Showing papers on "Collimated light published in 1997"

Optical detection system, device, and method utilizing optical matching

Abstract: An optical detection system and method detects movement of an optical pointing device in a data processing environment. The system works with any surface than can diffusely scatter a collimated beam from a coherent light source. Specifically, the system comprises a coherent light source and an optical sensing assembly. The optical sensing assembly comprises a plurality of photosensor arrays and a plurality of optical elements. Each photosensor array includes pixels of a particular size and shape. Each optical element has an artificially limited aperture and is associated, through optical matching, with a respective photosensor array. The coherent light source generates a collimated beam that is diffusely reflected off of the surface. The optical sensing assembly receives the diffusely reflected, or scattered, collimated beam and passes it through the artificially limited apertures of the optical elements to the associated corresponding photosensor array. Passing the scattered light through the optical elements generates speckle images that appear on the pixels of the photosensor arrays. Based on the pixel shape, a pixel value associated with the speckle image provides a speckle image data signal. When there is translation of the pointing device, a new set of speckle images, each reassembling to a translated version of the previous speckle image, arc generated and another speckle image data signal is generated. The new and the previous speckle image data signals are then used in a motion detection analysis to determine the points of the two data signals that give a displacement value.

A new airborne polar Nephelometer for the measurements of optical and microphysical cloud properties. Part I: Theoretical design

Abstract: A new optical sensor, the airborne Polar Nephelometer, is described. The sensor is designed to measure the optical and microphysical parameters of clouds containing either water droplets or ice crystals or a mixture of these particles ranging in size from a few micrometers to about 500 μm diameter. The probe measures the scattering phase function of an ensemble of cloud particles intersecting a collimated laser beam near the focal point of a paraboloidal mirror. The light scattered from polar angles from 3.49° to 169° is reflected onto a circular array of 33 photodiodes. The signal processing electronics and computer storage can provide one measurement of the scattering phase function every 100 ms or every 0.2 ms. The first part of the paper describes the theoretical design of a prototype version of the probe.

Planar polarizer for LCD projectors

Abstract: A liquid crystal display projector including a light source, a collimator lens, a planar polarization converter, a liquid crystal display panel, and projection lenses. The collimator lens is optically aligned to receive a beam of light from the light source and to produce a collimated light beam. The planar polarization converter is optically aligned in front of the collimator lens to receive the collimated beam of light. The polarization converter includes a prismatic film having a first prismatic surface, a reflective polarization film, and a quarter wave retarder film positioned between the prismatic film and the polarization film sheet. The prismatic surface has alternating transmissive prismatic facets and reflective prismatic facets positioned at supplementary base angles, the reflective prismatic facets positioned at a second base angle β and the transmissive prismatic facets positioned at a first base angle generally equal to 180°-β.

Fluorescence imaging system

Abstract: A fluorescence imaging system that includes an objective that is both achromatic and has an external entrance pupil. The objective also serves as a condenser for the system which substantially reduces the system's cost and footprint. With the objective positioned above a sample so that they are in close proximity to one another, a laser directs a collimated beam of light to a scan device located at the objective entrance pupil. The scan device reflects, refracts, or diffracts the light through the lens to illuminate a spot on the sample's surface. The scan device illuminates a line or an area on the sample surface by varying the angle of laser light, in one or two dimensions, into the objective. The sample emits fluorescent light in response to the illumination. The fluorescence light is collected by the objective and passes through the system along the path of the illumination light. A wavelength-discriminating dichroic filter is placed along the optical axis between the laser and the objective to direct the fluorescent light onto a photo-detector to produce a signal representing the sample surface emitting the fluorescent light. A display device is provided that displays the digitized data in a raster format.

