Abstract: An improved optical polarization switch which provides a wide field-of-view and achromatic action. Two liquid crystal cells are used and are selectively operated in a preferred embodiment to provide three distinct optical states. Interposed between the two nematic liquid crystal cells is a compensating member such as an half-wave retarder or an optical rotator. Such switches are of utility in shutter applications and in high-performance field-sequential color filters.

Abstract: An optical switch for arbitrarily polarized light having low cross-talk is made in which an input beam is split into its TE (s wave) and TM (p wave) polarization components, the TM component is converted to TE by total internal reflection, the two beams are either reflected or transmitted by liquid crystal cells, one of the beams is then converted to TM polarization, again by total internal reflection, and the two beams are recombined and outputted from one of two ports.

Abstract: A multiple port electromechanical optical fiber switch provides for the exchange redirection of one common optical path with one of several other optical paths through the switch. It is particularly useful when one standby laser transmitter must be quickly substituted for any single failed transmitter among a group of several actively operating transmitters. A single prism for exchanging the optical paths of two initially parallel beams by means of four refractions at their entry and exit points and at least two internal reflections per beam within the prism is set forth in modified rhombic form with two additional parallel facets that transmit undeflected in the deactivated position one of two beams so as to minimize required shift distance to the prism activated position where it exchanges the optical paths of both parallel beams.

Abstract: A quasi-achromatic configuration of two nonreciprocal optical rotators coupled by linear retardation elements based on total internal Fresnel reflection, such that wavelength or temperature effects on the optical rotator elements compensate one another to give quasi-achromatic isolation and/or temperature stability when this optical configuration is incorporated into an optical isolator or circulator. A quasi-achromatic optical isolator through which a light beam within a wavelength range about a nominal wavelength may propagate is made from a sequence of elements having a first plane polarizer accepting said light beam as an input, said light beam then passing through in sequence, a first Faraday rotator, a first wavelength independent linear retardation element, a second Faraday rotator, a second wavelength independent linear retardation element, and said light beam exiting said isolator undiminished in intensity through a second plane polarizer.

Abstract: A quasi-achromatic configuration of two Faraday elements and five birefringent plates which when suitably oriented between two linearly polarizing elements would constitute an optical isolator or circulator. The nominal Faraday rotations of the two elements are 45.degree. and 90.degree. at a center design wavelength about which the devices are to operate. Changes in these rotations due to either wavelength or temperature variations compensate one another because of their coupling by the birefringent plates. In this way a higher degree of isolation is obtained over a wider optical bandwidth than would be possible in a device using a single 45.degree. Faraday element. A group of three plates is used between the two Faraday elements and two more follow them to give the required polarization transformations which must themselves be quasi-achromatic over the desired wavelength range.

Abstract: A multichannel wavelength demultiplexer has two or more cascaded birefringent filter stages for dividing an input signal consisting of a plurality of adjacent channels of optical signals among a number of outputs, each of said filter stages having a transmission function with even symmetry about optical frequencies at the centers of both the longest and the shortest wavelength channels. This symmetry, common to all transmission functions, permits all birefringent filter stages to be constructed from sequences of the same one size crystal element, thereby greatly lowering the cost of construction because solely one size crystal element is fabricated, tested and assembled. A multichannel multiplexer, identical to the above defined demultiplexer, but operated in reverse, is set forth.

Abstract: A true n-by-n optical crosspoint matrix switch has n optical fiber outputs each carrying the same light that entered the switch at one of n fiber inputs, maintaining the full optical spectral characteristics although the polarization states may be modified. A mounting plate on a patch panel has an n-by-n array of connection adapters in n rows and no columns. An electromechanical positioning mechanism is utilized to position n input fibers along one row to any of n adapter positions each in a different column on a first side of said plate, and n output fibers along one column to any one of n adapter positions, each in a different row on a second side of said plate. Any input fiber can be connected to any output fiber and none of the adapters are shared by more than one input or one output connector.

Abstract: An expanded beam connector for optical fibers uses a transparent lensing device having integral alignment capability, that of a simplified design that facilitates its molding with high precision from optical plastic or glass.

Abstract: An achromatic birefringent retardation plate has a quarter wave of linear optical birefringence over a wavelength range centered about a nominal wavelength. The plate includes a combination of two birefringent optical disks in adjacent positions along a light beam axis. Each disk has a linear optical birefringence with a fast axis. The two disks have thicknesses such that, at the nominal wavelength, they have their linear optical birefringence at n and m quarter waves, respectively of the nominal wavelength, where n is an odd integer greater than one and where m is an even integer greater than n. The fast axes of the linear birefrigences of the disks have rotational orientations about the light beam axis whereby the fast axis orientation of the other disk differs from that of one disk by ninety degrees, plus or minus one-half of the angle whose cosine is equal to the ratio of n to m.

