimental approaches used at the various laboratories and their compatibility. It is noted that despite the very different conditions of the experiments, it is still possible to deduce some common relations and parameters. However, for the purpose of comparing laser-induced damage threshold data obtained at different facilities, standardized test conditions are essential.

Guenther, K. H.; Casparis, E.; Humpherys, T. W.; Bettis, J. R.; Balmer, J.; Ebert, J.; Kiesel, E.; Eichner, M.; Guenther, A. H.; Kuehnel, R.

1984-11-01

258

Reversal construction of polarization-controlled focusing field with multiple focal spots  

NASA Astrophysics Data System (ADS)

We propose an approach to control the polarization and intensity of the focusing field with multiple focal spots in a high-numerical-aperture imaging system. This focused field is explained as the reversal radiation of the dipole array with presupposed oscillating direction in the focal volume. By engineering the structure of the electric dipole array and reversing the radiation from this dipole array, the local manipulation of intensity and polarization in the focal region is achieved, and the required field at the pupil plane is derived. A focusing field with six vectorial focal spots is created as an example to verify this method. This multifocal field will meet potential application in polarization-dependent optical microscope and optical trapping for multiple particles.

Wang, Jiming; Liu, Qingliang; He, Chongjun; Liu, Youwen

2013-04-01

259

The AIRES Optical Design  

NASA Astrophysics Data System (ADS)

AIRES (Airborne InfraRed Echelle Spectrometer) is the facility spectrometer for SOFIA (Stratospheric Observatory For Infrared Astronomy). AIRES is a long-slit ( ~160'') spectrometer designed to cover the 17 to 210-? m range with good sensitivity using three spectroscopic arrays. Initially, only the 30 - 130 ? m, mid-wavelength array will be available. The instrument has a cryogenic K-mirror to perform field rotation and a slit-viewing camera (? < 28 ? m, FOV = 160'' diameter) to image source morphology and verify telescope pointing. AIRES employs a large echelle grating to achieve a spectral resolving power (? /? ? ) of approximately 1.0x 106/? ? , where ? ? is the wavelength in microns. Hyperfine, Inc. has ruled and tested the AIRES' echelle; its wave-front error is 0.028 waves RMS at 10.6 ? m. The instrument is housed in a liquid-helium cryostat which is constrained in diameter ( ~1 m) and length ( ~2 m) by the observatory. Hence, the length of the echelle ( ~1.1 m) and the focal length of its collimator ( ~5.2 m) severely drive the optical design and packaging. The final design uses diamond-turned aluminum optics and has up to 19 reflections inside the cryostat, depending on the optical path. This design was generated, optimized, and toleranced using Code V. The predicted performance is nearly diffraction-limited at 17 ? m; the error budget is dominated by design residuals. Light loss due to slit rotation and slit curvature has been minimized. A thorough diffraction analysis with GLAD was used to size the mirrors and baffles; the internal light loss is shown to be a strong function of slit width.

Haas, M. R.

2001-05-01

260

Artificial neural networks (ANNs) compared to partial least squares (PLS) for spectral interference correction in optical emission spectrometry  

NASA Astrophysics Data System (ADS)

Spectral interference arising from direct, wing or background-induced spectral overlaps are a key concern in optical emission spectrometry even if an optical spectrometer with a 1 m focal length is used (thus resulting in peaks with halfwidth of ~80 pm). The problem of spectral interferences becomes even more acute when a portable spectrometer with a relatively short focal length (e.g., 10-15 cm) is used. In our lab, we are addressing spectral interference correction methods using artificial neural networks (ANNs) and partial least squares (PLS). In this paper, the application of ANNS and of PLS for spectral interference correction is compared using spectral simulations (to avoid the effects of 1/f noise).

Li, Z.; Zhang, X.; Karanassios, Vassili

2013-05-01

261

Simultaneous multispectral framing infrared camera using an embedded diffractive optical lenslet array  

NASA Astrophysics Data System (ADS)

Recent advances in micro-optical element fabrication using gray scale technology have opened up the opportunity to create simultaneous multi-spectral imaging with fine structure diffractive lenses. This paper will discuss an approach that uses diffractive optical lenses configured in an array (lenslet array) and placed in close proximity to the focal plane array which enables a small compact simultaneous multispectral imaging camera [1]. The lenslet array is designed so that all lenslets have a common focal length with each lenslet tuned for a different wavelength. The number of simultaneous spectral images is determined by the number of individually configured lenslets in the array. The number of spectral images can be increased by a factor of 2 when using it with a dual-band focal plane array (MWIR/LWIR) by exploiting multiple diffraction orders. In addition, modulation of the focal length of the lenslet array with piezoelectric actuation will enable spectral bin fill-in allowing additional spectral coverage while giving up simultaneity. Different lenslet array spectral imaging concept designs are presented in this paper along with a unique concept for prefiltering the radiation focused on the detector. This approach to spectral imaging has applications in the detection of chemical agents in both aerosolized form and as a liquid on a surface. It also can be applied to the detection of weaponized biological agent and IED detection in various forms from manufacturing to deployment and post detection during forensic analysis.

Hinnrichs, Michele

2011-05-01

262

Programmable focal spot shaping of amplified femtosecond laser pulses and their application to micromachining  

NASA Astrophysics Data System (ADS)

We present programmable focal spot shaping of amplified femtosecond laser pulses by use of an optically addressed non-pixellated liquid crystal light valve. This extra-cavity phase filtering method is set-up in the frame of femtosecond micromachining processes. Various focal spot shapes are demonstrated together with drilling and marking results in metals and dielectrics. Photowriting of waveguides in bulk fused silica is also presented.

Huot, Nicolas; Sanner, Nicolas; Audouard, Eric

2006-10-01

263

[X-ray differential diagnosis of focal tuberculosis and peripheral lung cancer].  

PubMed

The paper deals with the differential diagnosis of focal tuberculosis and peripheral lung cancer. It presents data on 25 patients of whom 24 were misdiagnosed as having focal tuberculosis. The main reason for misdiagnoses was the similarity of early X-ray symptoms of the two diseases, namely, upper lobar site, increased and thickened lung pattern and focal shadows against this background. The most important differentially diagnostic criteria for the above diseases are varying optic densities of pulmonary structures at the site of involvement and different patterns of vascular changes in the lung portion with a pathological process. PMID:10067353

Mamiliaev, R M

1998-01-01

264

Focal cone ERGs of rhodopsin Pro347Leu transgenic rabbits.  

PubMed

A rhodopsin P347L transgenic (Tg) rabbit, a model of retinitis pigmentosa, has been generated in our laboratory. The purpose of this study was to determine the properties of focal areas of the retina in this rabbit model during the course of retinal degeneration. To accomplish this, we recorded focal ERGs from wild-type (WT) and Tg rabbits at ages 3, 6, and 12months. A 15° stimulus spot was used to elicit the focal ERGs from the center of the visual streak and from four surrounding areas. We found that the amplitudes of the focal cone ERG b-waves and oscillatory potentials (OPs) of the Tg rabbits in the five areas decreased progressively with increasing age and became almost non-recordable at 12months. There were no significant regional differences in the b-waves of Tg rabbits recorded from the 5 areas. The amplitudes of the OPs were better preserved than the b-waves and the OPs/b-wave ratio was higher than that in WT rabbits at every recording area. The summed OPs amplitudes, which most likely originate from the amacrine and/or ganglion cells, recorded from the area superior to the optic disc was significantly larger than that from other areas at 3- and 6-months-old. This indicated that the inner retinal neurons were not altered equally after photoreceptor degeneration in this rabbit model. PMID:23973440

Ueno, Shinji; Koyasu, Toshiyuki; Kominami, Taro; Sakai, Takao; Kondo, Mineo; Yasuda, Shunsuke; Terasaki, Hiroko

2013-08-21

265

Characterization of Bragg-Fresnel Optics for X-ray Microfocusing and Microscopy at the Advanced Photon Source  

Microsoft Academic Search

Bragg-Fresnel lenses(BFLs), fabricated as surface relieved Fresnel zones on single crystal substrates, are capable of focusing hard x-rays (up to 100 keV) into submicron spots, which have many applications in x-ray microdiffraction and microscopy. We have fabricated linear BFLs with different focal lengths and diffraction limited resolution on Si, GaAs and InP substrates, in order to optimize optical performance for

Youli Li; Gerard C. L. Wong; Cyrus R. Safinya; Dean Haeffner; Partricia Fernandez; Wenbing Yun

1998-01-01

266

SNAP Satellite Focal Plane Development  

SciTech Connect

The proposed SuperNova/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square degree field in the visible and near-infrared wavelength regime. The requirements for the instrument suite and the present configuration of the focal plane concept are presented. A two year R&D phase, largely supported by the Department of Energy, is just beginning. We describe the development activities that are taking place to advance our preparedness for mission proposal in the areas of detectors and electronics.

Bebek, C.; Akerlof, C.; Aldering, G.; Amanullah, R.; Astier, P.; Baltay, C.; Barrelet, E.; Basa, S.; Bercovitz, J.; Bergstrom, L.; Berstein, G.P.; Bester, M.; Bohlin, R.; Bonissent, A.; Bower, C.; Campbell, M.; Carithers, W.; Commins, E.; Day, C.; Deustua, S.; DiGennaro, R.; Ealet, A.; Ellis, R.; Emmett, W.; Eriksson, M.; Fouchez,D.; Fruchter, A.; Genat, J-F.; Goldhaber, G.; Goobar, A.; Groom, D.; Heetderks, H.; Holland, S.; Huterer, D.; Johnson, W.; Kadel, R.; Karcher,A.; Kim, A.; Kolbe, W.; Lafever, R.; Lamoureaux, J.; Lampton, M.; Lefevre, O.; Levi, M.; Levin, D.; Linder, E.; Loken, S.; Malina, R.; Mazure, A.; McKay, T.; McKee, S.; Miquel, R.; Morgan, N.; Mortsell, E.; Mostek, N.; Mufson, S.; Musser, J.; Roe, N.; Nugent, P.; Oluseyi, H.; Pain, R.; Palaio, N.; Pankow, D.; Perlmutter, S.; Prieto, E.; Rabinowitz,D.; Refregier, A.; Rhodes, J.; Schubnell, M.; Sholl, M.; Smadja, G.; Smith, R.; Smoot, G.; Snyder, J.; Spadafora, A.; Szymkowiak, A.; Tarle,G.; Taylor, K.; Tilquin, A.; Tomasch, A.; Vincent, D.; von der Lippe, H.; Walder, J-P.; Wang, G.

2003-07-07

267

SNAP satellite focal plane development  

NASA Astrophysics Data System (ADS)

The proposed SuperNova/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square degree field in the visible and near-infrared wavelength regime. The requirements for the instrument suite and the present configuration of the focal plane concept are presented. A two year R&D phase, largely supported by the Department of Energy, is just beginning. We describe the development activities that are taking place to advance our preparedness for mission proposal in the areas of detectors and electronics.

Bebek, Christopher; Akerlof, Carl W.; Aldering, Greg; Amanullah, R.; Astier, Pierre; Baltay, Charles; Barrelet, E.; Basa, Stephane; Bercovitz, John; Bergstrom, Lars; Berstein, Gary; Bester, Manfred; Bohlin, Ralph C.; Bonissent, Alain; Bower, Charles R.; Campbell, Myron; Carithers, William C., Jr.; Commins, Eugene D.; Day, C.; Deustua, Susana E.; DiGennaro, Richard S.; Ealet, Anne; Ellis, Richard S.; Emmett, William; Eriksson, Mikael; Fouchez, D.; Fruchter, Andrew; Genat, Jean-Francois; Goldhaber, Gerson; Goobar, Ariel; Groom, Donald E.; Heetderks, Henry D.; Holland, Stephen E.; Huterer, Dragan; Johnston, William E.; Kadel, Richard W.; Karcher, Armin; Kim, Alex G.; Kolbe, William F.; Lafever, Robin E.; Lamoureux, J. I.; Lampton, Michael L.; Le Fèvre, Oliver; Levi, Michael E.; Levin, Daniel S.; Linder, Eric V.; Loken, Stewart C.; Malina, Roger; Mazure, Alain; McKay, Timothy A.; McKee, Shawn P.; Miquel, Ramon; Morgan, Nicholas; Mortsell, E.; Mostek, N.; Mufson, Stuart; Musser, J. A.; Roe, Natalie A.; Nugent, Peter E.; Oluseyi, Hakeem M.; Pain, Reynald; Palaio, Nicholas P.; Pankow, David H.; Perlmutter, Saul; Prieto, Eric; Rabinowitz, David; Refregier, Alexandre; Rhodes, Jason; Schubnell, Michael S.; Sholl, Michael; Smadja, G.; Smith, R.; Smoot, George F.; Snyder, Jeffrey A.; Spadafora, Anthony; Szymkowiak, Andrew; Tarle, Gregory; Taylor, Keith; Tilquin, A.; Tomasch, Andrew D.; Vincent, D.; von der Lippe, Henrik; Walder, Jean-Pierre; Wang, Guobin

2003-12-01

268

Design of hybrid micro-diffractive-refractive optical element with wide field of view for free space optical interconnections  

NASA Astrophysics Data System (ADS)

A new design is presented to achieve a hybrid micro-diffractiverefractive lens with wide field of view (WFOV) of 80° integrated on backside of InGaAs / InP photodetector for free space optical interconnections. It has an apparent advantage of athermalization of optical system which working in large variation of ambient temperature ranging from 20 °C to 70 °C. The changing of focal length is only 0.504 m in the ambient temperature range with the hybrid microlens, which opto-thermal expansion coefficient matches with thermal expansion coefficient of AuSn solder bump used in corresponding flip-chip packaging system. The hybrid lens was designed via CODE-VTM professional software. The results show that the lens has good optical performance for the optical interconnection use.

Fu, Yongqi; Bryan, Ngoi Kok Ann

2002-07-01

269

Compact dual field of view SWIR/MWIR optical system  

NASA Astrophysics Data System (ADS)

This paper discusses the design and development of a dual field of view, all-refractive infrared optical system that images the mid-wave infrared (MWIR) light in one field of view and the short wave infrared (SWIR) light in the narrower second field of view onto the same detector. The narrow field of view images the SWIR radiation at a slow f/number of 10.0, while the wide field of view images the MWIR radiation at f/1.9. The field of view is changed via a single lens that changes its axial position within the lens, resulting in an axial zoom and an overall magnification change of 6X. The change in focal length and f/number at the same time enables an increased focal length without having to increase the aperture size by the ratio of the focal length change. The large field of view change is achieved by both the motion of the lens, and the use of the spectral properties of the materials that change with wavelength. The change in spectral bands is accomplished via the use of a spectral filter wheel.

Vizgaitis, Jay N.; Witte, Kyle; Littleton, Roy; Perconti, Philip

2011-05-01

270

Achromatic Focal Plane Mask for Exoplanet Imaging Coronagraphy  

NASA Astrophysics Data System (ADS)

Recent advances in coronagraph technologies for exoplanet imaging have achieved contrasts close to 1e-10 at 4 ?/D and 1e-9 at 2 ?/D in monochromatic light. A remaining technological challenge is to achieve high contrast in broadband light; a challenge that is largely limited by chromaticity of the focal plane mask. The size of a star image, and therefore the inner working angle of a coronagraph, scales linearly with wavelength. Focal plane masks are typically the same size at all wavelengths, and must be sized for the longest wavelength to avoid starlight leakage. However, this blocks useful discovery space from the shorter wavelengths. We present here the design, development, and testing of an achromatic focal plane mask based on the concept of optical filtering by a diffractive optical element (DOE). The mask consists of an array of DOE cells, the combination of which functions as a wavelength filter with any desired amplitude and phase transmission. The effective size of the mask varies nearly linearly with wavelength, and allows significant improvement in the inner working angle of the coronagraph at shorter wavelengths. The design is applicable to almost any coronagraph configuration, and enables operation in a wider band of wavelengths than would otherwise be possible.

Newman, Kevin; Belikov, R.; Guyon, O.

2013-01-01

271

A fast focal-reducing camera for CCD imaging  

NASA Astrophysics Data System (ADS)

This paper describes the design and performance of the OREAD focal-reducing camera, constructed for use at the Cassegrain focus of the Michigan-Dartmouth-MIT Observatory McGraw-Hill 1.3-meter telescope. OREAD is an all-refractive optical system providing a 50-mm collimated beam suitable for commercially available narrow-band filters or grisms. Its collimator and field lens are custom-made to decrease the severe coma which would otherwise be present at the extremities of its 30-arc-min field. When used with a CCD such as the TI 800 x 800, OREAD provides a field of view of 0.1 square degree at 1.5 arcsec/pixel. The focal ratio of OREAD of f/1.63 allows sky-limited narrow-band images to be obtained with exposures of only moderate duration. In an Appendix, some limitations inherent in coarsely sampled data obtained with CCDs are examined.

Aldering, Gregory S.; Bothun, Gregory D.

1991-12-01

272

Proximal femoral focal deficiency: a clinical appraisal.  

PubMed

In patients with unilateral proximal femoral focal deficiency, the leg length inequality is almost always greater than five inches at skeletal maturity. Consequently, prosthetic management should be planned before the patient walks. A standard plan of treatment of the patient with unilateral PFFD is not possible at this time, primarily because of the varying percentage of femur missing and the controversy of management of the hip in patients with type A or B deformity. However, we found that ankle disarticulation with Syme flap closure combined with arthrodesis of the knee is a reasonable plan in many patients with unilateral PFFD. This allows correction of the knee and hip flexion contractures and gives the patient a functional, cosmetic stump. By the time he begins school, he is functioning as an above-knee amputee. This is not an undesirable goal, as one of us (E.G.R.) recently examined an above-knee amputee, a Captain in the United States Army, who continued his hobby of sky diving. PMID:424795

Richardson, E G; Rambach, B E

1979-02-01

273

Limb Length Discrepancy  

MedlinePLUS

... area. This procedure will not cause an immediate correction in length. Instead, the limb length discrepancy will ... this option include the possibility of slight over-correction or under-correction of the limb length discrepancy. ...

274

A holographic projection system with an electrically tuning and continuously adjustable optical zoom.  

PubMed

A holographic projection system with optical zoom is demonstrated. By using a combination of a LC lens and an encoded Fresnel lens on the LCoS panel, we can control zoom in a holographic projector. The magnification can be electrically adjusted by tuning the focal length of the combination of the two lenses. The zoom ratio of the holographic projection system can reach 3.7:1 with continuous zoom function. The optical zoom function can decrease the complexity of the holographic projection system. PMID:23262672

Lin, Hung-Chun; Collings, Neil; Chen, Ming-Syuan; Lin, Yi-Hsin

2012-12-01

275

Spatial calibration of an optical see-through head mounted display  

PubMed Central

We present here a method for calibrating an optical see-through Head Mounted Display (HMD) using techniques usually applied to camera calibration (photogrammetry). Using a camera placed inside the HMD to take pictures simultaneously of a tracked object and features in the HMD display, we could exploit established camera calibration techniques to recover both the intrinsic and extrinsic properties of the HMD (width, height, focal length, optic centre and principal ray of the display). Our method gives low re-projection errors and, unlike existing methods, involves no time-consuming and error-prone human measurements, nor any prior estimates about the HMD geometry.

Gilson, Stuart J.; Fitzgibbon, Andrew W.; Glennerster, Andrew

2010-01-01

276

Lens design based on instantaneous focal function  

Microsoft Academic Search

The formula for the lens is derived based on the information of instantaneous focal function. Focal function is an important tool in designing lenses with extended depth of focus (EDoF) because this allows EDoF lens designers to try out various mathematical curves using computers to optimize their design. Once an optimal focal function information is obtained, the corresponding physical EDoF

Sung Nae Cho

2009-01-01

277

Hand-held optical fuel pin scanner  

DOEpatents

An optical scanner for indicia arranged in a focal plane perpendicular to an optical system including a rotatable dove prism. The dove prism transmits a rotating image to a stationary photodiode array.

Kirchner, Tommy L. (Richland, WA); Powers, Hurshal G. (Richland, WA)

1987-01-01

278

Effects of alkyl chain length on properties of 1-alkyl-3-methylimidazolium fluorohydrogenate ionic liquid crystals.  

