Photomultiplier gain control circuit

Claim 2

A gain control circuit for controlling the gain of a photomultiplier, said photomultiplier being exposed to a pulsed beam of electromagnetic radiation and operative when exposed to the pulsed beam of electromagnetic radiation to produce an output signal, said gain control circuit comprising: processing means adapted to be coupled to the photomultiplier and operative to receive an outPut signal produced by the photomultiplier when exposed to a pulsed beam of electromagnetic radiation and to produce a corresponding output signal having a value directly related to the value of the output signal produced by the photomultiplier; circuit means coupled to the processing means and operative in response to the output signal produced by the processing means to derive a signal having a value related to the maximum amplitude of the output signal produced by the processing means; comparator means coupled to the circuit means and adapted to compare the value of the signal derived by the circuit means with the value of a reference signal, the value of the reference signal being representative of a desired output signal produced by the photomultiplier, said comparator means being operative when the value of the signal derived by the circuit means bears a predetermined first relationship to the value of the reference signal to produce a first output signal having a value representative of the difference, and operative when the value of the signal derived by the circuit means bears a predetermined second relationship to the value of the reference signal to produce a second output signal having a value representative of the difference; and dc supply means coupled to the comparator means and adapted to be coupled to the photomultiplier, said dc supply means receiving the output signals produced by the comparator means and being operative in response to a first output signal received from the comparator means to supply a dc voltage to the photomultiplier in a first direction and varying at a rate determined by the value of the first output signal, and being operative in response to a second output signal received from the comparator means to supply a dc voltage to the photomultiplier in a second direction and varying at a rate determined by the value of the second output signal.

Claim 3

A gain control circuit for controlling the gain of a photomultiplier, said photomultiplier being exposed to a pulsed beam of electromagnetic radiation and operative when exposed to the pulsed beam of electromagnetic radiation to produce an output signal, said gain control circuit comprising: processing means adapted to be coupled to the photomultiplier and operative to receive an outPut signal produced by the photomultiplier when exposed to a pulsed beam of electromagnetic radiation and to produce a corresponding output signal having a value directly related to the value of the output signal produced by the photomultiplier; circuit means coupled to the processing means and operative in response to the output signal produced by the processing means to derive a signal having a value related to the maximum amplitude of the output signal produced by the processing means; comparator means coupled to the circuit means and adapted to compare the value of the signal derived by the circuit means with the value of a reference signal, the value of the reference signal being representative of a desired output signal produced by the photomultiplier, said comparator means being operative when the value of the signal derived by the circuit means bears a predetermined first relationship to the value of the reference signal to produce a first output signal having a value representative of the difference, and operative when the value of the signal derived by the circuit means bears a predetermined second relationship to the value of the reference signal to produce a second output signal having a value representative of the difference; and dc supply means coupled to the comparator means and adapted to be coupled to the photomultiplier, said dc supply means receiving the output signals produced by the comparator means and being operative in response to a first output signal received from the comparator means to supply a dc voltage to the photomultiplier in a first direction and varying at a rate determined by the value of the first output signal, and being operative in response to a second output signal received from the comparator means to supply a dc voltage to the photomultiplier in a second direction and varying at a rate determined by the value of the second output signal.

Claim 4

A gain control circuit for controlling the gain of a photomultiplier, said photomultiplier being exposed to a pulsed beam of electromagnetic radiation and operative when exposed to the pulsed beam of electromagnetic radiation to produce an output signal, said gain control circuit comprising: processing means adapted to be coupled to the photomultiplier and operative to receive an outPut signal produced by the photomultiplier when exposed to a pulsed beam of electromagnetic radiation and to produce a corresponding output signal having a value directly related to the value of the output signal produced by the photomultiplier; circuit means coupled to the processing means and operative in response to the output signal produced by the processing means to derive a signal having a value related to the maximum amplitude of the output signal produced by the processing means; comparator means coupled to the circuit means and adapted to compare the value of the signal derived by the circuit means with the value of a reference signal, the value of the reference signal being representative of a desired output signal produced by the photomultiplier, said comparator means being operative when the value of the signal derived by the circuit means bears a predetermined first relationship to the value of the reference signal to produce a first output signal having a value representative of the difference, and operative when the value of the signal derived by the circuit means bears a predetermined second relationship to the value of the reference signal to produce a second output signal having a value representative of the difference; and dc supply means coupled to the comparator means and adapted to be coupled to the photomultiplier, said dc supply means receiving the output signals produced by the comparator means and being operative in response to a first output signal received from the comparator means to supply a dc voltage to the photomultiplier in a first direction and varying at a rate determined by the value of the first output signal, and being operative in response to a second output signal received from the comparator means to supply a dc voltage to the photomultiplier in a second direction and varying at a rate determined by the value of the second output signal.

