Showing papers on "Collimated light published in 1981"

Measurements of temperature distribution of flames by moire deflectometry

Abstract: Mapping of temperature of a premixed hydrogen-oxygen flame by moire deflectometry is demonstrated. The technique is based on deflection mapping of rays from a collimated light beam due to gradients of the refractive index across the flame. For an axially symmetric flame the radial distribution of the refractive index was derived by Abel transformation. The temperature profile of the flame was calculated for a known gas composition assuming ideal gas behavior.

Fiber optics communications modules

Abstract: A fiber optics coupler module has a portion defining a spherical reflective surface characterized by a self-conjugate plane having the property that a point source of light in the self-conjugate plane is imaged in the self-conjugate plane. The coupler includes first and second optical transceiver terminals adapted to register a source, detector, or fiber end at each of first and second conjugate locations within the self-conjugate plane. The reflective surface passes a fraction of light incident thereon, whereupon a portion of light diverging from the first location passes through the reflective surface along a first optical path. Similarly a portion of light diverging from the second location passes through the reflective surface along a second optical path. The coupler further includes focusing means on the side of the reflective surface remote from the first and second locations for imaging light travelling along the first optical path at a third location, and also for imaging light travelling along the second optical path at a fourth location. In a first series of embodiments, the reflective surface is partially transmissive, partially reflective for wavelengths in a given range. In a second series of embodiments, the reflective surface is a dichroic surface. In a third series of embodiments, the coupler uses a plane reflection grating and collimated light.

Single channel optical slip ring

Abstract: A single channel optical slip ring assembly comprising first and second optic fibers, a first lens optically coupled to one end of the first optic fiber for collimating a light signal into a parallel light beam having a selected diameter substantially larger than the first and second optic fiber, a second lens optically coupled to one end of the second optic fiber for focusing a collimated light beam having the selected larger diameter into the second fiber end, and means for rotatably mounting the first lens to the second lens so that the lenses are axially aligned along the axis of rotation and are separated by a selected gap for axially transmitting a collimated light signal therebetween whereby the first and second fibers are optically coupled during relative rotation.

Boresighting of airborne laser designation systems

Abstract: A method and apparatus is described for boresighting the sighting systems ed with a 1.06 micrometer designator laser. The method enables boresighting visual direct view optics, TV, and forward looking infrared (FLIR) sights with respect to the laser itself, without the use of external targets. The laser beam is focused onto a refractory target in the boresight device, creating very briefly an incandescent hot spot which can be "seen" by all three sensors. The radiation from this hot spot is collimated by the boresight device optics and projected back into the sights exactly anti-parallel to the laser beam. By aligning the sight reticles with this hot spot, all three types of sights are aligned relative to the laser. Since the hot flash created by the laser energy is of such short duration, the alignment can be accomplished in flight where relative motion exists between the laser designator system and the boresight module. The apparatus disclosed includes a CO 2 laser alignment fixture and a reflective collimator with a phosphor thermal imaging disk for precision alignment of the laser input and FLIR output lines of sight of the boresight module.

Variable angle slant hole collimator

Abstract: A variable angle radiation collimator particularly for use in gamma-photon medical diagnostic systems in a gamma-photon camera system for radiological examination of human subjects. The collimator provides collimation of gamma-photon radiation along a single beam direction which may be varied along two axes to adjust exposure angle or to provide a scanning capability. The collimator is a stack of substantially identical radiation-opaque plates, each of which are apertured with a similar array of openings. The combined effect of the stacked aperture plates is to transmit radiation in a predetermined orientation. The collimated angle of the radiation thus generated is controlled by the coincidence of the array of openings. The stack is retained by a mechanism which permits adjustment of the collimation angle, and the plates are fabricated to provide ease of shear motion during such adjustment. In addition, the tradeoff between the resolution and intensity of radiation transmitted may be easily varied by adjusting stack thickness.

