Showing papers on "Collimated light published in 1979"

Single Photon Emission Computed Tomography Using Multi-Slice Fan Beam Collimators

Abstract: Scintillation camera systems using parallel collimation have been used for single-photon emission computed tomography (SP/ECT). A major problem is the limited resolution of present parallel-hole collimators. We have built and evaluated collimators for a SP/ECT system, consisting of two opposing LFOV scintillation cameras and a gantry, which have parallel collimation along the cranial-caudal axis of the patient and converging collimation in a direction perpendicular to this axis. The collimator converges to a line of focus located 58 cm from the collimator face and parallel to the cranial-caudal axis of the patient. Two converging collimators combined with opposing LFOV cameras are capable of simultaneously imaging 11 contiguous, 2.6 (or 1.3) cm thick, transverse sections from data collected during a single revolution of the cameras about the patient. A fan beam convolution algorithm reconstructs the transverse slices and provides partial compensation for ?-ray attenuation. It is concluded that the fan-beam collimator system, when compared with conventional parallel-hole collimator systems, produces simultaneous improvements in SP/ECT system sensitivity and resolution. This results in improved visualization of small centrally located organs.

Refractive index determination by the focusing method.

Abstract: We show that it is possible to determine the refractive index distribution of a fiber or preform with slight index variation by observing the power distribution of the light field that is focused by the core acting as a lens. This method requires index matching of the cladding and illumination of the core at right angles to its axis with a broad beam of incoherent collimated light. The refractive index distribution is obtained after two numerical integrations to be performed by computer. The first integration establishes the relation between the output and input ray positions from the observed power distribution, the second uses this information to determine the refractive index distribution. However, it is not necessary to solve a large system of simultaneous equations. The sensitivity of the method to measurement inaccuracies was tested by computer simulation. It was found that the method has a builtin smoothing effect that attenuates rather than amplifies measurement errors.

Theoretical and experimental study of space charge in intense ion beams

Abstract: The highly collimated beams of energetic neutral atoms used in controlled thermonuclear fusion research (CTR) require the virtual elimination of space-charge forces in the primary ion beam in order to minimize the angular divergence. A model is presented which describes the behavior of an intense ion beam passing through a gas cell. This theory is used to derive the space-charge field produced by such a beam and shows how its effect can be minimized. This model agrees well with experimental measurements and enables emittance-dominated beams of very high brightness to be obtained which could find applications in fields other than CTR.

Critical angle scattering by a bubble: physical-optics approximation and observations

Abstract: The intensity of light scattered by an air bubble in water is predicted by the geometric-optics calculation of Davis (1955) to have a divergent angular derivative as the critical scattering angle ϕc is approached. Effects of diffraction in the angular region near ϕc are described here. The Fraunhofer diffraction for scattering angles ϕ≤ϕc is estimated using a simplified physical-optics approximation. A ringing and decay of the far-field intensity is predicted that is formally similar to the near-field diffraction of a straight edge. Observation of millimeter radius bubbles in water with collimated monochromatic illumination confirm the existence of this ringing which has a quasi period ≃ 25 mrad. The diffraction calculation gives an approximate description of the relative ϕ of the observed maxima and minima. Fringes with a lower contrast and spacing ≃ 0.3 mrad were also observed; they appear to be caused by the interference of rays with distinct paths. Implications for the critical angle scattering of white light are discussed.

A transportable system for the measurement of liver cadmium in vivo.

Abstract: A system is described for liver cadmium measurement The neutron source is a 10 Ci238Pu/Be source which is double-encapsulated in a stainless steel cylinder The neutron output is collimated by placing it in a specially designed box LiF-doped resin effectively limits the beam spot to a diameter of 10 cm The detector used is a coaxial lithium-drifted germanium semiconductor

X-ray lithography system having collimating optics

Abstract: An X-ray lithography system for the production of micro-electronic circuits, of the type comprising a mask having detailed circuit patterns thereon which are irradiated by soft X-rays onto a wafer covered with a photosensitive material to replicate the mask patterns, includes an X-ray source spaced from the mask and operative to produce a plurality of input beams of X-rays which are substantially collimated by an array of grazing incidence mirrors to produce a plurality of output X-ray beams which are spaced from one another at the output of the collimator and which are projected in substantially parallel relation to one another toward the mask. Each output beam exhibits a small divergence which causes the several output beams to merge into a single, comparatively large cross-sectional area, composite beam of X-rays at a plane spaced from the collimator. The mask is positioned substantially in said plane for illumination by the composite beam of X-rays. Filters are provided, preferably in the region between the mask and the collimator, for adjusting the spatial uniformity and spectrum of the composite beam.

