Abstract: A modulator apparatus for modulating arrays of input data V.sub.in to be stored in a holographic recording medium is disclosed wherein the final output data array V.sub.out has frequent transitions from light to dark and from dark to light in either dimension across the data page and has the total amount of illuminated regions throughout the entire data page held constant. These two constraints are achieved by a first set of control arrays obtained from two fixed sets of m.times.n binary arrays {A.sub.0, A.sub.1, . . . , A.sub.n } and {B.sub.0, B.sub.1, . . . , B.sub.m } which in turn are obtained from fixed sets of binary control vectors {a.sub.0, a.sub.0, a.sub.1, . . . , a.sub.n }, {b.sub.0, b.sub.1, . . . , b.sub.m }, respectively. The control vectors a.sub.0, a.sub.1, . . . , a.sub.n any n+1 fixed elements of the inverse mapping, .phi. .sup.1 (C.sub.1), of the (t-2) error-correcting code C.sub.1 of length m. The control vectors b.sub.0, b.sub.1, . . . , b.sub.

Abstract: An optical data storage system comprises a multiple data surface medium and optical head. The medium comprises a plurality of substrates separated by a light transmissive medium. Data surfaces are located on the substrate surfaces which lie adjacent a light transmissive medium. The data surfaces are substantially light transmissive. The optical head includes an aberration compensator to allow the head to focus onto the different data surfaces and a filter to screen out unwanted reflected light.

Abstract: A substrate has a pair of overlapping optical couplers for separately coupling a first and a second polarization component of a light beam into a first and a second waveguide channel. The channels are oriented with their longitudinal axis approximately perpendicular to each other. A first and a second optical detector are located in the first and second waveguide channels, respectively, for measuring the light intensity of the first and second polarization components.

Abstract: An improved apparatus and method for detecting the polarization state of an optical wavefront is disclosed, which is especially suitable for use in an integrated magneto-optic recording head. An optically transparent waveguide structure transmits TE and TM modes of the wavefront propagated as a beam coupled into the waveguide by a TE/TM grating coupler. In the waveguide structure is a periodic structure comprising a birefringent mode separator that splits the propagating beam into TE and TM modes. The mode separator comprises an array of uniformly spaced volumes of identical configuration. Photosensitive devices detect the intensity of the light contained within each of the separated beams. The signals from these photosensitive devices are used to determine the state of polarization of the optical wavefront. The periodic structure may, if desired, comprise regions of alternating birefringence, such as a Bragg grating, either in a waveguide layer or a cladding layer.

Abstract: A brightfield/darkfield microscope illuminator has two axicon mirrors and a third plane mirror for use with two light beams from different sources. An open shutter positioned in the path of one beam provides brightfield illumination. An open shutter positioned in the path of the other beam provides darkfield illumination. This illuminator easily switches between operation in the darkfield and brightfield modes, uses substantially all the light in one beam for darkfield illumination and easily balances the illumination between the two light sources.

Abstract: An opto-optical light deflector/modulator has means for providing first and second coherent wave fronts of wavelength (.lambda..sub.0) to travel in a transparent optical active medium to produce an optically generated standing wave that induces a periodic refractive index variation in the medium suitable for diffraction purposes. The device also includes means for providing a third wavefront (.lambda..sub.1) to travel in said medium which is diffracted by the periodic refractive index variation induced by the first and second wavefronts.

Abstract: A frequency multiplexed optical spatial filter is based upon a thin film of a photochemical hole burning material. The filter stores a plurality of images in the photochemical hole burning medium. The images are formed at different optical frequencies and coexist in the same volume of the storage medium. Individual images are accessed by changing the frequency of the illuminating radiation.

Abstract: A holographic optical head for imaging a laser diode for optical storage or magnetic tracking applications includes three holograms, a beam director and a quarter-wave plate. In a preferred embodiment the beam director is a fourth hologram. The holographic optical head is corrected for aberrations arising from its use with light sources other than the design wavelength by having the first hologram diffract the light into the -1 order direction. This light is then diffracted by the second hologram into the +1 order so as to eliminate aberrations normally caused by wavelength shifts of the laser source.