PubMed

A series of 1-alkyl-3-methylimidazolium fluorohydrogenate salts (C(x)MIm(FH)(2)F, x=8, 10, 12, 14, 16, and 18) have been characterized by thermal analysis, polarized optical microscopy, IR spectroscopy, X-ray diffraction, and anisotropic ionic conductivity measurements. Liquid crystalline mesophases with a smectic A interdigitated bilayer structure are observed from C(10) to C(18), showing a fan-like or focal conic texture. The temperature range of the mesophase increases with the increase in the alkyl chain length (from 10.1?°C for C(10)MIm(FH)(2)F to 123.1?°C for C(18)MIm(FH)(2)F). The distance between the two layers in the smectic structure gradually increases with increasing alkyl chain length and decreases with increasing temperature. Conductivity parallel to the smectic layers is around 10?mS?cm(-1) regardless of the alkyl chain length, whereas that perpendicular to the smectic layers decreases with increasing alkyl chain length because of the thicker insulating sheet with the longer alkyl chain. PMID:20886475

Xu, Fei; Matsumoto, Kazuhiko; Hagiwara, Rika

2010-11-15

279

Novel micro interferometer for length measurements  

Microsoft Academic Search

A novel micro interferometer for length and displacement measurements based on sampling an optical standing wave was developed. The interference of two laser beams propagating in opposite direction results in a sinusoidal light intensity profile, which can be detected by thin transparent photodiodes. Two detectors positioned on the optical axis of a standing wave allow bi-directional fringe counting. The operation

H. Stiebig; V. Mandryka; E. Bunte; H.-J. Büchner; K. H. Jun

2004-01-01

280

Relation between Axial Length and Ocular Parameters  

Microsoft Academic Search

Purpose: To investigate the relation between axial length (AL) and ocular parameters. Methods: Measurements of ocular biometric parameters were performed with an optical biometer, pachymeter, optical coherence tomography, and an automatic refractometer. AL, refractive error (RE), central corneal thickness, anterior chamber depth (ACD), corneal curvature (CC), white-to-white distance (WWD), and retinal nerve fiber layer (RNFL) thickness were measured. AL was

Sang Hoon Park; Ki Ho Park; Joon Mo Kim; Chul Young Choi

2010-01-01

281

Staurosporine induces endothelial cell apoptosis via focal adhesion kinase dephosphorylation and focal adhesion disassembly independent of focal adhesion kinase proteolysis.  

PubMed Central

The survival of endothelial cells is dependent on interactions between the matrix and integrins mediated through focal adhesions. Focal adhesion kinase (FAK) is thought to play a key role in maintaining focal adhesion function and cell survival, whereas caspase-mediated FAK proteolysis is implicated in focal adhesion disassembly during apoptosis. We examined the relationship between changes in FAK phosphorylation and proteolysis during apoptosis of primary porcine aortic endothelial cells (PAEC) induced by staurosporine, a widely used apoptogenic agent in diverse cell types. Staurosporine-induced PAEC apoptosis was detected after 1 h and was preceded by disruption and loss of FAK localization to focal adhesions within a few minutes, whereas staurosporine-induced cleavage of FAK occurred only after 8-24 h. Staurosporine induced a very rapid dephosphorylation of FAK at Tyr(861) and Tyr(397) and caused dissociation of phosphorylated FAK from focal adhesions as early as 30 s. The effect of staurosporine was very potent with striking inhibition of Tyr(861) and Tyr(397) phosphorylation and focal adhesion disruption occurring in the range 10-100 nM. Selective inhibition of a known target of staurosporine, protein kinase C, using GF109203X, and of phosphoinositide 3'-kinase using wortmannin, did not reduce FAK tyrosine phosphorylation at Tyr(861) and Tyr(397), or cause disruption of focal adhesions. Cycloheximide, the protein synthesis inhibitor, induced PAEC apoptosis more slowly than staurosporine, but did not induce FAK dephosphorylation or rapid focal adhesion disruption, and instead caused a slower loss of focal adhesions and a marked increase in FAK proteolysis. These studies show that FAK dephosphorylation and focal adhesion disassembly are very early events mediating the onset of staurosporine-induced endothelial cell apoptosis and are dissociated from FAK proteolysis. Cycloheximide induces apoptosis through a pathway involving FAK proteolysis without dephosphorylation.

Kabir, Jahangir; Lobo, Melvin; Zachary, Ian

2002-01-01

282

Terahertz detectors and focal plane arrays  

NASA Astrophysics Data System (ADS)

Terahertz (THz) technology is one of emerging technologies that will change our life. A lot of attractive applications in security, medicine, biology, astronomy, and non-destructive materials testing have been demonstrated already. However, the realization of THz emitters and receivers is a challenge because the frequencies are too high for conventional electronics and the photon energies are too small for classical optics. As a result, THz radiation is resistant to the techniques commonly employed in these well established neighbouring bands. In the paper, issues associated with the development and exploitation of THz radiation detectors and focal plane arrays are discussed. Historical impressive progress in THz detector sensitivity in a period of more than half century is analyzed. More attention is put on the basic physical phenomena and the recent progress in both direct and heterodyne detectors. After short description of general classification of THz detectors, more details concern Schottky barrier diodes, pair braking detectors, hot electron mixers and field-effect transistor detectors, where links between THz devices and modern technologies such as micromachining are underlined. Also, the operational conditions of THz detectors and their upper performance limits are reviewed. Finally, recent advances in novel nanoelectronic materials and technologies are described. It is expected that applications of nanoscale materials and devices will open the door for further performance improvement in THz detectors.

Rogalski, A.; Sizov, F.

2011-09-01

283

Measurement of the radiometric and polarization characteristics of a microgrid polarizer infrared focal plane array  

NASA Astrophysics Data System (ADS)

Remote sensing applications make use of the optical polarization characteristics of a scene to enhance target detection and discrimination. Imaging polarimeters typically utilize polarizing arrays located in front of a focal plane array as a means of extracting polarization information from the optical scene. Over the last few years, technology development efforts have resulted in FPAs that integrate the polarizer with the infrared focal plane array (FPA). This paper will report on the radiometric and polarization characterization of a micro-grid polarizer FPA from DRS Infrared Technologies, L.P. (DRS). These measurements were performed to evaluate the radiometric performance and the polarization characteristics of the FPA.

Hubbs, John E.; Gramer, Mark E.; Maestas-Jepson, Diana; Dole, Gary A.; Fetrow, Matthew; Bowers, David; Boger, James

2006-09-01

284

Focal epithelial hyperplasia - an update.  

PubMed

Focal epithelial hyperplasia (FEH) is an asymptomatic benign mucosal disease, which is mostly observed in specific groups in certain geographical regions. FEH is usually a disease of childhood and adolescence and is generally associated with people who live in poverty and of low socioeconomic status. Clinically, FEH is typically characterized by multiple, painless, soft, sessile papules, plaques or nodules, which may coalesce to give rise to larger lesions. Human papillomavirus (HPV), especially genotypes 13 and 32, have been associated and detected in the majority of FEH lesions. The clinical examination and social history often allow diagnosis, but histopathological examination of lesional tissue is usually required to confirm the exact diagnosis. FEH sometimes resolves spontaneously however, treatment is often indicated as a consequence of aesthetic effects or any interference with occlusion. There remains no specific therapy for FEH, although surgical removal, laser excision or possibly topical antiviral agents may be of benefit. There remains no evidence that FEH is potentially malignant. PMID:23061874

Said, Ahmed K; Leao, Jair C; Fedele, Stefano; Porter, Stephen R

2012-10-14

285

Optical aligning and measuring methods for large aperture optical system  

NASA Astrophysics Data System (ADS)

How to implement high accuracy measurement of large-aperture coaxial optical system is crucial to the optical alignment and optical property evaluation. The methods of image quality measurement including interferometer-collimating testing, wave front testing by using Hartmann, image processing and analysis of out-of-focus image were introduced. Both the advantages and disadvantages of the three methods were compared, which showed that the alignment method based on interferometer-collimating testing is the one with the highest accuracy. The method of computer-aided alignment (CAA) based on interferometer-collimating was discussed in detail. By using a ZYGO interferometer, interferograms with different field of views and a series of Zernike coefficients were obtained to express the disalignment of the system, and then these incorrect parameters were calculated by CAA algorithms. An alignment experiment of coaxial three-mirror system with 4m focal length and 500mm aperture was carried out. The RMS value of the system is lower than 0.07? after iterations, which is close to the optical diffraction limit, proving the effectiveness of CAA method in alignment guidance.

Zhang, Xue-min; Wei, Ru-yi; Duan, Jia-you; Yang, Jian-feng; Li, Hua; Hou, Xiaohua

2012-10-01

286

Supercontinuum generation versus optical breakdown in CO(2) gas.  

PubMed

Threshold powers for optical breakdown (OB) and supercontinuum (SC) generation in high-pressure CO(2) gas have been measured at different focusing conditions. It has been found that by varying the focal length of the focusing lens, it is possible to pass from the case of OB without SC generation, through OB with SC generation, and into SC without OB. The experimental results demonstrate that plasma formation is not an essential mechanism for SC generation, whereas self-focusing causes SC generation characteristics to be dependent on conditions of external focusing. PMID:19802238

Ilkov, F A; Ilkova, L S; Chin, S L

1993-05-01

287

Optical fuel pin scanner  

DOEpatents

An optical scanner for indicia arranged in a focal plane at a cylindrical outside surface by use of an optical system including a rotatable dove prism. The dove prism transmits a rotating image of an encircled cylindrical surface area to a stationary photodiode array.

Kirchner, Tommy L. (Richland, WA); Powers, Hurshal G. (Richland, WA)

1983-01-01

288

Focal segmental glomerulosclerosis and kidney transplantation.  

PubMed

The recurrence rate of focal segmental glomerulosclerosis after kidney transplantation is ranging between 20% and 40%. Focal segmental glomerulosclerosis is associated with poor graft survival. In this review, the etiology, pathogenesis, clinicopathological features, risk factors of recurrence, and updated lines of management are discussed. PMID:23880801

Gheith, Osama; Hassan, Rashad

2013-07-01

289

Focal adhesion size uniquely predicts cell migration.  

PubMed

Focal adhesions are large protein complexes organized at the basal surface of cells, which physically connect the extracellular matrix to the cytoskeleton and have long been speculated to mediate cell migration. However, whether clustering of these molecular components into focal adhesions is actually required for these proteins to regulate cell motility is unclear. Here we use quantitative microscopy to characterize descriptors of focal adhesion and cell motility for mouse embryonic fibroblasts and human fibrosarcoma cells, across a wide range of matrix compliance and following genetic manipulations of focal adhesion proteins (vinculin, talin, zyxin, FAK, and paxilin). This analysis reveals a tight, biphasic gaussian relationship between mean size of focal adhesions (not their number, surface density, or shape) and cell speed. The predictive power of this relationship is comprehensively validated by disrupting nonfocal adhesion proteins (?-actinin, F-actin, and myosin II) and subcellular organelles (mitochondria, nuclear DNA, etc.) not known to affect either focal adhesions or cell migration. This study suggests that the mean size of focal adhesions robustly and precisely predicts cell speed independently of focal adhesion surface density and molecular composition. PMID:23254340

Kim, Dong-Hwee; Wirtz, Denis

2012-12-19

290

MR IMAGING OF FOCAL LIVER LESIONS  

Microsoft Academic Search

Imaging of focal liver lesions has become a major issue after the advent of cross sectional imaging modalities. With magnetic resonance imaging (MRI), another fascinating tool has become available some 20 years ago. Since then, refinements in technology have brought about significant advances in MRI of focal liver lesions, such as fast imaging techniques, fat suppression techniques, phased array body

Michael Laniado

291

Focal Glomerulosclerosis: Natural History and Treatment  

Microsoft Academic Search

70 cases of focal glomerulosclerosis (FGS) followed for periods ranging from 1 to 24 years are reported. 39 patients had a nephrotic syndrome. 31 patients had asymptomatic proteinuria. 97 renal biopsies were performed. At least one biopsy specimen from every patient showed focal and segmental involvement of glomeruli, but no lesions were observed on the first biopsy in 6 patients.

H. Beaufils; J. C. Alphonse; J. Guedon; M. Legrain

1978-01-01

292

Continuous manipulation of doughnut focal spot in a large scale.  

PubMed

We theoretically demonstrate that the doughnut focal spot can continuously be manipulated by synthetically using various beam modulation techniques. Comparatively, a more evident effect can be expected by different orders of phase modulation, while accurate manipulation stems from changing the phase diversity between two arms in an image inverting interferometer (III). The size of central dark spot can thus be continuously adjusted in a theoretically infinite scale, although it may actually be limited by resolution of Spatial Light Modulator (SLM). This approach brings additional flexibility to many applications, such as optical tweezers. PMID:22714298

Hao, Xiang; Kuang, Cuifang; Li, Yanghui; Liu, Xu

2012-06-01

293

Focusing Grating Couplers for Integrated Optics  

NASA Astrophysics Data System (ADS)

We aim at a design of an FGC in which a guided diverging wave is outcoupled as a spherical wave converging to a point above the waveguide. The incident guided wave (collimated in the experiments) is generated by prism-incoupling into the waveguide. The field distribution at the FGC and at the focal plane are investigated theoretically. FGC's are produced by holographic recording and are etched into the waveguide surface by wet chemical etching. The design of the optical systems, necessary to perform the holographical recording of the required grating, has been deduced from theoretical considerations. Our holographic setup was designed to compensate for the aberration caused by a wavelength shift between the recording and reconstruction processes. The intensity distribution in the recording plane has been calculated to evaluate the performance of our holographic setup. FGC's are to be recorded at the wavelength of 363.8nm for coupling a focused beam out of the waveguide using an incident collimated wave with a wavelength of 632.8nm. Multilayer waveguides produced on two-inch silicon substrate are used to make FGC's on the waveguides. The field distribution around the focus of the diffracted beam is studied by recording the intensity. From experimental results, a focal spot size of 2.9 ?m for an FGC with a focal length of 2.0mm and a grating diameter of 1.3 mm has been obtained. The coupling efficiency of this FGC is about 0.15.

Wang, Chieh-Wen

294

New multiband IR imaging optics  

NASA Astrophysics Data System (ADS)

We report new multispectral materials that transmit from 0.9 to < 12 µm in wavelength. These materials fill up the glass map for multispectral optics and vary in refractive index from 2.38 to 3.17. They show a large spread in dispersion (Abbe number) and offer some unique solutions for multispectral optics designs. One of the glasses developed is a very good candidate to replace Ge, as it has a combination of excellent properties, including high Abbe number in the LWIR, high index of 3.2, 60% lower dn/dT, and better thermal stability at working temperatures. Our results also provide a wider selection of optical materials to enable simpler achromat designs. For example, we have developed other glasses that have relatively high Abbe number in both the MWIR and LWIR regions, while our MILTRAN ceramic has low Abbe number in both regions. This makes for a very good combination of glasses and MILTRAN ceramic (analogous to crown and flint glasses in the visible) for MWIR + LWIR dual band imaging. We have designed preliminary optics for one such imager with f/2.5, 51 mm focal length and 22 degrees FOV using a spaced doublet of NRL's glass and MILTRAN ceramic. NRL's approach reduces the number of elements, weight, complexity and cost compared with the approach using traditional optics. Another important advantage of using NRL glasses in optics design is their negative or very low positive dn/dT, that makes it easier to athermalize the optical system.

Bayya, Shyam; Sanghera, Jasbinder; Kim, Woohong; Gibson, Daniel; Fleet, Erin; Shaw, Brandon; Hunt, Michael; Aggarwal, Ishwar

2013-06-01

295

Characterization of scatterers for an active focal plane Compton polarimeter  

NASA Astrophysics Data System (ADS)

In this work we present an active Compton scattering polarimeter as a focal plane instrument able to extend the X-ray polarimetry towards hard X-rays.Other authors have already studied various instrument design by means of Monte Carlo simulations, in this work we will show for the first time the experimental measurements of "tagging efficiency" aimed to evaluate the polarimeter sensitivity as a function of energy. We performed a characterization of different scattering materials by measuring the tagging efficiency that was used as an input to the Monte Carlo simulation. Then we calculated the sensitivity to polarization of a design based on the laboratory set-up. Despite the geometry tested is not optimized for a realistic focal plane instrument, we demonstrated the feasibility of polarimetry with a low energy threshold of 20 keV. Moreover we evaluated a minimum detectable polarization of 10% for a 10 mCrab source in 100 ks between 20 and 80 keV in the focal plane of one multilayer optics module of NuSTAR. The configuration used consisted of a doped p-terphenyl scatterer 3 cm long and 0.7 cm of diameter coupled with a 0.2 cm thick LaBr3 absorber.

Fabiani, Sergio; Campana, Riccardo; Costa, Enrico; Del Monte, Ettore; Muleri, Fabio; Rubini, Alda; Soffitta, Paolo

2013-04-01

296

Automatic location of microscopic focal planes for computerized stereology  

NASA Astrophysics Data System (ADS)

When applying design-based stereology to biological tissue, there are two primary applications for an auto-focusing function in the software of computerized stereology system. The system must first locate the in-focus optical planes at the upper and lower surfaces of stained tissue sections, thus identifying the top and bottom as well as the thickness of the tissue. Second, the system must find the start and end along the Z-axis of stained objects within a Z-stack of images through tissue sections. In contrast to traditional autofocus algorithms that seek a global maximum or peak on the focus curve, the goal of this study was to find the two "knees" of the focus curve that represent the "just out-of-focus" focal planes. The upper surface of the tissue section is defined as the image just before focus is detected moving down the Z-stack. Continuing down, the lower surface is defined as the first image of the last set of adjacent images where focus is no longer detected. The performance of seven focus algorithms in locating the top and bottom focal planes of tissue sections was analyzed by comparing each algorithm on 34 Z-stacks including a total of 828 images. The Thresholded Absolute Gradient algorithm outperformed all others, correctly identifying the top or bottom focal plane within an average of 1 ?m on the training data as well as the test data.

Elozory, Daniel T.; Bonam, Om Pavithra; Kramer, Kurt; Goldgof, Dmitry B.; Hall, Lawrence O.; Mangual, Osvaldo; Mouton, Peter R.

2011-03-01

297

Turbulence characterization at the Nasmyth focal plane of the VLT Melipal  

NASA Astrophysics Data System (ADS)

The Multi-conjugate Adaptive optics Demonstrator (MAD) has been developed by ESO, and installed at the Nasmyth focal plane of the Very Large Telescope Melipal at Cerro Paranal in Chile. Thanks to the multi-dimensional sensing and correction of MAD, the measurements recorded while the system is performing MCAO can be analyzed to retrieve the instantaneous characteristics of the turbulence seen from the focal plane of the telescope: seeing and turbulence profile. In this paper those measurements will be compared to the ones given by other tools at disposition at the focal plane: the guide probe and the active optics sensor, and at another location on the Paranal platform: DIMM and MASS.

Kolb, Johann

2008-07-01

298

Early vision and focal attention  

NASA Astrophysics Data System (ADS)

At the thirty-year anniversary of the introduction of the technique of computer-generated random-dot stereograms and random-dot cinematograms into psychology, the impact of the technique on brain research and on the study of artificial intelligence is reviewed. The main finding-that stereoscopic depth perception (stereopsis), motion perception, and preattentive texture discrimination are basically bottom-up processes, which occur without the help of the top-down processes of cognition and semantic memory-greatly simplifies the study of these processes of early vision and permits the linking of human perception with monkey neurophysiology. Particularly interesting are the unexpected findings that stereopsis (assumed to be local) is a global process, while texture discrimination (assumed to be a global process, governed by statistics) is local, based on some conspicuous local features (textons). It is shown that the top-down process of "shape (depth) from shading" does not affect stereopsis, and some of the models of machine vision are evaluated. The asymmetry effect of human texture discrimination is discussed, together with recent nonlinear spatial filter models and a novel extension of the texton theory that can cope with the asymmetry problem. This didactic review attempts to introduce the physicist to the field of psychobiology and its problems-including metascientific problems of brain research, problems of scientific creativity, the state of artificial intelligence research (including connectionist neural networks) aimed at modeling brain activity, and the fundamental role of focal attention in mental events.

Julesz, Bela

1991-07-01

299

Design of 10x uncooled thermal infrared zoom optical system  

NASA Astrophysics Data System (ADS)

For 320x240 pixel2 uncooled focal plane array detector, an infrared continuous zoom optical system of 10x zoom ratio for long-wavelength is designed in this paper. This system can be applied in joint transform correlator and other infrared tracing systems. The spectral band of the system is 8?m~12?m, the focal length is 20mm ~200mm , and the F number of the system is 2. The relative aperture is invariant during the zoom process, and the variable magnification curve and compensation curve are smooth as well. The system only consists of 7 lenses and one aspherical surface. The results have shown that when the maximum spatial frequency is 17lp/mm, the MTF(Modulation Transfer Function) curves in the whole range of focal length are all above 0.5 which are closed to diffraction limited curve. The stability of image plane is well, and the imaging quality is perfect, which show that the system meets the requirement of technical specification.

Mu, Da; Du, Yu-nan; Mi, Shi-long; Guo, Yan-chi

2013-09-01

300

Three-dimensional surface profiling and optical characterization of liquid microlens using a Shack-Hartmann wave front sensor  

PubMed Central

We demonstrate three-dimensional (3D) surface profiling of the water–oil interface in a tunable liquid microlens using a Shack–Hartmann wave front sensor. The principles and the optical setup for achieving 3D surface measurements are presented and a hydrogel-actuated liquid lens was measured at different focal lengths. The 3D surface profiles are then used to study the optical properties of the liquid lens. Our method of 3D surface profiling could foster the improvement of liquid lens design and fabrication, including surface treatment and aberration reduction.

Li, Chenhui; Hall, Gunnsteinn; Zeng, Xuefeng; Zhu, Difeng; Eliceiri, Kevin; Jiang, Hongrui

2011-01-01

301

Design of microlens illuminated aperture array fabricated by aligned ultraviolet imprinting process for optical read only memory card system  

NASA Astrophysics Data System (ADS)

A microlens illuminated aperture array (MLIAA) was designed for the multiprobe optical read only memory card system. As a method to integrate the microlens array (MLA) with the aperture array containing 1000×1000 apertures, an aligned ultraviolet imprinting process was used to satisfy the system objectives of reduced focal length and reduced spot size. An analysis using diffraction theory was performed to obtain the design tolerances for both MLIAA and the imprinting process. The maximum intensity of the optical probes at the Talbot [Philos. Mag. 9, 401 (1836)] position from the fabricated MLIAA was 12 times higher than that from the aperture array without a MLA.

