Showing papers on "Collimated light published in 1972"

A Scanning X-Ray Microscope Using Synchrotron Radiation

Abstract: Focused synchrotron radiation collimated by means of a pinhole has been used to construct a scanning x-ray microscope capable of making stereoscopic element-discriminating pictures of relatively thick specimens in an atmospheric environment.

Encapsulated solid state light emitting device

Abstract: A light emitting device containing an encapsulated light emitting diode, in which the light from the diode is collimated by a reflector and in which the front face of the encapsulated diode is formed with a plurality of lenses which disperse the collimated light. The device can be viewed over a wide angle, for example + OR - 45*, without a readily apparent reduction in brilliance or size. An optical filter-for increased contrast for example-can be used. More than one diode can be positioned in a device. Variation in the form of the lenses provides increased luminous intensity for particular viewing angles and by accepting some loss in effectiveness, for example some sectoring, the viewing angle can be increased up to approximately + OR - 90*.

Underwater Light-Beam Propagation in the Small-Angle-Scattering Approximation

Abstract: The radiance N, resulting from an initially narrow collimated beam, propagating in the ocean, is investigated with the aid of the small-angle-scattering theory of electron scattering The resulting expression for N is calculated approximately and compared both with experiments and numerical calculations Various properties of the approximate expression for N are explored; an observer, located off the axis of the beam at an axial distance z from the source, who attempts to determine the direction to the source by seeking the maximum of N with respect to ray direction, would sight a point on the beam axis at a distance z/3 from the source

Coupler for optical waveguide light source

Abstract: A light coupler for transferring optical wave energy to or from light transmitting means including at least one optical waveguide. The coupler comprises a tapered core of transparent material of refractive index n1 and a layer of transparent cladding material of refractive index n2 disposed upon the surface of the tapered core, n1 being greater than n2. The tapered core has a large diameter end which is aligned with an end of the light transmitting means and a small diameter end which is disposed adjacent to electro-optic energy conversion means such as a light emitting diode, a light detector or the like. When used at the transmitting end of an optical communication system, the small diameter end of the tapered core receives light from a source, and the coupler functions to collimate those light rays which enter the small diameter end and which reflect from the core-cladding interface thereof.

Simultaneous two‐wavelength selection in the N2 laser‐pumped dye laser

Abstract: A technique is reported which allows simultaneous two‐wavelength selection in the N2 laser‐pumped dye laser. The two wavelengths are continuously tunable anywhere within the optical gain region of the particular dye solution used, and the two output beams are collinear and collimated, have mutually orthogonal polarizations, and in general can be temporally synchronized. Following the description of this device, the extension of this technique to other lasers and a few potential applications will be briefly discussed.

Scanning light synchronization system

Abstract: A scanning light synchronization system generates a real time clock, the output signal of which indicates the precise position of a scanning light beam. A collimated light beam is diverted by a multi-faceted rotating mirror in a scanning direction. The scanning light beam is split along two paths by a light diverter: a utilization path and a synchronization path. That portion of the light beam traversing the synchronization path scans an optical grating. That portion of the light beam passing through the grating is thereafter reflected from the surface of an elliptical mirror to a light detection device. The elliptical mirror is positioned so that its first optical foci is located at the diversion point of the scanning mirror and its second optical foci is located at the light detector. The light detector provides an output signal indicating the real time position of the scanning beam traversing the utilization path. This output signal is utilized with stored information to modulate the scanning beam so that the light beam traversing the utilization path creates an image on a light receptive surface. The output of the light detection device is also utilized in conjunction with light reflected from a document surface placed in the utilization path to effect the clocking of information signals obtained from such reflected light.

Variable field of view scanning system

Abstract: A system for transforming incoming radiant energy (e.g., in the infrared region) having different fields of view into a visible real time image. Two scanning mirror surfaces are supported on a common mounting element. An afocal optical section varies the field of view of the incoming radiant energy. The afocal section accepts incoming collimated radiant energy and produces exiting collimated energy having a different beam diameter thereby changing the field of view of the system without having to modify the basic scanning optics. The collimated radiant energy exiting from the afocal section is reflected from one of the scanning mirror surfaces onto a plurality of detectors. Video circuitry coupling the detectors with a plurality of emitters modulates the emitters to produce light therefrom to be reflected from the other of said mirror surfaces. The image thus scanned is focused on a vidicon thereby producing a video signal that is coupled to a television display which produces a visible image of the incoming radiant energy.

