United States of America As Represented by the Secretary of the Air Force

United Technologies Corporation

Other

USA As Represented by Secretary of the Navy

Joseph M Geary

Phillip R Peterson

Dennis C Duneman

Raymond V Wick

Charles E Moeller

David F Holmes

Darius S Vunck

Charles G Hull-Allen

Ronald L Sessions

A method and apparatus for measuring scattered light reflectance. The apparatus comprises a plurality of individual light transmitting fibers having first receiving ends positioned at different angular locations about an object to be tested and second exiting ends positioned in a linear array. The apparatus can simultaneously receive different angular components of scattered light from the object being tested and convert the scattered light components into a linear array.

Fiber optic scatterometer for measuring optical surface roughness

An arrangement for testing a reflecting surface of a solid body, especially a relatively complex reflecting surface such as that of a grazing hyperboloid, for deviations of its actual shape from its ideal shape includes a laser source and a positive cylindrical lens interposed between the laser source and the reflecting surface to be tested. The lens optically modifies the laser beam in such a manner as to propagate between the lens and the reflecting surface substantially normal to the reflecting surface and to be reflected from the latter for propagation back to and through the lens toward the laser source as a return laser beam having a wave front indicative of the actual shape of the reflecting surface and any aberrations of the lens. The arrangement further includes an interferometer that forms an interference pattern between the original and return laser beams, and a circuitry for evaluating the interference pattern. The evaluating circuitry subtracts first and second reference signals respectively representative of the ideal shape of the reflecting surface and of the influence of the lens aberrations on the interference pattern from an initial signal representative of the sensed interference pattern.

Arrangement for testing grazing hyperboloids and similar reflective

An arrangement for testing a concave reflecting surface of a solid body, especially a relatively complex concave reflecting surface such as that of an X-ray barrel optics mirror element, for deviations of its actual shape from its ideal shape includes a laser source and a negative cylindrical lens interposed between the laser source and the reflecting surface to be tested. The lens optically modifies the laser beam in such a manner as to propagate between the lens and the reflecting surface substantially normal to the reflecting surface and to be reflected from the latter for propagation back to and through the lens toward the laser source as a return laser beam having a wave front indicative of the actual shape of the reflecting surface and any aberrations of the lens. The arrangement further includes an interferometer that forms an interference pattern between the original and return laser beams, and a circuitry for evaluating the interference pattern. The evaluating circuitry subtracts first and second reference signals respectively representative of the ideal shape of the reflecting surface and of the influence of the lens aberrations on the interference pattern from an initial signal representative of the sensed interference pattern.

Arrangement for testing complex concave reflecting surfaces for shape

A random wavefront is incident on an aperture plate with a double pinhole of variable separation that is followed by Fourier transforming optics which focuses an intensity profile on a detector array. The detector array is located in the Fourier transform plane of the Fourier transform lens. The time average of the intensity as a function of hole separation yields the root mean square phase and the phase correlation function of the applied wavefront.

Double pinhole spatial phase correlator apparatus

An arrangement for testing a cylindrical object, which may be constituted either by a reflective or refractive element capable of focusing collimated light into a focal line or by an elongated filament, employs cooperation of the element and of the filament, with a laser beam directed onto the element. The filament, especially an optical fiber, extends along the focal line of the element, so that a portion of the laser beam aimed at the element and focused thereby into a waist region extending along the focal line and thus onto the filament, is reflected back to the element and recollimated thereby for travel back along the path of the original laser beam, whereupon the return light beam is caused to interfere with the original laser beam and thus to provide an interferogram that can then be evaluated to obtain information about the magnitude and location of any deviations of the object being tested from its ideal shape.

Method of and arrangement for testing cylindrical objects for shape

An incident light field is applied to the two separate front fiber faces of a pair of identical optical fibers which are initially held in a common plane. One fiber face is always kept stationary. The other fiber face may be moved either laterally in a plane common to the stationary face, or longitudinally into and out of the common plane. The output end of the device comprises two separate rear fiber faces that are held in a common plane. These faces are stationary. There is no lateral or longitudinal motion of one relative to the other. The light emerging from these two faces interferes in the far field. Straight line interference fringes whose spacing depends upon the lateral separation of the rear fiber faces are formed. The fringe modulation, however, depends upon the relative position of the front fiber faces. This modulation changes as one front face is scanned either laterally or longitudinally. The modulation changes with such motion is related to the degree of spatial or temporal coherence of the incident light field.