A scanning head for an optical disc system

Abstract: In a scanning head for an optical disc system. a light beam from a laser (12) is transmitted through a monomode optical fiber (28) and then focussed on a record carrying surface of an optical disc (16) by a converging lens (22). The end of the fiber (28) can be reoriented within orthogonal planes perpendicular to the plane of the record carrying surface by transducers (36,38) so as to correct for tracking and timing errors. The laser diode (12) can function both as an emitter and, in an external cavity mode, as a detector of light reflected from the disc (16). Drive to the transducers (36, 38) is dependent on tracking and speed error signals generated from the detected light. Fortracking and speed error compensation, only lens fiber end, and, optionally, a collimating lens (34), which are negligible weight, need be moved rather than the entire scanning head. This provides a simple structure having a high frequency response and low power consumption.

Laser Doppler velocimeter with a novel optical fiber probe

Abstract: A practical laser Doppler velocimeter with optical fibers in the whole system was developed. The novel optical probe designed for this LDV is constructed of a graded-index rod lens attached to the end of an optical fiber. Since the laser beam from the probe is well collimated, the velocity accuracy and sensitivity are significantly improved. Mechanical vibration measurements were also carried out with this LDV; vibration amplitude down to 1.0 μm p-p can be measured at a frequency of 120 Hz with high accuracy.

Small fast large-aperture light modulator using attenuated total reflection

Abstract: An optical modulator is described which offers several advantages in terms of speed, aperture size, and ease of operation over other techniques for amplitude modulation of a collimated light beam. This simple device consists of a prism separated from a metallically reflecting surface by a small micron-size gap. Varying the gap thickness changes the intensity of the light reflected off the base of the prism. The prism acts as a coupler for the excitation of surface plasmons on the metallic surface. This paper explains the principle of operation and presents experimental results obtained on a simple realization of the device.

Low backscatter illumination system

Abstract: Methods and apparatus are disclosed for shaping illuminating beams from continuous duty searchlights or the like so as to minimize the effect of backscattered illumination and, to thereby increase the brightness contrast between illuminated target objects and background so as to improve visibility. More specifically, a continuous duty illumination system comprising an optical system in which the distribution of the light beam entering the entrance pupil of the optical system comprises a collimated beam of high radiant intensity which is thereafter split along an axis bisecting the distributional pattern, or image, with light from the respective halves of the distribution image being directed first in opposite directions and then being redirected in substantially parallel directions; and, wherein light from each half of the split distribution is imaged into respective ones of a pair of collimating lenses with each lens receiving light only from the upper half of its focal plane so that the parallel beams leaving the exit pupils of the optical system contain light only in the space below a generally horizontal plane passing through and containing the optical axes of the system.

Multibeam scanning apparatus provided with a function of changing magnification

Abstract: A multibeam scanning apparatus capable of changing magnification is is provided with a light source part, an afocal zoom lens, a first anamorphic optical system and a second anamorphic optical system. The light source part generates a plural number of collimated light beams and the afocal zoom lens changes the angular magnification of the collimated light beams. The first anamorphic optical system forms linear images from the beams transmitted through the afocal zoom lens. The linear images are parallel with the plane defined by the light beams as deflected by a deflector. The second anamorphic optical system is disposed between the deflector and a surface to be scanned to form good scanning spots on the scanned surface from the linear images on the reflecting surface of the deflector.

Method and equipment for mapping radiation deflection

Abstract: Equipment and method for mapping an object using moire deflectometry wherein collimated radiation deflected from the object is used to generate a moire pattern and wherein by measuring linear deflections in the pattern, variations in characteristics of the object is determined.

Parabolic focusing apparatus for optical spectroscopy

Abstract: An accessory for use in the sample region of a spectrometer is disclosed which combines a matched pair of off-axis paraboloid reflectors having their focii optically imaged on the sample (either imaged at a common point or at two points which are optically imaged on each other) and having relative locations and orientations such that each ray of radiation strikes the two reflectors at points on the reflectors having approximately the same focal lengths. This arrangement involves the use of collimated optical beams into and out of the accessory. The accessory may function as a transmission-type accessory, in which the radiation passes through the sample, or as an internal reflectance accessory, in which the radiation passes through the sample holder but is reflected by the sample. The focal length relationship set forth is accomplished by having the "back-to-back" paraboloid reflectors, i.e., their reflecting surfaces face in substantially different, preferably opposite, directions. A further aspect is the incorporation of means for adjusting the position of at least one of the paraboloid reflectors along a first line parallel to, and along a second line perpendicular to, the axis of the collimated optical beam reflected by the position-adjustable reflector.