Laser recording apparatus

Abstract: A laser recording apparatus includes a laser optical unit having an integral combination of a laser for emitting a laser beam and an optical system for converting the laser beam into an expanded and collimated beam; a deflector unit for directly receiving the laser beam emergent from the laser optical unit and directing the laser beam toward a recording medium; a photoreceptor unit having an integral combination of a reflecting member for reflecting the laser beam deflected by the deflector unit and a photoreceptor for receiving the laser beam reflected by the reflecting member; a support member having standard portions respectively for mounting the laser optical unit, the deflector unit and the photoreceptor unit.

Ion-beam lithography for IC fabrication with submicrometer features

Abstract: We report an entirely new pattern‐replication technique for IC fabrication. It has demonstrated submicrometer (<0.5 μm) resolution and it has the capability of large throughput (wafer‐levels/h). It utilizes high‐energy protons as the exposing radiation through a mask placed in proximity to a wafer covered with resist. We call this new technique ’’ion‐beam lithography’’ (IBL). System parameters and measurements relevant to the use of IBL as a production technology are discussed and SEM micrographs of submicrometer patterns in PMMA are presented. The technique is similar to x‐ray lithography, in that a pattern is produced in a thin resist film after exposing it to radiation through a mask. High‐energy protons have the same advantage as x rays in eliminating wavelength diffraction problems which limit the resolution of photolithography. Also, a gap (∠15–25 μm) is permitted between the mask and wafer. Ions have an advantage over x rays in that penumbral distortion is avoided by using highly collimated ion beams which are available with present state of the art; ions are collimated using conventional ion‐optical techniques, whereas use of a distant ’’point’’ source is the only feasible scheme for collimation of x rays.

Preform index profiling (PIP).

Abstract: An automatic and nondestructive focusing method to determine the refractive index distributions of optical fiber preforms is presented. The preform is immersed in index matching oil, and collimated light is passed transversely through it. The intensity distribution of the transmitted light is detected with a vidicon camera equipped with a low f-number lens focused just outside the core boundary. Recording and processing of the light distribution follow with the aid of a computer-controlled video-analysis system. The refractive index profile of the preform is computed from the intensity distribution, plotted, and fitted with a power-law curve within several minutes time. The repeatability of the index measurement is better than 1%, and excellent agreement is obtained with profiles determined interferometrically using slab samples from the tips of the same preforms.

Zoom light apparatus

Abstract: A zoom lighting device for projecting a generally rectangular illumination pattern whose size can be selectively changed. The device comprises a paraboloidal reflector and an artificial light source which cooperate to provide a collimated to nearly collimated beam of light which is circular in cross-section. The circularly-shaped light beam is intercepted by a pair of movably mounted crossed lenticular screens that are optically structured to change the circularly-shaped beam to a diverging generally rectangularly-shaped beam whose angles of divergence can be selectively changed by moving the screens relative to one another.

Method and apparatus for measurement of reradiation in particle flow cell systems

Abstract: Measurement of the energy and direction of radiation, typically scattered light, produced by particles passing through an optical sensing zone is improved in focusing of the scattered light and flexibility in the choice of focal length for positioning of photoresponsive devices. The improvement is obtained by collimating the collected scattered light entering a deviating device, typically a fresnel prism, and then focusing the emerging separate, independent beams for measurement. Collimation can be obtained using optical elements including lens systems or reflective systems such as those employing parabolic reflection.

Multispectral scanner optical system

Abstract: Disclosed is an optical system for use in a multispectral scanner of the type used in video imaging devices. Electromagnetic radiation reflected by a rotating scan mirror is focused by a concave primary telescope mirror and collimated by a second concave mirror. The collimated beam is split by a dichroic filter which transmits radiant energy in the infrared spectrum and reflects visible and near infrared energy. The long wavelength beam is filtered and focused on an infrared detector positioned in a cryogenic environment. The short wavelength beam is dispersed by a pair of prisms, then projected on an array of detectors also mounted in a cryogenic environment and oriented at an angle relative to the optical path of the dispersed short wavelength beam.

