Lens Mount Research Articles

Handheld Optical Coherence Tomography Scanner for Primary Care Diagnostics

The goal of this study is to develop an advanced point-of-care diagnostic instrument for use in a primary care office using handheld optical coherence tomography (OCT). This system has the potential to enable earlier detection of diseases and accurate image-based diagnostics. Our system was designed to be compact, portable, user-friendly, and fast, making it well suited for the primary care office setting. The unique feature of our system is a versatile handheld OCT imaging scanner which consists of a pair of computer-controlled galvanometer-mounted mirrors, interchangeable lens mounts, and miniaturized video camera. This handheld scanner has the capability to guide the physician in real time for finding suspicious regions to be imaged by OCT. In order to evaluate the performance and use of the handheld OCT scanner, the anterior chamber of a rat eye and in vivo human retina, cornea, skin, and tympanic membrane were imaged. Based on this feasibility study, we believe that this new type of handheld OCT device and system has the potential to be an efficient point-of-care imaging tool in primary care medicine.

P.8.a.003 Polypharmacy among psychiatric outpatients in Kuwait

With the disappearance of the radiuscope, alternative methods must be developed to accurately measure gas-permeable (GP) lenses. The purpose of this study was to design, manufacture, and test a novel attachment for the evaluation of spherical base curves of GP rigid contact lenses using a corneal topographer.A topographer attachment was devised with the intent of measuring the surface radii of GP lenses. A front-surface mirror was fixed at a 45° angle above a hemispherical GP lens mount taken from a radiuscope. The device was set in the chin rest of a Humphrey Atlas topographer (Carl Zeiss Meditec, Inc., Jena, Germany) such that the image from the back of a GP surface was focused. The base curve radii of 9 rigid polymer buttons nominally ranging from 5.00 mm to 9.00 mm in 0.5-mm steps were measured 3 times with a Neitz Auto CG (Neitz Instruments Co., Ltd., Tokyo, Japan), Reichert Radiuscope (Reichert Ophthalmic Instruments, Depew, New York), and Humphrey Atlas topographer using the base curve (BC) attachment.An analysis of variance with replication and without interaction, using the main effects of measurement method (n = 5) and nominal button radius (n = 9), found that there was no statistically significant effect of the base curve measurement method (F[4, 122] = 1.23; P = 0.303), although there was a statistically significant effect of nominal button radius (F[8, 122] = 4.70; P = 0.003).Although the optical system of the corneal topographer was designed for measurement of convex surfaces, measurement of base curve radii from concave surfaces was performed without a correction factor using the prototype attachment. The mean SimK and Axial radii were within the tolerance for GP base curve radius, 0.05 mm, cited in ANSI Z80.20-2004 and ISO 18369-2:2006. Thus, the clinical feasibility of this prototype BC attachment to support measurement of spherical base curve radii for GP lenses by a corneal topographer was demonstrated.

Minimizing Machining Distortion in Aluminum Alloys through Successful Application of Uphill Quenching—A Process Overview

Abstract Recently, emphasis has been placed on achieving maximum dimensional stability in a wide range of critical aluminum components such as large complex aerospace machined parts, space mirrors, optical stages, lens mounts, and computer disks. In these cases, absolute stability is required before putting a part into service. In many cases, successful operation of a complete system hinges on the stability of a single part such as a space mirror in a satellite or a component of a laser guided missile. Proper application of the uphill quenching process has enabled the successful production of parts to provide minimum stresses resulting in the optimum component at the lowest cost. Basic principles for achieving dimensional stability and considerations for proper application of unique tools such as polyalkylene glycol polymer (glycol) quenching and uphill quenching to achieve maximum dimensional stability are discussed. Properly applied, and combined with an understanding of all factors contributing to part instability, these tools can be used as effective elements in a systems approach, which when effectively employed by experienced technicians, will achieve results not obtainable by other means. In addition, examples are provided illustrating successful use of the process to produce low stress parts.

Athermal Elastomeric Lens Mount for Space Optics

We investigated the optimum adhesive thickness for athermalizing an elastomeric lens mount in our space optics application. Theoretical results were compared with finite element solutions using two different models; discrete circular pads and discrete circular pads with columns filling the insertion holes reflecting the reality. A noticeable difference between their optimal thicknesses was observed, and physical interpretation revealed the uncertainty of prevailing athermal equations. A pilot sample was made to check our results and thermo-optical stress was assessed using an interferometer after isothermal load. This study presented insight into preliminary design guidance in elastomeric lens mounting.