Kim, Hongmin; Lee, Jeeseung; Lim, Jiseok; Kim, Seok-Min; Kang, Shinill; Kim, Young-Joo; Busch, Christopher

2006-06-01

302

Three-dimensional surface profiling and optical characterization of liquid microlens using a Shack-Hartmann wave front sensor.  

PubMed

We demonstrate three-dimensional (3D) surface profiling of the water-oil interface in a tunable liquid microlens using a Shack-Hartmann wave front sensor. The principles and the optical setup for achieving 3D surface measurements are presented and a hydrogel-actuated liquid lens was measured at different focal lengths. The 3D surface profiles are then used to study the optical properties of the liquid lens. Our method of 3D surface profiling could foster the improvement of liquid lens design and fabrication, including surface treatment and aberration reduction. PMID:22046057

Li, Chenhui; Hall, Gunnsteinn; Zeng, Xuefeng; Zhu, Difeng; Eliceiri, Kevin; Jiang, Hongrui

2011-04-26

303

Three-element zoom lens with fixed distance between focal points.  

PubMed

This work deals with a theoretical analysis of zoom lenses with a fixed distance between focal points. Equations are derived for the primary (paraxial) design of the basic parameters of a three-element zoom lens. It is shown that the number of optical elements for such a lens must be larger than two. PMID:22739850

Mikš, Antonin; Novák, Ji?í; Novák, Pavel

2012-06-15

304

Polymer microlens array with tunable focal intensity by the polarization control of the incident light  

Microsoft Academic Search

This paper proposes an optically tunable focal intensity microlens array (MLA) by using a focusing unit with birefringent liquid crystalline polymer (LCP) and a tuning unit with photoalignment for controlling the polarization state of the incident light. Due to the different refractive indices of LCP, it acts as a positive or negative microlens with respect to the polarization state. The

San-Yi Huang; Tung-Chen Tung; Shin-Wei Ko; Chi-Lun Ting; Hung-Chang Jau; Ming-Shian Li; Hui-Chi Lin; Andy Ying-Guey Fuh

2010-01-01

305

Arc Length Gone Global  

ERIC Educational Resources Information Center

Everyone with a thorough knowledge of single variable calculus knows that integration can be used to find the length of a curve on a given interval, called its arc length. Fortunately, if one endeavors to pose and solve more interesting problems than simply computing lengths of various curves, there are techniques available that do not require an…

Boudreaux, Gregory M.; Wells, M. Scott

2007-01-01

306

FPAs and thin film binary optic microlens integration  

NASA Astrophysics Data System (ADS)

The relatively large detector size of conventional focal plane arrays often acts as a limiting source of noise currents and requires these devices to run at undesirably low temperatures. To reduce the detector size without reducing the detector's quantum efficiency, we have developed efficient on-focal plane collection optics consisting of arrays of thin film binary optic microlenses on the back surface of hybrid detector array structures. P/n polarity photodiodes of an unusual `planar-mesa' geometry were fabricated in epitaxial HgCdTe deposited by molecular beam epitaxy on the `front' side of a CdZnTe substrate. Diffractive (8 - 16 phase level) Ge microlenses were deposited on 48 micrometers centers in a registered fashion (using an IR mask aligner and appropriate marks on the front surface of the CdZnTe) on the back side of the substrate using a lifting process. The lifting process circumvents some of the process limitations of the more conventional chemical etching method to diffractive microlens processing, allowing them to approach more closely their theoretical efficiency limit of > 95%. Prior to microlens deposition, but after diode fabrication, the test structures were flip- chip bonded or `hybridized' using indium interconnections to metallic strip lines which had been photolithographically deposited on sapphire dice (a process equally compatible with a silicon integrated circuit readout). After hybridization, the CdZnTe was thinned to equal the focal length of the lenses in the CdZnTe material. Optical characterization has demonstrated that the microlenses combined with the detector mesas concentrate light sufficiently to increase the effective collection area. The optical size of the mesa detectors being larger than the theoretical diffraction limit of the microlenses precludes determining whether the lenses themselves produce the theoretical diffraction-limited gain, but they clearly decrease required detector area by at least 3 - 6X. To our knowledge, this is the first successful demonstration of IR detectors and binary optics microlens integration.

Motamedi, M. Edward; Tennant, William E.; Melendes, Robert; Gluck, Natalie S.; Park, Sangtae; Arias, Jose M.; Bajaj, Jagmohan; Pasko, John G.; McLevige, William V.; Zandian, Majid; Hall, Randolph L.; Steckbauer, Karla G.; Richardson, Patti D.; Cooper, Donald E.

1996-03-01

307

The use of short coherence length laser light for eye length measurement  

Microsoft Academic Search

There is a need for an accurate knowledge of the length of the eye, for example for improved precision in the design and manufacture of optical lens implants and other opthalmic surgical procedures. The parameter itself is not readily determined, and the primary method in use at the moment in ultrasonography, which gives a direct estimate of the eye length.

D. N. Wang; G. Dick; S. Chen; K. T. V. Grattan; A. W. Palmer

1992-01-01

308

Design of a dual field-of-view imaging system for infrared focal plane arrays  

Microsoft Academic Search

In this paper, the design of a dual field-of-view optical system for 3-5 micrometers infra-red focal-plane arrays is described. Preliminary calculations are done to determine the first-order parameters of the narrow and the wide-field modes. To achieve a switchable dual field-of-view system, two different optical configurations, one based on the axial motion of a lens group and the other based

Muhammad N. Akram

2002-01-01

309

The effect of focal depth error on moment tensor inversion  

Microsoft Academic Search

In the determination of focal mechanism and rupture process of earthquake sources by using moment tensor inversion technique,\\u000a it is difficult to guarantee the focal depth used in calculating the Green’s functions (theoretical focal depth) is exactly\\u000a equal to the real focal depth. The difference between the theoretical and real focal depths, i. e., the focal depth error,\\u000a will affect

Li-Sheng Xu; Yun-Tai Chen

1997-01-01

310

Calibration method of absolute orientation of camera optical axis  

NASA Astrophysics Data System (ADS)

Camera calibration is one of the most basic and important processes in optical measuring field. Generally, the objective of camera calibration is to estimate the internal and external parameters of object cameras, while the orientation error of optical axis is not included yet. Orientation error of optical axis is a important factor, which seriously affects measuring precision in high-precision measurement field, especially for those distant aerospace measurement in which object distance is much longer than focal length, that lead to magnifying the orientation errors to thousands times. In order to eliminate the influence of orientation error of camera optical axis, the imaging model of camera is analysed and established in this paper, and the calibration method is also introduced: Firstly, we analyse the reasons that cause optical axis error and its influence. Then, we find the model of optical axis orientation error and imaging model of camera basing on it's practical physical meaning. Furthermore, we derive the bundle adjustment algorithm which could compute the internal and external camera parameters and absolute orientation of camera optical axis simultaneously at high precision. In numeric simulation, we solve the camera parameters by using bundle adjustment optimization algorithm, then we correct the image points by calibration results according to the model of optical axis error, and the simulation result shows that our calibration model is reliable, effective and precise.

Xu, Yong; Guo, Pengyu; Zhang, Xiaohu; Ding, Shaowen; Su, Ang; Li, Lichun

2013-08-01

311

Nonlinear optical properties of novel forms of enriched carbon disulfide  

NASA Astrophysics Data System (ADS)

The ultimate goal of designing molecules with large third-order nonlinearities is to incorporate them into optical switching and limiting devices. To achieve this, the molecules must have large and fast optical nonlinearities. We undertook picosecond and femtosecond studies of carbon disulfide (CS2) enriched with sulfur, selenium, cadmium telluride nanoparticles and 2-methyl-4-nitroaniline (MNA) for enhanced optical nonlinearities, using the Z-scan technique. In this method, a sample is scanned along the optic axis (chosen as the z- direction) in the focal region of a single focused laser beam. The intensity transmitted through the region with an aperture (nonlinear refraction) or without an aperture (nonlinear absorption) in the far field is recorded as a function of the sample position. Due to the high intensity of the electromagnetic field in this region, the sample tends to behave as a lens of variable focal length and can focus or defocus the beam depending on the sign of the nonlinearity. Our measurements with a 130-fs source indicate that the nonlinear absorption coefficient of CS2 was enhanced by more than two orders of magnitude (over pure CS2) through sulfur and selenium enrichment; while their nonlinear refractive indices experienced minimal change. Enhanced nonlinearities of enriched CS2 molecules may be harnessed for sensor applications.

Edziah, Raymond

312

Infrared focal plane array modeling for aerospace and automotive applications  

NASA Astrophysics Data System (ADS)

To simulate an Enhanced Vision System (EVS), CEA/LETI Infrared Laboratory has developed two behavioural models of infrared focal plane arrays : one in the Short Wave IR and the other in the Long Wave IR band. These Infrared Focal Plane Arrays (IRFPAs) models will be implemented on simulation platform aimed at evaluating the impact and use of infrared sensors in automotive and aeronautic applications. To be realistic, model parameters are extracted from electro-optical characterization of real components. The SWIR detector is calibrated with a 320x256 HgCdTe cooled FPA component from SOFRADIR, and the LWIR one with an uncooled micro-bolometer array from ULIS (a_Si technology from LETI). The flexibility of the models allows to simulate cameras based on these components and to forecast future ones based on different read-out circuit or detector technologies. In this paper we present the IRFPAs models, the main electro-optical characterization results and we compare some experimental measurements with simulations.

Durand, Alain; de Borniol, Eric; Guerineau, Nicolas; Cathala, Thierry; Yon, Jean-Jacques; Ouvrier-Buffet, Jean-Louis; Castelein, Pierre; Tronel, Robert; Bisotto, Sylvette; Destefanis, Gerard L.; Chamonal, Jean-Paul

2004-08-01

313

Measuring Thermodynamic Length  

SciTech Connect

Thermodynamic length is a metric distance between equilibrium thermodynamic states. Among other interesting properties, this metric asymptotically bounds the dissipation induced by a finite time transformation of a thermodynamic system. It is also connected to the Jensen-Shannon divergence, Fisher information, and Rao's entropy differential metric. Therefore, thermodynamic length is of central interestin understanding matter out of equilibrium. In this Letter, we will consider how to denethermodynamic length for a small system described by equilibrium statistical mechanics and how to measure thermodynamic length within a computer simulation. Surprisingly, Bennett's classic acceptance ratio method for measuring free energy differences also measures thermodynamic length.

Crooks, Gavin E

2007-09-07

314

Seismic Discriminant Based on Focal Mechanism.  

National Technical Information Service (NTIS)

Using the observation that a predominant focal mechanism exists for a given hypocentral region, a seismic discriminant based on body-wave magnitude has been developed. This discriminant enables one to identify earthquakes that do not fit mechanisms expect...

A. A. Syed C. Kisslinger O. W. Nuttli

1971-01-01

315

Focal renal masses: magnetic resonance imaging  

SciTech Connect

Thirty patients with focal renal masses were evaluated on a .12-Tesla resistive magnetic resonance unit using partial saturation and spin echo pulse sequence. Fifteen patients had cystic lesions, nine patients had renal cell carcinoma, two had metastatic lesions, one had an angiomyolipoma, and three had focal bacterial infection. Renal cell carcinomas demonstrated areas of increased signal using a partial saturation sequence. Magnetic resonance imaging accurately detected perinephric extension and vascular invasion in all patients. Metastatic disease to the kidney was uniformly low in signal, in contrast to primary renal cell carcinoma; an angiomyolipoma demonstrated very high signal intensity. Two masses resulting from acute focal bacterial nephritis were uniformly low in signal. Magnetic resonance imaging appears to be an accurate way of detecting, identifying, and staging focal renal masses.

Choyke, P.L.; Kressel, H.Y.; Pollack, H.M.; Arger, P.M.; Axel, L.; Mamourian, A.C.

1984-08-01

316

Lens design based on instantaneous focal function  

Microsoft Academic Search

The formula for the lens is derived based on the information of instantaneous\\u000afocal function. Focal function is an important tool in designing lenses with\\u000aextended depth of focus (EDoF) because this allows EDoF lens designers to try\\u000aout various mathematical curves using computers to optimize their design. Once\\u000aan optimal focal function information is obtained, the corresponding physical\\u000aEDoF

Sung Nae Cho

2009-01-01

317

A CCD based focal spot camera.  

PubMed

Rapid, quantative assessment of x-radiation source intensity distributions would be useful in several areas of radiation physics. A simple x-ray sensitive CCD based camera for the measurement of focal spot and radiation beam intensity profiles has been constructed. Focal spot images recorded with the CCD camera and radiographic emulsion are compared and the advantage of the CCD camera in rapidly recording true radiation intensity distributions is demonstrated. PMID:7708858

Speller, R D; Martínez-Dávalos, A; Farquharson, M

1995-02-01

318

Determination of accuracy of measurements by NREL`s Scanning Hartmann Optical Test instrument  

SciTech Connect

NREL`s Scanning Hartmann Optical Test (SHOT) instrument is routinely used to characterize the surface of candidate dish concentration elements for solar thermal applications. An approach was devised to quantify the accuracy of these measurements. Excellent reproducibility was exhibited and high confidence established. The SHOT instrument was designed to allow the surface figure of large optical test articles to be accurately specified. Such test articles are nominally parabolic with an f/D ratio (in which f=focal length and D=aperture diameter) in the range of 0.5--1.0. Recent modifications of SHOT have extended the characterization range out to about f/D=3.0. A series of experiments was designed to investigate and quantify the uncertainties associated with optical characterization performed by SHOT. This approach involved making a series of measurements with an arbitrary test article positioned at a number of locations transverse to the optical axis of SHOT. 3 refs.

Jorgensen, G.; Wendelin, T.; Carasso, M.

1991-04-01

319

Determination of accuracy of measurements by NREL's Scanning Hartmann Optical Test instrument  

SciTech Connect

NREL's Scanning Hartmann Optical Test (SHOT) instrument is routinely used to characterize the surface of candidate dish concentration elements for solar thermal applications. An approach was devised to quantify the accuracy of these measurements. Excellent reproducibility was exhibited and high confidence established. The SHOT instrument was designed to allow the surface figure of large optical test articles to be accurately specified. Such test articles are nominally parabolic with an f/D ratio (in which f=focal length and D=aperture diameter) in the range of 0.5--1.0. Recent modifications of SHOT have extended the characterization range out to about f/D=3.0. A series of experiments was designed to investigate and quantify the uncertainties associated with optical characterization performed by SHOT. This approach involved making a series of measurements with an arbitrary test article positioned at a number of locations transverse to the optical axis of SHOT. 3 refs.

Jorgensen, G.; Wendelin, T.; Carasso, M.

1991-04-01

320

Prenatal Sonographic Diagnosis of Focal Musculoskeletal Anomalies  

PubMed Central

Focal musculoskeletal anomalies vary, and can manifest as part of a syndrome or be accompanied by numerous other conditions such as genetic disorders, karyotype abnormalities, central nervous system anomalies and other skeletal anomalies. Isolated focal musculoskeletal anomaly does, however, also occur; its early prenatal diagnosis is important in deciding prenatal care, and also helps in counseling parents about the postnatal effects of numerous possible associated anomalies. We have encountered 50 cases involving focal musculoskeletal anomalies, including focal limb dysplasia [radial ray abnormality (n=3), mesomelic dysplasia (n=1)]; anomalies of the hand [polydactyly (n=8), syndactyly (n=3), ectrodactyly (n=1), clinodactyly (n=6), clenched hand (n=5)]; anomalies of the foot [clubfoot (n=10), rockerbottom foot (n=5), sandal gap deformity (n=1), curly toe (n=2)]; amniotic band syndrome (n=3); and anomalies of the focal spine [block vertebra (n=1), hemivertebra (n=1)]. Among these 50 cases, five [polydactyly (n=1), syndactyly (n=2) and curly toe (n=2)] were confirmed by postnatal physical evaluation, two (focal spine anomalies) were diagnosed after postnatal radiologic examination, and the remaining 43 were proven at autopsy. For each condition, we describe the prenatal sonographic findings, and include a brief review.

Ryu, Jung Kyu; Choi, Jong Sun

2003-01-01

321

Focusing coherent x-rays with refractive optics  

Microsoft Academic Search

Refractive lenses have been used successfully to focus incoherent x-ray emission in the wavelength range from 2 to .5A with focal lengths on the order of one meter. A stack of N lens elements is employed to reduce the focal length by the factor N over a single element, and such a lens is terms a Compound Refractive Lens (CRL).

Richard H. Pantell; Joseph Feinstein; H. R. Beguiristain; Melvin A. Piestrup; Charles K. Gary; J. Theodore Cremer

2001-01-01

322

Planck Length and Cosmology  

NASA Astrophysics Data System (ADS)

We show that an unification of quantum mechanics and general relativity implies that there is a fundamental length in Nature in the sense that no operational procedure would be able to measure distances shorter than the Planck length. Furthermore we give an explicit realization of an old proposal by Anderson and Finkelstein who argued that a fundamental length in nature implies unimodular gravity. Finally, using hand waving arguments we show that a minimal length might be related to the cosmological constant which, if this scenario is realized, is time dependent.

Calmet, Xavier

323

Formation of optical microlens by laser polymerization method  

NASA Astrophysics Data System (ADS)

Optical lens of micrometer order diameter for coupling between optical fiber and laser diode were formed by argon ion laser polymerization method at visible light cured resin. Test resin materials consisted of triethylene glycol dimethacrylate for main resin, camphorquinon for photo initiator of visible light area, hydroquinon for inhibitor, and N,N-dimethylmethacrylate for reducing agent. In order to obtain the micro lens of short focal length and small spherical aberration, the use of this technique makes it possible to simultaneously form the polymerized aria on glass plate at the argon ion laser beam irradiation zone. The polmerized aria made a high quality micro lens without using molding pattern. We have verified our claims with visual inspection, ray trajectory calculations for measurement of side long spherical aberration (transverse aberration), Fourier transform infrared spectroscopy for degree of conversion analysis of polymerized resin area, and Duc de Chaulnes method for measurement of lens shape. The lens has a diameter of 300micrometers or more, a focal length of 500micrometers or more with an NA of 0.5, and transverse aberration plot of about 100% of the within the limits of +/- 25micrometers . This method can be applied for producing circular, non-circular, linear, and array micro lenses by scanning or patterning of argon ion laser beam.

Suzuki, Kaoru

2001-11-01

324

Visual Scanning Hartmann Optical Tester (VSHOT) Uncertainty Analysis (Milestone Report)  

SciTech Connect

In 1997, an uncertainty analysis was conducted of the Video Scanning Hartmann Optical Tester (VSHOT). In 2010, we have completed a new analysis, based primarily on the geometric optics of the system, and it shows sensitivities to various design and operational parameters. We discuss sources of error with measuring devices, instrument calibrations, and operator measurements for a parabolic trough mirror panel test. These help to guide the operator in proper setup, and help end-users to understand the data they are provided. We include both the systematic (bias) and random (precision) errors for VSHOT testing and their contributions to the uncertainty. The contributing factors we considered in this study are: target tilt; target face to laser output distance; instrument vertical offset; laser output angle; distance between the tool and the test piece; camera calibration; and laser scanner. These contributing factors were applied to the calculated slope error, focal length, and test article tilt that are generated by the VSHOT data processing. Results show the estimated 2-sigma uncertainty in slope error for a parabolic trough line scan test to be +/-0.2 milliradians; uncertainty in the focal length is +/- 0.1 mm, and the uncertainty in test article tilt is +/- 0.04 milliradians.

Gray, A.; Lewandowski, A.; Wendelin, T.

2010-10-01

325

Extended depth of focus adaptive optics spectral domain optical coherence tomography  

PubMed Central

We present an adaptive optics spectral domain optical coherence tomography (AO-SDOCT) with a long focal range by active phase modulation of the pupil. A long focal range is achieved by introducing AO-controlled third-order spherical aberration (SA). The property of SA and its effects on focal range are investigated in detail using the Huygens-Fresnel principle, beam profile measurement and OCT imaging of a phantom. The results indicate that the focal range is extended by applying SA, and the direction of extension can be controlled by the sign of applied SA. Finally, we demonstrated in vivo human retinal imaging by altering the applied SA.

Sasaki, Kazuhiro; Kurokawa, Kazuhiro; Makita, Shuichi; Yasuno, Yoshiaki

2012-01-01

326

Filamentation length for femtosecond laser radiation focused by conic and parabolic lenses  

NASA Astrophysics Data System (ADS)

Special features of filamentation of femtosecond laser radiation focused by parabolic lens and axicon are considered. Based on numerical solution of the nonstationary Schrödinger equation, simple expressions are derived for calculation of the filamentation length for laser radiation focused by the parabolic lens and axicon depending on the radiation power and focal lengths.

Zemljanov, A. A.; Bulygin, A. D.; Minina, O. V.

2013-08-01

327

Transparent Meta-Analysis: Does Aging Spare Prospective Memory with Focal vs. Non-Focal Cues?  

