Abstract: A system for monitoring the concentration level of a gas in a monitored environment, e.g., for monitoring the concentration level of a fire suppression agent in the engine bay and/or cargo bay of an aircraft. The system includes a light source for producing source light, an optical system that directs the source light along a plurality of different optical paths having different respective optical path lengths, and a plurality of photodectors that are positioned to receive the source light that traverses different respective ones of the plurality of different optical path lengths, and which produce a plurality of output signals indicative of the concentration level of the gas in the monitored environment. In the preferred embodiment, the system further includes a narrow band spectral filter positioned between the light source and each photodetector, wherein the narrow band spectral filter has a narrow band pass that is matched to a selected optical absorption wavelength of the gas.

Abstract: There is provided an optically pumped laser having highly reflective coatings on opposite sides such that multiple reflections of radiation between the reflective coatings of the opposed sides produce lasing in a transverse mode. A plurality of diode lasers mounted in a linear array along the opposed sides with reflective coatings provide pumping emission to the laser. An optical alignment means consisting of prisms receive the stimulating emission from individual diode lasers and align individual stimulating emission such that it is colinear with the reflective radiation within the laser cavity.

Abstract: A method and apparatus for producing an optical phase array includes a plurality n of phase shifters associated with a plurality n of optical signals and a number (n-1) of independent feedback loops for generating electrical correction functions which are then combined through a transformation matrix of rank (n-1) or one in which the rows are linearly independent into a plurality n of phase shift signals for driving the phase shifters. Each phase shifter has its associated phase shift signal and independently modulates its optical signal to bring all of the optical signals into phase.

Abstract: An alternating current (AC) driven laser diode array and a power supply for the laser diode array is disclosed in which all of the laser diodes in the array are in conductive heat transfer relation with a high thermal conductivity heat sink and in which all of the diodes in the array are simultaneously pumped or energized by means of an AC power source via a transformer having a single primary coil and one or more secondary coils with each of the secondary coils energizing a plurality of diodes. A method of energizing a laser diode array with AC power is also disclosed.

Abstract: A package for matching the characteristic impedance of a transmission line to the impedance of a pulsed semiconductor laser diode so that short duration pulses of light can be produced with a fast repetition rate. The package has a toroidal transformer in a cavity of a main body, with a multiturn primary connected to a transmission line. The laser diode is mounted at the edge of a known sandwich between two thin metal plates separated by an insulating layer. A spacer and metal cover cap are placed over the sandwich, and a screw passing through holes of all the parts is threaded into the main body. The screw passing through the transformer core forms a one-turn secondary. Not only does this allow the matching of the characteristic impedance, but also provides heat sinking for the diode. Assembly with a screw makes the unit easy to fabricate, and to replace the laser diode sandwich.

Abstract: A package for matching the characteristic impedance of a transmission line to the impedance of a pulsed semiconductor laser diode so that short duration pulses of light can be produced with a fast repetition rate. The package mounts the laser diode on the center post of a one turn secondary of a toroidal transformer whose multiturn primary is connected to the transmission line. Not only does this allow the matching of the characteristic impedances, but the center post provides heat sinking for the diode.