Experimental evidence of an x-ray laser.

Abstract: A three-stage neodymium:glass laser has been used to produce collimated x-radiation from an aqueous copper(II) sulfate gel. The 1.06-μm Q-switch pulse from the neodymium laser was focused by a cylindrical lens to a horizontal line traversing a microscope slide sandwich that contained a thin film of gel. The emission from the gel was detected as a 0.2-mm spot on shielded, standard x-ray photographic film at distances that varied from 30 to 110 cm from the sandwich. Spot size did not increase with distance, suggesting coherence of the x-rays.

Opto-electronic apparatus for measuring and controlling the concentration of solutions

Abstract: An improved opto-electronic apparatus for determining the concentration of solutions includes a probe having a prismatic immersion tip with at least two internally reflecting surfaces. A light-emitting means in the probe body directs a collimated beam of light through the prism toward a first reflecting surface of the probe tip, the incident beam making an angle with the first reflecting surface approximately equal to a critical angle of total reflection corresponding to the nominal index of refraction of the solution being examined. The included angle between subsequent reflecting surfaces is preferably approximately at least twice this critical angle. The light beam is reflected from a last reflecting surface toward an adjacent light receiving surface optically connected with a light-sensitive means in the probe body. Variations in the concentration of the solution in which the probe tip is immersed affect the intensity of the light beam finally reflected to the light-sensitive means, and the amplified output of the light-sensitive means provides a voltage suitable for use in measuring and controlling the concentration of the solution.

Method of exposure for ghost line suppression

Abstract: A photographic method and apparatus for exposing a light sensitive layer using a mask spaced from said layer while avoiding "ghost lines" due to diffraction effects in the developed pattern on the layer. The mask is illuminated by pairs of collimated ray sets, either sequentially or simultaneously, at an angle relative to each other so that the constituent diffraction pattern on the light sensitive layer resulting from one ray set of a pair is shifted with respect to the constituent diffraction pattern attributable to the other ray set of the pair. The shift is such that the ratio of the "ghost line" intensity to the maximum intensity in the composite diffraction pattern is reduced relative to the corresponding ratio in each of the constituent diffraction patterns. The pairs of ray sets are produced by spacially displaced fixed light sources or by a rotating optical system using a single light source.

Method and apparatus for recording and projecting holograms

Abstract: A method and apparatus for recording and projecting single color or multiple color encoded image-plane carrier holograms are described. An object is illuminated with a coherent collimated laser beam. The parallel spatially modulated rays are focused on a monochrome recording medium located in a recording plane with the rays maintained essentially parallel. A collimated reference beam, which is coherent with the object beam, is directed at the recording medium to form an image-plane hologram having a single discrete spatial carrier frequency in case of a single color laser or additional spatial carrier frequencies for as many colors as are in the laser. The processed image-plane hologram is projected by directing a generally collimated beam of incoherent white light upon the hologram to form separated wavefront reconstructions of parallel rays. A lens projects the parallel rays in a viewing plane after their convergence at a focal spot in a focal plane. A spatial filter located in the focal plane provides selection of desired color images and blocks undesired ghosts. A control for moving and adjustment of the spatial filter is provided to attain hue and saturation control as well as brightness of the projected image. An embodiment for recording of image-plane holograms of diffuse objects or diffusely illuminated objects as well as three-dimensional objects is described.

Bragg Diffraction Sampling of a Sound Field

Abstract: In this paper we describe a novel method of probing a sound field in three dimensions with a focused light beam. In our method, the spatial‐temporal modulation impressed upon the light by the sound is extracted by the use of either polarization sensitive elements or spatial filters placed in front of a photodiode. The technique is inherently capable of high‐resolution sampling because, as is shown, phase and amplitude of the resulting rf current are indicative of the complex sound pressure in a narrow region around the focus of the light beam. This is in contrast to earlier methods using a narrow collimated light beam which only give an indication of sound‐pressure amplitude and phase integrated over the entire width of the sound field traversed by the light beam. The first part of the paper analyzes the mode of operation and discusses sensitivity and resolution in a heuristic manner. The second part provides experimental results for various frequencies and sound media. The third part treats the rigorous theory.