High resolution optical-addressing device and electronic scanner and/or printer apparatus employing such device

Abstract: An optical-address device, useful e.g. in electronic imaging, features (i) a lens array including a plurality of discrete lens means, each adapted to focus incident collimated light, from a plurality of different incidence directions, onto respectively different pixel spots of its associated multi-spot address zone (of a multi-zone, optical-address region) and (ii) light directing structure for sequentially illuminating the lens array with collimated light of different incidence directions. Printer apparatus, scanner apparatus and scanner/printer apparatus incorporating such optical-address device are disclosed.

Stereoscopic head-up display for pilot's helmet - uses FLIR and TV cameras with IR filters providing reconstructed CRT image via processor for infinite focus viewing through fibre=optics

Abstract: Two cameras (1, 2) mounted on a common support (3) are aligned along parallel optical axes (X1, X2) whose separation (D) is adjustable by other is a TV camera operating in the near infrared region. The band spectrum of each camera (1, 2) is determined by a set of filters (5, 6). Pref. the cameras (1, 2) operate in a sweep scanning mode and provide respective outputs (SV1, SV2) to a processor (7). The processor (7) in perform a histogram analysis, contrast dilation or a contour emphasis and outputs to circuit (21) to provide each camera signal (SV1, SV2) onto different parts of a single c.r.t. display (20). The images are transmitted along fibres (22, 23) which terminate at each eye of the helment wearer. Observation is through ocular optical elements (24, 25) placed at the inter-pupil distance. The respective images are collimated and and are viewed by reflection on a semi-reflecting screen at infinite focus.

Ion beam lithography process and apparatus using step-and-repeat exposure

Abstract: A high-resolution, high-throughput ion beam lithography process and apparatus is used in the fabrication of semiconductor integrated circuits and devices. Lateral wafer distortions which occur in wafer workpieces create the problem of accurate alignment of the ion beam with the wafer. Furthermore, it is difficult to produce a collimated ion beam of sufficient diameter for a large area target. These problems are overcome by exposing selected segments of the wafer to a projected ion beam pattern in a step-and-repeat manner until the entire target is exposed, thereby optimizing the resolution, throughput, yield and cost of the process. First there is provided: a target (12) having predetermined segments (14) defined thereon; a mask (16) placed in proximity to the target (12), to define the patterned ion beam; a collimated ion beam which is projected through the mask (16) to form the patterned ion beam; and a means (22, 34, 35) for aligning the mask (16) and a selected segment (14) of the target (12). The size of the pattern area of the mask (16) is approximately equal to the size of one of the predetermined segments (14) of the target (12). Next, the mask (16) is aligned with a first selected segment (14) of the target (12) and this first segment (14) is exposed to the patterned ion beam, formed by projecting the collimated ion beam through the mask (16). Then, the mask (16) is aligned with a second selected segment of the target (12) and this second segment is exposed to the patterned ion beam.

Reflective alignment light for computerized tomography

Abstract: The conventional cylindrical lens of a laser alignment device is replaced with a non-planar reflective device for spreading the collimated laser beam into a fan-shaped linear pattern for patient alignment use. In one form, a mirror-coated cylindrical rod is used to generate axial alignment lines, and in another form, a mirror-coated cone is used to generate the coronal alignment lines.

Selectable field-of-view infrared lens

Abstract: A selectable field-of-view infrared lens is disclosed for projecting an image from object space onto a flat image plane, the selectable field-of-view infrared lens being corrected over the spectral region of 3.3 to 4.2 microns and having a selectable wide field-of-view comprising: an objective lens system having a plurality of lens elements formed of material optically transparent over the spectral region of 3.3 to 4.2 microns; a selectable refractive Galilean afocal telescope having a plurality of lens elements formed of material optically transparent over the spectral region of 3.3 to 4.2 microns, the telescope being coupled to the objective lens in select field-of-view determining relation with the objective lens whereby, upon selection, the selectable refractive Galilean afocal telescope cooperates with the objective lens system to provide a wide field-of-view; a means for scanning, the means scanning having an optical element interposed between and coaxially aligned with the selectable refractive Galilean afocal telescope and the objective lens system, the means for scanning being adapted to oscillate the optical the optical element through a predetermined angle thereby, angularly displacing the collimated rays whereby, upon selection, the selectable refractive Galilean afocal telescope receives collimated light from object space and provides the collimated rays to the means for scanning optical element, the collimated rays passing through the oscillating optical element and being reciprocally displaced, the reciprocally displaced collimated rays passing to the objective lens system, the objective lens system focusing the reciprocally displaced collimated rays on the flat image plane; thereby, forming a reciprocally displaced image.

