Abstract: A light source constructed from a two dimensional array of light emitting devices. The light emitting devices include first, second and third types of light emitter. The first type of light emitting device covers a first area in the two dimensional array and emits light in a first region of the optical spectrum. The second type of light emitting device covers a second area in the two dimensional array and emits light in a second region of the optical spectrum, and the third type of light emitting device covers a third area in the two dimensional array and emits light in a third region of the optical spectrum. The first, second, and third areas are chosen such that the simultaneous output from all emitters generates white light. At least one of the emitter types covers an area larger than that covered by the others.

Abstract: A composition for use in constructing a photosensitive film for recording an image. The composition includes first, second, and third particle types, each the particle type including a crystalline base material having a trap dopant and a color dopant deposited therein. Each of the color dopants has a different spectral sensitivity. One of the particle types is sensitive to light in the red portion of the visible spectrum. This particle type includes a crystalline base material including an alkaline earth sulfide or selenide doped with Yb.sup.+2.

Abstract: A simplified, cost effective optical apparatus for solid state photorecording of optical images with enhanced resolution. The optical apparatus of the invention includes an array of optical apertures and a plurality of portions of a phosphorescent material. Each portion is optically coupled to a respective one of the apertures. The apertures are exposed to an optical image so as to record the image in the plurality of portions of the phosphorescent material. A number of the apertures of the invention is large, preferably within a range of approximately one million to seven million apertures. For example in a preferred embodiment the number of the apertures is approximately six million apertures. Preferably, the optical apertures are microscopic optical apertures. For example, each aperture has a respective width dimension within a range of approximately ten to fifty microns. Preferably, the respective width dimension of each aperture is approximately twelve microns.

Abstract: An electrically tunable optical oscillator. An acoustooptically tunable filter is located in a feedback path of an optical oscillator. The filter non-collinearly diffracts the light signal to selectively tune the oscillator. In one embodiment the light signal passes twice through a single filter in a single transit around the feedback path. In another embodiment the light passes through a pair of filters which are arranged such that any frequency shift created by one is cancelled by the other.

Abstract: An external cavity laser is formed by feeding back light from a laser through two or more acoustooptic tuneable filters back to the laser. The Doppler shifts introduced by the filters do not entirely cancel. The net Doppler shift caused by the filters is continuously tuned to cause the bandpass of the filter to follow the shifting resonating frequency of the laser to prevent mode hopping.

Abstract: A bilithic laser resonator having a first block separated from a second block by a gap that can be adjusted to tune the wavelength of the laser. At least one of these blocks consists of a material that is capable of lasing and at least one of these blocks consists of a material that is capable of producing Faraday rotation of an optical beam.

Abstract: An optical time domain reflectometer that injects at least two complementary code sequences into an optical fiber and detects the return signal produced by each of these code sequences. These return signals are processed to extract the function h.sub.k that is equal to the response function for the fiber when a single pulse is injected into the fiber. This processing utilizes a correlation scheme that has no sidelobe distortion. Various combinations of Golay codes are suitable for use as the complementary codes.

Abstract: A quasi-planar monolithic unidirectional ring laser is disclosed including an Nd:YAG crystal shaped so that a ring formed therein has an out-of-plane angle of about 1.degree.. The reflection opposite the output-coupling point on the front face is off the rear face. This arrangement provides for a very low pumping threshold and reduced magnetic field requirements. The disclosed laser can be pumped with a semiconductor laser and yield single mode 1.319 .mu.m and 1.338 .mu.m outputs suitable for fiber optic communications.

Abstract: An alignment method in which light is diffracted from a mask grating to a wafer grating and back through the mask grating to produce a set of output diffraction orders. The intensity of the zeroth output order is monitored and the mask is translated and rotated within the plane containing the mask to align the mask with the wafer. Alignment occurs when the intensity of the zeroth output order is at an extremum. The distance between the mask and wafer is also adjusted to extremize the intensity of the zeroth output order to make the wafer lie within the focal plane of the exposure optics. The wafer mask is preferrably a holographic phase grating to simplify production of the grating and to eliminate resist related interference. Two dimensional gratings can be used to achieve alignment with only one grating on each wafer.

Abstract: An improved photoetch technique is presented of the portable-conformable-mask type wherein a thin top layer of resist and a thick planarizing layer are deposited on a substrate and the thin layer is exposed and developed to produce a portable-conformable-mask. The improvement involves dissolving a suitable dye in a layer between the thin top layer and the substrate. The dye is preferably selected to absorb light of the wavelengths used to expose the top layer but does not interfere with processing of the other layers.

Abstract: The wavelength of an optical pump beam is down converted to a longer wavelength in a Raman active gaseous medium by stimulated Raman scattering. The Raman active gaseous medium is contained in the space between a pair of optical reflectors of an optical resonator of the type for producing a focus of the optical beam energy at a point intermediate the length of the resonator within the Raman active medium to enhance conversion of pump energy into the output longer wavelength of the Stokes wave. The pump beam is directed into the optical resonator at an angle to the optical axis of the optical resonator such that the optical beam path is folded back and forth within the optical resonator to cause the beam spot to walk over the surfaces of the reflectors and out of the optical resonator.