Claim 5

A gain control circuit in accordance with claim 1 wherein the dc supply means comprises: first means coupled to the comparator means and receiving the output signals produced by the comparator means, said first means being operative during a portion of the time of exposure of the photomultiplier to the pulsed beam of electromagnetic radiation and in response to a first or second output signal from the comparator means to supply a dc voltage to the photomultiplier in the first or second direction, respectively, said dc voltage varying at a first rate determined by the value of the first or second output signal; and second means coupled to the comparator means and receiving the output signals produced by the comparator means, said second means being operative following the aforesaid portion of the time of exposure of the photomultiplier to the beam of electromagnetic radiation and in response to a first or second output signal from the first circuit means to supply a dc voltage to the photomultiplier in the first or second direction, respectively, said dc voltage varying at a second rate determined by the value of the first or second output signal and differing from the first rate.

Claim 6

A gain control circuit in accordance with claim 2 wherein the first rate is greater than the second rate.

Claim 7

A gain control circuit for controlling the gain of a photomultiplier, said photomultiplier being exposed to a pulsed beam of electromagnetic radiation and operative when exposed to the pulsed beam of electromagnetic radiation to produce an output signal, said gain control circuit comprising: processing means adapted to be coupled to the photomultiplier and operative to receive an output signal produced by the photomultiplier when exposed to a beam of electromagnetic radiation and to derive a corresponding output signal therefrom; sampling means coupled to the processing means and operative to sample the output signal produced by the processing means at predetermined first and second time intervals, thereby to provide first and second sampled signals, respectiveLy; first circuit means coupled to the sampling means and adapted to determined the difference in the values of the first and second sampled signals produced by the sampling means and to compare the value of the difference with the value of a reference signal, the value of the reference signal being representative of a desired output signal produced by the photomultiplier, said first circuit means being operative when the value of the difference between the values of the first and second samples signals bears a predetermined first relationship to the value of the reference signal to produce a first output signal having a value representative of the difference, and operative when the value of the difference between the values of the first and second sampled signals bears a predetermined second relationship to the value of the reference signal to produce a second output signal having a value representative of the difference; and second circuit means coupled to the first circuit means and adapted to be coupled to the photomultiplier, said second circuit means receiving the output signals produced by the first circuit means and being operative in response to a first output signal received from the first circuit means to supply a dc voltage to the photomultiplier in a first direction and varying at a rate determined by the value of the first output signal, and being operative in response to a second output signal received from the first circuit means to supply a dc voltage to the photomultiplier in a second direction and varying at a rate determined by the value of the second output signal.