New plane-grating monochromators for third generation synchrotron radiation light sources

Abstract: For the electron storage ring BESSY II a new type of plane-grating monochromators working with collimated light is proposed. The operation with collimated light is a well-known optical technique, which enables us to keep the focusing condition fulfilled automatically for all photon energies. The additional degree of freedom gained allows the monochromator to comply with the most different needs of the users. An additional feature of the design is the further extension of the already widely accessible energy range of a PGM towards lower photon energies. The BESSY beamline concept, which requires an additional mirror in front of the monochromator allows the collimation of the light with the presently planned number of optical elements.

Distributed-processing motion tracking system for tracking individually modulated light points

Abstract: Disclosed is a distributed-processing motion capture system (and inherent method) comprising: plural light point devices, e.g., infrared LEDs, in a motion capture environment, each providing a unique sequence of light pulses representing a unique identity (ID) of a light point device; a first imaging device for imaging light along a first and second axis; and a second imaging device for imaging light along a third and fourth axis. Both of the imaging devices filter out information not corresponding to the light point devices, and output one-dimensional information that includes the ID of a light point device and a position of the light point device along one of the respective axes. The system also includes a processing device for triangulating three-dimensional positions of the light point devices based upon the one-dimensional information. The system is very fast because the necessary processing is distributed to be maximally parallel. The motion capture system uses a cylindrical collimating (CC) optics sub-system superimposed on a cylindrical telecentric (CT) optics sub-system. The outputs of the plural light point devices are modulated to provide a unique sequence of light pulses representing a unique identifier (ID) for each of the light point devices according to a predetermined cycle of modulation intervals based upon synchronization signals provided via RF communication. At least two of the light point devices concurrently provide light during the cycle.

Variable polarization beam splitter, combiner and mixer

Abstract: Collimated light from two input fibers are directed against the interface of a beam splitter cube formed by two right-angle prisms. Light transmitted through, or reflected by, depends upon the polarization of the incoming light. A collimator subassembly for an output fiber receives light from the beam splitter cube. Polarization of the incoming light is controlled by orientation of the optical axes of one or two liquid crystal cells placed between each input fiber and beam splitter cube. By controlling the optical axes of the liquid crystal cells light from the two input fibers can be sent to the output fiber in any desired ratio. By rearranging the optical fibers, right-angle prisms and liquid crystal cells, a variable polarization beam combiner can be formed. A combination of the variable polarization beam combiner and beam splitter provides a variable polarization beam mixer, in which two input light signals can be combined and then split into two different output signals by control of liquid crystal cells. Finally, birefringent crystals and laminated beam splitter plates may also be used for the right angle prisms.

Multiplexing device with precision optical block

Abstract: An optical multiplexing device demultiplexes collimated light from a fiber-optic source into separate individual wavelength sub-ranges or channels, and/or multiplexes separate channels to a common fiber-optic waveguide or other destination. An optical block defines an optical gap between two parallel surfaces having an optical port on a first such parallel surface for passing the multi-channel collimated light into the optical gap. A channel port and at least one other reflective element, e.g., multiple channel ports arrayed in spaced relation to each other, are secured to the optical block at the parallel surfaces, providing an unobstructed, epoxy-free multi-point light path within the optical gap. At each channel port an interference filter secured to the optical block spans the optical gap. Each filter transmits a wavelength sub-range of the multi-channel collimated light passed by the optical port, and reflects other wavelengths. Thus, a wavelength sub-range of the multi-channel light passed through the optical gap to a first channel port, which is in-band of that first channel port, is transmitted through that first channel port. Light not transmitted through that first channel port is reflected back through the optical gap, e.g., to strike a second channel port, at which a second, different wavelength sub-range is transmitted. The reflected optical signal thus cascades in a "multiple-bounce" sequence through the optical gap of the multiplexing device, sequentially adding and/or removing channels.

