US Government As Represented by the Secretary of the Army

USA As Represented by Secretary of the Navy

Neal T Nomiyama

Rudolph G Buser

Robert S Rohde

Aubrey J Dunn

Gregory R Osche

An optical receiver for a pulsed TEA laser output. The output has a high-amplitude portion followed by a lower amplitude tail; information is modulated onto the tail. For the high-amplitude output portion, a photodetector in the receiver is biased to low sensitivity; during the tail of the laser, the bias is increased to increase the photodetector sensitivity.

Modulated TEA laser receiver

A substrate of a dimensionally-stable material is formed with precision m cavities therein for various linear or nonlinear optical elements or electro-optical elements such as lenses, beam splitters, reflectors, detectors, polarizers, Kerr cells, Pockel cells, etc. Various openings are also made in the substrate for function as optical paths or waveguides. The elements are then bonded into their respective cavities by glueing or soldering; the optical system thus formed is sealed in an air-tight housing.

Method of integrated optical system

The tail of a carbon-dioxide (CO.sub.2) transverse electrode discharge at mospheric pressure (TEA) laser pulse optical signal is pulse code modulated by a Pockels Cell. A modulation depth of 100% is obtained to prevent high false alarm rates under dynamic transmission conditions. The device external to the laser cavity will extend the capabilities of the CO.sub.2 TEA laser by using a tail for information transfer while preserving the gain switch spike for rangefinding. A high repetition rate is achieved using a power supply that electrically charges and discharges the Pockels Cell which, in turn, activates the polarization switch.

Pulse code modulation of laser pulse tail

A short pulse CO.sub.2 transverse electrode discharge at atmospheric pressure (TEA) laser device for ranging and target identification which uses an electro-optics Pockels Cell modulator to chop the transmitted laser beam into a train of 0.5 to 2 nanosecond pulses and a broadband receiver for observing the time broadened reflected signals that results from integration of the finite depths of the targets. Because a target has a unique three dimensional profile, the target signature may be identified by comparison with known signatures previously generated by computer simulation or field measurements. The present shortened pulse laser transmitter and a plurality of receiver field-of-view options meet the temporal and signal-to-noise requirements for pattern recognition. The device can be used to provide high accuracy target ranging along with target identification.

Short pulse CO.sub.2 laser for ranging and target identification

A high power laser interrogator with a dedicated receiver transmits a first ulse having a cryptic interrogation meassage therein which is detected by a suitable detector in a retroreceiver aboard a friendly target. At a predetermined time later, a second laser pulse, which is unmodulated, is transmitted to the friendly target. The friendly target has a laser retroreflector receiver/transponder with a modulating device therein which the cryptic interrogation message can only be decoded by a friendly target wherein the retroreflector reflects laser light only when the correct preselected cryptic interrogation message in the first pulse is detected and only during the duration of the unmodulated second pulse. The leading edge of the second pulse is detected and initates the modulation of the modulating device which allows the second pulse to pass therethrough with a preassigned intensity modulation as determined by the transponder. As intensity modulation occurs the pulse is reflected by the retroflector back through the modulator to the dedicated receiver in the laser interrogator, and if the modulation code is the same as preassigned, the target is deemed friendly but if not the target is determined to be an enemy.

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Reston, VA, United States of America

Neal T Nomiyama