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Photomultiplier Control Circuit

IP.com Disclosure Number: IPCOM000091901D
Original Publication Date: 1968-Jul-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Kamentsky, LA: AUTHOR [+2]

Abstract

In this photomultiplier control circuit, a feedback loop which controls the gain of the photomultiplier is removed from the circuit. Such occurs when desired signals which exceed a given threshold are applied to a visual readout device. The circuit includes feedback path 1 consisting of amplifier 2 which amplifies the output of anode 3 of photomultiplier 4. The output of amplifier 2 is normally directed to a scope, not shown, and to the input of comparator 5. The latter is arranged, by virtue of variable potentiometer 6, to permit only signals which exceed a threshold, set by potentiometer 6, to pass. The output of comparator 5, is applied to gate 7 which closes on receipt of a signal from comparator 5, effectively removing feedback path 1 from the circuit.

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Photomultiplier Control Circuit

In this photomultiplier control circuit, a feedback loop which controls the gain of the photomultiplier is removed from the circuit. Such occurs when desired signals which exceed a given threshold are applied to a visual readout device. The circuit includes feedback path 1 consisting of amplifier 2 which amplifies the output of anode 3 of photomultiplier 4. The output of amplifier 2 is normally directed to a scope, not shown, and to the input of comparator 5. The latter is arranged, by virtue of variable potentiometer 6, to permit only signals which exceed a threshold, set by potentiometer 6, to pass. The output of comparator 5, is applied to gate 7 which closes on receipt of a signal from comparator 5, effectively removing feedback path 1 from the circuit. When gate 7 remains open, integrator 8 and amplifier 9 complete feedback path 1 to control the value of voltage 10, applied to dynodes 11 of photomultiplier 4. This arrangement for removing a feedback path from a circuit is useful where it is desired to obtain a video signal which is proportional to the change in radiant energy intensity due to the interposition of an object between a radiant energy source and the photomultiplier, The circuit eliminates possible error due to fluctuations in the radiant energy source, vibration in associated optical systems, and line noise pickup.

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