Abstract: The device and method for performing an optical Hall test provide means for on-destructive measurement of free carrier concentration or effective mass in semiconductor materials using Faraday rotation spectra. A beam emitted by a Fourier transform infrared (FTIR) spectrometer is transmitted through the sample that is mounted between a polarizer and analyzer and the opposite poles of a magnet before finally being incident on a detector. The ratio of the samples's transmission spectrum with the magnetic field on to that with the magnetic field off is converted, through a suitable mathematical formula, to Faraday rotation. The rotation is, then, plotted versus the square of the wavelength. The slope of the graph at longer wavelengths is directly proportional to the carrier concentration and the effective mass. With one known, the other can be easily determined.

Abstract: A modulated Faraday rotation signal is produced by passing a linearly polarized laser beam through a semiconductor wafer sample in a modulated magnetic field that is induced in an electromagnet by a sine wave generator and driver coupled thereto. The rotation signal is normalized by dividing by a transmission signal produced by modulating the beam with a chopper that operates at a different frequency from the frequency of the driver. The result is a Faraday rotation measurement with high signal-to-noise ratio and compensation for laser drift in intensity.

Abstract: A method of copying a thick hologram, recorded at wavelength .lambda..sub.1, so that the copy can be efficiently read out with a beam .lambda..sub.3 at the same incident angle as used to efficiently read out the original. The method involves copying the hologram using wavelength .lambda..sub.2 at a predetermined incident angle, which incident angle provides fringe angles in the copy to yield maximum diffraction efficiency of the read-out beam .lambda..sub.3.

Abstract: A beamrider guidance system for missiles wherein a laser beam is given two circular motions around the boresight axis to produce amplitude and phase modulation on the signal received at the missile. The information on distance from boresight is contained in the amplitude modulation and the angular information is contained as phase modulation. A laser optical system with a spinning holographic element provides one of the circular motions for the beam. The other circular motion is provided by a low frequency, circular scanning mirror.

Abstract: Reference scenes stored in a filter set containing an array of sets of suimposed, holographic, matched filters are optically correlated with input images displayed on an optically-addressed, liquid crystal, light modulator 34. In operation, a selected laser diode is energized to direct a polarized light beam through the collimating lens L1 to the reflecting surface of a polarizing beam splitter 35. After reflecting off the beamsplitter surface, the beam is expanded by positive lens L2 and passed to the liquid crystal modulator. There it is modulated by the input image and reflected; after which it is recollimated by positive lens L2, transmitted by the beamsplitter, and directed to a particular array location of the filter set dependent upon which particular laser diode is energized. The filter set is positioned to be in the back focal plane of lens L4 so that the Fourier-transform of the input image is incident on the particularly located, superimposed matched filter at 31.

Abstract: A packageable system employs principles of Doppler holography on near-field objects to produce images from which photographs, transparencies or video reproductions can be made with simultaneous improvements in depth of field, foreground-backregion exposure ratio, and resolution (where degraded by the object medium). The apparatus consists of two units: a main unit containing a laser and optics, and an external platform that rotates at an appropriate angular velocity, through a very small arc, during image recording of an object on the platform.

Abstract: The Doppler frequency shift of coherent light reflected from moving objects is used to obtain resolution much greater than the classical limit for imaging systems. The Doppler information is processed by using the temporal and spatial filtering properties of modulated reference wave holograms formed with a reference wave having a range of frequencies across it matching the Doppler frequencies received from the moving object.