Light valve imaging apparatus having improved optical configuration

Abstract: Electronic imaging apparatus of the kind having an imaging zone; a light valve array comprising a plurality of discretely-addressable light-modulating pixel regions; illuminating means for directing light to the imaging zone via the array and means for addressing the pixels in accordance with image information, features light control means located between the illuminating means and such array for collimating illuminating light in a direction substantially normal to the ingress surface of the array.

Optical system which provides a collimated light beam

Abstract: An optical system which provides a collimated light beam, having a tubular holder, a semiconductor laser and a system of lenses incorporated in the holder, in which the semiconductor laser is positioned against an abutment in the axial direction of the holder and a resilient element is placed between the system of lenses and the abutment, while on the side of the system of lenses remote from the resilient element a locking element is present which, after axial adjustment in the holder, is fixed in such a location that the system of lenses, after moving in the axial direction against the pressure of the resilient element, is in the position in which its focus coincides with the laser element in the semiconductor laser.

Rotating laminar emission camera with GE-detector: Experimental results

Abstract: Experimental results of a prototype rotating laminar emission camera (ROLEC) for nuclear medicine imaging are reported. A 11.5 mm thick, 45×45 mm high‐purity germaniumdetector is segmented into 30 1.47 mm wide parallel channels and collimated with 39 mm high parallel plates. Projection data acquired at multiple angular orientations as the detector‐collimator assembly is rotated about its center are mathematically reconstructed to image the activity distribution. The spatial resolution of the ROLEC is at least twice as good, at all distances, as that of gamma cameras with high resolution collimators. The better energy resolution of the germanium enhances the detection and resolution of the ROLEC in comparison to gamma cameras with NaI(T1) crystals, the relative superiority increasing with greater volumes and with greater depths. Adequate sensitivity is maintained while achieving these improvements in spatial resolution and in practice; ROLEC images are acquired in less time than pinhole collimatorimages with gamma cameras. Key words: emission camera, laminar camera,germaniumcamera

A benchmark gamma-ray skyshine experiment

Abstract: A benchmark gamma-ray skyshine experiment is descibed in which /sup 60/Co sources were either collimated into an upward 150-deg conical beam or shielded vertically by two different thicknesses of concrete. A NaI(Tl) spectrometer and a high pressure ion chamber were used to measure, respectively, the energy spectrum and the 4..pi..-exposure rate of the air-reflected gamma photons up to 700 m from the source. Analyses of the data and comparison to DOT discrete ordinates calculations are presented.

Method and apparatus for generating optical scans

Abstract: A system is disclosed for transforming a collimated beam of light, such as that generated by a laser, into a beam of light which repetitively scans a fixed path by utilizing a mirror which is repetitively rotated through a predetermined angular displacement. The angle between the mirror axis of rotation and the mirror position relative to the axis varies between subsequent mirror rotations and defines a scanning beam rotational axis error which is eliminated by the present invention. An input beam of collimated light is directed onto the rotating mirror along a first path to produce a first scanned reflected output beam for each rotation of the mirror. A second scanned reflected output beam is generated by redirecting the first scanned reflected output beam through a prism and back onto the mirror along a second path. The second path is vertically displaced from the first path by a distance related to the mirror rotational axis error. Each point at which the second scanned output beam intercepts the mirror is laterally offset from a corresponding point at which the input beam intercepts the mirror by a distance related to the relative angle between the mirror and the input light beam. The second scanned reflected output beam is reflected from the mirror to generate a third scanned reflected output beam for each deflection of the mirror. The repetitive deflections of the mirror produce a plurality of third scanned reflected output beams which define a grouping of non-coincident surfaces which are also nonintersecting with respect to the input beam. The third scanned reflected output beams are converged onto the fixed path such that the optical output beam repetitively scans the fixed path without any perceptible deviations caused by the mirror rotational axis error.