Apparatus for scanning an underwater area

Abstract: The apparatus of this invention is designed to be generally operated from either a towed or self-propelled underwater vehicle. A nearly collimated beam of light from a rotating cylinder traces a narrow strip of the target area during each rotation. The strip is substantially perpendicular to the direction of travel of the apparatus. During subsequent rotations, a series of parallel strips are traced on the target area. The speed of rotation and corresponding raster scan on the display monitor is synchronized to the forward speed of the vehicle to which the apparatus is attached. The instantaneous field of view of the receiving optics is stopped down so that only the light from a small area at the center of the intersection of the collimated source beam and the target area is viewed. The size of this area corresponds to the minimum resolution element of the device. The location of the field stop of the receiving optics is a function of the viewing range, and is adjusted accordingly. The automatic gain control on the output signal from the photomultiplier tube compensates for the varying propagation losses due to varying path lengths in the mapping geometry. The intensity displayed at a particular spot on the video monitor or stored at a given location on the video tape is therefore a map of the optical reflectivity of the corresponding spot on the surface of the target area.

Physical Parameters in High-Accuracy Spectrophotometry.

Abstract: The measured apparent transmittance TA of a filter or liquid sample depends on the beam geometry in the spectrophotometer. For focused light incident upon the sample, TA is different for systems having different f-numbers, and also depends on the state of polarization of the light. These effects are eliminated when the incident light is collimated; in this case TA approaches the "true" transmittance τ of the sample. Both modes of operation suffer from stray light and interference effects. The former may be reduced significantly by using mirror rather than lens optics, and the latter by suitable choice of the monochromator slit width. A new spectrophotometer based upon the above-mentioned design principles is described. The photometric precision of this instrument is shot-noise limited, permitting measurements to better than 10-4 transmittance units. The double-aperture method of testing detector linearity to this level of precision is discussed. The conventional method of finding the nonlinearity correction can be replaced by a curve-fitting procedure giving better precision. Data on detector nonlinearity, and its dependence on wavelength, are presented.

Interferometer for testing telescope optics

Abstract: This is an interferometer of Twyman-Green type adapted for testing the optics of a stellar telescope. Coherent light from a source, such as a star, through the telescope is collimated and divided into a reference beam, and a main beam, which are, respectively, a fractional cross-sectional area of the collimated beam, and the remaining cross-sectional area thereof. The reference beam is expanded to be the same diameter as the main beam by an afocal telescope and the two are then combined in superimposed relation. The optical path lengths of the reference and main beams are made approximately the same and means is provided for cyclically lengthening and shortening the length of one of them at a predetermined rate so that one of the paths is cyclically shorter than, equal to and longer than the other. The combined beams are filtered and focussed to image the telescope pupil (usually the primary mirror) in a plane, and at least a pair of photodetectors in this plane detect the light respectively at different points on the image, and produce signals proportional to the light received. The signals from the respective photodetectors are compared as to phase when the signal is sinusoidal, or time delay when the signal is a pulse, to detect the deviation of the wavefront exiting the telescope from the ideal wavefront, such deviation being linearly proportional to aberrations of the telescope resulting from poor optical figure on the individual optical elements or misalignment of the telescope optics.

Aircraft armament alignment

Abstract: An alignment device for aligning the boresight axis of armament with the line-of-sight axis of an optical sight including a novel collimating apparatus for field use. The collimating apparatus includes a collimator and a collimated light beam generator. The collimator includes an objective lens having its optical axis parallel to one of the axes to be aligned, a translucent screen for rear projection and a projection lens between the objective lens and the screen. A remote collimated light beam generator includes a battery energized incandescent light bulb, a projection reticle, and an objective lens for collimating the light source, the optical axis of the lens being parallel to the second of the axes to be aligned. The angular displacement between the axes is indicated by the position of a light spot on the screen. The apparatus also includes fittings whereby the light beam generator is temporarily attached to the collimator housing in known relationship for checking the alignment of the optical elements by observing the position of the light spot on the screen.