Prototype base curve attachment for the topographer: What will replace the vanishing radiuscope?

Background With the disappearance of the radiuscope, alternative methods must be developed to accurately measure gas-permeable (GP) lenses. The purpose of this study was to design, manufacture, and test a novel attachment for the evaluation of spherical base curves of GP rigid contact lenses using a corneal topographer. Methods A topographer attachment was devised with the intent of measuring the surface radii of GP lenses. A front-surface mirror was fixed at a 45° angle above a hemispherical GP lens mount taken from a radiuscope. The device was set in the chin rest of a Humphrey Atlas topographer (Carl Zeiss Meditec, Inc., Jena, Germany) such that the image from the back of a GP surface was focused. The base curve radii of 9 rigid polymer buttons nominally ranging from 5.00 mm to 9.00 mm in 0.5-mm steps were measured 3 times with a Neitz Auto CG (Neitz Instruments Co., Ltd., Tokyo, Japan), Reichert Radiuscope (Reichert Ophthalmic Instruments, Depew, New York), and Humphrey Atlas topographer using the base curve (BC) attachment. Results An analysis of variance with replication and without interaction, using the main effects of measurement method (n = 5) and nominal button radius (n = 9), found that there was no statistically significant effect of the base curve measurement method (F[4, 122] = 1.23; P = 0.303), although there was a statistically significant effect of nominal button radius (F[8, 122] = 4.70; P = 0.003). Conclusions Although the optical system of the corneal topographer was designed for measurement of convex surfaces, measurement of base curve radii from concave surfaces was performed without a correction factor using the prototype attachment. The mean SimK and Axial radii were within the tolerance for GP base curve radius, 0.05 mm, cited in ANSI Z80.20-2004 and ISO 18369-2:2006. Thus, the clinical feasibility of this prototype BC attachment to support measurement of spherical base curve radii for GP lenses by a corneal topographer was demonstrated.

Multiple optical calibration system–based effective multiviews video processing

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.

Focus on lasers and optics

Focus on lasers and optics

Investigation of Micro Solid Immersion Lens Mounting Systems

Concept, design and analysis of several solid immersion lens (SIL) mounting systems utilizing high-index refractive micro SILs are described. This paper proposes several designs for wafer-scale SIL assemblies capable of a numerical aperture of 2.2.

카메라폰 렌즈의 MTF 측정장치 개발

직경과 초점거리가 수 mm인 카메라폰 렌즈의 성능을 평가하는 변조전달함수(Modulation Transfer Function: MTF) 측정장치를 개발 하였다. 전체 측정장치는 물체부, 상분석부, 렌즈 마운터로 구성되며, 물체부는 비축상 측정을 위하여 회전한다. 렌즈의 정밀한 정렬을 위하여 정밀한 수평형 거치대를 제작하였으며 광축 조정과 렌즈의 기울어짐 등의 문제를 매우 효과적으로 개선하였다. 시험렌즈의 초기정렬이 끝나면 자동으로 MTF를 측정하며 측정시간은 10초 이내이다. In order to evaluate the performance of phone camera lenses, we have developed equipment for measuring the modulation transfer function(MTF) for small size lenses. The equipment is composed of an an image analyzer, object generator, and a lens mount. The object generator is rotated for on and off-axis measurement. The lens mount is of horizontal type and tiltable for precise alignment to the optical axis. After the initial alignment process, the measurement is done within 10 seconds automatically

Packaging Multiple Active and Passive Elements in a Hybrid Optical Platform

The commercial market for telecom components has had an increasing demand for laser transmitter packages with higher functionality and smaller form factor. These higher levels of integration require an optical bench platform that can incorporate multiple active and passive elements and withstand stringent reliability requirements. Furthermore, the laser package must be compatible with high-volume manufacturing. We have developed an optical platform for building hybrid (multiple active elements) optoelectronic devices in a stable, hermetically sealed package. Two novel approaches to optical packaging have been developed: a localized laser soldering process and a flexure-based lens mount with large dynamic range. We present the optical bench and component design and the results of engineering reliability testing of the assembled package.