Non-invasive estimation of kidney function by X-ray fluorescence analysis. Method for in vivo measurements of iodine-containing contrast media in rabbits

Abstract: It is shown that quantitative determination of the iodine concentration in the soft tissue of rabbits is possible by in vivo measurements using the X-ray fluorescence technique. The influence on the measurements of variable factors such as weight is negligible, due to the use of a well collimated geometry.

Method and apparatus for refracting a laser beam

Abstract: This invention is a method and apparatus for refracting a laser beam. The beam can be collimated, focused, or expanded by passing it along the longitudinal axis of a volume of gas which has a radial pressure gradient. The pressure gradient causes a corresponding gradient in density and refractive index. Such a gradient can conveniently be established by the use of a gas vortex chamber. A vortex chamber will act as a negative lens. It can be located at or near the focal point of a focused laser beam as a collimating element. A gas vortex lens is useable at power densities above those which conventional optical materials can withstand.

Multiple-reflection optical gas cell

Abstract: A multiple-reflection optical cell for Raman or fluorescence gas analysis consists of two spherical mirrors positioned transverse to a multiple-pass laser cell in a confronting plane-parallel alignment. The two mirrors are of equal diameter but possess different radii of curvature. The spacing between the mirrors is uniform and less than half of the radius of curvature of either mirror. The mirror of greater curvature possesses a small circular portal in its center which is the effective point source for conventional F1 double lens collection optics of a monochromator-detection system. Gas to be analyzed is flowed into the cell and irradiated by a multiply-reflected composite laser beam centered between the mirrors of the cell. Raman or fluorescence radiation originating from a large volume within the cell is (1) collected via multiple reflections with the cell mirrors, (2) partially collimated and (3) directed through the cell portal in a geometric array compatible with F1 collection optics.

Rotating laminar emission camera with GE-detector: an analysis

Abstract: Design criteria for a germanium detector emission camera with laminar collimator-detector geometry are reported In this design, parallel plates above a grooved germanium slab form detector channels which accumulate data in multiple projections through 180 degrees Activity distribution is determined through mathematical reconstruction from the projections The laminar design has greater efficiency than a hole-collimated device due to a favorable open area ratio and due to collimation in only one dimension The relative sensitivity at the center of the detector strip increases with detector length and distance from collimator face Spatial resolution depends upon the design geometry (septal penetration and scatter within the crystal are of such small magnitude that degradation of the point spread function is minimal) A 30 channel protype device (ROLEC) shows good correlation with theoretically determined PSF and signal-to-noise ratio (SNR) Measuring times projected for a clinical sized device (300 mm diam) are about 46 times that of the Anger camera (with same SNR) and high resolution collimator

Measurement of refractive index profile

Abstract: A method of sensing the optical deflection function of an approximately cylindrical object, such as an optical fibre preform, comprises illuminating the object with collimated light; focusing the transmitted light so that in the focal plane the distance of the light from the optical axis is linearly proportional to the angle through which light has been deviated by the object; optically modulating the focused light so that a property of the light varies as a function of said distance, and calculating the deflection function from the modulated light. The modulations may be spatial or temporal. The refractive index profile can also be calculated.

Test image projector for testing imaging devices

Abstract: A test image projector operating in the ultraviolet through infrared specm that is comprised of two symmetrically mounted identical mirrors which are off-axis sections of an astronomical quality parabola. The first mirror produces collimated beams from object points and reflects these collimated beams onto the second mirror while the second mirror refocuses the collimated beams into diffraction limited image points, and thus provides a diffraction limited test image. The test image is used to check the quality of optical and electrooptical systems.

Device for measurement of the torsional angular deviation of a loaded rotating or static shaft

Abstract: A torsional angular deviation measuring device comprising a first diffraction grating which is placed at one end of a shaft and a second diffraction grating placed at the other end or at least some distance from the first end. A beam of light from a light source is then passed through the first diffraction grating generating zeroth order and other order beams. The beams are thence passed through collimating optics and then through the second diffraction grating. The beams from the second diffraction grating are sensed by split photodiodes and the amount of angular deviation is then measured by comparing the phases of pulse trains generated from the different photodiodes with one another.