Photometer optical system having viewing magnification and light attenuation means

Abstract: An optical instrument including means for selecting one of several magnifications of an image being viewed, the selective magnification means being positioned in a collimated light path between an objective lens and a viewing lens and without change of conjugate distances therebetween; also an aperture stop located at one conjugate plane of a relay lens, the other conjugate plane being the nodal plane of the objective lens, which serves as a light-attenuating means without interference with the viewing optical system or without affecting the field being measured.

Optical apparatus for producing and/or using photoconductive film having a specular surface selectively deformed in image areas thereof

Abstract: Optical apparatus to produce and/or use photoconductive and thermoplastic film having a specular surface selectively deformed in image areas thereof. A preferred form of this film is opaque. In one recording form of this apparatus an objective lens unit in an optical path defined by optical elements thereof receives a recording beam of light consisting of a bundle of light rays reflected from an image of a field of view, e.g., a flood lighted record sheet, and transmits this beam as an essentially collimated bundle of the rays bearing an image of the field of view to means holding such a film with its specular surface exposed in an optical aperture to this image-bearing beam. Electrostatic charge and heat applying means are located closely adjacent to, but spaced from the optical aperture to impose upon the film specular surface the electrostatic charge in a latent pattern corresponding to the darker areas of the image borne by the beam and to heat soften and deform by depression the electrostatically charged film surface areas which, upon cessation of radiation of the heat to this film surface, causes by cooling the temporary fixing or freezing of the deformed image darker portions to produce a rippled specular surface film. In another, projection form of the apparatus a projecting light source is associated with a beam splitter optically beyond such optical aperture and such an objective lens unit to project the bundle of light rays of an initial portion of a projection light beam from the beam splitter through the lens unit to such a rippled specular surface film exposed in the optical aperture. A secondary portion of this projection beam is then reflected back from the rippled specular surface of the film at the optical aperture along a common path through the lens unit to the beam splitter, where it is separated by the latter from the initial projection beam portion to be projected in focus to a display or read-out plane, such as a viewing screen. In still another form of the apparatus these recording and projection equipments or systems are combined to employ alternatively in the recording and projecting modes the same objective lens unit, the same film exposing optical aperture and the viewing screen which, in the recording mode, provides a support for any properly sized record sheet. A common light beam path is provided between the film exposing optical aperture and the viewing screen which has mounted therein between the beam splitter and the viewing screen a movable prism mount which selectively inserts into this path a common reflective prism in the recording mode and an amici prism in the projecting mode.

Dynamic Radiography A New Imaging Technique Using Penetrating Radiation

Abstract: One of the authors (ESK) and his students (Refs. 1-4) have, for several years, investigated system dynamics information contained in the gamma ray field emerging from an operating nuclear reactor core. Early experiments were directed along the lines of obtaining the sys-tem transfer function (frequency response). Either a driven perturbation or the natural noise generated in a neutron chain reaction represented the input to the system. The emerging gamma rays represented the system output. In later experiments, two highly collimated detectors were used to respond to the gamma rays generated in two narrow, intersecting channels through the reactor core. As with the earlier experiments, either a driven perturbation or natural noise phenomena can be used as dynamic system input. Selectivity in gamma ray energy detection and correlation of the two detector outputs yield information regarding the fission rate in the volume of intersection of the two channels under surveilance provided that the input process correlation is of dimensions on the order of (or smaller than) the volume of intersection.© (1972) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Reduction of X-Ray Dose by Variable Rectangular Collimation and Reflex Optical Direction of Dental X-Ray Beams and by the Supine Position of the Patient

Abstract: High-quality radiographic images and protection of the patient and operator from excess irradiation are requirements for any dental X-ray system. Two proposed techniques fulfill these requirements. A collimating device, designed to produce a rectangular X-ray beam of variable dimension, is used. The size, shape, and location of the X-ray beam is marked first by a projected light beam. This beam can be used to cast a shadow of the teeth on the film packet that is identical to the radiographic image. The X-ray tube is aimed vertically from above the patient who is in a supine position. Radiosensitive regions of the body are outside the path of primary radiation.