Residual Stress Distributions in Glass/Metal‐Joints produced by Ultrasonic Torsion Welding

AbstractThe development and industrial application of efficient methods to join glass with metals which combine the individual advantages of both material groups are a great technological challenge. One research field of the Institute of Materials Science and Engineering is the production of glass/metal joints by means of ultrasound. Industrial applications are for example the sealing of glass vessels, fixtures in the vacuum technique or lens mounts. For this reason an industrial ultrasonic torsion welding system normally used for metal weldings was modified to be suitable for the demands of high sensitive glass/metal‐joints. With the developed welding system helium‐tight joints of glass and metals can be realized. In comparison to the conventional welding techniques [1] for glass like diffusion welding or adhesive bonding, ultrasonic torsion welding is characterized by very short welding times (< 1s) as well as low welding temperatures (< 450°C). Further advantages of this joining technique are the high automation potential and the environmental compatibility. Furthermore this technique can be applied under normal or specific atmospherical conditions. In spite of the low joining temperatures thermal residual stresses occur during the cooling of the joints due to the different coefficients of thermal expansion of the used materials [2]. In the present paper the measurement and calculation of the temperature distribution and the development of thermal residual stresses are described.

Stereoscopic particle image velocimetry measurements of the flow around a Rushton turbine

The principles of stereoscopic particle image velocimetry (PIV), including distortion compensation, were applied to the turbulent flow in a vessel stirred by a Rushton turbine. An angular offset configuration was used and tilt-axis lens mounts were incorporated in order to satisfy the Scheimpflug condition, significantly reducing the ordinarily large depth of field requirements of such configurations. A distortion compensation procedure, or in situ calibration, was utilized in place of the ray tracing, or mechanical registration, used in previous studies. The calibration procedure was validated using two tests, one a rigid translation of a speckle target, the other the viscous flow between two concentric cylinders. The results of the tests suggest the success with which the distortion compensation procedure may be applied to real fluid flows. Phase-locked instantaneous data were ensemble averaged and interpolated in order to obtain mean 3-D velocity fields on a cylindrical shell enclosing the turbine blade. From these fields, the tip vortex pairs and the radial jet documented in previous studies of mixer flows were easily identified.

Refractive collimating microlens arrays by surface tension self-assembly

A new process for fabrication of refractive collimating microlens arrays is demonstrated. The lens mount is formed in the bonded layer of a bonded silicon-on-insulator wafer, and rotated out of plane by the surface tension obtained by melting rectangular pads of thick photoresist. The lenses are formed by melting circular pads of the same resist. Correct alignment of the mount normal to the substrate is achieved by sequential self-assembly of a supporting frame.

Key factors for radiuscope measurement accuracy: including an improved lens mount design

The importance of practitioners being able to measure back optic zone radius in verifying rigid gas permeable contact lenses is emphasized. Despite improved standards of manufacturing, errors can occur, and the capacity to verify lenses can be crucial to effective management, especially when new rigid gas permeable materials with unproven stability characteristics are used. Circumstances under which back optic zone radius discrepancies can cause frustration to both patient and practitioner are analyzed as the basis for illustrating the value of either problem anticipation and prevention, or recognition and resolution. Procedures that increase the accuracy of radiuscope measurements are described, including the use of a new lens mount design. The psychology of contact lens verification measurements is discussed, with consideration of procedures that help reduce conflict between laboratory and practitioner on the occasion of questionable quality control.

