Showing papers on "Collimated light published in 1971"

Light scanning and printing system

Abstract: A light scanning system of controlled spot motion variation perpendicular to the direction of scan utilizing a rotating mirror and two cylindrical or toroidal lenses positioned relative to the rotating mirror to allow increased nominal axis of rotation to facet angular tolerances while maintaining a distinct non-overlapping line scan. Specifically, for one application the axis of rotation of the mirror is orthogonal to the plane formed by the incoming and reflected beam from the mirror. The first cylindrical or toroidal lens, which has little or no power in the scan plane, focuses the incoming beam in the azimuth perpendicular to the scan onto the mirror while the second cylindrical lens acts as a beam configurer to configure the beam to substantially collimated shape while directing it towards a spherical lens for focusing onto an image plane.

Target measurement system for precise projectile location

Abstract: A target system for measuring the location and diameter of a projectile in a frame of reference, including vertical and horizontal banks of light sources for projecting collimated beams of light across the target area, and corresponding vertical and horizontal banks of light receptors for indicating the location and diameter of a projectile passing through the target frame. A plurality of light receptors receive impinging light from each light source, each light receptor receiving a predetermined portion of a corresponding collimated light beam. When a light beam is interrupted by a projectile, the light receptors indicate the location and diameter of a projectile in increments less than the width of the collimated beam. Output signals from the light receptors are converted to numerically coded signals by coupling the output signals from the light receptors to a plurality of amplifiers, less in number than the number of light receptors, according to a predetermined coding pattern.

Non-contacting measuring probe

Abstract: A non-contacting optical probe capable of giving a continuous reading of the distance from a given reference to a contoured surface. A collimated beam is projected on a first optical axis to the surface to be measured. A second optical axis extends from the surface to be measured at an angle to the first optical axis. When the projected beam meets the surface at the point of intersection of the second optical axis, a reflected beam passes along the second optical axis to a sensor which detects this beam. The projected light beam and its optical axis are caused to reciprocate at an angle to the surface, this being accomplished by passing the collimated beam through a rotating prism. The prism is a regular polygon. A second sensor detects the rotation of the prism. The distance to the surface being measured is detected as the interval of time between the detecting of the prism position by the second sensor and the detecting of the reflected light beam by the first sensor.

Calculation of Second‐Harmonic Generation in a Piston Beam

Abstract: We discuss the nonlinear generation of a second‐harmonic component in the first‐harmonic beam from a circular plane piston, radiating into a fluid. First‐order perturbation theory is used; higher harmonics, absorption, and depletion of each harmonic are ignored, although a partial correction for the last two effects is applied later. The ratio of piston diameter to first‐harmonic acoustic wavelength is assumed to be about 30 or greater. In particular, the axial behavior of the second harmonic, which has marked structure, is found to agree well with experimental results in water. Also, the average value of the second‐harmonic field is calculated over a circle coaxial with the source, parallel to it, and of the same size. This average differs considerably from the result of an oversimplification that treats the first‐harmonic beam as cylindrically collimated plane waves. When compared with measurements in water, the average agrees well at a source pressure of 3 atm but progressively less well at 5 and at 6 ...

Scattering of Sound by Sound

Abstract: The debate about scattering of interaction‐frequency components when two sound waves interact at a non‐zero angle has not been resolved because no positive evidence of such scattering outside the interaction volume has been put forward. In this contribution, an attempt is made to review the situation in view of the available experimental evidence relating to interaction between a plane wave and a “collimated” pump wave.

Optical analyzer for microparticles

Abstract: There is described a method and apparatus for identifying submicroscopic particles by directing the particles through a highly collimated beam of light and simultaneously measuring the light intensity at a plurality of different angles relative to the point where the particles move through the beam.

Electro-optical incremental motion and position indicator

Abstract: A compact electro-optical system provides electrical signals for indicating extent and direction of incremental movement. By employing a plurality of moire fringe-generating grating pairs in optical series, the system eliminates the need for a collimated light source or imaging optics, and further provides a multiplication of sensitivity.