PubMed Central

Background Prospective memory (ProM) is the ability to become aware of a previously-formed plan at the right time and place. For over twenty years, researchers have been debating whether prospective memory declines with aging or whether it is spared by aging and, most recently, whether aging spares prospective memory with focal vs. non-focal cues. Two recent meta-analyses examining these claims did not include all relevant studies and ignored prevalent ceiling effects, age confounds, and did not distinguish between prospective memory subdomains (e.g., ProM proper, vigilance, habitual ProM) (see Uttl, 2008, PLoS ONE). The present meta-analysis focuses on the following questions: Does prospective memory decline with aging? Does prospective memory with focal vs. non-focal cues decline with aging? Does the size of age-related declines with focal vs. non-focal cues vary across ProM subdomains? And are age-related declines in ProM smaller than age-related declines in retrospective memory? Methods and Findings A meta-analysis of event-cued ProM using data visualization and modeling, robust count methods, and conventional meta-analysis techniques revealed that first, the size of age-related declines in ProM with both focal and non-focal cues are large. Second, age-related declines in ProM with focal cues are larger in ProM proper and smaller in vigilance. Third, age-related declines in ProM proper with focal cues are as large as age-related declines in recall measures of retrospective memory. Conclusions The results are consistent with Craik's (1983) proposal that age-related declines on ProM tasks are generally large, support the distinction between ProM proper vs. vigilance, and directly contradict widespread claims that ProM, with or without focal cues, is spared by aging.

Uttl, Bob

2011-01-01

328

Focal mechanisms of earthquakes in Mongolia  

NASA Astrophysics Data System (ADS)

Focal mechanism data provide information on the relative magnitudes of the principal stresses, so that a tectonic regime can be assigned. Especially such information is useful for the study of intraplate seismic active regions. A study of earthquake focal mechanisms in the territory of Mongolia as landlocked and intraplate region was conducted. We present map of focal mechanisms of earthquakes with M4.5 which occurred in Mongolia and neighboring regions. Focal mechanisms solutions were constrained by the first motion solutions, as well as by waveform modeling, particularly CMT solutions. Four earthquakes have been recorded in Mongolia in XX century with magnitude more than 8, the 1905 M7.9 Tsetserleg and M8.4 Bolnai earthquakes, the 1931 M8.0 Fu Yun earthquake, the 1957 M8.1 Gobi-Altai earthquake. However the map of focal mechanisms of earthquakes in Mongolia allows seeing all seismic active structures: Gobi Altay, Mongolian Altay, active fringe of Hangay dome, Hentii range etc. Earthquakes in the most of Mongolian territory and neighboring China regions are characterized by strike-slip and reverse movements. Strike-slip movements also are typical for earthquakes in Altay Range in Russia. The north of Mongolia and south part of the Baikal area is a region where have been occurred earthquakes with different focal mechanisms. This region is a zone of the transition between compressive regime associated to India-Eurasian collision and extensive structures localized in north of the country as Huvsgul area and Baykal rift. Earthquakes in the Baikal basin itself are characterized by normal movements. Earthquakes in Trans-Baikal zone and NW of Mongolia are characterized dominantly by strike-slip movements. Analysis of stress-axis orientations, the tectonic stress tensor is presented. The map of focal mechanisms of earthquakes in Mongolia could be useful tool for researchers in their study on Geodynamics of Central Asia, particularly of Mongolian and Baikal regions.

Sodnomsambuu, D.; Natalia, R.; Gangaadorj, B.; Munkhuu, U.; Davaasuren, G.; Danzansan, E.; Yan, R.; Valentina, M.; Battsetseg, B.

2011-12-01

329

Advances in hybrid optics physical sensors for extreme environments  

NASA Astrophysics Data System (ADS)

Highlighted are novel innovations in hybrid optical design physical sensors for extreme environments. Various hybrid design compositions are proposed that are suited for a particular sensor application. Examples includes combining freespace (wireless) and fiber-optics (wired) for gas turbine sensing and combining single crystal and sintered Silicon Carbide (SiC) materials for robust extreme environment Coefficent of Thermal Expansion (CTE) matched frontend probe design. Sensor signal processing also includes the hybrid theme where for example Black-Body radiation thermometry (pyrometry) is combined with laser interferometry to provide extreme temperature measurements. The hybrid theme also operates on the optical device level where a digital optical device such as a Digital Micromirror Device (DMD) is combined with an analog optical device such as an Electronically Controlled Variable Focal Length Lens (ECVFL) to deliver a smart and compressive Three Dimensional (3-D) imaging sensor for remote scene and object shape capture including both ambient light (passive) mode and active laser targeting and receive processing. Within a device level, the hybrid theme also operates via combined analog and digital control such as within a wavelength-coded variable optical delay line. These powerful hybrid design optical sensors have numerous applications in engineering and science applications from the military to the commercial/industrial sectors.

Riza, Nabeel A.

2010-04-01

330

Microstructured optical arrays for smart x-ray optics  

NASA Astrophysics Data System (ADS)

The Smart X-ray Optics (SXO) programme is developing advanced active-adaptive optics for X-rays. There are two main themes: large optics for applications in astronomy and small scale optics for micro-probing of biological cells and tissue samples using Ti or Cr K? radiation (4.5keV and 5.4keV, respectively) in studies related to radiation induced cancers. For the latter objective, microstructured optical arrays (MOAs) have been proposed. These consist of an array of channels deep etched in silicon. They use grazing incidence reflection to focus the X-rays through consecutive aligned arrays of channels, ideally reflecting once off a channel wall in each array. Bending the arrays allows variable focal length. The adaptivity is achieved by flexing the arrays using PZT (Lead Zirconate Titanate)-based piezo actuators. The array bending has been modelled using finite element analysis (FEA) and the results showed that for reasonable efficiency, the wall roughness of the channels should not exceed 2nm. This paper describes two techniques of fabrication the MOAs: dry etching and wet etching. The first method requires a special equipment called "inductively coupled plasma" (ICP) using Bosch processes that are designed to produce features with a high aspect ratio with vertical walls. The second method involves using an alkaline solution for etching <110> silicon wafers. This type of wafer was selected because of the large wet etch ratio between the (111) and (100) planes that leads to smooth vertical walls. For our application tetra-methyl-ammonium hydroxide (TMAH) was used as it is fully compatible with CMOS integrated circuit processes.

Dunare, Camelia; Parkes, William; Stevenson, Tom; Michette, Alan; Pfauntsch, Slawka; Sahraei, Shahin; Shand, Matthew; Zhang, Dou; Rodriguez Sanmartin, Daniel; Button, Tim; Feldman, Charlotte; Willingale, Richard; Doel, Peter; Wang, Hongchang; James, Ady

2009-05-01

331

The Statistics of Calcium-Mediated Focal Excitations on a One-Dimensional Cable  

PubMed Central

It is well known that various cardiac arrhythmias are initiated by an ill-timed excitation that originates from a focal region of the heart. However, up to now, it is not known what governs the timing, location, and morphology of these focal excitations. Recent studies have shown that these excitations can be caused by abnormalities in the calcium (Ca) cycling system. However, the cause-and-effect relationships linking subcellular Ca dynamics and focal activity in cardiac tissue is not completely understood. In this article, we present a minimal model of Ca-mediated focal excitations in cardiac tissue. This model accounts for the stochastic nature of spontaneous Ca release on a one-dimensional cable of cardiac cells. Using this model, we show that the timing of focal excitations is equivalent to a first passage time problem in a spatially extended system. In particular, we find that for a short cable the mean first passage time increases exponentially with the number of cells in tissue, and is critically dependent on the ratio of inward to outward currents near the threshold for an action potential. For long cables excitations occurs due to ectopic foci that occur on a length scale determined by the minimum length of tissue that can induce an action potential. Furthermore, we find that for long cables the mean first passage time decreases as a power law in the number cells. These results provide precise criteria for the occurrence of focal excitations in cardiac tissue, and will serve as a guide to determine the propensity of Ca-mediated triggered arrhythmias in the heart.

Chen, Wei; Asfaw, Mesfin; Shiferaw, Yohannes

2012-01-01

332

FPAs and thin film binary optic microlens integration  

Microsoft Academic Search

The relatively large detector size of conventional focal plane arrays often acts as a limiting source of noise currents and requires these devices to run at undesirably low temperatures. To reduce the detector size without reducing the detector's quantum efficiency, we have developed efficient on-focal plane collection optics consisting of arrays of thin film binary optic microlenses on the back

M. Edward Motamedi; William E. Tennant; Robert Melendes; Natalie S. Gluck; Sangtae Park; Jose M. Arias; Jagmohan Bajaj; John G. Pasko; William V. McLevige; Majid Zandian; Randolph L. Hall; Karla G. Steckbauer; Patti D. Richardson; Donald E. Cooper

1996-01-01

333

Photodynamic Therapy Rescue for Subretinal Fluid Exacerbation After Focal Laser Treatment in Idiopathic Central Serous Chorioretinopathy  

PubMed Central

Purpose To report a case of subretinal leakage after focal laser treatment for idiopathic central serous chorioretinopathy (ICSC). This rare complication was successfully treated with photodynamic therapy (PDT). Methods Interventional case report. Results A 36-year-old male presented with ICSC in his right eye. After a period of observation without resolution, he was treated with focal laser. That treatment resulted in a massive exacerbation of his subretinal fluid. PDT was successfully used to treat the severe exacerbation with rapid resolution of the subretinal fluid, improvement in visual acuity, decreased leakage on fluorescein angiography, and reduction of subretinal fluid on ophthalmoscopic exam and by optical coherence tomography. Conclusions Ophthalmologists should consider the use of PDT in cases where focal laser causes an exacerbation of subretinal fluid in ICSC.

Leng, Theodore; Sanislo, Steven R; Jack, Robert L

2011-01-01

334

Progress on the development of active micro-structured optical arrays for x-ray optics  

NASA Astrophysics Data System (ADS)

The Smart X-Ray Optics (SXO) project comprises a U.K.-based consortium developing active/adaptive micro-structured optical arrays (MOAs). These devices are designed to focus X-rays using grazing incidence reflection through consecutive aligned arrays of microscopic channels etched in silicon. The silicon channels have been produced both by dry and wet etching, the latter providing smoother channel walls. Adaptability is achieved using piezoelectric actuators, which bend the device and therefore change its focal distance. We aim to achieve a 5 cm radius of curvature which can provide a suitable focal length using a tandem pair MOA configuration. Finite Element Analysis (FEA) modelling has been carried out for the optimization of the MOA device design, consider different types of actuators (unimorph, bimorph and active fibre composites), and different Si/piezoelectric absolute and relative thicknesses. Prototype devices have been manufactured using a Viscous Plastic Processing Process for the piezoelectric actuators and dry etched silicon channels, bonded together using a low shrinkage adhesive. Characterisation techniques have been developed in order to evaluate the device performance in terms of the bending of the MOA channels produced by the actuators. This paper evaluates the progress to date on the actuation of the MOAs, comparing FEA modelling with the results obtained for different prototype structures.

Rodriguez Sanmartin, Daniel; Zhang, Dou; Button, Tim; Atkins, Carolyn; Doel, Peter; Wang, Hongchang; Brooks, David; Feldman, Charlotte; Willingale, Richard; Michette, Alan; Pfauntsch, Slawka; Sahraei, Shahin; Shand, Matthew; James, Ady; Dunare, Camelia; Stevenson, Tom; Parkes, William; Smith, Andy

2009-08-01

335

Fiber loop optical buffer  

Microsoft Academic Search

Fiber loop optical buffers enable data storage for discrete time intervals and therefore appear suitable for applications in optical asynchronous transfer mode (OATM)-based networks where data are transmitted in cells of fixed length. In this paper, the feasibility and the limitations of optical data storage in a fiber loop optical buffer are studied theoretically and experimentally, A model of a

R. Langenhorst; M. Eiselt; W. Pieper; G. Grosskopf; R. Ludwig; L. Kuller; E. Dietrich; H. G. Weber

1996-01-01

336

Aplanatic four-mirror system for optical telescopes with a spherical primary mirror  

NASA Astrophysics Data System (ADS)

An exact analytical solution for the design of an optical system without spherical aberration that satisfies the sine condition is presented. The system consists of two parts. The first two mirrors form a strictly afocal system with a spherical primary and the second convex aspherical mirror. The next two mirrors form a focusing system that compensates the coma aberration of the afocal system. A complete description of the optical design, with system data, is given. The spherical primary mirror has a diameter of 10 m. The focal length of the entire system is 152 m, length is 13.5 m, angular field is 7 arcmin, and its theoretical resolution is 0.03 arcsec.

Puryayev, Daniil T.; Gontcharov, Alexander

1998-08-01

337

Optical zoom module based on two deformable mirrors for mobile device applications.  

PubMed

In recent years, optical zoom functionality in mobile devices has been studied. Traditional zoom systems use motors to change separation of lenses to achieve the zoom function, but these systems result in long total length and high power consumption, which are not suitable for mobile devices. Adopting micromachined polymer deformable mirrors in zoom systems has the potential to reduce thickness and chromatic aberration. In this paper, we propose a 2× continuous optical zoom system with five-megapixel image sensors by using two deformable mirrors. In our design, the thickness of the zoom system is about 11 mm. The effective focal length ranges from 4.7 mm at a field angle of 52° to 9.4 mm. The f-number is 4.4 and 6.4 at the wide-angle and telephoto end, respectively. PMID:22505173

Lin, Yu-Hung; Liu, Yen-Liang; Su, Guo-Dung J

2012-04-10

338

Focal plane cameras for ESA optical astronomy missions  

Microsoft Academic Search

Charge-coupled devices (CCDs) have played an important role in imaging and spectroscopic measurements for visible wavelength astronomy. Their introduction has been largely responsible for driving the deployment of 8–10m class telescopes, and in consequence have revolutionized experimental cosmology. Other scientific initiatives such as planet-finding are rapidly increasing in importance for the astronomical community, and we review two future European Space

D. H. Lumb; N. Rando; A. Peacock; F. Favata; M. A. C. Perryman

2003-01-01

339

Measuring microfocus focal spots using digital radiography  

SciTech Connect

Measurement of microfocus spot size can be important for several reasons: (1) Quality assurance during manufacture of microfocus tubes; (2) Tracking performance and stability of microfocus tubes; (3) Determining magnification (especially important for digital radiography where the native spatial resolution of the digital system is not adequate for the application); (4) Knowledge of unsharpness from the focal spot alone. The European Standard EN 12543-5 is based on a simple geometrical method of calculating focal spot size from unsharpness of high magnification film radiographs. When determining microfocus focal spot dimensions using unsharpness measurements both signal-to-noise (SNR) and magnification can be important. There is a maximum accuracy that is a function of SNR and therefore an optimal magnification. Greater than optimal magnification can be used but it will not increase accuracy.

Fry, David A [Los Alamos National Laboratory

2009-01-01

340

LWIR hyperspectral imager based on a diffractive optics lens  

NASA Astrophysics Data System (ADS)

A diffractive optics lens based longwave infrared hyperspectral imager has been used to collect laboratory and outdoor field test data. The imager uses a specially designed diffractive optics Ge lens with a 320×256 HgCdTe focal plane array (FPA) cooled with a Sterling-cooler. The imager operates in 8-10.5 ?m (long wave IR, LWIR) spectral region and an image cube with 50 to 200 bands can be acquired rapidly. Spectral images at different wavelengths are obtained by moving the lens along its optical axis. An f/2.38 diffractive lens is used with a focal length of 70 mm at 8 ?m. The IFOV is 0.57 mrad which corresponds to an FOV of 10.48°. The spectral resolution of the imager is 0.034 ?m at 9 ?m. The pixel size is 40×40 ?m2 in the FPA. In post processing of image cube data contributions due to wavelengths other than the focused one are removed and a correction to account for the change in magnification due to the motion of the lens is applied to each spectral image. A brief description of the imager, data collection and analysis to characterize the performance of the imager will be presented in this paper.

Gupta, Neelam

2009-05-01

341

Optical probe design with extended depth-of-focus for optical coherence microscopy and optical coherence tomography  

NASA Astrophysics Data System (ADS)

In this report, Optical probe system for modality, optical coherence tomography (OCT) and optical coherence microscope (OCM), is presented. In order to control the back focal length from 2.2 mm to 27 mm, optical probe is designed using two liquid lenses and several lenses. The narrow depth of focus (DOF) in microscope is extended by phase filter such as cubic filter. The filter is modified so that DOF is extended only In the OCM mode. The section for the extended DOF of probe is controlled by iris. Therefore in OCT mode, the phase filter does not affect on the DOF of lens. In OCM mode, the Gaussian light and modified light will affect the DOF. The probe dimension is less than 4 mm diameter and less than 60 mm long. The scan range of system is 0.88 mm wide, 1 mm deep in the OCT and 510 ?m wide, 1 mm deep in the OCM mode. The lens curvature and iris aperture are operated by digital microelectrofluidic lens and iris.

Lee, Seungwan; Choi, Minseog; Lee, Eunsung; Jung, Kyu-Dong; Chang, Jong-hyeon; Kim, Woonbae

2013-03-01

342

Optic disc findings in normal tension glaucoma  

Microsoft Academic Search

One hundred thirty stereo photographs of optic discs in patients with normal tension glaucoma (NTG) were reviewed in order to identify characteristics of the three following types of NTG: focal ischemic, senile sclerotic, and generalized cup enlargement. Twenty patients in each group were selected. Focal ischemic patients were more frequently women, had a higher incidence of migraine, a relatively smaller

Yoshio Yamazaki; Fukuko Hayamizu; Satoshi Miyamoto; Takako Nakagami; Chizuru Tanaka; Shigeri Inui

1997-01-01

343

Axial super resolution topography of focal adhesion by confocal microscopy.  

PubMed

The protein organization within focal adhesions has been studied by state-of-the-art super resolution methods because of its thin structure, well below diffraction limit. However, to achieve high axial resolution, most of the current approaches rely on either sophisticated optics or diligent sample preparation, limiting their application. In this report we present a phasor-based method that can be applied to fluorescent samples to determine the precise axial position of proteins using a conventional confocal microscope. We demonstrate that with about 4,000 photon counts collected along a z-scan, axial localization precision close to 10 nm is achievable. We show that, with within 10 nm, the axial location of paxillin, FAK, and talin is similar at focal adhesion sites, while F-actin shows a sharp increase in height towards the cell center. We further demonstrated the live imaging capability of this method. With the advantage of simple data acquisition and no special instrument requirement, this approach could have wide dissemination and application potentials. Microsc. Res. Tech., 76:1070-1078, 2013. © 2013 Wiley Periodicals, Inc. PMID:23897846

Chiu, Chi-Li; Gratton, Enrico

2013-07-29

344

Multiple optical calibration system-based effective multiviews video processing  

NASA Astrophysics Data System (ADS)

A new multiple optical calibration system (MOCS)-based effective multiview video processing (MVP) is proposed. The proposed MOCS can be classified as intracamera processing and intercamera processing (IP). In IP, unequal brightness intensity is rectified by using a brightness difference map, and geometric distortion of the optical lens is corrected. In IP, several important factors, such as unequal camera sensor location, tilt degree of lens mount, and focal length, among multiple cameras are calibrated. Furthermore, an effective disparity matching algorithm, called an as adaptive-based disparity matching algorithm (A-DMA), is proposed for MVP. The proposed A-DMA enhances the performance of MVP in terms of accuracy of disparity estimation and computational overhead.

Bae, Kyung-Hoon; Park, Sanghoon; Cha, Si-Ho

2009-03-01

345

Development of high-performance optical system for small satellites  

NASA Astrophysics Data System (ADS)

Funded by the Ministry of Commerce, Industry, and Energy of Korea, Satrec Initiative has initiated the development of the prototype model of a TMA-based electro-optical system as part of the national space research and development program. Its optical aperture diameter is 120 mm, the effective focal length is 462 mm, and its full field-of-view is 5.08 degrees. The dimension is about 600 mm × 400 mm × 400 mm and its weight is less than 15 kg. To demonstrate its performance and versatility, multi-spectral imaging in visible and near-infrared region was chosen as the application of the prototype. In this paper, the progress made so far on the prototype development and the future plan will be presented.

Choi, Young-Wan; Yang, Seung-Uk; Kang, Myung-Seok; Kim, Ee-Eul

2007-10-01

346

Implementation of a micro-optical pickup using a focusing waveguide grating coupler  

NASA Astrophysics Data System (ADS)

A micro-optical pickup has been implemented by using a focusing waveguide grating coupler. The grating coupler was designed and fabricated on a single mode BPSG (boron phosphor silica glass) waveguide layer. The coupling area was 1×1mm2 containing more than 1,500 grating lines, where the maximum and minimum grating pitch were 296nm and 811nm, respectively. The focal length and the numerical aperture of the present grating coupler were 530 ?m and 0.68 with 632.8nm He-Ne red laser. The full width half maximum diameter of the focal spot was measured to be 450 nm and 510 nm in x and y direction.

Paek, Mun Cheol; Sohn, Yeung J.; Suh, Dongwoo; Ryu, Hojun; Park, Yongwoo

2003-09-01

347

A Case of Focal Acral Hyperkeratosis  

PubMed Central

Focal acral hyperkeratosis (FAH) is a rare genodermatosis with an autosomal dominant pattern of inheritance; however, it may also be sporadic. FAH is characterized by late-onset crateriform keratotic papules, some coalescing into plaques, along the borders of the hands and feet. We herein report a case of FAH in a 47-year-old male with a family history of similar lesions in three generations. The histological findings revealed focal areas of orthohyperkeratosis over an area of depressed but otherwise normal epidermis. The dermis showed no specific changes, which distinguished this case from acrokeratoelastoidosis, which shows elastorrhexis of clinically similar lesions.