Claim 8

A gain control circuit for controlling the gain of a photomultiplier, said photomultiplier being exposed to a pulsed beam of electromagnetic radiation and operative when exposed to the pulsed beam of electromagnetic radiation to produce an output signal, said gain control circuit comprising: processing means adapted to be coupled to the photomultiplier and operative to receive an output signal produced by the photomultiplier when exposed to a beam of electromagnetic radiation and to derive a corresponding output signal therefrom; sampling means coupled to the processing means and operative to sample the output signal produced by the processing means at predetermined first and second time intervals, thereby to provide first and second sampled signals, respectiveLy; first circuit means coupled to the sampling means and adapted to determined the difference in the values of the first and second sampled signals produced by the sampling means and to compare the value of the difference with the value of a reference signal, the value of the reference signal being representative of a desired output signal produced by the photomultiplier, said first circuit means being operative when the value of the difference between the values of the first and second samples signals bears a predetermined first relationship to the value of the reference signal to produce a first output signal having a value representative of the difference, and operative when the value of the difference between the values of the first and second sampled signals bears a predetermined second relationship to the value of the reference signal to produce a second output signal having a value representative of the difference; and second circuit means coupled to the first circuit means and adapted to be coupled to the photomultiplier, said second circuit means receiving the output signals produced by the first circuit means and being operative in response to a first output signal received from the first circuit means to supply a dc voltage to the photomultiplier in a first direction and varying at a rate determined by the value of the first output signal, and being operative in response to a second output signal received from the first circuit means to supply a dc voltage to the photomultiplier in a second direction and varying at a rate determined by the value of the second output signal.

Claim 9

A gain control circuit in accordance with claim 4 wherein the second circuit means comprises: first means coupled to the first circuit means and receiving the output signals produced by the first circuit means, said first means being operative during a portion of the time of exposure of the photomultiplier to the beam of electromagnetic radiation and in response to a first or second output signal from the first circuit means to supply a dc voltage to the photomultiplier in the first or second direction, respectively, said dc voltage varying at a first rate determined by the value of first or second output signal; and second means coupled to the first circuit means and receiving the output signals produced by the first circuit means, said second means being operative following the aforesaid portion of the time of exposure of the photomultiplier to the beam of electromagnetic radiation and in response to a first or second output signal from the first circuit means to supply a dc voltage to the photomultiplier in the first or second direction, respectively, said dc voltage varying at a second rate determined by the value of the first or second output signal and differing from the first rate.

Claim 10

A gain control circuit in accordance with claim 5 wherein the first rate is greater than the second rate.

Claim 11

A gain control circuit in accordance with claim 6 wherein: the first means is operative to supply a dc voltage to the photomultiplier during the predetermined second time interval; and the second means is operative to supply a dc voltage to the photomultiplier after the predetermined second time interval.

Claim 12

A gain control circuit in accordance with claim 7 wherein: the first means comprises: first resistance means; switch means coupled to the first circuit means and to the first resistance means and operative during the predetermined second time interval to couple a first or second output signal produced by the first circuit means to the first resistance means; said first resistance means being operative to derive a first current signal from the first or second output signal coupled thereto by the switch means, said first current signal having a value directly related to the value of the first or second output signal; and dc amplifier circuit means coupled to the first resistance means and operative in response to the first curRent signal derived by the first resistance means to supply a dc voltage to the photomultiplier at the first rate, said first rate varying directly with the value of the first current signal; and the second means comprises: second resistance means coupled to the first circuit means and operative following the predetermined second time interval to derive a second current signal from a first or second output signal produced by the first circuit means, said second current signal having a value directly related to the value of the first or second output signal; and the aforesaid dc amplifier circuit means, said dc amplifier circuit means being coupled to the second resistance means and operative in response to the second current signal derived by the second resistance means to supply a dc voltage to the photomultiplier at the second rate, said second rate varying directly with the value of the second current signal.

Claim 13

A gain control circuit in accordance with claim 8 wherein: the value of the first resistance means is less than the value of the second resistance means whereby the value of the first current signal is greater than the value of the second current signal.

Claim 14

A gain control circuit in accordance with claim 5 wherein: the sampling means comprises: first switch means coupled to the processing means and timed to sample the output signal produced by the processing means at its minimum-value point, thereby to derive the first sampled signal; first storage means coupled to the first switch means and operative to store the first sampled signal; second switch means coupled to the processing means and timed to sample the output signal produced by the photomultiplier at its maximum-value point, thereby to derive the second sampled signal; and second storage means coupled to the second switch means and operative to store the second sampled signal.

Claim 15

A gain control circuit in accordance with claim 10 wherein: the first storage means includes a first capacitance; the second storage means includes a second capacitance; and the first circuit means comprises: differential amplifier circuit means having a first input terminal coupled to the first capacitance and a second input terminal coupled to the second capacitance; and means coupled to the second input terminal of the differential amplifier circuit means for establishing the reference voltage signal.