Fiber optic coherence meter

An optical testing method and apparatus employing a non-interferometric technique, making use of axial intensity information, in which the intensity of the light pattern along the optical axis is calibrated to achieve improved measurement of spherical aberration.

Method of measuring spherical aberration and apparatus therefor

A method of photographically recording at high speed the far field pattern of a high energy infrared laser beam over a selected period of time for providing rapid repetitive samples of information on beam parameters such as far field beam intensity, jitter, and absolute beam size and power. A sample from a high energy infrared laser beam is directed into an enclosure that is light tight to visible radiation and contains an operating lensless movie camera loaded with suitable movie film. The infrared beam is focused on the film plane of the camera so that consecutive frames of the film are irradiated by the infrared beam each time the camera shutter is open. The period of irradiation is of sufficient duration to sensitize the film to visible radiation in the areas where the infrared radiation impinges on the film. The position of the camera shutter is detected and an electrical trigger signal generated just before the shutter is closed for each frame. The trigger signal is applied to appropriate circuitry which actuates a light source to generate a pulse of visible light that irradiates the film plane of the camera near the end of each shutter movement to expose each frame of the film. The exposed film strip is developed to provide a continuous record of the infrared laser beam characteristics over the selected period of time.

Method and apparatus for high speed, sustained recording of infrared

Turbulence measurement interferometer apparatus includes a station having an entrance pupil and an aerodynamically stable boom connected to the station. The station houses an optical mirror arrangement defining an optical axis which extends through the entrance pupil. The boom has an end point spaced from the station but disposed on the optical axis. A laser generates a low power beam which is split into first and second portions. The first portion is guided to the boom end point and launched therefrom as a spherical wavefront through turbulence in front of the entrance pupil and toward the mirror arrangement, which in turn transforms it into an object collimated wavefront. The second portion of the beam is transformed into a second collimated reference wavefront which is combined with the first collimated wavefront and produces an interference pattern which is recorded on a medium, such as a photographic plate. The interference pattern provides information on the turbulence structure present at the entrance pupil of the station.

Turbulence measurement interferometer apparatus

A light-scattering disc collector member useable in converting a classical (coherence-dependent) microdensitometer to a linear (mode) microdensitometer that is coherence-independent. The member is made of material that is transmissive, non-absorbing, and high scattering as to light, and it preferably comprises a right circular cylinder which is made opaque (such as with black paint), except for a light-transmissive entrance aperture which is located on one base of the cylinder and which is shaped as an inwardly formed hemispherical dome, and a light-transmissive exit aperture which is located on the other base of the cylinder in geometric alignment with the entrance aperture. When used to convert a classical microdensitometer to a linear microdensitometer, the light-scattering disc collector member replaces the objective of the microscope in the sensor optics assembly of the classical microdensitometer.

Light-scattering disc collector

A waveguide line spread function analyzing apparatus utilizing a scanning optical slab waveguide that is sandwiched between two opposing x-ray fluorescent screens to provide access to the fluorescent light which is trapped between the two screens.

Waveguide line spread function analyzing apparatus

Real time presentation and evaluation of any selected interferogram is realized by electronically simulating optical aberration patterns and displaying them on a cathode ray tube (CRT). The optical aberration patterns include PISTON; X and Y TILT; DEFOCUS; SPHERICAL; COMA; and ASTIGMATISM. The aberration patterns are generated electronically in response to the CRT beam sweep drive signal and are displayed as a function of CRT beam intensity. Any combination of aberration patterns, each having selectable coefficients, can be displayed. The aberration pattern coefficient values are indicated by a digital readout. Evaluation of an unknown interferogram is accomplished by varying aberration pattern combinations and coefficients until a substantial match with the unknown interferogram is achieved. The contributing aberration patterns are then known and their magnitudes are determined from the digital read-out.

Growing community of inventors

Edgewood, NM, United States of America

Joseph M Geary