Compton backscattered collimated x-ray source

Abstract: A high-intensity, inexpensive and collimated x-ray source for applications such as x-ray lithography is disclosed An intense pulse from a high power laser, stored in a high-finesse resonator, repetitively collides nearly head-on with and Compton backscatters off a bunched electron beam, having relatively low energy and circulating in a compact storage ring Both the laser and the electron beams are tightly focused and matched at the interaction region inside the optical resonator The laser-electron interaction not only gives rise to x-rays at the desired wavelength, but also cools and stabilizes the electrons against intrabeam scattering and Coulomb repulsion with each other in the storage ring This cooling provides a compact, intense bunch of electrons suitable for many applications In particular, a sufficient amount of x-rays can be generated by this device to make it an excellent and flexible Compton backscattered x-ray (CBX) source for high throughput x-ray lithography and many other applications

Fluorescence imaging system compatible with macro and micro scanning objectives

Abstract: Provided is a coaxial illumination and collection laser scanning system designed to provide substantially uniform detection sensitivity across the field of view of an objective lens (27; 127) by reducing lateral chromatic aberrations at the expense of amplifying axial chromatic aberrations. Axial chromatic aberrations in the system are removed in the path of a retro-beam (31). A laser (18; 117, 118) is in optical communication with the objective lens. The laser (18; 117, 118) produces a collimated beam of coherent light (19; 119) that is directed by a scanner (25) through the objective lens (27; 127) to illuminate a raster of spots on the sample's surface (29), thereby stimulating a series of small regions of the sample to emit light.

Method and apparatus for positioning subjects before a single camera

Abstract: A system and method of positioning a head of a subject to be photographed by a single camera uses a mirror and at least one collimated light beam. The single camera is positioned so that there is a selected specific location in space within a field of view of the camera at which the head or eye of the subject is desired to be positioned. A light source directs a collimated light beam or light sheet so that the light beam or light sheet intersects a line running from the mirror through the selected specific location in space and can be seen by an eye at the selected specific location in space that is looking at the mirror. The user is told to position his head across from the mirror and move his head until he sees the collimated light beam or light sheet and his eye in the mirror. When the subject is so positioned the single camera can take an image of the eye from which the subject can be identified. If desired a second mirror can be used in place of the light source.

Illumination device and application thereof to the illumination of a transmissive screen

Abstract: An illumination device comprises a light source coupled to a waveguide. the waveguide comprises a diffracting element capable of diffracting emergent light rays coming from the source, in a direction substantially perpendicular to the surface of the waveguide. A device of this kind is particularly well-suited to transmissive display screens of the liquid crystal display screen type. It can generate a highly collimated, polarized light.

High speed opto-electronic gage and method for gaging

Abstract: An method and apparatus for determining deviation of characteristics of a sample workpiece from predetermined characteristics of a control workpiece. The apparatus preferably includes an illumination system for producing a collimated beam having substantially parallel rays, a positioning system for placing a sample workpiece between outer edges of the collimated beam so that the sample workpiece partially occludes the collimated beam to produce a silhouette within the collimated beam, an imaging apparatus oriented normal to said collimated beam and including a plurality of discrete light sensing elements for producing pixel data representative of an image including the silhouette, and a processor for determining deviation of characteristics of the sample workpiece from predetermined characteristics of a control workpiece using the pixel data according to pixel data representative of a diffraction band generated through interaction of the sample workpiece and the collimated beam. A preprocessor for preprocessing the pixel data to compensate for imaging defects and for normalizing the diffraction band may also be included.

Multi spectral imaging system

Abstract: An optical imaging system provides automatic co-registration of a plurality of multi spectral images of an object which are generated by a plurality of video cameras or other optical detectors. The imaging system includes a modular assembly of beam splitters, lens tubes, camera lenses and wavelength selective filters which facilitate easy reconfiguration and adjustment of the system for various applications. A primary lens assembly generates a real image of an object to be imaged on a reticle which is positioned at a fixed length from a beam splitter assembly. The beam splitter assembly separates a collimated image beam received from the reticle into multiple image beams, each of which is projected onto a corresponding one of a plurality of video cameras. The lens tubes which connect the beam splitter assembly to the cameras are adjustable in length to provide automatic co-registration of the images generated by each camera.

