Abstract: A method of suppressing retroreflector fringe noise in TDL spectrometers (TDLS) that use a laser and retroreflector. The path between the laser and each retroreflector element is changed mechanically for example by using a movable support for the retroreflector. The phase of light reaching the retroreflectors is very sensitive to the pathlength. A pathlength change of a fraction of the light wavelength will significantly change the phase of the light. In this method the pathlength to each retroreflector is modulated by mechanical means and this modulation is both stronger and faster than atmospheric effects on phase. If mechanical modulation occurs at a sufficiently high frequency retroreflector fringe noise can be averaged by integration of the spectrometer output over a reading period of typically one second.

Abstract: A method of suppressing retroreflector fringe noise in TDL spectrometers (TDLS) that use a laser and retroreflector. The path between the laser and each retroreflector element is changed mechanically for example by using a movable support for the retroreflector. The phase of light reaching the retroreflectors is very sensitive to the pathlength. A pathlength change of a fraction of the light wavelength will significantly change the phase of the light. In this method the pathlength to each retroreflector is modulated by mechanical means and this modulation is both stronger and faster than atmospheric effects on phase. If mechanical modulation occurs at a sufficiently high frequency retroreflector fringe noise can be averaged by integration of the spectrometer output over a reading period of typically one second.

Abstract: A thermal stabilization system for a packaged diode laser. An outer thermoelectric cooler (TEC) stabilizes the temperature of the laser package and an inner TEC stabilizes the temperature of the laser diode element of the packaged laser. The inner and outer TECs may be controlled by electronics which is also stabilized in temperature, for example using resistive heating. The packaged laser may be mounted on a heat spreader mounted on the outer TEC and may be surrounded by an insulated covering on all sides other than the surface mounted on the heat spreader. There may also be a thermally conductive cap over the packaged laser, with the insulation arranged outside the cap if both are present.

Abstract: A thermal stabilization system for a packaged diode laser. An outer thermoelectric cooler (TEC) stabilizes the temperature of the laser package and an inner TEC stabilizes the temperature of the laser diode element of the packaged laser. The inner and outer TECs may be controlled by electronics which is also stabilized in temperature, for example using resistive heating. The packaged laser may be mounted on a heat spreader mounted on the outer TEC and may be surrounded by an insulated covering on all sides other than the surface mounted on the heat spreader. There may also be a thermally conductive cap over the packaged laser, with the insulation arranged outside the cap if both are present.

Abstract: A photodynamic therapy apparatus and method in which (1) phototoxic drug is supplied to a target tissue, (2) delivery of drug activating light to the target tissue through probes is controlled by sequential selection of operation of the probes, (3) an automatic radiance probe is used for efficient optical characterization of the target tissue, and (4) an optical dose is monitored by sequential selection of probes as transmitters and receivers.

Abstract: A photodynamic therapy apparatus and method in which (1) phototoxic drug is supplied to a target tissue, (2) delivery of drug activating light to the target tissue through probes is controlled by sequential selection of operation of the probes, (3) an automatic radiance probe is used for efficient optical characterization of the target tissue, and (4) an optical dose is monitored by sequential selection of probes as transmitters and receivers.

Abstract: Endoscopes are well known devices used for examining surfaces contained within an enclosed cavity. Typical applications for these devices are the examination of tissues within human body cavities or mechanical components contained within engine compartments. An endoscopic apparatus for measuring blood flow contained within an enclosed body cavity is claimed.

Abstract: A photodynamic therapy apparatus and method in which (1) phototoxic drug is supplied to the arterial supply of a target tissue, (2) deliver of drug activating light to target tissue through probes is controlled by sequential selection of operation of the probes, (3) an automatic radiance probe is used for efficient optical characterization of target tissue and (4) optical dose is monitored by sequential selection of probes as transmitters and receivers.

Abstract: A mobile gas detector comprising a laser transmitter and signal analyser carried on a vehicle, the vehicle having an exterior, a laser absorption cell carried on the exterior of the vehicle, a light guide connecting light from the laser transmitter into the laser absorption cell, a photo-detector mounted with the laser absorption cell exterior to the vehicle to convert light that has traversed the laser absorption cell into electrical signals, and a cable connecting the photodetector to the signal analyser.

Abstract: A large area slab laser, wherein disharge is confined between two large area electrodes. A two dimensional array of inductors is placed across the electrodes so that the standing wave patterns associated with the propagation of the high frequency driving current are corrected. In one embodiment, the electrodes are planar, in another, the electrodes are annular.

Abstract: A large area slab laser, wherein the laser discharge is confined between two large area electrodes. A two dimensional array of inductors is placed across the electrodes so that the standing wave patterns associated with the propagation of the high frequency driving current are corrected. In one embodiment, the electrodes are planar, in another, the electrodes are annular.