Double Purkinje eye tracker

Abstract: An eye tracker measures the point in space on which the eye is fixated. An input mirror reflects an input image into the eye and directs the Purkinje images so formed in the eye back into the eye tracker mechanism. The images are gathered by a collimating objective and directed through focusing and deflecting optics so as to be incident on light flux measuring devices (photodetectors). The optics and detectors are connected in closed loop servo systems which keep the first and fourth Purkinje images centered on their respective photodetectors, keep the input beam properly positioned in the eye, and at the same time generate signals responsive to movement of the first Purkinje image to give a measure of both translational and rotational horizontal and vertical eye movement and movement of the fourth Purkinje image to give a measure of purely horizontal and vertical eye movement. Circuitry combines the signals to generate a measure of purely translational horizontal and vertical signals. The first Purkinje image is also directed to be focused nominally at a given focal distance. Light flux measuring devices are positioned equal distances before and behind the given focal distance, whereby the output signal from the devices provides a measure of focus and axial position of the eye and the difference in output signals is used in a servo system to drive the collimating objective, thereby to focus the first Purkinje image at the given focal distance.

Phase sensitive spectrum analyzer

Abstract: Apparatus is provided comprising a laser source, collimating optics for collimating light provided by the laser source, focusing optics for focusing the collimated light provided by the collimating optics, and a detector array disposed at the focal plane of the focusing optics. Two surface acoustic wave transducers are disposed adjacent to one another and adjacent to an optical path between the collimating and focusing optics. The surface acoustic wave transducers are individually connected to antennas which are oriented substantially parallel to one another. The surface acoustic wave transducers launch surface acoustic waves which interact with the laser light and cause the light to be deflected in proportion to the amplitude and frequency of signals applied to the surface acoustic wave transducers by the antennas. The beams deflected by the two surface acoustic waves result in an interference pattern created at the detector array. A microcomputer is provided and coupled to the detector array for comparing the amplitude of the main sidelobes of the interference pattern which is indicative of the direction of arrival of energy received by the two antennas.

Broadband optical radiation detector

Abstract: A method and apparatus for detecting optical radiation by optically monitoring temperature changes in a microvolume caused by absorption of optical radiation to be detected. More specifically, a thermal lens-forming material is provided which has first and second opposite, substantially parallel surfaces. A reflective coating is formed on the first surface, and a radiation-absorbing coating is formed on the reflective coating. Chopped, incoming optical radiation to be detected is directed to irradiate a small portion of the radiation-absorbing coating. Heat generated in this small area is conducted to the lens-forming material through the reflective coating, thereby raising the temperature of a small portion of the lens-forming material and causing a thermal lens to be formed therein. The thus-formed thermal lens is optically detected by irradiating the thermal lens by a collimated light beam. The light beam, after having passed through the thermal lens, is reflected by the reflective coating back through the thermal lens, and directed by a beam splitter to an optical detector. In a further embodiment of the invention, the optical radiation to be detected is passed through a template, thereby defining a plurality of areas on the radiation absorbing coating to be irradiated. A corresponding template is provided in a spread, collimated light beam to define a plurality of coherent light beams, each of which passes through a thermal lens in the lens-forming material. Each beam is then reflected by the reflective coating, passes back through the thermal lens, and is directed by a beam splitter to an optical detector. The invention is particularly useful as a broadband infrared detector.

Performance of a directional detector of molecular density

Abstract: A directional detector of molecular density was developed and applied to the measurements of angular distributions of desorbed molecules from Mo surfaces and outgassing rates from small test surfaces. The detector is composed of a mass spectrometer installed in a detector chamber and a collimator set on the entrance of the detector chamber. The collimator has two apertures and a pumping surface between them. The performance of the collimator is analyzed and compared with experiment data. The ratio of the incident flux intensities of molecules to the detector coming directly from a test surface to the one of chaotic background molecules, collimation efficiency, depends on the pumping speed of the collimator and the bell jar. When the pumping speed of the collimator is increased by cooling the inner wall and/or deposition of evaporated Ti on it, the collimation efficiency can be increased by the factor of 102.