Abstract: An n channel birefringent multiplexer/demultiplexer consists of log.sub.2 n sequences of birefringent crystal elements in Solc-type filter configuration. The configuration of polarizing beam splitters have one such beam splitter before the first sequence, one such beam splitter after the last sequence, and solely one such beam splitter between adjacent sequences of birefringent elements. With such multiplexer/demultiplexer horizontally and vertically polarized components of an input beam are separated at the input beam splitter, independently traverse all of the sequences of the birefringent elements and are recombined to form output beams only upon reaching the output beam splitter.

Abstract: The present invention relates to a dosing composition useful in high pressure sodium lamps. The invention relates specifically to new multicomponent alloy fills for HPS lamps and the design of such fills. The present invention provides an HPS lamp dosing composition that will supply the required amount of sodium and mercury for proper lamp operation, but which will have a lower vapor pressure during the sealing operation, such that mercury loss from the composition will be lower than that from the presently used sodium amalgam. In the present invention, either one of the compounds, Ti.sub.3 Hg or Zr.sub.3 Hg, is mixed with an intermetallic compound of sodium that has a melting point above about 600.degree. C., such that both the mercury and sodium metal are stabilized to avoid melting or vaporization at about 600.degree. C. The preferred sodium compound is Na.sub.3 Bi, which melts at 755.degree. C., although Na.sub.3 Sb and Na.sub.2 Te with higher melting points may be used.

Abstract: The simultaneous and equal tuning of two birefringent crystal elements of a Solc type optical filter by pairs of quarter-wave plates adjacent to each and oriented such that equal and opposite physical rotations between the plates of each pair tunes its adjacent birefringent element in the same direction without changing the relative orientations of the filter input and output. Also, the simultaneous and equal tuning of two birefringent crystal elements of a Solc type optical filter by the rotation of a single contiguous group of optical components.

Abstract: An improved geometry for an optical beam splitter prism permits all input and output beams to be parallel and to remain parallel while the prism is misaligned. It is particularly useful in conjunction with fiber optic couplers and is applicable to splitting with respect to light intensity, polarization or wavelength. This can be achieved through the construction of a beam splitting prism having an additional reflecting surface on one input beam and on one output beam, whereby each of these surfaces are parallel to the beam splitting surface and with two parallel input and output surfaces through which all beams pass so as to make all input and output beams parallel and remain parallel as the prism is translationally or rotationally misaligned about any axis.

Abstract: A multiple port electromechanical optical fiber switch provides for the exchange redirection of one common optical path with one of several other optical paths through the switch. It is particularly useful when one standby laser transmitter must be quickly substituted for any single failed transmitter among a group of several actively operating transmitters. A prism for exchanging the optical paths of two initially parallel beams by means of four refractions at their entry and exit points and at least two internal reflections per beam within the prism is set forth in modified rhombic form with two additional parallel facets that transmit undeflected in the deactivated position one of two beams so as to minimize required shift distance to the prism activated position where it exchanges the optical paths of both parallel beams.

Abstract: An active system for restoring the polarization state of light emerging from a single-mode optical fiber. The system changes the slowly varying elliptical polarization resulting from environmental effects on the long fiber to a linear polarization state of fixed orientation. The elliptically polarized light is converted into two orthogonal linearly polarized beams. One of the beams is used in a feedback circuit to null its intensity thereby restoring all the input light to the other linear polarization state.

Abstract: An electro-mechanical optical fiber rotary switch provides for latched reconnection of two optical paths among four optical fiber ports of a 2.times.2 switching array. A right isosceles triangular optical prism is used in the switch, the prism being rotated 90.degree. in either direction to change the switch position.

Abstract: A fluorescent light source and power supply adapted therefore in which a set of three D.C. mercury discharge paths are provided adjacent each other in a single tubular envelope. A cathode is provided at the base end of each path and a single anode at the other end. The three discharge paths are isolated longitudially extended semi-circular glass insulator partitions. The power supply provides D.C. voltage across the anode and cathodes and a switching circuit which transfers energy from a transformer during portions of the switching cycle to efficiently power the tube.

Abstract: A mercury-releasing assembly for dosing lamps, tubes, and the like with a charge of mercury, contains a mixture of an intermetallic compound of mercury and a metal. When the mixture is heated to a particular temperature the mixture reacts yielding a molten eutectic and mercury vapor. The mixture may be protected from contamination by a foil shield which ruptures under pressure of the released mercury.

Abstract: A ballast circuit for direct current gaseous electrical discharge devices includes a rectifying bridge, and an inductive ballast for storing excess energy. The rectifying bridge uses a pair of thyristors which must be gated on for the bridge to supply rectified voltage to the inductor and device. Gating is delayed at the beginning of each half-cycle to allow the inductor to discharge most of its stored energy.

Abstract: An electric arc lamp in combination with an electronically controlled incandescent filament to provide auxiliary illumination during warm-up and hot restart of the arc lamp, the filament control circuit being responsive to the arc lamp voltage and current and operative in three modes, full off, full on, and switching on and off the latter so as to allow capacitive and inductive coupling of energy into the arc lamp for the purpose of starting it and bringing it into the arc mode of operation.