Claim 16

A gain control circuit for controlling the gain of a photomultiplier, said photomultiplier being exposed to successive pulsed beams of electromagnetic radiation and operative when exposed to the successive pulsed beams of electromagnetic radiation to produce corresponding successive output signals, said gain control circuit comprising: processing means adapted to be coupled to the photomultiplier and operative to receive the successive output signals produced by the photomultiplier when exposed to the successive beams of electromagnetic radiation and to derive corresponding output signals therefrom:: sampling means coupled to the processing means and operative to sample each output signal produced by the processing means at predetermined first and second time intervals, thereby to provide first and second sampled signals, respectively, for each output signal produced by the processing means; first circuit means coupled to the sampling means and adapted to determine the difference in the values of the first and second sampled signals produced by the sampling means for each output signal produced by the processing means and to compare the value of the difference with the value of a reference signal, the value of the reference signal being representative of desired output signals produced by the photomultiplier, said first circuit means being operative when the value of the difference between the values of the first and second sampled signals bears a predetermined first relationship to the value of the reference signal to produce a first Output signal having a value representative of the difference, and operative when the value of the difference between the values of the first and second sampled signals bears a predetermined second relationship to the value of the reference signal to produce a second output signal having a value representative of the difference; first means coupled to the first circuit means and receiving the output signals produced by the first circuit means, said first means being operative during each predetermined second time interval and in response to a first or second output signal from the first circuit means to supply a dc voltage to the photomultiplier in a first direction or in a second direction, respectively, and varying at a first rate determined by the value of the first or second output signal; and second means coupled to the first circuit means and receiving the output signals produced by the first circuit means, said second means being operative in the time between successive second time intervals and in response to a first or second output signal from the first circuit means to supply a dc voltage to the photomultiplier in the first direction or in the second direction, respectively, and varying at a second rate determined by the value of the first or second output signal, said second rate differing from the first rate.

Claim 17

A gain control circuit for controlling the gain of a photomultiplier, said photomultiplier being exposed to successive pulsed beams of electromagnetic radiation and operative when exposed to the successive pulsed beams of electromagnetic radiation to produce corresponding successive output signals, said gain control circuit comprising: processing means adapted to be coupled to the photomultiplier and operative to receive the successive output signals produced by the photomultiplier when exposed to the successive beams of electromagnetic radiation and to derive corresponding output signals therefrom:: sampling means coupled to the processing means and operative to sample each output signal produced by the processing means at predetermined first and second time intervals, thereby to provide first and second sampled signals, respectively, for each output signal produced by the processing means; first circuit means coupled to the sampling means and adapted to determine the difference in the values of the first and second sampled signals produced by the sampling means for each output signal produced by the processing means and to compare the value of the difference with the value of a reference signal, the value of the reference signal being representative of desired output signals produced by the photomultiplier, said first circuit means being operative when the value of the difference between the values of the first and second sampled signals bears a predetermined first relationship to the value of the reference signal to produce a first Output signal having a value representative of the difference, and operative when the value of the difference between the values of the first and second sampled signals bears a predetermined second relationship to the value of the reference signal to produce a second output signal having a value representative of the difference; first means coupled to the first circuit means and receiving the output signals produced by the first circuit means, said first means being operative during each predetermined second time interval and in response to a first or second output signal from the first circuit means to supply a dc voltage to the photomultiplier in a first direction or in a second direction, respectively, and varying at a first rate determined by the value of the first or second output signal; and second means coupled to the first circuit means and receiving the output signals produced by the first circuit means, said second means being operative in the time between successive second time intervals and in response to a first or second output signal from the first circuit means to supply a dc voltage to the photomultiplier in the first direction or in the second direction, respectively, and varying at a second rate determined by the value of the first or second output signal, said second rate differing from the first rate.

Claim 18

A gain control circuit in accordance with claim 12 wherein the first rate is greater than the second rate.