Visual display arrangements

Abstract: Visual display apparatus, particularly for an aircraft flight simulator or other vehicle motion simulator, providing a wideangle, collimated visual display for one or more observers, for example trainee pilot and co-pilot. The apparatus includes an optical projector, a large concave mirror and a curved optical element between the observer and the mirror. The projector projects an image onto the optical element, the image being viewed after reflection, and collimation, by the mirror. The optical element is of special construction so that it serves as a projection screen but permits reflected light from the mirror to pass therethrough. In one particular construction, the optical element is a spherical surface having strip-like diffusing and deflecting grooves with intermediate window strips.

Thermal transient effects in optically pumped repetitively pulsed lasers

Abstract: An approximate formulation of the thermal transient effects in laser rods, such as the temperature distribution in the laser rod and the effect of rod distortion on a collimated light beam passing through the rod, is described. Also, a computation is made for a practical case and compared to experimental results.

Lens Aberration Correction by Holography

Abstract: The correction of lens aberrations using a hologram made with a collimated reference is discussed. Two geometries in which the theoretical third-order hologram aberrations may be avoided are demonstrated. The results of experiments which demonstrate the aberration correction using the Ronchi and DeVany tests are presented.

Optical scanning assembly with helical-shaped rotating reflector

Abstract: An optical scanning assembly employs a reflector constructed in the form of a cylindrical helix which is rotatable about the axis of the helix. A light source is arranged to direct a collimated beam of light parallel to the helix axis, so that the light beam strikes a first reflective surface of the reflector. Depending upon the angle of the reflective surface of the reflector with respect to a radial line of the cylinder, the beam of light from the light source will be deflected away from the axis of the cylinder in a predetermined direction. The light then strikes a desired surface and may be reflected therefrom into the photosensitive element for further processing. Because of the rotation of the helix-shaped reflector, the light beam from the light source is scanned back and forth along the line parallel to the helix axis.

Automatic electron microscope field counter

Abstract: Electron microscope stage is equipped with remotely controlled stepping devices; cycling signals cause presentation of successive fields, whose image is fed by fiber optics to a television image tube, such as an image orthicon, or an intensified vidicon. Image seen by orthicon is reproduced on oilfilm light-valve. Coherent collimated light is fed through oilfilm to a transform lens, located its own focal length from oil film; transform filter is transparent only to transform of particular shape to be identified, and is located at back focal plane of transform lens. Imaging lens is located with its front focal plane at filter; viewing screen at back focal plane of imaging lens shows field corresponding to microscope field, with light spots showing where objects matching filter in shape and size appear in field. Automatic spot counting plus automatic indexing of stage provide automatic field count.

Acousto-optical system with simplified optics

Abstract: In the preferred embodiment of disclosed acousto-optical systems, a collimated beam of coherent light is projected from an entrance pupil through a beam of sound to an exit pupil. The light beam is diffracted by the sound which propagates transversely to the light beam. A cylinder lens is disposed at the entrance pupil to spread the light in a direction that is parallel to the propagation of the sound. Confocal with the cylinder lens is a spherical lens that recollimates the light in the direction of sound propagation while at the same time focusing it in a direction perpendicular to the sound beam. Another spherical lens, located beyond the sound beam, serves to concentrate the diffracted light beam in the direction of sound propagation, and a further cylinder lens system, disposed at the exit pupil and confocal with the second spherical lens, recollimates the light beam.

Laser beam probing of jet exhaust turbulence.

Abstract: A He–Ne (6328-A) laser beam was passed through the highly turbulent region in the exhaust of a jet engine (J-57 with afterburner). Estimates of a structure constant that would characterize the turbulence in the exhaust are made from the beam spread of focused and collimated beams. The structure constant obtained in this manner is then compared with that determined from scintillation measurements of a (10.6-μ) beam and with the results of hot-wire anemometer readings taken in the exhaust. The various methods yield results for the structure constant that are in good agreement (typically a structure constant of the order of 3×10-5m-13).