Tunable filter for use in wavelength division multiplexer and demultiplexer

Abstract: The characteristic pass and rejection bands of an interference filter may be altered by changing the angle of incidence of light upon the filter. If the input beam is first collimated by a GRIN lens before it is transmitted to the interference filter, the characteristic wavelength bands of the filter can be altered by altering the distance of the input beam from the axis of the GRIN lens. Therefore, ferrules having imbedded therein input/output optical fibers may be provided to vary the distance of the input and output optical paths from the axis of the GRIN lens so that the desired spectral components in these paths are rejected or passed by the filter for performing multiplexing and demultiplexing.

Light source for projection display

Abstract: A compact and energy efficient projection display can be made by starting with relatively pure red, green, and blue light sources. The output beams of the colored light sources are received by at least one spatial light modulator. The modulated output beams are collimated and combined. A projection lens receives the collimated and combined output beams and directs them towards a projection screen. All of the above may be contained in a housing to provide a compact and lightweight projection display.

Interferometer having combined beam splitter compensator plate

Abstract: A Michelson-type interferometer which includes apparatus for producing a suitable collimated interferometer input beam; a beam splitter and recombiner for first splitting the input beam into two beams which have components arranged to travel along parallel forward paths and then to recombine them into a single output beam as they are returned along reverse paths to the beam splitter and recombiner; an OPD scanner for scanning the optical path difference between the two split beams travelling along said paths while substantially maintaining the parallelism between the components, and a beam reverser common to the parallel beam components for reversing their direction of travel along the reverse paths and returning them for recombination into the single output beam at the beam splitter and recombiner.

Laser treatment apparatus

Abstract: PROBLEM TO BE SOLVED: To obtain a laser treatment apparatus enabling selective irradiation by arbitrarily changing the shape of the mask set to an irradiation optical system on the basis of the modified image of the image of the lesion part on the imaged surface of the body or body cavity. SOLUTION: The laser beam emitted from a laser oscillator 10 is expanded by a beam expander to be collimated by a collimate lens 16 to reach the surface of a lesion part 22 by an irradiation optical system 32. The laser beam transmitted through the shape changeable mask 18 arranged to the irradiation optical system 31 is condensed to the surface of the lesion part 22 by a condensing lens 20 to perform laser treatment matched with the shape of the mask 18. At this time, the reflected beam from the surface of the lesion part 22 is taken out of the irradiation optical system 32 by a half mirror 24 to be guided to a television camera 26. Herein, the shape of the shape changeable mask 18 is altered and the adjustment of a light cut-off region is performed to control the laser treatment shape on the surface of the lesion part 22.

Spherical aberration effects in lens–axicon doublets: theoretical study

Abstract: Effects of spherical aberrations in converging and diverging lens-axicon doublets are investigated. Intensity profiles are obtained in the line and ring focal regions by numerically solving the Fresnel-Kirchhoff integral. Comparisons with aberration-free computations show that higher peak irradiances occur for the converging doublet when spherical aberrations are included. Results are presented for axicons with small apex angles in lens-axicon combinations illuminated by collimated Gaussian 1.064-mum laser beams.

Integrated bi-directional gradient refractive index wavelength division multiplexer

Abstract: A wavelength division multiplexer integrating a dispersive element having a gradient refractive index with optical lenses to provide efficient coupling from a plurality of input optical fibers (each delivering a plurality of discrete wavelengths to the device) which are multiplexed to a single polychromatic beam for output to a single output optical fiber. The device comprises: (a) an input means for accepting a plurality of optical input beams of different wavelengths from a plurality of optical sources, the means including a planar front surface onto which the optical beams are incident; (b) a dispersive element comprising a radial (or axial) gradient refractive index for combining the plurality of optical input beams into a single optical beam and operatively associated with the planar front surface; (c) a coupler subsystem secured to the dispersive element and comprising (1) a first homogeneous index boot lens having a planar front surface onto which the single optical beam from the dispersive element is incident, (2) an axial gradient refractive index collimating lens affixed to the first homogeneous index boot lens, and (3) a planar back surface from which the single optical beam exits, operatively associated with the axial gradient refractive index collimating lens; and (d) an output means for outputting at least one multiplexed, polychromatic output beam to an optical receiver, the means including the planar back surface. The device is fully bi-directional and may be operated in the forward direction as a multiplexer and in the reverse direction as a demultiplexer.

