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The United States of America As Represented by the Administrator of the

Charles W Rutledge

Robert T Menzies

Phillip A Harris

A system for remote absorption spectroscopy of trace species using a diode laser (14) tunable over a useful spectral region of 50 to 200 cm.sup.-1 by control of diode laser temperature over range from 15.degree. K. to 100.degree. K., and tunable over a smaller region of typically 0.1 to 10 cm.sup.-1 by control of the diode laser current over a range from 0 to 2 amps. Diode laser temperature and current set points are transmitted to the instrument in digital form and stored in memory (32) for retrieval under control of a microprocessor (28) during measurements. The laser diode current is determined by a digital-to-analog converter (62) through a field-effect transistor (Q.sub.1) for a high degree of ambient temperature stability, while the laser diode temperature is determined by set points entered into a digital-to-analog converter (64) under control of the microprocessor. Temperature of the laser diode is sensed by a sensor diode (18) to provide negative feedback to the temperature control circuit that responds to the temperature control digital-to-analog converter (64).

Digital control of diode laser for atmospheric spectroscopy

An electronic circuit having two states, at least one of which is stable and which permits information to pass from one terminal to the other. The circuit can be activated by the flow of a minute electric current through the human body. The circuit is particularly suitable for any hand-held instrument such, for example, as an electronic calculator watch of the digital type and including electronic logic. It permits to activate certain functions or to carry out certain calculations by activating a conductive surface by means of a hand-held metallic pin or the like. This makes it possible to provide a large number of functions or operations and to display numbers say on the face of a watch and to activate each one by touching it with a pin held by the wearer of the watch or instrument.

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Temple City, CA, United States of America

Charles W Rutledge