Lee, Eun Ah; Kim, Hei Sung; Kim, Hyung Ok

2009-01-01

348

A Future Generation High Angular Resolution X-ray Telescope Based Upon Physical Optics  

NASA Astrophysics Data System (ADS)

Although the highest priority objective for the next major X-ray mission is high resolution spectroscopy we will ultimately want the next generation high angular resolution X-ray observatory. This author believes that the 0.5 arc second angular resolution of the Chandra X-Ray Observatory is likely to be close to the best that can be obtained with grazing incidence optics, especially with larger effective area. Telescopes based upon physical optics, diffraction and refraction that transmit rather than reflect X-rays can have an angular resolution of a mili arc second or better. Combining the diffractive and refractive components into one unit can neutralize the chromatic aberration of each individually over a ~15% bandwidth at 6 keV. The aperture could be divided into several diffractive-refractive pairs to broaden the bandwidth. Furthermore these telescopes would be very low cost, very light weight, and more tolerant of figure errors and surface roughness than grazing incidence telescopes. However, focal lengths are of the order of 1000 km, which requires a new mission architecture consisting of long distance formation-flying between two spacecraft, one hosting the optics, the other, the detector. One of the spacecraft requires propulsion, provided by, for example, ion engines to maintain the optics-detector alignment by counteracting gravity gradient forces, and for changing targets. Although their effective area can be large and their angular resolution very high diffractive-refractive telescopes are not necessarily more sensitive than Chandra because their large focal plane scale (1 mili arc second ~ 1 mm) subjects them to a higher level of cosmic ray background and their opacity results in a lower energy limit of 2 keV. The intrinsic field of view is wide but the large focal length scale and practical limits on the size of the detector array results in a small field of view.

Gorenstein, Paul

2013-04-01

349

Design of the segmented primary optical telescope  

NASA Astrophysics Data System (ADS)

Following with the "high-resolution upsurge" appeared in many counties in recent few years, it is an inevitable trend to increase the size of the Optical Telescope. However, because of the volume constrains of space-borne astronomical instruments, segmented reflector is thought as the main measure of future astro-physical missions by many scientists. In this paper, a coaxial three-mirror anastigmatic system (TMA) with a segmented primary mirror is modeled in optical software. The optical system, which has 2.4m aperture, 48m focal length and the field-view angle of 0.3°×0.06°, works in the 450nm~900nm wave band. The `1+6' aperture-stiching model is applied. Firstly, the initial structure of the system is inputted to the CODEV, and a certain constraint functions are set, and then the system automatically optimizes. Finally, designing results show that the Modulation Transfer Function (MTF) is really very near to the limit of diffraction. We get a good image quality of the optical system design results.

Zhang, Kaisheng; Yan, Aqi; Cao, Jianzhong; Fan, Zheyuan; Wu, Li; Zhang, Zhi; Zhu, Qing

2013-09-01

350

Modeling of optical gel electroactive response  

NASA Astrophysics Data System (ADS)

In this paper a model is postulated to describe the optical response of an electroactive polymer hydrogel due to applied electrical fields. This model consists of a series of several modules: an electrical module that identifies the relationship between the applied voltage/current, electrode location and material and applied electrical field; a chemical module that correlates the percentage monomer in the gel, percentage cross linker, solvent ionic strength and pH; a mechanical module that employs the output of the chemical module to calculate deformation, taking into consideration experimentally measured elastic and viscoelastic characteristics; an optical module that will incorporate results from the previous modules to yield important optical characteristics (such as focal length and refractive index). It is anticipated that ultimately this model will set the required voltage to produce particular optical characteristics. Using an elastic modulus of 2160 Pa, a Poisson's ratio of 0.33 and experimentally measured gel response force of 0.1 N has resulted in a mechanical module which fully describes the gel motion. This result is promising; however, the mechanical module is currently using elastic properties, whereas viscoelastic properties are ideally needed.

Paxton, Robert A.; Al-Jumaily, Ahmed M.; Ramos, Maximiano V.; Easteal, Allan J.

2004-07-01

351

Coefficients of Effective Length.  

ERIC Educational Resources Information Center

Under certain conditions, a validity Coefficient of Effective Length (CEL) can produce highly misleading results. A modified coefficent is suggested for use when empirical studies indicate that underlying assumptions have been violated. (Author/BW)

Edwards, Roger H.

1981-01-01

352

The finite element modeling and thermal analysis of the special focal plane of LAMOST  

NASA Astrophysics Data System (ADS)

The Large Area Multi-Object Spectroscopic Telescope (LAMOST) is a meridian reflecting Schmidt telescope with a 40m optical axis between the reflecting Schmidt plate and the spherical primary mirror. In the middle is located the spherical focal plane, through which there are corresponding 4000+ unit mounting holes for the fibers, and on its back, there attached a support truss adapted from Serrurier concept. The mechanical stabilization of the focal plane system naturally has magnificent impact on the observation efficiency of the LAMOST. A comprehensive Finite Element Model of the focal plane system has been built to evaluate thermally induced degradation of its mechanical accuracy using the nodal modification technique within ANSYS, and diverse temperature load cases have been considered on the Finite Element model and related thermal analyses have been carried out to investigate thermal deformation of the focal plane. Subsequently the calculated deflection of the working surface has been extracted and reconstructed with least square fitting in MATLAB. The results show that temperature change around the telescope has little effect on the performance of the focal plane within temperature variation requirements of the LAMOST. The methods of modeling and analyzing used in this research are informative for future large telescope projects.

Zuo, Heng; Yang, Dehua; Li, Guoping

2010-07-01

353

Optical coupling  

NASA Astrophysics Data System (ADS)

This paper describes contributions to the CMBpol Technology Study Workshop concerning optical coupling structures. These are structures in or near the focal plane which convert the free space wave to a superconducting microstrip on a SI wafer, or to the waveguide input to a HEMT receiver. In addition to an introduction and conclusions by the editor, this paper includes independent contributions by Bock on 'Planar Antenna-Coupled Bolometers for CMB Polarimetry', by Gunderson and Wollack on 'Millimeter-Wave Platlet Feeds', and by Lee on 'Multi-band Dual-Polarization Lens-coupled Planar Antennas for Bolometric CMB polarimetry.'

Bock, J. J.; Gundersen, J.; Lee, A. T.; Richards, P. L.; Wollack, E.

2009-03-01

354

Length of Stay  

PubMed Central

Five methodologies for predicting hospital length of stay were developed and compared. Two—a subjective Bayesian forecaster and a regression forecaster—also measured the relative importance of the symptomatic and demographic factors in predicting length of stay. The performance of the methodologies was evaluated with several criteria of effectiveness and one of cost. The results should provide encouragement for those interested in computer applications to utilization review and to scheduling inpatient admissions.

Gustafson, David H.

1968-01-01

355

Designing an all-reflective, long focus and large field of view optical system with freeform surface  

NASA Astrophysics Data System (ADS)

All-reflective optical system has been widely used in the deep space detection applications. We studied the application of freeform surface in all-reflective, off-axis optical systems, which have long effective focal length and large field of view, were designed. The freeform surface was employed to achieve better performance, while reduce the system size and weight. The starting point of the design was calculated by using the geometrical optics and properties of conic. After that we optimized the starting point using the strategy of successive approximation optimization method to reduce the design difficulty. Based on the theory of aberration, the best position of freeform surface in the off-axis system was analyzed. At last, two four-mirror optical systems with long EFL and large field of view were designed, the effective focal length are 1.95m and 4.5m, respectively; the field of view for both systems are 3°. The modulation transfer function is close to diffraction limit.

Wang, Qingfeng; Cheng, Dewen; Wang, YongTian; Liu, Yue

2012-11-01

356

The hurdles to long focal length, high altitude stand-off photography  

Microsoft Academic Search

A detailed introduction is given to the problems inherent in the design of high altitude aereal reconnaissance photographic equipment. Among the topics covered are: (1) system need vs. cost analysis; (2) attainability of proposed performance standards; (3) aircraft platform characteristics and availability; (4) the attractiveness of radar as an alternative to photography; (5) natural phenomena affecting photographic quality, such as

F. B. Gorman

1980-01-01

357

Editorial: Redefining Length  

SciTech Connect

Technological changes have moved publishing to electronic-first publication where the print version has been relegated to simply another display mode. Distribution in HTML and EPUB formats, for example, changes the reading environment and reduces the need for strict pagination. Therefore, in an effort to streamline the calculation of length, the APS journals will no longer use the printed page as the determining factor for length. Instead the journals will now use word counts (or word equivalents for tables, figures, and equations) to establish length; for details please see http://publish.aps.org/authors/length-guide. The title, byline, abstract, acknowledgment, and references will not be included in these counts allowing authors the freedom to appropriately credit coworkers, funding sources, and the previous literature, bringing all relevant references to the attention of readers. This new method for determining length will be easier for authors to calculate in advance, and lead to fewer length-associated revisions in proof, yet still retain the quality of concise communication that is a virtue of short papers.

Sprouse, Gene D. [American Physical Society (United States)

2011-07-15

358

Manipulation of doughnut focal spot by image inverting interferometry.  

PubMed

Based on image inverting interference combined with phase modulation, we theoretically demonstrate that the doughnut focal spot can readily be manipulated, and either shrinkage or expansion of size of the central dark spot is possible in a large scale (peak-to-peak value: 0.555?-0.830?, or 93.3%-140.8% compared with the standard one). As the interference and phase modulation can both be achieved by a double Porro prism, it is feasible to introduce this approach into optical tweezers to improve their performance. As much as 33.9% intensity of stimulated emission depletion (STED) beam can be reduced if the further optimized configuration is utilized in STED microscopy. PMID:22378405

Hao, Xiang; Kuang, Cuifang; Li, Yanghui; Liu, Xu

2012-03-01

359

Three-course graduate electro-optics laboratory sequence at the University of Dayton  

NASA Astrophysics Data System (ADS)

The UD Electro-Optics Graduate Program offers the M.S. and Ph.D. degrees. It is an interdisciplinary program between the Electrical and Computer Engineering Department and the Physics Department and is designed for students with a B.S. in either of these fields. In order to strengthen skills in applied optics, optical measurement techniques, photonics and data acquisition and analysis methods, a required three- course laboratory sequence was designed. The first course in the fall term has seven basic optics projects that include focal length measurements, lens systems, radiation detection, polarization, interference, near and far field diffraction, interferometry and coherence. The first half of the second course, given in the summer term, covers fiber optics and fiber optical systems. In the second half, the students propose, design, construct, test and report on an electro-optical/photonics system. The third course in the fall term has five advanced projects on the topics of optical spectroscopy, holography, characterization of lasers, laser Doppler velocimetry and optical pattern recognition. Details on the design of these courses are presented along with examples of student work and the results of student evaluations and responses to the lab program.

Yaney, Perry P.; Duncan, Bradley D.; Little, Gordon R.

2002-05-01

360

Development of a real time MTF test bench for visible optical systems  

NASA Astrophysics Data System (ADS)

A real-time MTF test bench for visible optical systems is presented in this paper. This test bench can perform quick on-axis and off-axis MTF measurement of optical systems whose aperture are less than 200mm in visible wavelength. A high quality off-axis parabolic collimator is used as object generator of this test bench. The image analyzer is a microscopy with CCD camera installed on a multi-axis motion stage. The software of this MTF test bench provides a good interface for the operators to set measurement parameters and control this bench. Validation of this test bench, performed with a 50mm plano-convex audit lens, shows that MTF measurement error of this bench is within 0.04. Besides MTF measurement, this bench can also perform effective focal length (EFL) and back focal length (BFL) without any hardware modification. Transmittance of optical system can also be performed on this bench with an integrating sphere.

Chen, Xinhua; Chen, Yuheng; Fan, Jiming; Xiang, Chunchang; Shen, Weimin

2010-11-01

361

Design of an all-reflective unobscured optical-power zoom objective.  

PubMed

A novel design for an all-reflective unobscured optical-power zoom (OPZ) objective with a zoom factor of 3 is presented. In contrast to OPZ objectives based on liquid lenses, all-reflective objectives use only reflective elements and are therefore free of chromatic aberrations. Thus, they can be used for a wide spectral range or in combination with image sensors that differ in their spectral characteristics. To avoid a decrease in image contrast encountered in on-axis designs with central obscuration, an unobscured off-axis or "Schiefspiegler" approach is adopted. The effective focal length of the objective is changed by two deformable mirrors, each with one actuator only. The simulated final design shows adequate image quality over the whole zooming range. Before starting the complex and cost-intensive development of deformable mirrors with the size, curvature, and dynamic range needed, the optical design should be evaluated first with respect to the practical achievable optical performance. Therefore, optomechanical setups with ultraprecision-manufactured solid mirrors were realized for three different focal lengths. PMID:19623223

Seidl, Kristof; Knobbe, Jens; Grüger, Heinrich

2009-07-20

362

Optical system design for infrared imaging system of Korea Superconducting Tokamak Advanced Research (KSTAR) device  

NASA Astrophysics Data System (ADS)

The first infrared imaging system, for monitoring the temperature of the inner wall and localized hot spot such as the ICRH antenna was installed on the midplane of the D-port in the Korea Superconducting Tokamak Advanced Research (KSTAR). The cassette system of KSTAR makes a periscope inevitable for infrared imaging system. The periscope is composed of a 3 functional optical lens set (input beam shaper, beam deliverer, output beam shaper). CaF2 was chosen for the material of the lens elements. As an infrared image camera, FLIR/ThermoVision SC6000HS is used. The infrared camera has 640 × 512 pixel resolution and a camera lens set with 25.4 mm of focus length and 50 mm of input pupil. The periscope was designed to have 2.7 m of overall length, 19.07 mm of focal length and 3.81 of f-number.

Oh, S.; Seo, D.; KSTAR Team

2012-02-01

363

Adaptive optical probe design for optical coherence tomography and microscopy using tunable optics.  

PubMed

We present a tunable, adaptive optical imaging probe for multimodal imaging such as optical coherence tomography and microscopy. The probe is compatible with forward-looking scanning laser imaging devices such as an endoscope. The lens configuration includes a tunable iris and two varifocal lenses, both driven by microelectrofluidics, as well as several conventional fixed focus lenses. The modulation transfer function and spot size in the focal plane is evaluated, and we show using optical simulations that there are three possible imaging modes with different transverse resolutions and focal depths. PMID:23389140

Choi, Minseog; Lee, Seungwan; Chang, Jong-Hyeon; Lee, Eunsung; Jung, Kyu-Dong; Kim, Woonbae

2013-01-28

364

The impact of domestication on the chicken optical apparatus.  

PubMed

Domestication processes tend to release animals from natural selection and favour traits desired by humans, such as food-production and co-operative behaviour. A side effect of such selective breeding is the alteration of unintended traits. In this paper, we investigate how active selection for egg production in chickens has affected the visual system, in particular the optical sensitivity that relates to the ability of chickens to see in dim light. We measured eye dimensions as well as the pupil diameter at different light intensities (the steady state pupil dynamics), in adult male and female White Leghorns and the closest relatives to their ancestor, the Red Junglefowls. With this information, we calculated the focal length and optical sensitivity (f-number) of the eyes. Males have larger eyes than females in both breeds and White Leghorn eyes are larger than those of Red Junglefowls in both sexes. The steady state pupil dynamics is less variable, however, the combination of pupil dynamics and eye size gives a higher optical sensitivity in Red Junglefowl eyes than in White Leghorns at light intensities below approximately 10 cd/m(2). While eye size and focal length match the larger body size in White Leghorns compared to Red Junglefowls, the steady state pupil dynamics do not. The reason for this is likely to be that eye morphology and the neuro-muscular control of the pupil have been affected differently by the strong selection for egg production and the simultaneous release of the selection pressure for high performing vision. This study is the first description of how optical sensitivity has changed in a domesticated species and our results demonstrate important considerations regarding domestication processes and sensory ability. PMID:23776492

Roth, Lina S V; Lind, Olle

2013-06-12

365

Focal and Non-focal Prospective Memory Performance in Very Mild Dementia: A Signature Decline  

PubMed Central

Objective In a recent study, performance on a certain kind of prospective memory task (PM), labeled focal PM, was sensitive to the very early stages of Alzheimer’s disease (AD; Duchek, Balota, & Cortese, 2006). The present study sought to replicate and extend these findings by investigating both focal and non-focal PM, as well as possible influences of alleles of the apolipoprotein E (APOE) gene. Method Thirty-five healthy older adults and 33 adults in the very earliest stages of AD, as determined by the clinical dementia rating scale, completed both focal and non-focal PM tasks. Performance on these tasks has been linked to qualitatively different cognitive processes (Scullin, McDaniel, Shelton, & Lee, 2010), thereby providing leverage to illuminate the specific processes underlying PM failures in very early AD. Approximately half of the adults in each group were APOE e4 carriers and half were non-carriers. We also obtained participants’ scores on a battery of standard psychometric tests. Results There was a significant interaction between the type of PM task and dementia status, p < .05. ?2p = .12, demonstrating that the AD-related decline was more robust for focal than for non-focal PM. Further, focal PM performance significantly discriminated between the very earliest stages of AD and normal aging, explaining variance unique to that explained by typical psychometric indices. APOE status, however, was not associated with PM performance. Conclusions The pronounced deficit observed in the focal PM task suggests that spontaneous retrieval processes may be compromised in very early AD.

McDaniel, Mark A.; Shelton, Jill Talley; Breneiser, Jennifer E.; Moynan, Sarah; Balota, David A.

2011-01-01

366

LSST Camera Optics Design  

SciTech Connect

The Large Synoptic Survey Telescope (LSST) uses a novel, three-mirror, telescope design feeding a camera system that includes a set of broad-band filters and three refractive corrector lenses to produce a flat field at the focal plane with a wide field of view. Optical design of the camera lenses and filters is integrated in with the optical design of telescope mirrors to optimize performance. We discuss the rationale for the LSST camera optics design, describe the methodology for fabricating, coating, mounting and testing the lenses and filters, and present the results of detailed analyses demonstrating that the camera optics will meet their performance goals.

Riot, V J; Olivier, S; Bauman, B; Pratuch, S; Seppala, L; Gilmore, D; Ku, J; Nordby, M; Foss, M; Antilogus, P; Morgado, N

2012-05-24

367

Adaptation in the optical properties of the crystalline lens in the eyes of the Lessepsian migrant Siganus rivulatus.  

PubMed

Vision is an important source of information for many animals. The crystalline lens plays a central role in the visual pathway and hence the ecology of fishes. In this study, we tested whether the different light regimes in the Mediterranean and Red Seas have an effect on the optical properties of the lenses in the rivulated rabbitfish, Siganus rivulatus. This species has migrated through the Suez Canal from the Red Sea and established a vital population in the Mediterranean Sea. Longitudinal spherical aberration curves and focal lengths of the fish lenses were measured by laser scans and compared between the two populations. In addition, rivulated rabbitfish from the Mediterranean Sea were exposed to colored light (yellow, green and blue) and unfiltered light for periods of 1 or 13 days to test for short-term adjustments. Lens focal length was significantly longer (3%) in the Rea Sea population. The shorter focal length of the Mediterranean population can be explained as an adaptation to the dimmer light environment, as this difference makes the Mediterranean eyes 5% more sensitive than the eyes of the Red Sea population. The difference may be due to genetic differences or, more likely, adaptive developmental plasticity. Short-term regulatory mechanisms do not seem to be involved. PMID:21795569

Gagnon, Yakir L; Shashar, Nadav; Kröger, Ronald H H

2011-08-15

368

Development and testing of an innovative two-arm focal-plane thermal strap (TAFTS)  

NASA Astrophysics Data System (ADS)

Temperature control of optical focal planes comes with the intrinsic challenge of creating a pathway that is both extremely flexible mechanically and highly conductive thermally. The task is further complicated because science-caliber optical focal planes are extremely delicate, yet time, cost, and their unique nature means that their mechanical resiliency is rarely tested and documented. The mechanical engineer tasked with the thermo-mechanical design must then create a highly conductive thermal link that minimizes the tensile and shear stresses transmitted to the focal plane without design parameters on an acceptable stiffness and without data on the stiffness of previously implemented thermal links.This paper describes the development and testing of the thermal link developed for the Portable Remote Imaging Spectrometer (PRISM) instrument. It will provide experimentally determined mechanical stiffness plots in the three axes of interest. Analytical and experimental thermal conductance results for the two-arm focal-plane thermal strap (TAFTS), from cryogenic to room temperatures, are also presented. The paper also briefly describes some elements of the fabrication process followed in developing a novel design solution, which provides high conductance and symmetrical mechanical loading, while providing enhanced flexibility in all three dimensions.

Urquiza, E.; Vasquez, C.; Rodriguez, J.; Van Gorp, B.