Method for the determination of the distance and the angular position of an object

Abstract: A method of determining distances and angular positions of stationary and moving objects (3), for example in an area to be monitored in connection with for instance swing doors. The determination is done by means of triangulation where light, which in the main part is collimated, is transmitted (1) into the area at different angles and in a certain sequence. The reflected light is correspondingly registered on a position-sensitive sensor (5) which is positioned at a certain distance from the transmitter (1). The position (5a, 5b), where the reflected light falls on the sensor (5), represents the distance, and the moment when the light is received represents the angular position of the detected object. The values are compared to stored reference values which change when the angle of the door's opening is changed.

Fluorescence imaging system having reduced background fluorescence

Abstract: A coaxial illumination and collection laser scanning system designed to provide increased sensitivity by reducing auto-fluorescence while having a substantially uniform detection sensitivity across the field of view of an objective lens by reducing lateral chromatic aberrations at the expense of amplifying axial chromatic aberrations. Axial chromatic aberrations in the system are removed in the path of a retro-beam. A laser is in optical communication with the objective lens. The laser produces a collimated beam of coherent light that is directed by a scanner through the objective lens to illuminate a raster of spots on the sample's surface, thereby stimulating a series of small regions of the sample to emit light. The system may be used as a confocal or non-confocal imaging system.

Laser collimation of a chromium beam

Abstract: We have studied laser collimation of a chromium atomic beam using a transverse polarization gradient cooling scheme. We present detailed measurements of the angular distribution of atoms on the beam axis, over a broad range of laser intensities and detunings, including those that produce significant excitation, and observe collimation angles as small as 0.16\ifmmode\pm\else\textpm\fi{}0.01 mrad (50% quantile). We compare our results with existing calculations based on assumptions of steady-state conditions and low excited-state population.

Design of a CZT based breast SPECT system

Abstract: A high-resolution SPECT instrument dedicated to breast imaging has been designed incorporating arrays of collimated Cadmium-Zinc-Telluride (CZT) detectors tiled on either a cylindrical surface or a hemispherical surface surrounding the breast. The performance characteristics of a three-segment rotating parallel-hole collimator as well as a stationary multiple pin-hole collimator were considered for the cylindrical system. A stationary multiple pin-hole collimated system was also considered for the hemispherical design. Monte Carlo studies suggest that at almost equal spatial resolution of 0.5 cm, the cylindrical design with parallel-hole collimator would have an approximately a factor of two higher geometrical efficiency than the hemispherical pinhole collimated system including effects of attenuation in the breast. However, whereas the parallel-hole collimator must be rotated to acquire data from multiple angles of view, the pin-hole version has the advantage of recording data from 112 views in a stationary mode. Monte Carlo studies of filtered backprojection as well as a Bayesian reconstruction approach including attenuation and scatter within the breast, where the breast was modeled as a 15 cm hemisphere of uniform activity distribution containing three spherical lesions of diameters 1.0 cm, 0.7 cm and 0.5 cm respectively suggest that the 0.5 cm could be detected with either design in a one-hour SPECT study assuming a 10:1 tumor to background ratio. The authors conclude that a high resolution breast SPECT instrument where the resolution is limited to about 0.5 cm is viable with CZT detectors.

Experimental comparison of mechanical and electronic gamma-ray collimation.