Integration sphere type turbidimeter

Abstract: An integration sphere type turbidimeter having a cylindrical sample cell passing through an integration sphere and an optical system disposed so as to permit a collimated beam of light to be projected into the sample cell from one end to the other end thereof, whereby the diffused rays of light produced by the dispersed particles in the sample liquid are substantially completely picked up by the integration sphere.

Angular intensity of a gas‐phase field ionization source

Abstract: Angular intensities of 1 μA sr−1 have been measured for a gas‐phase field ionization source in an optical column under practical operating conditions The source, which was differentially pumped and cooled to 77 K, utilized a 〈110〉‐oriented iridium emitter and precooled hydrogen gas at 10−2 Torr The ion beam was collimated with an electrostatic lens and detected below an aperture subtending 0164 msr A transmitted current of ∼10−10 A was measured at voltages corresponding to a field of ?22 V/A at the emitter

Method of inspecting the surface of an object and apparatus therefor

Abstract: This invention discloses inspection apparatus for detecting unfavorable foreign matters existent on the surface of an object such as semiconductor wafer. The apparatus includes a collimated beam generator portion which projects a collimated beam towards the object to-be-inspected from a side thereof, and a mechanism which senses light reflected from the surface of the object, through a polarizer plate. In accordance with this invention, the signal-to-noise ratio between a detection signal generated by a pattern of the foreign matter to-be-detected and a signal generated by a normal pattern of the object surface and sensed as a noise component can be enhanced.

Pattern generating entertainment device

Abstract: A collimated light source, preferably coherent, is directed at an optical system comprising a plurality of controllably rotatable mirrors, the source going from one to the next in seriatim, and each mirror being mounted a small number of degrees "off" the optical axis, so as to oscillate upon rotation. With the rotational speed of each mirror individually controllable, a substantially infinite number of patterns can be generated. Further variations in pattern generation can be achieved with a beam clipper, pulse modulation by an analog (e.g. audio) signal, and/or other known beam-modifying devices. A preferred embodiment is adapted for entertainment purposes and employs a low-power laser and three mirrors. Other applications include pattern-recognition testing of individuals for optometric or psychological purposes.

Apparatus and method for determining the refractive characteristics of a test lens

Abstract: An automatic lensmeter (48) for determining the refractive properties of a test lens (76) including optics (52, 58, 62, 64, 68, 70, 72, 74) for producing a collimated, nonrotational beam of light, equally disposed about and propagating along an optical axis (50), which is refracted by the test lens (76), a nonrotational mask (18) having an annulus (24) for generating a stationary elliptical loop (28) of light at a detecting plane (26), the loop (28) having a shape, size and location dependent on the refractive properties of the test lens (76), and a photodetector (31) at the plane (26) to intercept the loop 28. The lensmeter (48) has no moving optical components and, due to the loop 28, provides an infinite number of points to determine very accurately one or more of the refractive properties, thereby overcoming problems with prior automatic lensmeters having relatively rotational optics and/or providing a finite number of points at a detecting plane.

Refractive-index profiling of single-mode optical fibers and preforms.

Abstract: The application of the focusing method to measure the refractive-index profiles of single-mode optical fibers and preforms is described. In this automatic and nondestructive technique, the fiber or preform is immersed in index-matching oil, and collimated light is passed transversely through it. The intensity distribution of the transmitted light is detected with a video camera and processed with the aid of a computer-controlled video analysis system that provides the profile within a few minutes. The profiles of boron-doped and germanium-doped fibers and preforms with maximum Δn varying from 0.0006 to 0.012 were measured with a repeatability of better than 1% and with a resolution better than 1 μm. The profiles of the preforms are in good agreement with those of the fibers and also with those of slab samples taken from the tips of the same preforms.

Non‐destructive investigation of texture by neutron diffraction

Abstract: Texture measurement as a function of depth with a collimated thermal neutron beam is demonstrated for a `two-layer plate' geometry sample with preliminary results for a copper cone.