2012-04-01

369

Electrophysiological assessment of focal nerve lesions  

Microsoft Academic Search

A technique is described for quantitatively characterizing focal lesions in peripheral nerves. At the lesion site, conduction fails in some fibers and is abnormally delayed in others. The technique computes the fraction of conducting fibers and the distribution of added delays (DAD). Compound action potentials (CAPs) are evoked by stimulating distally and proximally to the lesion. Then, using a model

S. J. Xiao; K. C. McGill; V. R. Hentz

1988-01-01

370

Kinesthesia is impaired in focal dystonia  

Microsoft Academic Search

Parkinson's disease (PD) and focal dystonia (FD) are both predominantly characterized by motor symptoms. Also, recent research has shown that sensory processing is impaired in both movement disorders. FD is characterized by involuntary movements and abnormal limb postures; thus, ab- normal kinesthesia could be involved in the pathogenesis. We examined passive index finger movements in patients with FD (n 12)

Norman Putzki; Philipp Stude; Jürgen Konczak; Karoline Graf; Hans-Christoph Diener; Matthias Maschke

2006-01-01

371

Multiple Molecular Penumbras After Focal Cerebral Ischemia  

Microsoft Academic Search

Though the ischemic penumbra has been classically described on the basis of blood flow and physiologic parameters, a variety of ischemic penumbras can be described in molecular terms. Apoptosis-related genes induced after focal ischemia may contribute to cell death in the core and the selective cell death adjacent to an infarct. The HSP70 heat shock protein is induced in glia

Frank R. Sharp; Aigang Lu; Yang Tang; David E. Millhorn

2000-01-01

372

Noninvasive early detection of focal cerebral ischemia  

Microsoft Academic Search

Describes analyzing somatosensory evoked potentials for detecting cerebral injury in its earlier phases. Cerebral vascular diseases (CVDs) are significant factors in causing morbidity and mortality. Early diagnosis is the key to rapid recovery and improve prognosis. Most CVDs are associated with brain ischemia\\/hypoxia, making ischemic cerebral vascular disease a major concern. A noninvasive technique for early detection of focal brain

Ji-Wu Zhang; Ji-Ren Liu; Chong-Xun Zheng; Wei-Zhong Tao; Nitish V. Thakor; An Xie

2000-01-01

373

Noninvasive detecting the focal cerebral ischemia  

Microsoft Academic Search

This study shows that the time-frequency distribution of the Somatosensory Evoked Potential (SEP) is very sensitive to cerebral ischemia. SD rats are used for animal experiments and a model for SD rat focal ischemic cerebral injury is presented. Then, based on the Discrete Gabor Spectrogram (DGS), SEP signals from the animal experiment are analyzed. Center of power (COP) and weight

Zhang Jiwu; Zheng Chongxun; Tao Weizhon; Xie An; Hao Lei; N. V. Thakor

1997-01-01

374

Microarray Analysis of Focal Segmental Glomerulosclerosis  

Microsoft Academic Search

Background: Focal segmental glomerulosclerosis (FSGS) is a leading cause of chronic renal failure in children. Recent studies have begun to define the molecular pathogenesis of this heterogeneous condition. Here we use oligonucleotide microarrays to obtain a global gene expression profile of kidney biopsy specimens from patients with FSGS in order to better understand the pathogenesis of this disease. Methods: We

Kristopher Schwab; David P. Witte; Bruce J. Aronow; Prasad Devarajan; S. Steven Potter; Larry T. Patterson

2004-01-01

375

Cerebral Microvessel Responses to Focal Ischemia  

Microsoft Academic Search

Cerebral microvessels have a unique ultrastructure form, which allows for the close relationship of the endothelium and blood elements to the neurons they serve, via intervening astrocytes. To focal ischemia, the cerebral microvasculature rapidly displays multiple dynamic responses. Immediate events include breakdown of the primary endothelial cell permeability barrier, with transudation of plasma, expression of endothelial cell-leukocyte adhesion receptors, loss

Gregory J. del Zoppo; Takuma Mabuchi

2003-01-01

376

[Subtle focal diffusion abnormality in the hippocampus].  

PubMed

A 53-year-old female patient presented with sudden onset confusion and disorientation. Further neurological examination was unremarkable and the patient showed a complete recovery after several hours. A magnetic resonance imaging (MRI) examination performed 2 days later revealed a tiny focal lesion in the lateral hippocampus in the diffusion weighted images consistent with transient global amnesia. PMID:22710991

Macht, S; Hellen, F; Wenzel, D; Turowski, B

2012-07-01

377

Variable focal lens controlled by an external voltage: An application of electrowetting  

Microsoft Academic Search

:   We use electrocapillarity in order to change the contact angle of a transparent drop, thus realizing a lens of variable focal\\u000a length (B. Berge, J. Peseux, Patent deposited in Grenoble France, October 8th 1997, num?ro d'enregistrement national 97 12781).\\u000a The key point is the application of gradients of wettability, which control the shape of the drop edge, in our

B. Berge; J. Peseux

2000-01-01

378

Anisoplanatism in Adaptive Optics Using Synthetic Beacons.  

National Technical Information Service (NTIS)

The residual phase structure function of a main laser beam with synthetic beacons is derived. The effects of focal anisoplanatism on the compensation efficiency of adaptive optical system using synthetic beacons are discussed.

Y. Wang

1996-01-01

379

Deriving an estimate for the Fried parameter in mobile optical transmission scenarios.  

PubMed

Measuring the Fried parameter r(0) (atmospheric optical coherence length) in optical link scenarios is crucial to estimate a receiver's telescope performance or to dimension atmospheric mitigation techniques, such as in adaptive optics. The task of measuring r(0) is aggravated in mobile scenarios, when the receiver itself is prone to mechanical vibrations (e.g., when mounted on a moving platform) or when the receiver telescope has to track a fast-moving signal source, such as, in our case, a laser transmitter on board a satellite or aircraft. We have derived a method for estimating r(0) that avoids the influence of angle-of-arrival errors by only using short-term tilt-removed focal intensity speckle patterns. PMID:21221148

Giggenbach, Dirk

2011-01-10

380

Optics for long-range camera modules with QWIP 640x480 detectors  

NASA Astrophysics Data System (ADS)

In airborne applications there is a need for compact long range camera modules to be fitted into gyro-stabilized gimbals. The QWIP 640x480 detector operating in LWIR gives, with its high spatial and thermal resolution, a good performance. For the optics, long range means narrow field of view and long focal length. The challenge is to combine the narrow field of view with two wider fields of view for surveillance and still make it compact. The solution is to fold the optics. This normally gives optics with mounting difficulties, but by keeping the position requirement of each lens element low, the assembly is simplified. Design efforts combined with improved production techniques creates a solution based on diamond turned mirrors, lenses and diffractive elements. Narcissus effects are dealt with by means of customized AR coatings.

Johansson, Stefan A.

2003-09-01

381

Measuring the flatness of focal plane for very large mosaic CCD camera  

NASA Astrophysics Data System (ADS)

Large mosaic multiCCD camera is the key instrument for modern digital sky survey. DECam is an extremely red sensitive 520 Megapixel camera designed for the incoming Dark Energy Survey (DES). It is consist of sixty two 4k2k and twelve 2k2k 250-micron thick fully-depleted CCDs, with a focal plane of 44 cm in diameter and a eld of view of 2.2 square degree. It will be attached to the Blanco 4-meter telescope at CTIO. The DES will cover 5000 square-degrees of the southern galactic cap in 5 color bands (g, r, i, z, Y) in 5 years starting from 2011. To achieve the science goal of constraining the Dark Energy evolution, stringent requirements are laid down for the design of DECam. Among them, the atness of the focal plane needs to be controlled within a 60-micron envelope in order to achieve the specied PSF variation limit. It is very challenging to measure the atness of the focal plane to such precision when it is placed in a high vacuum dewar at 173 K. We developed two image based techniques to measure the atness of the focal plane. By imaging a regular grid of dots on the focal plane, the CCD oset along the optical axis is converted to the variation the grid spacings at dierent positions on the focal plane. After extracting the patterns and comparing the change in spacings, we can measure the atness to high precision. In method 1, the regular dots are kept in high sub micron precision and cover the whole focal plane. In method 2, no high precision for the grid is required. Instead, we use a precise XY stage moves the pattern across the whole focal plane and comparing the variations of the spacing when it is imaged by dierent CCDs. Simulation and real measurements show that the two methods work very well for our purpose, and are in good agreement with the direct optical measurements.

Hao, Jiangang; Estrada, Juan; Cease, Herman; Diehl, H. Thomas; Flaugher, Brenna L.; Kubik, Donna; Kuk, Kevin; Kuropatkine, Nickolai; Lin, Huan; Montes, Jorge; Scarpine, Vic; Schultz, Ken; Wester, William

2010-07-01

382

Fast measurement of photonic stop bands by back focal plane imaging  

NASA Astrophysics Data System (ADS)

Back focal plane imaging microscopy of the autofluorescence of a colloidal photonic crystal at fixed wavelength is used to visualize photonic stop bands. Emission angles of up to 74? against the crystals surface normal are detected. Structure and orientation of the crystal lattice, quality of the ordering, and the influence of defects on the optical properties can be probed at high spatial resolution. Exemplary results reveal domains with four-, six- and threefold symmetry, where the latter dominates, as expected for fcc lattices.

Wagner, Rebecca; Cichos, Frank

2013-04-01

383

Design and performance of a sub-nanoradian resolution Autocollimating optical lever  

NASA Astrophysics Data System (ADS)

Precision goniometry using optics has the advantage that it does not impose much stress on the object of investigation and, as such, is adopted extensively in gravitational wave detection, in torsion balances investigating fundamental forces and in specialized studies of biological samples. It has potential applications in condensed matter physics. We have developed an autocollimating optical lever which has a very high resolution and dynamic range. An array of 110 slits, of 84 micron width and a pitch of 182 microns, is located in the focal plane of a field lens, of focal length 1000 mm, and is illuminated by a CCFL-tube. This array is imaged back on to the focal plane after retro-reflection from a mirror placed just beyond the lens. The image was recorded on a linear CCD array at the rate of 1000 images per second and was processed through a special algorithm to obtain the centroid. The instrument has a centroid stability of ˜ 3.10-10 rad.Hz-1/2 and a dynamic range of ˜ 10^7.

Cowsik, Ramanath; Srinivasan, R.; Kasturirengan, S.; Senthil Kumar, A.; Wagoner, Kasey

2006-04-01

384

Binary Optics Microlens Arrays in CdTe. (Reannouncement with New Availability Information).  

National Technical Information Service (NTIS)

Arrays of miniature focusing optics located at the focal plane can improve the performance of focal plane systems. By more completely collecting the light at the focal plane and concentrating it into a smaller spot size on the detector plane, the photodet...

M. B. Stern W. F. Delaney M. Holz K. P. Kunz K. R. Maschhoff

1991-01-01

385

Sampling by Length.  

ERIC Educational Resources Information Center

Discussion of sampling methods used in information science research focuses on Fussler's method for sampling catalog cards and on sampling by length. Highlights include simple random sampling, sampling with probability equal to size without replacement, sampling with replacement, and examples of estimating the number of books on shelves in certain…

Handley, John C.

1991-01-01

386

Reversible variable length codes  

Microsoft Academic Search

Proposes some reversible variable length codes (RVLCs) which can be decoded instantaneously both in the forward and backward directions and have high transmission efficiency. These codes can be used, for example, in the backward reconstruction of video signals from the data last received when some signal is lost midway in the transmission. Schemes for a symmetrical RVLC requiring only a

Y. Takishima; M. Wada; H. Murakami

1995-01-01

387

Sampling by Length.  

ERIC Educational Resources Information Center

|Discussion of sampling methods used in information science research focuses on Fussler's method for sampling catalog cards and on sampling by length. Highlights include simple random sampling, sampling with probability equal to size without replacement, sampling with replacement, and examples of estimating the number of books on shelves in…

Handley, John C.

1991-01-01

388

Physical Activity Performance of Focal Middle School Students  

ERIC Educational Resources Information Center

|Histograms of push-ups and curl-ups from a sample of more than 9,000 students show periodic spikes at five and 10 unit intervals. This article argues that these spikes are related to focal points, a game theoretic concept popularized by Nobel Laureate Thomas Schelling. Being focal on one test makes one more likely to be focal on the other. Focal

Erfle, Stephen E.; Gelbaugh, Corey M.

2013-01-01

389

Hybrid refractive/diffractive optical system design for light and compact uncooled longwave infrared imager  

NASA Astrophysics Data System (ADS)

Compares with traditional optics,the difractive optical element(DOE) has unique property of minus dispersion.The special state can be used in the optical system to improve performance,lighten weight and reduce volume effectively.In the paper,an infrared optical system with DOE for LWIR thermal imager is proposed.The primary optical parameters of thermal imager are wavelength range 8.0- 12.0?m,effective focal length (EFL) 150 mm,f/numbe 1.0 and field of view 8.58 degrees.The system uses uncooled infrared detector with 320×240 pixels and 45?m pixel size. The f/number matches the sensitivity range of detector array. The infrared optical system is designed by CODE-V optical design software.It is consisted of two lens,the materials of the two lenses are Germanium.The DOE is fabricated on the convex of the first lens and it can be fabricated by diamond turning technology.The imaging quafity of the optical system approached to diffraction limit.The value of modulation transfer function (MTF) at Nyquist frequency(11lp/mm) is great than 0.78.

Wang, Hu; Bai, Yu; Luo, Jianjun

2012-10-01

390

Selecting a high-power fiber-optic laser beam delivery system  

SciTech Connect

Multimode optical fibers enable efficient flexible laser beam delivery but at a loss in the quality of the delivered beam. The fiber-optic beam delivery system effectiveness is strengthened by the optimal selection of its components not only for minimizing beam quality degradation but also for robustness. Smaller fibers tend to produce less degradation to beam quality but the minimum usable fiber size is limited by the quality of the laser beam, focusing optic, and the numerical aperture of the fiber. Selection of appropriate fiber type is important because the characteristics of the output beam enhance or degrade the utility of the fiber-optic-delivered beam for different applications. The other components of the beam delivery system also impact performance. High-power handling requires high- quality fiber end-face finish and special connectors that can withstand back-reflections. Recent developments in optical materials allow manufacture of very low aberration optics useful for short focal length lenses in output optics. Harnessing the power of a high- power laser requires that knowledgeable and prudent choices be made when selecting the laser and its beam delivery system. We will focus on issues relevant to understanding and specifying a fiber-optic beam delivery system and provide guidelines for specifying a system. Data obtained with high power Nd:YAG lasers will be used as examples.

Hunter, B.V. [LightPath Technologies, Inc., Albuquerque, NM (United States); Leong, K.H. [Argonne National Lab., IL (United States); Miller, C.B.; Golden, J.F.; Glesias, R.D.; Laverty, P.J. [U.S. Laser Corp., Wyckoff, NJ (United States)

1996-10-01

391

Acute anticholinergic action in focal dystonia.  

PubMed

We have investigated the effects of the intravenous administration of three anticholinergic drugs (atropine, benztropine, and chlorpheniramine) with variable antihistaminic properties in comparison with saline in adult-onset focal dystonias. In many patients, the severity of the involuntary movements varied from one observation to the next. Patients with spasmodic torticollis, writer's cramp, and segmental dystonia showed little change with any of the active drugs. The occasional individual who improved by more than 20% did so at the expense of drug-induced drowsiness. We conclude that cholinergic mechanisms are not of general importance in the pathogenesis of these conditions. However, the beneficial response to benztropine and chlorpheniramine in two of 20 patients emphasizes the continuing need for a trial-and -error approach in the therapy of these focal dystonias. PMID:6134443

Lang, A E; Sheehy, M P; Marsden, C D

1983-01-01

392

Myxoid adrenal adenoma with focal pseudoglandular pattern.  

PubMed

Adrenal cortical tumors with myxoid change are rare tumors. To our knowledge, only 22 cases have been described so far in literature, which include 13 carcinomas and 9 adenomas. A pseudoglandular pattern has been described in 9 of these tumors. We report a case of a myxoid adenoma of the left adrenal gland in a 67-year-old woman, with a focal pseudoglandular pattern involving about 20% of the studied tumor. Rest of the tumor was composed of anastomosing cords of tumor cells. Abundant myxoid stroma was present, which stained positively with alcian blue and was weakly focally positive with periodic acid Schiff. Immunophenotype was consistent with an adrenal tumor, i.e., positive for vimentin, inhibin, and melan A. Cytokeratin AE1/AE3 and chromogranin were negative. MIB-1 index was < 0.1%. PMID:18579979

De Padua, Michelle; Rajagopal, V

2008-05-01

393

Starbugs: focal plane fiber positioning technology  

NASA Astrophysics Data System (ADS)

We report on the technological achievements of our latest Starbug prototypes and their implications for smart focal plane fiber positioning applications for wide-field astronomy. The Starbugs are innovative self-motile miniature robotic devices that can simultaneously and independently position fibers or payloads over a field plate located at the telescope's focal plane. The Starbugs concept overcomes many of the limitations associated with the traditional 'pick and place' positioners where a robot places fixed buttons onto the field plate. The new Starbug prototypes use piezoelectric actuators and have the following features: (i) new 'lift-and-step' method (discrete step) for accurate positioning over different surfaces; and (ii) operate in an inverted hanging position underneath a transparent field plate, removing the need for fibercable retractors. In this paper, we present aspects of the Starbug prototypes, including the theoretical model, mechanical design, experimental setup, algorithms, performance and applications for astronomical instrumentation.

Goodwin, Michael; Heijmans, Jeroen; Saunders, Ian; Brzeski, Jurek; Saunders, Will; Muller, Rolf; Haynes, Roger; Gilbert, James

2010-07-01

394

Artificial urinary bladder - focal technical challenges  

Microsoft Academic Search

The design of an artificial urinary bladder for the treatment of patients after bladder excision is been challenged by various\\u000a aspects from an engineering point of view. Focal technical challenges are at least that the system has to imitate the functionality\\u000a of the human bladder, it has to be safe, reliable and small in construction size. The materials have to

M. Roth; D. Kirchleitner; D. Jocham; H. Wassermann

395

The Simbol-X focal plane  

Microsoft Academic Search

The Simbol-X focal plane is designed to detect photons focused by the mirror in the 0.5 to 100 keV energy band. Composed of two detectors, it will measure the position, energy, and arrival time of each incoming X-ray. On top of it will be a collimator to shield all photons not coming from the mirror field of view. The whole

P. Laurent; P. Lechner; M. Authier; U. Briel; C. Cara; S. Colonges; P. Ferrando; J. Fontignie; E. Kendziorra; O. Limousin; J. Martignac; A. Meuris; L. Ravera; Y. Rio

2008-01-01

396

Focal cystic endometrial hyperplasia in a bitch.  

PubMed

Rapid abdominal enlargement and weight gain occurred in a four-year-old Rhodesian ridgeback bitch in late oestrus. The bitch was nulliparous. Severe cardiovascular dysfunction followed and an exploratory laparotomy was performed. A large, single, spheroid mass weighting 17 kg was located in the middle section of the left uterine horn. A diagnosis of sterile, focal, cystic endometrial hyperplasia was made from gross pathology, histopathology and bacteriology. The bitch made a complete recovery following an ovariohysterectomy. PMID:7723293

Cockcroft, P D

1995-02-01

397

Crowding in the GAIA spectrograph focal plane  

NASA Astrophysics Data System (ADS)

Superpositions of stellar tracings are present in every slitless spectrograph. The probability for such overlaps in the GAIA RVS spectrograph focal plane is estimated using photometric observations of 66 stellar fields, mostly close to the Galactic plane. It is shown that overlaps of bright stars (V<17) are common near the Galactic plane, and no spectrum is free from superpositions of faint star tracings. Most overlappers are of spectral type K.

Zwitter, T.; Henden, A. A.

398

Technology of large focal planes of CCDs  

Microsoft Academic Search

e2v technologies has demonstrated capability in the supply of state-of-the-art CCDs for large area scientific focal planes. We discuss technical developments and lessons learnt from the manufacture and supply of large-format CCDs. Several large mosaics have now been built or are under construction using e2v sensors - these include CFHT Megacam, ESO VST, SAO Megacam, Kepler, and GAIA. Design, assembly

Paul R Jorden; David G Morris; Peter J Pool

399

Technology of large focal planes of CCDs  

Microsoft Academic Search

e2v technologies has demonstrated capability in the supply of state-of-the-art CCDs for large area scientific focal planes. We discuss technical developments and lessons learnt from the manufacture and supply of large-format CCDs. Several large mosaics have now been built or are under construction, using e2v sensors- these include CFHT Megacam, ESO VST, SAO Megacam, Kepler, and GAIA. Design, assembly and

Paul R. Jorden; David G. Morris; Peter J. Pool

2004-01-01

400

Focal dystonia: The role of botulinum toxin  

Microsoft Academic Search

Botulinum toxin (BTX) has been found to be effective in a wide range of focal dystonias. Debate surrounds the selection of\\u000a injection sites. In general, localization is satisfactory by clinical examination, but poor response, requiring localization\\u000a of deep muscles, may necessitate use of electromyography for localization. Delineation of optimal doses of BTX is a work in\\u000a progress; as studies have

Ron Tintner; Joseph Jankovic

2001-01-01

401

On the Implementation and Calibration of the Focal Plane for GAIA  

NASA Astrophysics Data System (ADS)

We review the focal plane specifications for GAIA, as derived from the measurement principle and payload implementation concept. Design requirements must be tailored to the needs of the mission, taking into account optical performance, detector geometry and electro-optical properties, as well as Time Delay Integration (TDI) operation at the level of both single chip characteristics and overall layout. By optimization of both mosaic manufacturing and in-flight calibration based on the scientific data, we deduce requirements comparable to those of Charge-Coupled Device (CCD) mosaics for modern ground based telescopes

Gai, M.; Busonero, D.

