Abstract: An optical switching device is described which comprises a substrate of light absorbent material, a plurality of holes defined through the substrate containing a liquid material having an index of refraction which is highly temperature dependent within a selected temperature range of operation, the liquid-filled holes defining a plurality of waveguides for conducting light through the substrate.

Abstract: A high resolution infrared densitometer system is described which comprises an intense thermal light source, an optical system for projecting first and second images of the light source along respective parallel first sample and second reference optical axes, adjustable optical attenuators for selectively balancing the light intensity of the images projected along the sample and reference axes at selected optical density, a spectrometer for filtering background radiation from the projected images except for a selected wavelength, and a detector for measuring intensities of the filtered projected images. A method for making optical density measurements is described.

Abstract: High total transmission, tunable comb filter structures are described which comprise moderately thick layers of optical material having periodic or multiply periodic refractive index modulation features comprising a multiplicity of coherently-coupled, weakly-resonant optical cavities, resulting in and characterized by spectra of high order (5 or higher) relative to a fundamental (lowest order) cavity resonance, consisting of narrow, moderate to high density reflection lines occurring in one or more sets, each set being characterized by lines equally spaced by wave number if optical dispersion is neglected. Filters of the inversion can be structured to be tuned, electro-optiRIGHTS OF THE GOVERNMENTThe invention described herein may be manufactured and used by or for the Government of the United States for all governmental purposes without the payment of any royalty.

Abstract: High total transmission, tunable comb filter structures are described which comprise moderately thick layers of optical material having periodic or multiply periodic refractive index modulation features comprising a multiplicity of coherently-coupled, weakly-resonant optical cavities, resulting in and characterized by spectra of high order (5 or higher) relative to a fundamental (lowest order) cavity resonance, consisting of narrow, moderate to high density reflection lines occurring in one or more sets, each set being characterized by lines equally spaced by wave number if optical dispersion is neglected. Filters of the invention can be structured to be tuned, electro-optically or mechanically such that the peaks within a spectral band of interest shift by one harmonic order and/or from one peak position to the next, to reflect or transmit light of any specific wavelength within a band.

Abstract: Solid propellant test strands are inhibited, i.e., prevented from burning in an uncontrolled fashion, by coating the strands with a liquid composition containing a partially cured phenolformaldehyde in a volatile solvent, then volatizing the solvent.

Abstract: A propellant sample combustion apparatus employing a multiply optical ported pressure vessel for sample illumination, sample viewing, and sample burn face elevation is described. High-speed motion picture filming using short-duration high-intensity laser provided optical illumination from a copper-vapor laser is employed. Details of the employed pressure vessel, a burn inhibiting coating for the propellant sample, a laser coherence spoiler, and a sample level maintaining closed-loop apparatus are also disclosed.

Abstract: A trigger circuit arrangement for controlling the operation of a metal vapor laser in conjuction with a high-speed motion picture camera. The disclosed circuit accommodates acceleration, deceleration, speed jitter, and the desired presence of marker images in the camera system while also accommodating temperature maintenance, double triggering prohibition, moderate trigger pulse energy requirements, and accurate synchronization requirements in the laser. The disclosed circuit employs conventional electronic components principally of the CMOS integrated circuit type, and utilizes magnetic transducer sensing of film transport movement.

Abstract: A propellant sample combustion apparatus employing a multiply optical ported pressure vessel for sample illumination, sample viewing, and sample burn face elevation is described. High-Speed motion picture filming using short-duration high-intensity laser provided optical illumination from a copper-vapor laser is employed. Details of the employed pressure vessel, a burn inhibiting coating for the propellant sample, a laser coherance spoiler, and a sample level maintaining closed-loop apparatus are also disclosed.

Abstract: An optical data correlator for the analysis of images of random fields is provided which comprises a light source for projecting a beam of light along a preselected optical axis, a first lens system for receiving the beam and focusing it onto a first image, a second lens system for receiving light transmitted by the first image and focusing the light so transmitted onto a second image, a third lens system for receiving light transmitted by the second image and projecting this transmitted light onto a photodetector, and suitable electronics including an amplifier and an analog-to-digital converter for analyzing the output of the photodetector and displaying the output in useful form. Spatial filters may be included to define the projected beam, and an alignment system preferably attachable to the second image may be included to selectively position the second image.

Abstract: A precise position control for maintaining the burn face of a propellant sample within a precise optical depth of field positional range during burn face recession that may be non-uniform in nature. The position control employs an array of laser excited binary signal optical sensors with closed loop digital and analog electronic signal processing.