Electro-optical level

Abstract: A U-shaped device wherein the presence or absence of a transparent liquid or solid between the legs of the U is sensed. The device utilizes a collimated light source mounted in one leg of the U with an associated limited field of view sensor in the other leg of the U-shaped device. The light source is placed so as to cause the transmitted light beam to strike the surface of the material to be sensed at an angle which is substantially off of a line perpendicular to the surface of the sensed material. The light sensor is placed so as to receive the light beam when there is no liquid or solid material present between the source and the sensor and to prevent the refractively bent light beam from striking the sensor when a transparent liquid or solid is placed between the light source and sensor. The presence or absence of a transparent liquid or solid between the light source and sensor is indicated by an electronic circuit which provides current pulses to drive the light source and amplifies the light sensor current sufficiently to be able to drive a visible light emitting diode or acoustic warning device.

Surface deformation image device

Abstract: A device capable of spatially modulating a collimated read-out light beam with an input image is described. The most essential elements of the key unit in this device include a photoconducting layer, charged grille-structure, an elastomer, and a thin metal anode. Real-time and storage operation is possible.

Method for measuring the density of lightweight materials

Abstract: This invention relates to a nondestructive method for measuring the density of articles composed of elements having a low atomic number such as plastic and carbon composites. The measurement is accomplished by striking the article with a collimated beam of X radiation, simultaneously monitoring the radiation scattered and the radiation transmitted by the article, then relating the ratio of the radiation scattered to the radiation transmitted with the density of the article. The above method is insensitive to all variables except density.

Mask lighting optical system

Abstract: PURPOSE: To provide a system of high aggregating efficiency by providing a convergent collimation lens between an elliptical mirror and an optical integrator and matching the front side focus of this lens roughly to the 2nd focus of the elliptical mirror. CONSTITUTION: A light emitting tube 1 has a high-luminance light source (a) which emits ultraviolet rays and far ultraviolet rays, and this light source (a) is positioned at the 1st focus of an elliptical mirror 2. The elliptical mirror 2 forms the image a' of the light source (a) in its 2nd focus position. A cold mirror 3 transmits the greater part of infrared light, and reflects far ultraviolet rays. the collimation lenses 4 consisting of two positive lenses are disposed in alignment to the image a', and make the light from the image a' to parallel luminous fluxes. An optical integrator 5 for forming multiple secondary light sources are disposed in said luminous fluxes. A positive lens 6 and a stop 7 are provided just behind this integrator 5, and the luminous fluxes reflected by a reflecting mirror 8 are condensed onto an object surface 10 by a collimator lens 9. COPYRIGHT: (C)1981,JPO&Japio

NBS reference hazemeter: its development and testing.

Abstract: A research hazemeter has been developed by the Radiometric Physics Division of the National Bureau of Standards for the quantitative analysis of light scattering by optical materials. The instrument is designed to measure percentage haze as set forth in the prescribed conditions recommended in ASTM Test Method D 1003. The hazemeter has several special features which make it possible to vary the geometrical conditions of the collimated light beam and the integrating sphere detector system for detailed studies of light scattering. Light scattering associated with the instrument source and collimating optics has been reduced to less than 0.1% of the total light beam by using a diffraction limited off-axis parabolic mirror to collimate the hazemeter light beam. The source optics provide a collimated light beam of approximately 6800 K. The detector is a silicon cell photodiode with a V(λ) window. This combination gives the system a response corresponding to the visual luminosity function. The detector nonlinearity and instrumental errors associated with the accuracy of the integrating sphere geometry have been analyzed. The over-all uncertainty in percentage haze has been reduced to ±0.2%, and light scattering of less than 0.5% can readily be measured.

Efficient frequency converter utilizing higher order Stokes-Raman scattering

Abstract: A device for translating the frequency of the energy contained in a laser beam. Higher order Raman scattering is utilized to convert the energy in a laser beam into a collimated beam of radiation at a frequency removed from that of the original beam by an amount corresponding to the frequency shift exhibited by higher order Raman scattering processes. A Raman cell is utilized as a saturated amplifier at power density levels below that required for oscillation, so as to obtain efficient conversion. By selecting the path length within the Raman cell, nearly all of the energy exiting the cell is caused to appear in a single, higher order Stokes wave.