Abstract: A mobile gas detector comprising a laser transmitter and signal analyser carried on a vehicle, the vehicle having an exterior, a laser absorption cell carried on the exterior of the vehicle, a light guide connecting light from the laser transmitter into the laser absorption cell, a photo-detector mounted with the laser absorption cell exterior to the vehicle to convert light that has traversed the laser absorption cell into electrical signals, and a cable connecting the photodetector to the signal analyser.

Abstract: Endoscopes are well known devices used for examining surfaces contained within an enclosed cavity. Typical applications for these devices are the examination of tissues within human body cavities or mechanical components contained within engine compartments. An endoscopic apparatus for measuring blood flow contained within an enclosed body cavity is claimed.

Abstract: A gas detector, comprising a laser transmitter, a laser receiver, a gas reference cell formed of a sealed encircling wall defining an interior volume, a liquid partially filling the gas reference cell, a reference gas dissolved in the liquid and forming a vapor within the interior volume, at least a portion of the sealed encircling wall being transparent to electromagnetic radiation emitted by the laser transmitter to permit electromagnetic radiation to enter the gas reference cell, traverse a path through the vapor and exit the gas reference cell; and the laser transmitter, laser receiver and gas reference cell being coupled together with light guiding elements to form light paths that pass from the laser transmitter to the laser receiver through the gas reference cell and from the laser transmitter to the laser receiver through a target zone.

Abstract: Light from a laser transmitter propagates along several optical light guides from a laser transmitter to a laser receiver. The optical light guides form a guided light path traversing each of several target zones where unwanted gas may be present. An optical switch permits selection of one of the paths and hence one of the target zones for the detection of gas. A preferred light guide uses optical fibers with optical switches, or a combination of a splitter and a switch. A lens system provides for the collection of light from a transmitting fiber optic and receiving fiber optic. The gas detector is provided with means to eliminate phase sensitivity of the detector.

Abstract: A gas detector of gas in a target zone has a transmitter of frequency modulated light and a receiver. In the receiver, a homodyne detection circuit mixes a detected signal with a reference signal at one of the modulation frequencies, where the reference signal has been derived from light that has passed through the target zone. The homodyne detection circuit includes a bandpass filter, amplifier, phase lock loop and phase shifter. Etalon fringes are reduced by moving them to high frequencies and filtering them out. Gas density is measured by comparison of the detected signal from the target zone with a signal from a gas reference cell. A method of detecting gas includes transmitting frequency modulated light through a target zone, receiving the light, and homodyne detection of the detected signal by mixing the detected signal with a reference signal at one of the modulation frequencies, where the reference signal has been derived from light that has passed through the target zone.

Abstract: A slab laser amplifier array includes a plurality of parallel, stacked, laser resonators, with each resonator having a walk-off mode of propagation of laser light from an input side of the resonator to an output side of the resonator where the exiting light diffracts around the resonator mirror. A source of a plurality of phase related, for example co-phasal, light beams supplies phase related light to each input side. The source of phase related light may be a source of one single mode beam followed by a telescope with an aperture having plural stops or a co-phasal array of laser resonators. A laser array of open resonators also has circular concentric electrodes.

Abstract: A laser lithotriptor includes a laser adapted to emit pulsed light which is absorbed by water in the vicinity of a human stone or concrement to cause rapid erosion of the stone. A light transmitting device such as a fibreoptic cable is employed inside of an endoscope to direct the laser pulses to the vicinity of the stones. An irrigation apparatus also ensures that the tip of the light transmitting device and the stone are continuously immersed in water and also serves to remove the powder-like debris of the disintegrated stone from the body. Preferably, a NdYAG laser operating at 1.44 .mu.m which emits 27 pulses per second is coupled to the body stone through an anhydrous quartz fibreoptic cable passing through the interior of an endoscope.

Abstract: A neodymium laser provides output at about 1.44 .mu.m, by selection of a neodymium doping level of between about 0.3 and 0.7N, preferably at 0.4N with reflectivity of the output mirror at about 90% for 1.44 .mu.m output. Selection of the reflectivity of the output mirror is adjusted to ensure that the excess of the gain over the absorption and transmission losses is maximized.

Abstract: A laser lithotriptor includes a laser adapted to emit pulsed light which is absorbed by water in the vicinity of a human stone or concrement to cause rapid erosion of the stone. A light transmitting device such as a fibreoptic cable is employed inside of an endoscope to direct the laser pulses to the vicinity of the stones. An irrigation apparatus also ensures that the tip of the light transmitting device and the stone are continuously immersed in water and also serves to remove the powder-like debris of the disintegrated stone from the body. Preferably, a NdYAG laser operating at 1.44 .mu.m which emits 27 pulses per second is coupled to the body stone through an anhydrous quartz fibreoptic cable passing through the interior of an endoscope.