Browse Prior Art Database

Dynamic Radiometer

IP.com Disclosure Number: IPCOM000076485D
Original Publication Date: 1972-Mar-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Chwalow, ML: AUTHOR

Abstract

Because of the nonlinearity and instability of the response of photoelectric detectors and that of the associated circuitry, the quantitative measurement of time-varying optical radiation, such as single short laser pulses and trains of uniform or nonuniform pulses spaced at equal or unequal intervals, is difficult.

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Dynamic Radiometer

Because of the nonlinearity and instability of the response of photoelectric detectors and that of the associated circuitry, the quantitative measurement of time-varying optical radiation, such as single short laser pulses and trains of uniform or nonuniform pulses spaced at equal or unequal intervals, is difficult.

In the present system, the radiation to be measured (unknown) is compared to that from a reference source. The reference source is optically modulated by a signal originating in a photoelectric pickup of the unknown radiation, thereby duplicating the time-varying pattern of the radiation. The unknown pulse gates the reference source so that the detector sees the reference only for the interval over which the unknown beam is active. The unknown beam is then detected in a separate operation; and the ratio of the two beams indicates the amplitude or intensity of the unknown pulse.

Reference source 1 may be a commercially available tungsten lamp or black body. When the radiation from the reference source 1 is being measured, the reflector 2 is directed toward electrooptic modulator 3, as shown. Shutter 4 is open and shutter 5 is closed.

During this time, the radiation pulse from unknown source 6 is partially reflected from beam splitter 7 and sensed by photoelectric pickup 8. This signal is amplified by amplifier 9 and activates modulator 3 for the duration of the unknown pulse. For this period, then, detector 10 receives time-varying r...