Abstract: Electronically collimated gamma cameras based on Compton scattering are gaining increased attention as the associated hardware and physical principles are further developed. To date, however, there has not been a direct, simultaneous experimental comparison between electronic collimation and mechanical collimation. This paper examines the relative performance of these two techniques at medium gamma-ray energies (0.1 – 1 MeV). A mechanically collimated (pinhole) camera was built and its performance was compared to an electronically collimated camera. Planar radioactive sources were imaged simultaneously by both cameras for identical periods of real time. Data are presented for several radioactive sources of various energies and shapes, including a multi-energy source. Results using an iterative image reconstruction techniques are presented. Comparing critical performance measures such as spatial resolution and efficiency for the two cameras may highlight differences between them, but does not provide an unambiguous basis for comparison. A tool from estimation theory, the resolution-variance curve, was applied to analyze their relative performance. Additionally, data from the two cameras were combined, creating a ‘dual-collimated camera’, and its resolution-variance performance was also examined. All data sets were also compared on a ‘per detected photon’ basis by reconstructing an equal number of events. Results showed that the pinhole camera performed better at the lowest energy examined, 279 keV. At 412 keV, the electronically collimated camera performed best on a ‘per detected photon’ basis, but the higher efficiency of the pinhole camera caused both cameras to have nearly identical performance when all the data was included. At 811 keV, the highest energy used, the electronically-collimated camera demonstrated superior performance. At all energies tested, the combined data set performed as well as, or better than, the best camera operating individually.

Optical system for illuminating a spatial light modulator

Abstract: A novel optical system operative to transfer, with high efficiency, optical power from a line source, such as a LDB, built from a plurality of individual light sources with different angular distribution in two orthogonal axis into a rectangular area with a particular aspect ratio and two different numerical apertures. The near field pattern of a LDB is imaged onto the plane of an SLM. The system utilizes light generated from an LDB having a plurality of individual light sources to illuminate a microlens array. The microlens array, consisting of a plurality of microlenses, functions to collimate the light from the LDB in the slow axis. An optical element adjacent the microlens array refracts the light in the fast axis. In the slow axis, the light from the microlens array is incident upon an optical element which focuses the light onto the SLM plane such that the light from each point light source illuminates the entire active pixel area of the SLM. An additional optical element focuses the light in the fast axis to generate the required spot image. The optical system of the present invention utilizes natural aberrations and/or artificial aberrations to decrease the sensitivity of the optical system to the smile phenomena exhibited by most laser diode bars.

Long-wavelength radiation along a straight-section axis in an electron storage ring

Abstract: The long-wavelength radiation emitted along a straight-section axis of an electron storage ring is considered. A bending magnet at the beginning or end of a straight section produces cylindrically-symmetric “edge” radiation with radial polarization, collimated in a cone with opening angle of -1 ly, where y is the relativistic mass factor. A small deflection from a steering magnet or misaligned quadrupole results in “kicker” radiation, also collimated with an opening angle of -1 ly, for which the photon flux is proportional to the square of the deflection angle. Intermediate deflection angles of -1 ly produce a photon flux comparable to edge radiation. Downstream of a typical straight section which includes entrance and exit bending magnet edges, wiggler or undulator. and miscellaneous steering kicks comparable to 1 /y. the long-wavelength radiation is a superposition from numerous sources, each producing a comparable photon flux with opening angle of -1 /y,

Optical displacement measuring apparatus including a light-emitting element and an adjacent ball lens

Abstract: An optical displacement detecting apparatus is provided for detecting information on a relative displacement with respect to an object having a diffraction grating. The apparatus includes a light-emitting element for emitting a diverging light beam, a ball lens for converting the diverging light beam from the light-emitting element into a nearly collimated beam, a grating interference optical system for using the light beam from the ball lens to finally form interference light in such a form that two diffracted light beams from the diffraction grating are coupled, and a light detecting element for detecting the interference light from the grating interference optical system, wherein the relative displacement information with respect to the object is attained from a periodic signal from the light detecting element.