SU1296850A1 - Electronic photometer - Google Patents

Abstract

The invention relates to the electrophotometry of weak light signals of the visible spectral region by the photon counting method. The purpose of the invention is to improve the accuracy of measuring the light flux. The photometer consists of a photoelectric device I connected in series, an amplifier 2, a discriminator 3 and a distributor 4, the first output 5 of which is connected to the first input 6 of the reversing counter 7, and the second output 8 to a frequency converter 9 connected by the output to the second input 10 of the reversing counter 7 The photometer comprises a modulator AND a luminous flux 12 with a position sensor 13 connected by an output to the control input 14 of the distributor 4, thereby increasing the signal-to-noise ratio. I il. with "(L ND CO O5 00 ate

Description

112

The image refers to photoelectric luminous flux meters and is intended primarily for measuring weak light signals in the visible spectral region in astronomy, biophysics, spectroscopy.

The purpose of the invention is to increase the measurement accuracy of the luminous flux.

The drawing shows the block diagram of the photometer.

The device consists of a serially connected photoelectronic device, for example, a PMT 1, an amplifier 2, a discriminator 3 and a distributor 4, the first output 5 of which is connected to the first input 6 of a reversing counter 7, and the second output 8 to a frequency converter 9 connected by an output to the second input 10 reversible counter 7. In addition, the device includes a modulator 11 of the luminous flux 12 with a state of the sensor 13 connected output with control

input 14 distributor 4.

The device works as follows.

The luminous flux 12, the passage of the modulator 11, affects the photomultiplier 1, which converts the photons that constitute the flux 12, into one-electron pulses, the amplitude of which is insufficient, as a rule, for direct operation of logic circuits. Therefore, single-electron pulses are amplified by amplifier 2, and then fed to discriminator 3, where they are selected by amplitude to cut off the low-energy noise of the FEP and amplifier. Selected and generated pulses from the output of the discriminator 3 are fed to the distributor 4, which supplies them to the summing input of the reversible counter 7. Together with the single-electron pulses in the counter 7, the dark pulses of the FEP I are also summed, coinciding with them in amplitude, Therefore, when closed modulator 1I, the distributor 4 according to the signal of the sensor I3 connects the output of the discriminator 3 to the subtractive input of the reversing counter 7, whereby dark pulses are subtracted from the containing counter 7, so that it becomes possible to determine the number of pulses One-electron mix pulses. Since in this scheme the registration is not blocked at the time of the transition process, some of the pulses must be

registered with a different statistical weight, which is determined by the configuration of the modulator 11. This statistical weight is taken into account by a frequency converter 9 connected to one of the inputs 10 of the reversible counter 7.

Let the average arrival frequency of one-electron pulses with modulator II fully open for time T be n, and dark pulses with modulator 11 completely closed for time Tj - n j .. The transition period has duration T, and the modulator average transparency at that time em Ud. Then during time T the number is recorded

in time T. - N, impulses N (n + n) T, T, j - N., j, in time (n, j (+ n,) T,

In accordance with the invention, the subtraction is carried out only during

time T, and the rest of the time is summation, i.e. in time +

T, T,

T get

 N N,)

pulses. Joint decision

for Ng and N

gives

- (N -) / (T, + M / K.

The measured luminous flux F is determined by this equation with an accuracy up to the quantum efficiency of FEU:

F p.

In this case, the coefficient K T + V T can be taken into account, which makes it possible to accumulate in the counter a value M proportional to the measured light flux. In order to accumulate M, it is necessary to change the frequency of the pulses arriving at the input of the subtraction of the reversible counter 7 in p T / T times by the transducer 9. If px1, then frequency multiplication is necessary, and if p I, then division. The invention makes it possible to increase the signal-to-noise ratio of the photon counter by an average of 35% of that provided by the base device, i.e. improve measurement accuracy.

Claims (1)

Invention Formula Electronic photometer containing a light flux modulator with a sensor3129 com state behind which a photoelectronic device is installed, to the output of which a series-connected amplifier and discriminator are connected, the distributor, the control input of which is connected to the output of the state sensor, and a reversible counter connected by the first input to the first output of the distributor, Editor S. Lisin Compiled by A. Churbakov Tehred M. Khodanych Order 766/42 Circulation 777 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 This is because, in order to improve the measurement accuracy of the luminous flux, a frequency converter is inserted into it, including between the second output of the distributor and the secondary input of the reversible counter, and the output of the discriminator is connected to the input of the distributor. Proofreader S. Shekmar