Method of detecting pinhole defects in sheet material

Abstract: Method of detecting pinhole defects in sheet materials for example tin plate, galvanized steel and thin metallic foils. A modulated ultra-violet light source is directed at right angles onto the advancing sheet material, the edges of the sheet material are shielded from both ambient and ultra-violet light, all non-ultra-violet light is shielded out from beneath the advancing strip, ultra-violet light which has been transmitted through the pinhole defects and said filtering is photomultiplied as a function of pinhole defects in the advancing material. The method is distinguished from prior art in collimating the ultra-violet light source so as to transmit the light at a right angle to the direction of motion of the sheet material and independently baffling the photomultiplier units with respect to each other, so as to define precise lineal zones of detection in said advancing material.

Method and apparatus for aligning an interferometer mirror

Abstract: A method and apparatus for aligning an interferometer mirror orthogonal to an incident collimated light beam is described. A retroreflector is placed in the collimated beam before the mirror so that a reference beam is obtained to which the light reflected by the interferometer mirror can be aligned on the view screen of the interferometer. Once adjustment has been achieved, the retroreflector can be removed.

Radiation source simulation means

Abstract: Advanced sensor evaluation and test apparatus comprises a vacuum chamber with an inner cryoshroud, housing an on-axis optical parabolic collimator, a radiant energy source assembly having an output aperture located in the focal plane of the collimator, a calibration monitor consisting of a Cassegrainian type radiometer that occupies one portion of the collimated radiant energy beam and which forms an image of the source on a bolometer, and a pair of scanning mirrors directing energy from another portion of the collimated beam into the entrance aperture of the optical sensor under test. In addition, a background radiant energy generator can direct radiant energy simulating elevated radiation background to the sensor under test which, in turn, forms an enlarged image of the background source in its own detector plane. One version of the source assembly includes at least one blackbody radiation source of variable aperture and temperature with a chopper operating to provide modulated radiation which is projected into an integrating sphere coupled with a source projector. An adjustable dual reflector with one specularly and one diffusely reflecting surface is mounted inside the integrating sphere and can be rotated to predetermined orientations to function in either a specularly reflecting mode or diffusely reflecting mode. In a third mode of operation, the mirror is rotated into an inactive orientation in which it does not intercept the beam entering the integrating sphere. This is the integrating sphere mode of operation. Another version of the source assembly includes at least one blackbody radiation source providing radiation to an integrating sphere coupled with a radiation guide (pipe). The radiation guide can be either a single or dual guide (pipe) and is cooperatively structured to operate with selected transmission patterns (transparent portions) on a movable disc sector positioned at the end of the guide.

Fluid film thickness measurement with moiré fringes.

Abstract: A mathematical analysis of the application of moire fringe contouring to fluid film thickness measurement is made. Two special cases are treated. The first considers the generation of contours with a collimated light source and distant observer. The second analyzes the fringe patterns viewed by an observer near the grid when there is a point source of light. Geometrical restrictions imposed on the experimental setup are detailed. Experimental results are included.

A method of and apparatus for analysing objects with two or three dimensional shapes and/or patterns