GROUP DELAY TRACKING WITH THE SYDNEY UNIVERSITY STELLAR INTERFEROMETER

ABSTRACT The Sydney University Stellar Interferometer (SUSI) is a long baseline optical interferometer, located at the Paul Wild Observatory near Narrabri, in northern New South Wales, Australia. It is designed to measure stellar angular diameters using light collected from a pair of siderostats, with 11 fixed siderostats giving separations between 5 and 640 m. Apertures smaller than Fried's coherence length, r0, are used and active tilt-compensation is employed. This ensures that when the beams are combined in the pupil plane the wavefronts are parallel. Fringes are detected when the optical path-difference between the arriving wavefronts is less than tne coherence length of light used for the observation. While observing a star it is necessary to compensate for the changes in pathlength due to the earth's rotation. It is also highly desirable to compensate for path changes due to the effects of atmospheric turbulence. Tracking the path-difference permits an accurate calibration of the fringe visibility, allows larger bandwidths to be used, and therefore improves the sensitivity of the instrument. I describe a fringe tracking system which I developed for SUSI, based on group delay tracking with a PAPA (Precision Analog Photon Address) detector. The method uses short exposure images of fringes, 1-10 ms, detected in the dispersed spectra of the combined starlight. The number of fringes across a fixed bandwidth of channeled spectrum is directly proportional to the path-difference between the arriving wavefronts. A Fast Fourier Transform, implemented in hardware, is used to calculate the spatial power spectrum of the fringes, thereby locating the delay. The visibility loss due to a non-constant fringe spacing on the detector is investigated, and the improvements obtained from rebinning the photon data are shown. The low light level limitations of group delay tracking are determined theoretically with emphasis on the probability of tracking error, rather than the signal-to-noise ratio. Experimental results from both laboratory studies and stellar observations are presented. These show the first closed-loop operation of a fringe tracking system based on observations of group delay with a stellar interferometer. The Sydney University PAPA camera, a photon counting array detector developed for use in this work, is also described. The design principles of the PAPA camera are outlined and the potential sources of image artifacts are identified. The artifacts arise from the use of optical encoding with Gray coded masks, and teh new camera is distinguished by its mask-plate, which was designed to overcome artifacts due to vignetting. Nw lens mounts are also presented which permit a simplified optical alignment without the need for tilt-plates. The performance of the camera is described.

Interference fit equations for lens cell design using elastomeric lens mountings

Optical designs often consist of lenses that are mounted in a common lens barrel. For lenses having diameters greater than 20 cm and subject to large temperature differentials and/or shock loading, standard metal retainer ring mountings may not be acceptable. An alternate method for mounting these lenses is to mount each individual lens in its own subcell using an adhesive and then to use an interference or press fit to mount these subcells in the lens barrel. When mounting lenses in this manner, it is necessary to evaluate the stress induced in the glass and the residual difference in the optical path. A closed-form analytical derivation was made for a simple lens mount that relates the allowable magnitude of the interference fit to the stress in the glass. This theoretcal expression was then modified using finite element models for use with complex lens designs. Moreover, since lens mountings may require the use of relatively thick layers of flexible elastomer to mount the lenses in their individual cells to prevent large thermal and/or mechanical stresses, the equation for determining the decentration of lenses mounted in circumferential flexible elastomers is also derived. The theoretical expression was used to verify finite element models that then may be used for more complex mounts.

Sound insulated interchangeable lens

An interchangeable lens suitable for use in conjunction with a motion picture camera features a lens mount 13 that is removably attached to such motion picture camera, a lens casing 11 commecting to lens mount 13, and an external casing 10 that both houses the adjusting elements of such interchangeable lens and is connected through sound-absorbing rings 16, 17, 18 to lens casing 11. An object-side buffer ring 16 and a camera-side buffer ring 17 both center and radially support, in its end zones, external casing 10 upon lens casing 11.

Technical aspects of measurement for optically sophisticated eyeglasses

This paper deals with the question of how aspherical ophthalmic lenses can be measured outside the reference point given by the manufacturer in order to make a lens comparison or to test the shape faithfulness of the lens surface. Three procedures are presented with measuring examples - vertex power measurement with swiveled lens mount, probe scan in a three-coordinate measurement, and interferometer measurement using a non-ideal reference lens. The basic problem inherent in an application-related interpretation of the measuring data sets gained by these methods is shown.

American National Standard for Motion-Picture Cameras–Threaded Lens Mounts— 16-mm and 8-mm Cameras

American National Standard for Motion-Picture Cameras–Threaded Lens Mounts— 16-mm and 8-mm Cameras

Thermo-Optical Analysis Of Two Long-Focal-Length Aerial Reconnaissance Lenses

A 36-inch f/5.0 lens and a 24-inch f/3.5 lens used for aerial reconnaissance missions are described. During design, these lenses were analyzed over t heir full operating temperautre range of 20 to 60 C. Their performance at ambient conditions and at the maximum operating temperature is reported. The results indicate that at steady state the performance of each lens is affeted only modestly over the operating temperature range when the image is held in focus by a thermal comensating lens mount.