Light transmission monitor

Abstract: An opacity monitor for measuring the light transmissibility of gases in a furnace stack wherein a collimated light source is directed through the stack, a pair of photocells disposed to measure respectively the intensity of the source and the intensity of the light after it passes through the stack, the two measurements being balanced for normal conditions and the ratio of the two measurements being used as an indication of the opacity of the stack gas.

Absorbed dose, dose equivalent and LET distributions in cylindrical phantoms irradiated by a collimated beam of monoenergetic neutrons.

Abstract: A Monte Carlo code was used to study dose and LET distributions, in a specially designed tissue-equivalent cylindrical phantom, due to cylindrical beams of neutrons collimated to diameters of 5 cm. Dose due to ions produced by neutron interactions and dose due to (n, gamma) interactions for neutrons of energy 0.025 eV and 1, 5, 7 and 14 MeV are determined separately and are compared with broad-beam results. LET spectra are given for selected regions inside the phantom. Doses at the front of the phantom, in the center of the restricted beam, were found to approximate those of a broad beam for 14 MeV neutrons and to decrease with decreasing neutron energy, converging to a value of 80–85% of those for broad beams at 1 MeV. Dose from recoil ions averaged over a region 1 cm thick, immediately outside the volume of the incident beam, was found to be lower by- about an order of magnitude (for all energies except thermal, where a factor of 4 was observed) as compared with dose at comparable depths within the beam.

Supercollimation of Negative Ion Beams with Apertures

Abstract: A technique for producing highly collimated beams of negative ions using apertures is discussed. The application of the method produced a 30 μ diam H− beam with an angular divergence of 1.5 mdeg. The results of a study of the small angle scattering of protons from a carbon are presented. Other possible applications are outlined.

Achromatic depth-of-field correction for off-axis optical system

Abstract: Unmodulated, collimated white light is angularly directed to a target reflecting surface which is deformable to represent a subject, and the subject-modulated light reflected from the target surface is directed to a viewing screen by a schlieren optical system including a projection lens and a stop at the focal point of the lens. A prism is located adjacent the real subject-bearing target surface for rendering the apparent target surface parallel, and the light reflected therefrom orthogonal, to the principal plane of the lens and the screen; and for so reducing any color dispersion of the reflected light as to obtain adequate resolution of the image of the subject projected onto the screen.

Direct reading optical leaf area planimeter

Abstract: SUMMARY An optical planimeter is described in which the light beam from a small source is collimated and subsequently focused on a photocell. It is shown that the area of even a thin leaf placed in the collimated part of the beam is measured accurately without the need for a correction for transmitted light. The instrument features linear response, digital read-out, high speed, good stability, five ranges of 50 up to 1000 cm2, and an accuracy of 1% of the range.

Simplified flat mirror scanner

Abstract: A system is disclosed for translating a collimated beam of light, such as that generated by a laser, into a raster scan on a planar target. The laser beam is directed at a first rotating mirror provided with a plurality of faces from which it is redirected toward a first stationary mirror with the first rotating mirror causing a linear sweep across the concave face of the first stationary mirror. From the first stationary mirror, the laser beam is directed toward a second multiface rotating mirror disposed beyond the focal point of the first stationary mirror. The second rotating mirror imparts a second scan direction to the laser beam which is substantially normal to the first scan direction. From the second rotating mirror, the laser beam is redirected toward a second stationary concave mirror from which it is redirected in a raster scan to a planar target disposed at a distance from the secondary stationary mirror at which the beam is substantially in focus. A line scan embodiment of the invention is achieved by directing the beam from the laser directly onto the second rotating mirror.

Device for optically measuring a dimension of an object

Abstract: An apparatus for measuring a dimension of a physical object and comprising means for producing a collimated beam of light having a dimension at least as large as acceptable variations in the dimension of the object being measured, means for dividing the collimated beam of light into spatial digits, and means for counting the digits of light, the latter means spaced from the light beam source sufficiently to accommodate therein between the portion of the object to be measured.