Abstract: 1293348 Photo-electric investigation of geometrical characteristics of objects SIRA INSTITUTE 10 Dec 1969 [10 Dec 1968] 58649/68 Heading G1A [Also in Division G2] The geometrical characteristics of an object e.g. shape or the pattern within its external shape, are analysed by a Fourier transform technique involving irradiating the object with a beam of electromagnetic radiation to form a diffraction pattern, particular areas of which are investigated to derive electrical signals representative of the object characteristics. The object may be a diffraction grating, target, scale, graticule, photographic transparency, or mechanical component, and a typical application is to compare the object with a standard object to detect differences therebetween (e.g. faults). Fixed objects may be analysed or a series of photographs of an article or articles on a production line may be taken on a moving, progressively developed, film which is passed through the apparatus for analysis. Optical apparatus. In one embodiment, Fig. 1, light from a laser 10, is chopped at 9, split into two beams by a prism or half-silvered mirror 12, and one beam used to illuminate object 4 and the other a similar (e.g. reference) object B. Each beam comprises a microscope objective 15 (or 23), a pinhole 16 (or 24), a collimator 17 (or 25) and a lens 18 (or 26) focusing the light diffracted by the object in the plane of a spatial filter member 19 (or 27), a detector e.g. photo-multiplier or vidicon tube 20 (or 28), picking up light transmitted thereby. A comparator 29 detects any difference in the detector output signals as indicative of differences between the spatial frequencies introduced into the respective beams by the two objects A, B. Thus a zero difference indicates identity of the objects. In a second embodiment, Fig. 7 (not shown), only one light beam and detector is used, with the two objects placed side by side in the collimated beam. A chopper member in the path cuts off the light reaching each object alternately. In a third embodiment, Fig. 8 (not shown) - another single beam arrangement - a single test object A in the collimated beam can give an absolute measurement value or a comparison measurement if a spatial filter 19 in the form of a photographic mask prepared by photographing the diffraction pattern formed by a standard object is also introduced. Devices for scanning different areas of the diffraction pattern are described and can be used, if required, in combination with a spatial filter 19. In one arrangement, Fig. 4 (not shown), a cone-shaped lens (30) is placed in the plane of the or each diffraction pattern, the spherical aberration of the lens causing spreading along the optical axis of the beam the foci of the different annular bands in diffraction pattern. An aperture (31), moving along the axis, thus allows different areas of the diffraction pattern to be passed to the detector (32) which moves with it. In Fig. 5 (not shown) an arrangement of annular photo-cells of increasing diameter is used, the outputs thereof being switched so as to scan continuously or incrementally annular bands in the diffraction pattern. The arrangement of Fig. 6 (not shown) as the same, but uses an annular aperture of continuously increasing diameter formed by a variable iris and a moving cone. An integrating sphere collects light passing through for detection by photo-cell(s).

A dc X‐Ray Fiducial Pulse Generator for Light‐Gas Gun Work

Abstract: Interruption of a dc x‐ray beam by a projectile has been used to produce a timing pulse for light‐gas gun work. A finely collimated x‐ray beam from a conventional dc x‐ray generator intersects the projectile path at the muzzle. This beam is detected by a detector consisting of a thin NaI(Tl) scintillator, a beam splitter, and two photomultiplier tubes. The projectile, as it leaves the gun barrel, interrupts the x‐ray beam; this results in a current drop from the photomultiplier tubes. Associated electronics convert this drop into a single electrical pulse. Response time of the electronics is approximately 3 μsec.

Acoustic Field of Circular Plane Piston in Limits of Short Wavelength or Large Radius

Abstract: The acoustic beam of a circular plane piston (radius a) is analyzed as it approaches either the short‐wavelength limit (SWL) or the large‐radius limit (LRL). Using a new expression for the beam, we show that with no absorption the SWL would be a cylindrically collimated beam, with radius a, of plane waves. If absorptive effects are minor, the chief deviations during approach to the SWL occur in two decreasing volumes, a horn‐shaped paraxial region and a cylindrical shell of mean radius a. One consequence is that any second harmonic, self‐generated in the beam, approaches its own SWL more rapidly than does the first harmonic. Approach to the LRL yields a known paradox: Even the piston's nearfield need not approach a uniform plane wave. We show that the presence of absorption does make the LRL a plane wave and that in the absence of absorption there is a valid reason for the paradox: The piston beam must have a unique axis of cylindrical symmetry; an unbounded plane wave cannot.

Thick window transmission spectrophotometer and method

Abstract: A spectrophotometer for ascertaining transmission of enery by a test piece and having a housing with a source of energy in the housing and means carried by the housing for forming an image limiting aperture. Optical means within the housing is provided for receiving energy from the source for forming a beam of energy and imaging the source in the aperture. Means is provided for chopping the beam. Filter means is provided for passing selected narrow spectral bands of energy in the beam. Optical means is provided for receiving energy passing through the aperture and includes collimating means and means for causing the beam to be tilted at an angle with respect to the test piece. Means including a detector is provided for receiving the beam after it has passed through the test piece. In the method, a beam of energy is provided which is collimated and is offset at an angle with respect to the test piece so that back reflected energy is substantially eliminated and will not influence the tests being made on the test piece. Tests are made with and without the test piece in the beam.

Focussed image holographic memory

Abstract: Apparatus for recording and retrieving graphical information comprising at least one laser and means for directing onto a light sensitive carrier two collimated beams of laser radiation are employed and superimposed images are recorded. The azimuth angle between the first and second beams is adjusted.