402

Anticholinergics in adult-onset focal dystonia.  

PubMed

Anticholinergics are one of the most common treatments used in adult-onset focal dystonias although their general efficacy has not been proven. We have investigated the effects of intravenous administration of atropine, benztropine and chlorpheniramine, in comparison to normal saline, in 20 patients with adult-onset focal dystonias (spasmodic torticollis (9), cranial dystonia (6), writer's cramp (5), and have retrospectively reviewed the notes of 78 patients (spasmodic torticollis (38), cranial dystonia (25), writer's cramp (15), who had received chronic oral anticholinergic therapy in varying doses at some time in the past. Patients with spasmodic torticollis and writer's cramp showed no consistent change with any of the intravenous drugs, while the few with cranial dystonia who improved usually did so at the expense of drug-induced sedation. The natural variability of these disorders was evident in the response to normal saline, which caused changes in the scores for severity of the involuntary movements of 20% or more in some patients. Only 8 of the patients who had received chronic oral therapy obtained more than mild benefit, and in 3 of them this improvement was transient. We conclude that cholinergic mechanism are not of general or prime importance in the pathogenesis of adult-onset focal dystonias. However, each new patient warrants a trial of chronic oral anticholinergic therapy in view of the occasional useful responses obtained with these drugs. PMID:7116238

Lang, A E; Sheehy, M P; Marsden, C D

1982-08-01

403

Therapeutic targets in focal and segmental glomerulosclerosis  

PubMed Central

Purpose of review Focal and segmental glomerulosclerosis occurs due to a defect in the glomerular filtration barrier. This review highlights contributions from the past year that have enhanced our understanding of the pathophysiology of focal and segmental glomerulosclerosis with emphasis on discoveries which may lead to the identification of therapeutic targets. Recent findings Slit diaphragm proteins have become increasingly important in signal transduction and in mediating downstream events. Actin polymerization occurs after the podocin–nephrin–Neph-1 complex is phosphorylated by Src kinase and Fyn. Recent studies of angiotensin receptor antagonists, corticosteroids and erythropoietin unravel new mechanisms that ameliorate proteinuria by targeting the cell cycle within the podocyte. The discovery that an N-acetylmannosamine kinase (MNK) mutant mouse has glomerulopathy is suggestive that human sialylation pathways may represent therapeutic targets. Proteinuria before podocyte effacement demonstrated in laminin-?2 null mice highlights the importance of the glomerular basement membrane. Interferon-? reduced proteinuria in three models of kidney injury, showing greatest effect on glomerular endothelial cells in vitro. Summary Basic research has illuminated mechanisms by which classic therapies have antiproteinuric effects directly on the podocyte. As knowledge expands with improved molecular techniques, understanding signaling pathways in health and proteinuric states should lead to potential therapeutic targets in focal and segmental glomerulosclerosis.

Lavin, Peter J.; Gbadegesin, Rasheed; Damodaran, Tirupapuliyur V.; Winn, Michelle P.

2009-01-01

404

Critical line length determination  

Microsoft Academic Search

One of the most severe faults for a circuit breaker to interrupt is the short-line fault (SLF). In this paper, digital testing is applied to determine the critical line length, i.e. the short-line fault percentage that stresses the circuit breaker most, for three different circuit breakers. Three arc models have been used for the calculations and three indicators have been

P. H. Schavemaker; L. van der Sluis; A. J. P. de Lange

2000-01-01

405

Optical properties of a nuclear reactor pumped gas laser  

NASA Astrophysics Data System (ADS)

Ray paths and focal lengths are derived to fourth order for a nuclear-reactor wall-pumped gas laser. Ray paths in the laser gain cell are shown to be nearly random for a long gain region. Focal lengths calculated from the ray paths exiting the laser are shown to oscillate between + or - infinity during pumping. The use of stimulated Brillouin scattering as a means for beam clean-up is discussed with the conclusion that the phase conjugated beam would cycle on and off as the ray paths and focal lengths oscillate between extremes. The parameters determining this cycling effect and its characteristics are also derived.

Corvo, A.

1991-01-01

406

Participation of autonomic nerve in tonsillar focal infection.  

PubMed

Participation of the autonomic nerve in tonsillar focal infection was investigated by measuring neurotransmitters, receptors and microvibration. In focal infection patients, the volume of norepinephrine in the tonsil increased significantly and the number of a-adrenergic receptors decreased. These findings suggest that the focally infected tonsil exhibits a high degree of sympathetic nerve activity. The ratio of N-type in microvibration decreased systematically, which indicates some imbalance or immaturity of the autonomic nervous system in focal infection patients. Based on this data, the production mechanism of tonsillar focal infection was speculated from the point of view of the autonomic nerve. PMID:3223255

Yamashita, T; Kozuki, K; Kubo, N; Ishibe, T; Kumazawa, H; Otani, K; Kumazawa, T

1988-01-01

407

Biaxial coherence length in a nematic ?-cell.  

PubMed

In a highly frustrated calamitic nematic phase, the strain can be relaxed by lowering the nematic order: the starting uniaxial symmetry can be broken and it can be replaced locally with transient biaxial domains. Using simple optical retardation measurements, we estimate the length scale over which the biaxial disturbance decays in space within a ?-cell submitted to a weak electric field. We also characterise the transition cascade from the uniaxial splay texture to a bend texture through slow defect motion. PMID:24122278

Hamdi, R; Lombardo, G; de Santo, M P; Barberi, R

2013-10-16

408

Dynamic holographic optical tweezers  

Microsoft Academic Search

Optical trapping is an increasingly important technique for controlling and probing matter at length scales ranging from nanometers to millimeters. This paper describes methods for creating large numbers of high-quality optical traps in arbitrary three-dimensional configurations and for dynamically reconfiguring them under computer control. In addition to forming conventional optical tweezers, these methods also can sculpt the wavefront of each

Jennifer E. Curtis; Brian A. Koss; David G. Grier

2002-01-01

409

Lengthy Relationships: Foot Length, Stride, Leg Length, Height  

NSDL National Science Digital Library

Paleontologists occasionally find ancient tracks and footprints preserved in the rocks. This lesson opens the door to analysing those footprints, and gleaning information about body size and activities of the extinct animals that made the tracks. Students will learn that patterns can reveal much about the past, in light of the present; and that bipedalism has appeared several times. Relationships will be found between foot length and leg length; foot length and height; leg length and height; stride length and leg length; and stride length and speed.

Johnson, Jennifer

410

Focal Ca2+ transient detection in smooth muscle.  

PubMed

Ca2+ imaging of smooth muscle provides insight into cellular mechanisms that may not result in changes of membrane potential, such as the release of Ca2+ from internal stores, and allows multiple cells to be monitored simultaneously to assess, for example, coupling in syncytial tissue. Subcellular Ca2+ transients are common in smooth muscle, yet are difficult to measure accurately because of the problems caused by their stochastic occurrence, over an often wide field of view, in an organ that it prone to contract. To overcome this problem, we've developed a series of imaging protocols and analysis routines to acquire and then analyse, in an automated fashion, the frequency, location and amplitude of such events. While this approach may be applied in other contexts, our own work involves the detection of local purinergic Ca2+ transients for locating transmitter release with submicron resolution. ATP is released as a cotransmitter from autonomic nerves, where it binds to P2X1 receptors on the smooth muscle of the detrusor and vas deferens. Ca2+ enters the smooth muscle, resulting in purinergic neuroeffector Ca2+ transients (NCTs). The focal Ca2+ transients allow the optical monitoring of neurotransmitter release in a manner that has many advantages over electrophysiology. Apart from the greatly improved spatial resolution, optical recording has the additional advantage of allowing the recording of transmitter release from many distinguishable sites simultaneously. Furthermore, the optical plane of focus is easier to maintain or correct during long recording series than is the repositioning of an intracellular sharp microelectrode. In summary, a method for imaging of Ca2+ fluorescence is outlined which details the preparation of tissue, and the acquisition and analysis of data. We outline the use of several scripts for the analysis of such Ca2+ transients. PMID:19564842

Young, John S; Amos, Robert J; Brain, Keith L

2009-06-29

411

Focal Ca2+ Transient Detection in Smooth Muscle  

PubMed Central

Ca2+ imaging of smooth muscle provides insight into cellular mechanisms that may not result in changes of membrane potential, such as the release of Ca2+ from internal stores, and allows multiple cells to be monitored simultaneously to assess, for example, coupling in syncytial tissue. Subcellular Ca2+ transients are common in smooth muscle, yet are difficult to measure accurately because of the problems caused by their stochastic occurrence, over an often wide field of view, in an organ that it prone to contract. To overcome this problem, we've developed a series of imaging protocols and analysis routines to acquire and then analyse, in an automated fashion, the frequency, location and amplitude of such events. While this approach may be applied in other contexts, our own work involves the detection of local purinergic Ca2+ transients for locating transmitter release with submicron resolution. ATP is released as a cotransmitter from autonomic nerves, where it binds to P2X1 receptors on the smooth muscle of the detrusor and vas deferens. Ca2+ enters the smooth muscle, resulting in purinergic neuroeffector Ca2+ transients (NCTs). The focal Ca2+ transients allow the optical monitoring of neurotransmitter release in a manner that has many advantages over electrophysiology. Apart from the greatly improved spatial resolution, optical recording has the additional advantage of allowing the recording of transmitter release from many distinguishable sites simultaneously. Furthermore, the optical plane of focus is easier to maintain or correct during long recording series than is the repositioning of an intracellular sharp microelectrode. In summary, a method for imaging of Ca2+ fluorescence is outlined which details the preparation of tissue, and the acquisition and analysis of data. We outline the use of several scripts for the analysis of such Ca2+ transients.

Young, John S.; Amos, Robert J.; Brain, Keith L.

2009-01-01

412

Optics, illumination, and image sensing for machine vision III; Proceedings of the Meeting, Cambridge, MA, Nov. 8, 9, 1988  

SciTech Connect

Various papers on optics, illumination, and image sensing for machine vision are presented. Some of the optics discussed include: illumination and imaging of moving objects, strobe illumination systems for machine vision, optical collision timer, new electrooptical coordinate measurement system, flexible and piezoresistive touch sensing array, selection of cameras for machine vision, custom fixed-focal length versus zoom lenses, performance of optimal phase-only filters, minimum variance SDF design using adaptive algorithms, Ho-Kashyap associative processors, component spaces for invariant pattern recognition, grid labeling using a marked grid, illumination-based model of stochastic textures, color-encoded moire contouring, noise measurement and suppression in active 3-D laser-based imaging systems, structural stereo matching of Laplacian-of-Gaussian contour segments for 3D perception, earth surface recovery from remotely sensed images, and shape from Lambertian photometric flow fields.

Svetkoff, D.J.

1989-01-01

413

Dynamics of similariton pulses in length-inhomogeneous active fibres  

SciTech Connect

The possibility of producing self-similar frequency-modulated (FM) optical wave packets in length-inhomogeneous active fibres is studied for optical pulses with the initial Gaussian, hyperbolic-secant or parabolic shape. The conditions for converting these pulses into stable parabolic-type pulses with a constant frequency-modulation rate are considered. It is shown that the use of FM pulses of parabolic shape in active and length-inhomogeneous fibres can ensure the creation of an all-fibre generator-amplifier-compressor system with peak powers up to 1 MW and higher in the generated pulses. (nonlinear optical phenomena)

Zolotovskii, Igor' O; Sementsov, Dmitrii I; Yavtushenko, M S [Ulyanovsk State University, Ulyanovsk (Russian Federation); Senatorov, A K; Sysolyatin, A A [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2010-05-26

414

Wound complications and stitch length  

Microsoft Academic Search

The effect of suturing with a very short stitch on the development of wound complications in midline incisions was investigated. Three hundred sixty-eight patients were analysed. The suture length to wound length ratio and mean stitch length were calculated. Wound infection occurred in 4% (four of 103) of patients sutured with a mean stitch length of less than 4 cm, in

D. Millbourn; L. A. Israelsson

2004-01-01

415

Effects of thermal deformations on the sensitivity of optical systems for space application  

NASA Astrophysics Data System (ADS)

In this paper the results of the thermo-elastic analysis performed on the Stereo Imaging Channel of the imaging system SIMBIO-SYS for the BepiColombo ESA mission to Mercury is presented. The aim of the work is to determine the expected stereo reconstruction accuracy of the surface of the planet Mercury, i.e. the target of BepiColombo mission, due to the effects of the optics misalignments and deformations induced by temperature changes during the mission lifetime. The camera optics and their mountings are modeled and processed by a thermo-mechanical Finite Element Model (FEM) program, which reproduces the expected optics and structure thermo-elastic variations in the instrument foreseen operative temperature range, i.e. between -20 °C and 30 °C. The FEM outputs are elaborated using a MATLAB optimization routine: a non-linear least square algorithm is adopted to determine the surface equation (plane, spherical, nth polynomial) which best fits the deformed optical surfaces. The obtained surfaces are then directly imported into ZEMAX raytracing code for sequential raytrace analysis. Variations of the optical center position, boresight direction, focal length and distortion are then computed together with the corresponding image shift on the detector. The overall analysis shows the preferable use of kinematic constraints, instead of glue classical solution, for optical element mountings, this minimize the uncertainty on the Mercury Digital Terrain Model (DTM) reconstructed via a stereo-vision algorithm based on the triangulation from two optical channels.

Segato, Elisa; da Deppo, Vania; Debei, Stefano; Cremonese, Gabriele; Cherubini, Giovanni

2010-07-01

416

Test validated alignment and stability performance of the JMAPS program focal plane array assembly in a cryogenic vacuum environment  

NASA Astrophysics Data System (ADS)

Focal Plane Arrays (FPA) consisting of multiple Sensor Chip Assemblies (SCA) in a precision aligned mosaic are being increasingly used in optical instruments requiring large format detectors. The Joint Milli-Arcsecond Pathfinder Survey Mission (JMAPS) requires very precise positional alignment and stability of its 2 x 2 SCA mosaic at operational temperatures to meet its precision sky mapping mission requirements. Key performance requirements include: detector active area co-planarity, in-plane alignment, and thermal stability. This paper presents an overview of the JMAPS Focal Plane Array Assembly, its alignment and thermal-mechanical stability requirements, and associated test-validated performance in a cryogenic vacuum environment.

Thompson, Brian C.; Sevilla, Pedro; Watson, Mike; Newswander, Trent; Miles, Duane; Peterson, James

2013-09-01

417

Characterization of DECam focal plane detectors  

SciTech Connect

DECam is a 520 Mpix, 3 square-deg FOV imager being built for the Blanco 4m Telescope at CTIO. This facility instrument will be used for the 'Dark Energy Survey' of the southern galactic cap. DECam has chosen 250 ?m thick CCDs, developed at LBNL, with good QE in the near IR for the focal plane. In this work we present the characterization of these detectors done by the DES team, and compare it to the DECam technical requirements. The results demonstrate that the detectors satisfy the needs for instrument.

Diehl, H.Thomas; Angstadt, Robert; Campa, Julia; Cease, Herman; Derylo, Greg; Emes, John H.; Estrada, Juan; Kibik, Donna; Flaugher, Brenna L.; Holland, Steve E.; Jonas, Michelle; /Fermilab /Madrid, CIEMAT /LBL, Berkeley /Argonne /Pennsylvania U.

2008-06-01

418

Modeling brain adaptation to focal damage.  

PubMed Central

Determining how feature maps in the cerebral cortex adapt to sudden, focal damage is important for gaining a deeper understanding of neurological illnesses such as stroke. In this paper we describe a neural model of the region of primary sensory cortex related to upper extremity proprioception, and show how the feature map there reorganizes following a simulated lesion. A perilesion zone with decreased activity appears and then gradually expands with time. These results differ from those seen with previous models of cortical lesions, and offer an alternative mechanism to the "ischemic penumbra" seen in certain types of stroke.

Goodall, S.; Reggia, J. A.; Cho, S.

1994-01-01

419

Limits for Reduction of Effective Focal Volume in Multiple-Beam Light Microscopy  

PubMed Central

Recently developed microscopy techniques, such as 4Pi, break the Abbe diffraction limit and allow for imaging at unprecedented resolution. The effective focal volume is also reduced, leading to more sensitive measurements in fluorescence microphotolysis or correlation spectroscopy. In 4Pi microscopy, the improvement is due to the utilization of two interfering laser beams for illumination, rather than a single one as in conventional microscopy. We study theoretically the possibility of further reduction of the focal volume with employment of three or more interfering beams, including the limiting case of an inifinite number of beams. The volume is indeed reduced, but reaches a limit quickly as beams are added. The volume obtained in the setups with three or four beams is about half of that in the 4Pi case and is close to the volume computed for the limit of an infinite number of beams. The setups suggested employ purely optical principles, and, thus, the considered limiting case arguably represents the maximal reduction in focal volume possible for a purely optical far-field setup.

Arkhipov, Anton; Schulten, Klaus

2011-01-01

420

PtSi Schottky-barrier infrared focal plane array for ASTER/SWIR  

NASA Astrophysics Data System (ADS)

A PtSi Schottky-barrier infrared focal plane array (FPA) has been developed for the short wavelength infrared radiometer (SWIR) of the advanced spaceborne thermal emission and reflection radiometer (ASTER). Six linear image sensors, which correspond to six observation bands, are integrated on the FPA to simplify the cooling system and the optics. Each linear sensor has a stagger layout of 2100 PtSi Schottky-barrier detectors and has an effective fill factor of 100%. The detector size is 20 micrometers by 17 micrometers with a cross-track pitch of 16.5 micrometers and a spacing between adjacent sensors of 1.33 mm. The charge transfer in each linear sensor is carried out by two 4-phase buried-channel CCD shift registers. The driving clock and structure of the CCD are optimized to achieve a large charge handling capacity and low transfer inefficiency. To assure a high reliability and a focal plane flatness, we have developed an original multilayer ceramic package with a filter holding structure. A focal plane flatness less than 14 micrometers and a heat shock endurance over 4000 cycles are achieved by using this packaging technology. The wavelength region between 1.5 micrometers and 2.5 micrometers is separated into six bands by optical band-pass filters attached to the package.

Ueno, Masashi; Shiraishi, Tadashi; Kawai, Makoto; Yoneda, Yoshikazu; Kimata, Masafumi; Nunoshita, Masahiro

1995-09-01

421

Design of apochromatic telescopic optical system based on PWC method  

NASA Astrophysics Data System (ADS)

According to technical requirements,an apochromatic telescopic optical system which is characterized by the focal length 1.5m~2m,with the visible region spectrum band is needed.The successful design consists in using normal glasses based on PWC method to get a completely secondary-spectrum-removed and cramped construction telescopic optical system in this paper.Firstly, by the aberration theory and ZEMAX optical design software,a catadioptric achromatic optical system composed of a reflecting mirror and a couple of air-spaced negative doublets are designed.The initial configuration of optical system is calculated by PWC method and the proper couple of air-spaced negative doublets are chosen by the theory of achromatic.By comparing with various optical systems with different couple of air-spaced negative doublets, it is found that the combination of the heavy crown glass ZK7 and heavy flint glass ZF3 is effective to correct chromatic aberration and its secondary spectrum value is minimality.It can conclude that fact with the abbe number of ZK7 is twice than ZF3 make the good result and give guiding to the design of the same type of optical system. Secondary,according to the theory of secondary spectrum,the secondary spectrum value to be corrected is analyzed and the compensation can be changed by adjust the magnification power.The comparison is presented and the final telescopic optical system with cramped construction is achieved, and the goal of apochromatism and other aberration is reached.

Wei, Xiao-Xiao; Xu, Feng; Yu, Jian-Jun

2011-11-01

422

Exact optics: a unification of optical telescope design  

Microsoft Academic Search

A perfect-focus telescope is one in which all rays parallel to the axis meet at a point and give equal magnification there. It is shown that these two conditions define the shapes of both primary and secondary mirrors. Apart from scale, the solution depends upon two parameters: s, which gives the mirror separation in terms of the effective focal length,

D. Lynden-Bell

2002-01-01

423

Influence of axial length on IOL constants.  