Abstract: Apparatus for producing a line source of a desired shape from a radiation source such as a laser comprising means for directing the radiation source along a predetermined path as a playback beam to impinge upon a hologram at a predetermined angle to produce a continuous self-luminous source of the desired shape. The hologram is recorded upon a substrate coated with a photosensitive material by interference between recording and object beams derived from the same source of coherent radiation. The recording beam is directed toward the substrate at an orientation and angle so that the playback beam is a conjugate of the recording beam. The object beam is directed to the substrate over a path which includes a diffuser plate covered with an opaque material in all areas except for a continuation area which defines the desired shape. The part of the object beam which impinges upon the substrate is limited by an aperture comprising a sector of an annulus which defines the numerical aperture of the radiation source.

Abstract: An optical fluid analyzing apparatus is shown comprising transparent means (12,13) of known refractive index (n.sub.1) providing a cell (14) for receiving a fluid sample of unknown refractive index (n.sub.2). A diffraction grating 10 is formed in an inner wall (11) of the cell. A light source (15) is positioned at an incident angle (.theta..sub.0) with a grating to satisfy the Bragg condition. A pair of detectors (16, 17) intercept the 0th order and 1st order diffracted light. Circuitry (18) responds to signals generated by the detectors to provide an output indicative of the refractive index of the sample.

Abstract: An inexpensive, high quality transmissive holographic optical element and method for making same are described. The holographic optical element consists of a potentially aberrating substrate which supports a layer of holographic recording material. The material contains a recorded fringe pattern that cancels the aberrations induced in an image wavefront as it passes through the aberrating substrate. This optical element is formed by a method having the following steps. A first wavefront from a source, for example a point focus, is passed through the aberrating substrate, becomes distorted, and then passes through the holographic recording material to a wavefront conjugator. The conjugator launches a conjugate of the distorted wavefront back to the holographic recording material. A second wavefront is then passed through the holographic recording material to form a fringe pattern or hologram as a result of the interference of the conjugate waveform and the second waveform.

Abstract: A method for making high diffraction efficiency holograms from dichromated gelatin (DCG) including the steps of curing the DCG for a specified time under controlled temperature and humidity conditions, periodically removing the DCG material from the curing conditions, placing a dye spot on the cured DCG material, measuring the extent of diffusion of the dye spot after a predetermined time, replacing the DCG material into the curing conditions, repeating the method until dye spot diffusion of a predetermined size occurs, and using the DCG material at that cure state to make holograms.

Abstract: An interactive projection display system having a light pen device for use thereon is described. The projection display system has an image of a light valve on a projection screen which is formed by visible light of specified wavelengths. The projection screen also has a translatable crosswire image thereon which is formed by radiation which includes the visible light used to form the light valve image and an additional spectral component. The light pen device is sensitive to this additional spectral component. In a preferred embodiment, the image of the light valve and the crosswires are formed with white light (0.3 to 0.7 microns). The additional spectral component used for the crosswire image and the light pen sensing is a band of near-IR radiation (0.7 to 1 micron).

Abstract: A projection display device is provided in which variation in the index of refraction is used to modulate attenuated total reflection.

Abstract: An optical modulator suitable for use with a collimated light beam having a moderate cross section and a fast response time and operational at relatively low voltage includes, for example, a glass prism and a smooth metal surface that are separated by an adjustable gap. The gap is filled with a medium, for example, air, having an index of refraction lower than the prism. A beam of monochromatic light is passed into the prism at a specific angle of incidence to undergo total internal reflection at the glass prism-gap interface. A change of approximately 1 micron in the thickness of the gap is sufficient to change the reflectivity from greater than 95% to essentially zero. The size of the gap is mechanically adjusted and this mechanical device determines the frequency response of the light modulation.

Abstract: A direct view display device comprises a pair of conductive electrodes in spaced relationship and a recording medium having the properties of being both photo-ionizable and capable of electro-chemically producing colored species occupies the space between the electrodes. The display device is exposed to an optical pattern of radiation to which the recording material is sensitive to produce a latent image, and a potential is applied between the electrodes to produce a very dense image corresponding to the optical pattern. The image can be erased by reversing the potential between the electrodes so that the expose and enhance process can be repeated.