Time-Dependent Multiple Backscattering

Abstract: Multiple backscattering of pulsed light is formulated for linearly polarized incident radiation. The method is based on the selection of a particular geometry in which the primary and nth order backscattering return to the receiver simultaneously. It is shown that the returned power from water clouds at a range of 1 km due to orders of scattering higher than the second may be neglected in a collimated pulsed lidar system whose field of view is less than 10−2 rad.

Erration storage system with collimated electron beam for minimal spherical ab

Abstract: A storage system for the mass recording and readout of digital data with ultra high resolution. An electron beam structure is provided for forming a beam of extremely small focused spot diameter, on the order of 0.1 microns, and high current density capability, on the order of 1,000 amperes per sq. cm., which records data by scanning over defined areas of the storage medium surface and micromachining elemental portions of said medium as a function of beam modulation. Readout may be subsequently accomplished by similarly scanning the beam at reduced power density and detecting electrons that have been transmitted by or reflected from the storage medium.

Multi-axis optical alignment system including a spatial filter

Abstract: A MULTI-AXIS OPTICAL ALIGNMENT SYSTEM USING A HOLOGRAPHIC LENS. A SPATIALLY FILTERED, COLLIMATED BEAM OF LIGHT IS DIVIDED BY THE HOLOGRAPHIC LENS INTO THREE DISTINCT PATH, AN UNDIFFRACTED BEAM, A CONVERGING BEAM, AND A DIVERGING BEAM. THE UNDIFFRACTED BEAM INTERCEPTS A POSITION-SENSITIVE PHOTODETECTOR TO MONITOR LINEAR DISPLACEMENT AND THE CONVERING BEAM IS FOCUSED ON A SIMILAR DETECTOR TO MONITOR ANGULAR DISPLACEMENT. THE DIVERGING BEAM IS DIRECTED THROUGH A WOLLASTON PRISM AND DETECTOR ARRANGEMENT TO MONITOR DISPLACEMENT ABOUT THE ROLL AXIS. TWO METHODS FOR MAKING THE HOLOGRAPHIC LENS USED IN THE SYSTEM ARE DISCLOSED.

Angular alignment error measuring system

Abstract: Collimated light is directed to a mirror mounted on a missile gimbal system and to a mirror mounted on a navigation optical reference Any angular deviation from the ideal missile alignment results in light reflected from the mirrors non-parallel to the directed light The angular variation is detected by a sensor in the collimator and the light beam is deviated by a wedge drive unit until the light is normal to the reflector An electrical signal is generated proportional to the light beam angular compensation, to realign the missile This invention is an improvement to the previously used angular alignment system; the improvement comprising fixed azimuth error indicator station assemblies, one station assembly mounted between each pair of missiles in a longitudinal or series array of missiles within the submarine Each station assembly has a pair of reflectors assembled as a pentamirror, directing the collimated light to either the port or starboard missiles, or the pentamirror can be arranged to pass the light through to the next successive station, and each station assembly has a pair of wedge drive assemblies to deviate the light and measure the missile bearing misalignment angle of the port and starboard missiles

A Simple Inverting Interferometer

Abstract: A simple, common path inverting interferometer is described. The interference pattern shows the anti-symmetrical wavefront error about the axis of inversion and the path difference is always zero at the centre of the pattern. It is shown that, in this interferometter, collimation errors have negligible effect. The interferometer is suitable for testing concave mirrors and convex lenses.

Multiple-Scattering Model for Light Transmission through Optically Thick Clouds*†

Abstract: A linear-system model has been developed to predict irradiance distributions of visible light below an idealized optically thick atmospheric cloud, which is illuminated from above in an arbitrary manner. The model offers elegant mathematical simplicity at the expense of some precision. As such, it is applicable to a broad class of problems in which correct functional forms are required, but levels of accuracy better than a factor of 2 are not necessary. Optical thicknesses can range from about 5 to 32. One example of a problem in this class, the design of a laser communication system to operate through clouds, provided the original motivation for development of the light-transmission model. The optical effects of the cloud are calculated by means of a four-dimensional linear superposition integral, which takes account of multiple scattering. Two illustrations of the method are given in detail, with incident illumination represented by a tightly collimated beam and by a sum of infinite plane waves, respectively.