PubMed

In IOL formulas, the lens itself is represented by specific constants. Usually, these are given by the manufacturers as averages that need customization to allow for individual measurement setups. Apart from the instrumentation, patient characteristics such as axial length distribution may influence IOL constants, as demonstrated in this study. The effect of axial length on different IOL constants was studied on model calculations in theoretical ametropic eyes derived from the standard Gullstrand eye as well as in clinical results obtained for different surgical centers within the ULIB project in optical biometry. The model calculations showed definite dependence of IOL constants of different formulas on axial length, which was strongest for the SRK II A-constant. Clinical results are in good qualitative and quantitative agreement with SRK/T A-constants varying within 0.4 D for axial length averages of 23.2 to 24.2 mm. Even if the same instrumentation is used, different IOL constants may be necessary due to different axial length means in the respective patient populations. Thus, for best refractive results, constant individualization should be done at the surgeon level. Published constants like ULIB constants are nevertheless a good starting point. PMID:23431726

Haigis, Wolfgang

2012-12-01

424

Advanced optical tweezers for the study of cellular and molecular biomechanics  

Microsoft Academic Search

Optical tweezers are an important tool for studying cellular and molecular biomechanics. We present a robust optical tweezers device with advanced features including: multiple optical traps, acousto-optic trap steering, and back focal plane interferometry position detection. We integrate these features into an upright microscope, with no compromise to its capabilities (differential interference contrast microscopy (DIC), fluorescence microscopy, etc.). Acousto-optic deflectors

Gary J. Brouhard; Henry T. Schek; Alan J. Hunt

2003-01-01

425

Activation of pyk2\\/Related Focal Adhesion Tyrosine Kinase and Focal Adhesion Kinase in Cardiac Remodeling  

Microsoft Academic Search

Cellular remodeling during progression of dilation in- volves focal adhesion contact reorganization. However, the signaling mechanisms and structural consequences leading to impaired cardiomyocyte adhesion are poorly defined. These events were studied in tropomodulin- overexpressing transgenic mice that develop dilated cardiomyopathy associated with chronic elevation of in- tracellular calcium. Analysis of tropomodulin-overex- pressing transgenic hearts by immunoblot and confocal microscopy revealed

Jaime Melendez; Sara Welch; Erik Schaefer; Christine S. Moravec; Shalom Avraham; Hava Avraham; Mark A. Sussman

2002-01-01

426

Euclid ENIS spectrograph focal-plane design  

NASA Astrophysics Data System (ADS)

The ENIS wide-field spectrograph is part of the instrument package on board of the European space mission Euclid devoted to map the dark universe and proposed for launch in 2017. ENIS will operate in the near-IR spectral region (0.8-2 ?m) and will provide in 4-5 years an accurate and extremely large survey of cosmological redshifts. The instrument focal-plane is based on a combination of state of the art detectors light fed by a slitless spectrograph allowing coverage and analysis of a high number of targets per cycle. During the feasibility study a spectrograph option based on Digital Micromirror Device (DMD) programmable slits, allowing a significant increase in instrumental sensitivity and accuracy, has also been examined. ENIS has been recently (Feb this year) pre-selected for a phase-A study within a group of three medium class missions; final selection is foreseen for the end of next year after a new phase of instrument revision. A description of the work done during the feasibility-study phase for the ENIS focal-plane is here presented.

Bortoletto, Favio; Bonoli, Carlotta; D'Alessandro, Maurizio; Giro, Enrico; de Caprio, Vincenzo; Corcione, Leonardo; Ligori, Sebastiano; Morgante, Gianluca

2010-07-01

427

Fabrication of wavefront sensor microlens array and atmospheric turbulence generator for adaptive optics of a telescope  

NASA Astrophysics Data System (ADS)

Nalux has developed a unique 3D nanometric fabrication technology in several years. Unlike conventional diamond turning machines that are restricted to symmetric components, this device is capable of cutting any free-form surface which can be specified by a xyz coordinate map. This 3D nanometric fabrication technology includes CAD/CAM, ultra-precision machining using single crystal diamond, and high precise shape evaluation. The capabilities of the technology are demonstrated in this paper. We have succeeded in fabricating two unique optical components used in an adaptive optics system at the Subaru 8.2 m Telescope of National Astronomical Observatory of Japan. The first component is a microlens array that is used in the wavefront curvature sensor. This 37- element array has the individual lens elements distributed in a nonrectangular pie pattern, with very tight tolerances on focal point, focal length, lens shape, and the radius of each lens. The second component is an atmospheric phase plate that generates the atmospheric phase aberrations. This component requires a prescribed random surface yet requires a high degree of smoothness. This component is used to test adaptive optic systems.

Kitagawa, Seiichiro; Kotani, Yoichi; Kubo, Junichi; Owari, Hiroshi

1999-03-01

428

Significance of microtubule catastrophes at focal adhesion sites  

PubMed Central

Directional cell migration requires cell polarization and asymmetric distribution of cell signaling. Focal adhesions and microtubules are two systems which are essential for these. It was shown that these two systems closely interact with each other. It is known that microtubule targeting stimulates focal adhesion dissociation. Our recent study shows that focal adhesions, in turn, specifically induce microtubule catastrophe via a biochemical mechanism. We were able to track down one of the focal adhesion proteins paxillin which is involved in this process. Paxillin phosphorylation was previously shown to be the key component in the regulation of focal adhesion assembly or disassembly. Since microtubule catastrophe dynamic differs at the leading edge and cell rear, similar to paxillin phosphorylation levels, we suggest a model connecting asymmetric distribution of focal adhesions and asymmetric distribution of microtubule catastrophes at adhesion sites as a feedback loop.

Kaverina, I

2009-01-01

429

Role and significance of focal adhesion proteins in hepatocellular carcinoma.  

PubMed

Focal adhesions are structural links between the extracellular matrix and actin cytoskeleton. They are important sites where dynamic alterations of proteins in the focal contacts are involved during cell movement. Focal adhesions are composed of diverse molecules, for instance, receptors, structural proteins, adaptors, GTPase, kinases and phosphatases. These molecules play critical roles in normal physiological events such as cellular adhesion, movement, cytoskeletal structure and intracellular signaling pathways. In cancers, aberrant expression and altered functions of focal adhesion proteins contribute to adverse tumor behavior. It is evident that these proteins do not function alone, but rather associate and work together in the process of tumor development and cancer metastasis. Focal adhesion proteins have been shown to play critical roles in hepatocellular carcinoma. Understanding the molecular interactions and mechanisms of the interconnected focal adhesion proteins is of particular importance in understanding mechanisms underlying hepatocellular carcinoma progression and development of potential effective treatment. PMID:19368632

Yam, Judy Wai Ping; Tse, Edith Yuk Ting; Ng, Irene Oi-Lin

2009-04-01

430

First-order design of a reflective viewfinder for adaptive optics ophthalmoscopy.  

PubMed

Adaptive optics (AO) ophthalmoscopes with small fields of view have limited clinical utility. We propose to address this problem in reflective instruments by incorporating a viewfinder pupil relay designed by considering pupil and image centering and conjugation. Diverting light from an existing pupil optical relay to the viewfinder relay allows switching field of view size. Design methods that meet all four centering and conjugation conditions using either a single concave mirror or with two concave mirrors forming an off-axis afocal telescope are presented. Two different methods for calculating the focal length and orientation of the concave mirrors in the afocal viewfinder relay are introduced. Finally, a 2.2 × viewfinder mode is demonstrated in an AO scanning light ophthalmoscope. PMID:23187514

Dubra, Alfredo; Sulai, Yusufu N

2012-11-19

431

New abnormal dispersion liquid for use in the design of high-performance optical systems  

NASA Astrophysics Data System (ADS)

The requirements for superior polychromatic optical performance, low cost, and thermal stability have guided the search at Lockheed for abnormal dispersion optical liquids to be used in combinations with inexpensive, normal dispersion glass in a new generation of lens designs. Our research suggests that an optimal liquid would combine the properties of very high abnormality and dispersion with high viscosity and a low freezing point. A liquid with these properties has recently been developed and its identity and characteristics will be reported. The performance benefits of using this new liquid are then explored through the design of a very high performance F/2.8, 300 mm focal length, telephoto lens for 35 mm cameras.

Sigler, Robert D.

1993-12-01

432

Adaptive optics technique to overcome the turbulence in a large-aperture collimator.  

PubMed

A collimator with a long focal length and large aperture is a very important apparatus for testing large-aperture optical systems. But it suffers from internal air turbulence, which may limit its performance and reduce the testing accuracy. To overcome this problem, an adaptive optics system is introduced to compensate for the turbulence. This system includes a liquid crystal on silicon device as a wavefront corrector and a Shack-Hartmann wavefront sensor. After correction, we can get a plane wavefront with rms of about 0.017 lambda (lambda=0.6328 microm) emitted out of a larger than 500 mm diameter aperture. The whole system reaches diffraction-limited resolution. PMID:18709077

Mu, Quanquan; Cao, Zhaoliang; Li, Dayu; Hu, Lifa; Xuan, Li

2008-03-20

433

Hollow fiber optic probe for in vivo Raman measurement  

NASA Astrophysics Data System (ADS)

A hollow optical fiber Raman probe equipped with a ball lens is developed to study the stomach cancer. The probe generates little Raman scattering or fluorescence noise because the HOF confine light into the air core. In order to maximize the collection efficiency and the spatial resolution, material and size of the ball lens is optimized. The total diameter of the probe head is 0.64 mm. The probe is useful for measurement of layered sample by the contact mode because it has very short focal length and high depth resolution. In vivo experiments in a stomach of a living rat demonstrate the high viability of the probe for noninvasive diagnosis of the stomach cancer.

Katagiri, Takashi; Hattori, Yusuke; Komachi, Yuichi; Matsuura, Yuji; Tashiro, Hideo; Sato, Hidetoshi

2006-10-01

434

Factory acceptance test results for the DIRSP projection optics  

NASA Astrophysics Data System (ADS)

The Factory Acceptance Test (FAT) results for the projection optical subsystem (POS) of US Army STIRCOM's dynamic infrared scene projector (DIRSP) are presented in this paper. DIRSP is a low background (-35 degrees Celsius) hardware-in-the- loop (HWIL), long-wave infrared (LWIR) scene projector built by Mission Research Corporation (MRC) for use by the Redstone Technical Test Center (RTTC). It has an effective emitter array size of 1632 X 672 suspended-membrane micro-resistor elements. The POS is responsible for generating this effective array size from three smaller arrays using a mosaic image combiner, adding background light from an external blackbody, and collimating the combined radiation with a 5:1 vacuum enclosed -35 degree Celsius zoom lens. The FAT results reported demonstrate good POS performance compared to the design for focal length, F/#, MTF and apparent temperature.

Thomas, Matthew C.; Ward, Craig S.

2000-07-01

435

Feature tracking linear optic flow sensor chip  

Microsoft Academic Search

This paper presents a VLSI-friendly linear optic flow sensor capable of being implemented on a single chip. This sensor belongs to the “token method” class of optic flow sensors: motion is measured by tracing the movement of a “token” or a feature across the focal plane. Specially shaped photoreceptor circuits and simple analog circuitry implement an array of feature detectors

K. T. Miller; G. L. Borrows

1999-01-01

436

Optical processing for 3D digital imaging  

Microsoft Academic Search

Conventional optical imaging systems perform both information sensing and image formation functions. The optical system is generally designed to implement processing for image formation with a goal of optimizing analog image quality measures. Digital image involves a fundamental paradigm shift in which the “image” is no longer synonymous with the focal plane field distribution. A digital system may be designed

D. J. Brady

2000-01-01

437

Segmented mirror phasing using the focal-plane intensity.  

PubMed

We develop a method for subaperture piston phase retrieval in a telescope using a segmented primary mirror. We assume that the mirror subapertures are arranged on a two-dimensional lattice, and in addition, the separate subaperture point-spread functions are focused and overlapped on the focal plane. Therefore, the residual errors are the subaperture piston phase errors, represented as a phasor, a unit modulus complex number, for each subaperture. Under these conditions, we find considerable simplicity in the calculated optical transfer function (OTF) at special subaperture lattice spatial frequencies. We then construct a phasor-based error function based on the modulus squared of the difference between the measured OTF and the calculated OTF. The remaining steps in our piston phase retrieval algorithms are developed by calculating the error-function variation, with respect to each phasor element. The resulting equations for the error gradient are then used iteratively, in a phasor-based algorithm, to find the minimum of the error function. In the applications, we simulate photon-noise-limited piston retrieval for a segmented primary with 18 hexagonal subapertures. When we invoke phase diversity, the piston retrievals prove unique and accurate. PMID:22270655

Dente, Gregory C; Tilton, Michael L

2012-01-20

438

Kalman filtering techniques for focal plane electric field estimation.  

PubMed

For a coronagraph to detect faint exoplanets, it will require focal plane wavefront control techniques to continue reaching smaller angular separations and higher contrast levels. These correction algorithms are iterative and the control methods need an estimate of the electric field at the science camera, which requires nearly all of the images taken for the correction. The best way to make such algorithms the least disruptive to science exposures is to reduce the number required to estimate the field. We demonstrate a Kalman filter estimator that uses prior knowledge to create the estimate of the electric field, dramatically reducing the number of exposures required to estimate the image plane electric field while stabilizing the suppression against poor signal-to-noise. In addition to a significant reduction in exposures, we discuss the relative merit of this algorithm to estimation schemes that do not incorporate prior state estimate history, particularly in regard to estimate error and covariance. Ultimately the filter will lead to an adaptive algorithm which can estimate physical parameters in the laboratory for robustness to variance in the optical train. PMID:23456009

Groff, Tyler D; Jeremy Kasdin, N

2013-01-01

439

Botulinum Toxin Physiology in Focal Hand and Cranial Dystonia  

PubMed Central

The safety and efficacy of botulinum toxin for the treatment of focal hand and cranial dystonias are well-established. Studies of these adult-onset focal dystonias reveal both shared features, such as the dystonic phenotype of muscle hyperactivity and overflow muscle contraction and divergent features, such as task specificity in focal hand dystonia which is not a common feature of cranial dystonia. The physiologic effects of botulinum toxin in these 2 disorders also show both similarities and differences. This paper compares and contrasts the physiology of focal hand and cranial dystonias and of botulinum toxin in the management of these disorders.

Karp, Barbara Illowsky

2012-01-01

440

Focal therapy for prostate cancer: rationale and treatment opportunities.  

PubMed

Focal therapy is an emerging treatment modality for localised prostate cancer that aims to reduce the morbidity seen with radical therapy, while maintaining cancer control. Focal therapy treatment strategies minimise damage to non-cancerous tissue, with priority given to the sparing of key structures such as the neurovascular bundles, external sphincter, bladder neck and rectum. There are a number of ablative technologies that can deliver energy to destroy cancer cells as part of a focal therapy strategy. The most widely investigated are cryotherapy and high-intensity focussed ultrasound. Existing radical therapies, such as brachytherapy and external beam radiotherapy, also have the potential to be applied in a focal manner. The functional outcomes of focal therapy from several phase I and II trials have been encouraging, with low rates of urinary incontinence and erectile dysfunction. Robust medium- and long-term cancer control outcomes are currently lacking. Controversies in focal therapy remain, notably treatment paradigms based on the index lesion hypothesis, appropriate patient selection for focal therapy and how the efficacy of focal therapy should be assessed. This review articles discusses the current status of focal therapy, highlighting controversies and emerging strategies that can influence treatment outcomes for the future. PMID:23759249

Kasivisvanathan, V; Emberton, M; Ahmed, H U

2013-06-04

441

Imaging with extended focal depth by means of lenses with radial and angular modulation  

NASA Astrophysics Data System (ADS)

The paper presents imaging properties of modified lenses with the radial and the angular modulation. We analyze three following optical elements with moderate numerical apertures: the forward logarithmic axicon and the axilens representing the radial modulation as well as the light sword optical element being a counterpart of the axilens with the angular modulation. The abilities of the elements for imaging with extended depth of focus are discussed in detail with the help of structures of output images and modulation transfer functions corresponding to them. According to the obtained results only the angular modulation of the lens makes possible to maintain the acceptable resolution, contrast and brightness of the output images for a wide range of defocusing. Therefore optical elements with angular modulations and moderate numerical apertures seem to be especially suitable for imaging with extended focal depth.

Mikula, G.; Jaroszewicz, Z.; Kolodziejczyk, A.; Petelczyc, K.; Sypek, M.

2007-07-01

442

Design of optical system for autonomous APS star sensors  

NASA Astrophysics Data System (ADS)

The modern spacecrafts harassed by the "lost-in-space" problem frequently desire for retrieving their orientations autonomously while performing missions especially in deep space. Star sensor becomes a preferred assistant which determines the attitudes with very high accuracy. Autonomous APS star sensors have been the development trends in virtue of their lighter weight, smaller size, less power, and the ability to acquire attitude knowledge autonomously. By analyzing the principle of attitude measurement applying star identification algorithm, the requirements for the aberration correction and imaging quality of their optical systems are discussed. The statistics of star numbers in different orientations is analyzed making use of guide star catalogs established with various limiting star magnitudes and fields of view (FOV). The method to determine parameters of the optical system including aperture size, FOV, focal length and spectrum range is introduced. These parameters meeting the demand of the Pyramid identification algorithm utilized in this paper to realize the autonomous attitude reorganization in any orientations are calculated. Accordingly, a star camera is designed with STAR 1000 APS as its detector. Its focal length, aperture diameter and circular field of view are 43.56mm, 27.3mm and 20 degrees, respectively. Structure selection and aberration correction schemes are presented. Aberrations including coma, astigmatism, and distortion and lateral color are corrected, and spherical aberration and longitudinal color are controlled. This camera is telecentric in the image field which assures that the star identification is still valid even though the image plane suffers from a deviation as a result of the environmental alteration and manufacture errors.

Wu, Feng; Shen, Weimin

2009-11-01

443

Design of large aperture focal plane shutter  

NASA Astrophysics Data System (ADS)

To satisfy the requirement of large telescope, a large aperture focal plane shutter with aperture size of ?200mm was researched and designed to realize, which could be started and stopped in a relative short time with precise position, and also the blades could open and close at the same time at any orientation. Timing-belts and stepper motors were adopted as the drive mechanism. Velocity and position of the stepper motors were controlled by the PWM pulse generated by DSP. Exponential curve is applied to control the velocity of the stepper motors to make the shutter start and stop in a short time. The closing/open time of shutter is 0.2s, which meets the performance requirements of large telescope properly.

Hu, Jia-wen; Ma, Wen-li; Huang, Jin-long

444

Giant hepatic angiomyolipoma simulating focal nodular hyperplasia.  

PubMed

A case of hepatic angiomyolipoma occurring in a 41-year-old woman, the eighteenth case in literature, is reported herein. The radiographic imagings of the tumor simulated those of focal nodular hyperplasia; namely, the tumor was hyperechoic on ultrasound, hypodense on computed tomography, hypervascular on angiography, and exhibited an uptake of technetium (Tc)-99m phytate. The diagnosis was established after successful removal of the huge tumor from the right hepatic lobe. Histologically, the tumor was angiomyolipoma which was made up of three components, blood vessels, smooth muscle and fatty tissue. Furthermore, extramedullary hematopoiesis, which is usually seen in this tumor was confirmed. The differentiation of hepatic angiomyolipoma from FNH is also discussed. PMID:3404779

Miyahara, M; Kobayashi, M; Tada, I; Okada, K; Sato, K; Kim, Y I; Hiraoka, T; Yokoyama, S

1988-05-01

445

Focal hand dystonia in musicians: a synopsis.  

PubMed

Focal hand dystonia in musicians (FHDM), also known as 'musicians' cramp', is a relatively rare, task-specific, pain-free disorder of control, causing unintentional, abnormal movements and/or positions in a part of the body directly involved in playing a musical instrument. Few physicians are familiar with the diagnosis, yet the exact cause of the disorder remains unknown and there is no generally effective therapy. In this synopsis, the authors present their experience with the diagnosis and treatment of FHDM and their aetiology hypothesis that musicians' cramp is caused by a loss of central motor control initiated by a failure of coping mechanisms, which (try to) compensate for the effects of peripheral local movement disturbing factors in the hand. Recent publications focus on the role of the central nervous system and on motor pattern relearning. We recommend further (prospective) research of the results of operative (peripheral) therapy, followed by (central) motor pattern relearning, and of neuropsychological contributions. PMID:23515596

Rietveld, A B M; Leijnse, J N A L

2013-03-21

446

Idiopathic focal segmental glomerulosclerosis and HLA antigens.  

PubMed

The objective of the present study was to investigate a possible association between HLA class II antigens and idiopathic focal segmental glomerulosclerosis (FSGS). HLA-A, -B, -DR and -DQ antigens were determined in 19 Brazilian patients (16 white subjects and three subjects of Japanese origin) with biopsy-proven FSGS. Comparison of the HLA antigen frequencies between white patients and white local controls showed a significant increase in HLA-DR4 frequency among FSGS patients (37.7 vs 17.2%, P < 0.05). In addition, the three patients of Japanese extraction, not included in the statistical analysis, also presented HLA-DR4. In conclusion, our data confirm the association of FSGS with HLA-DR4 previously reported by others, thus providing further evidence for a role of genes of the HLA complex in the susceptibility to this disease. PMID:9698788

Gerbase-DeLima, M; Pereira-Santos, A; Sesso, R; Temin, J; Aragão, E S; Ajzen, H

1998-03-01

447

Optic Nerve Elongation  

PubMed Central

The length of the optic nerves is a reflection of normal postnatal cranio-orbital development. Unilateral elongation of an optic nerve has been observed in two patients with orbital and skull base neoplasms. In the first case as compared to the patient's opposite, normal optic nerve, an elongated length of the involved optic nerve of 45 mm was present. The involved optic nerve in the second patient was 10 mm longer than the normal opposite optic nerve. The visual and extraocular function was preserved in the second patient. The first patient had only light perception in the affected eye. In this paper, the embryology, anatomy, and physiology of the optic nerve and its mechanisms of stretch and repair are discussed. ImagesFigure 1Figure 2Figure 3Figure 4Figure 5Figure 6Figure 7Figure 8Figure 9Figure 10Figure 11Figure 13

Alvi, Aijaz; Janecka, Ivo P.; Kapadia, Silloo; Johnson, Bruce L.; McVay, William

1996-01-01