SU1603201A1 - Method of recording optical pulse - Google Patents

Abstract

The invention relates to a technique for detecting optical signals and can be used in luminescent studies, optical location, pulsed photometry, photobiology, scintillation technology. The aim of the invention is to improve the accuracy of registration. The essence of the invention consists in amending the recorded signal taking into account the linear interpolation of the law of the change in the dark current level and the change in the slope of the photoelectric conversion characteristic, which take place under the influence of the recorded pulse. To do this, a periodically repeating reference optical signal is applied to the input of the photoelectric device before the beginning of the recorded pulse and immediately after it ends, the value of which is determined from the condition of obtaining the converted signal in the middle of the linearity section of the photoelectric conversion characteristic. The smoothed electrical signal Y (T) is measured at various times T and magnitudes of the total smoothed electrical signal G ₁ at time T ₁ under the influence of the reference signal at the device input and the signal F ₁ after it is turned off, as well as the corresponding values of G ₂ and F ₂ at time T ₂ after the end of the optical pulse, after which the refined values of the recorded optical pulse are determined by the appropriate formula. 2 Il.

Description

The invention relates to a technique for detecting optical signals and can be used in centration studies, optical location, pulse photometry, photobiology, scintillation techniques.

The aim of the invention is to increase the accuracy of recording a pulsed optical signal by reducing the range of variation of the photocurrent during the registration process and ensuring that the photoelectric conversion characteristics and the dark current of the device can be monitored after the passage of the noise signal.

Figure 1 shows the time diagrams that explain the essence of the proposed method; FIG. 2 is a diagram of an apparatus for implementing a method for detecting an optical pulse with a photoelectric device.

The method is carried out as follows. ---; ... ..; . . Before the start of a photoelectric device, the input signal of the photoelectric device and, after its completion, a periodically repeating reference optical signal is supplied, the value of which is determined from the condition of receiving the converted signal in the middle of the linearity section of the photoelectric conversion characteristic of the photoelectric device; the smoothed electrical signal y (t) at various points in time t and the magnitude of the total smoothed electrical signal g ,. at time t, when the reference signal is applied at the input of the device and the signal f after it is turned off, as well as the values of -g and f at the time moment t after the end of the optical pulse, after which the refined values of x (t) of the recorded optical pulse determine according to the formula

.a, | W- ,, .j..r.i. (,. ,,,

at t, t t2

where k (t) 1+

 (p 1) - coefficient,

. V reading from - 0

changing the photoelectric conversion characteristic of the photoelectron 45 device.

Photoelectric registration errors occurring both due to the change in the research institute of the t-magnet current and due to changes in the slope of the characteristic,

The photoelectric conversion is monitored both before the appearance of the registered impulse and immediately after its termination,. This allows you to interpolate and account for the registration error for any point in time.

The method can be implemented on the basis of a device for researching forms

.Q. g 25

five

0

five

,

We have a decaying luminescence pulse, the circuit of which is shown in Fig. 2. The device includes a luminescence excitation source 1, a cuvette 2 with the test substance, an optical system 3, a photomultiplier 4, a low-pass filter 5, a light emitting device "

6 with a generator 7 to start it, an analog-to-digital converter 8, a block for triggering a photo excitation source and an interface 10 for communicating with a computer. In the device, the source 1 of the excitation and the cell 2 with the test substance are installed at the input of the optical system 3. At the output The optical system 3 is installed photomultiplier 4, the output of which is connected to the filter 5 of the lower frequencies. The input of the analog-digital converter 8 is connected to the output of the low-pass filter 5, and its output is connected to the data input of the interface 10. The outputs of the control signals from the interface 10 are connected to the inputs of the generator 7 and the excitation source trigger unit 9, and the outputs the latter - to the light-emitting device 6 and the source of luminescence excitation 1. The channel I / o interface 10 is connected to the channel of the computer.

The device works as follows.

In the initial state, the excitation source 1 is turned off, a predetermined optical signal (Fig. La) from the light-emitting device 6 is fed to the cuvette 2, which is periodically triggered by generator pulses 7. After reflection from the walls of the cuvette 2, this signal is transmitted through the optical system 3 after-

blunt to the input of the photomultiplier 4, the output of which (Fig. 1d) is amplified and smoothed by the low-pass filter 5, encoded by the analog-to-digital converter 8, transmitted via the interface 10 and stored in the computer's random access memory. In this case, the obtained codes are recorded in two different computer memory cells, into which code g is inserted, the total converted signal during the action of the reference pulse and the code f after it is turned off.

Codes g and f are periodically updated until the start of the registration of the optical pulse.

At the time of ignition of the excitation source 1 from the start-up unit 9 (Fig. 16), the action of the generator 7 is prohibited by the signal from the interface 10 and the supply of the reference signal from the light-emitting device 6 is stopped. The luminescence luminescence pulse (Fig. 1b) through the optical filter 3 is received by the photomultiplier 4, and the received signal y (t), after amplification and smoothing, is digitized and stored in the given cells of the computer memory.

After a pause, the duration of which is set depending on the duration; of the detected: lasers, the computer removes the prohibition through interface 10, the generator 7 is turned on and the reference signal to the input of the photoelectric multiplier 4 is resumed. After measuring and storing the values of the total signal gg and the dark current f, the computer corrects the registered signal, y (t), in accordance with the initial expressions.

The features of the practice of the invention are explained by the following examples of calculating the signal x (t) for a point in time

t, +

2

t2

Example 1. The case of varying photoelectric conversion and zero dark current characteristics:, 0; g Substituting the indicated values of the measured signal levels gives K (1.05; x (t) 0.952y (t)).

Example 2. The case of a change in the photoelectric conversion characteristic of stagnation and linear dark current growth: gz 0.9g; f, 0; f 0,2g; y (t) 2g ,. Substituting the specified values gives K (t) 0.85; x (t) 1.08y (t).

P p and M e p 3. The case of the constancy of the photoelectric conversion characteristic and the dark current:

25 h

f ,. In this case, K (t) 1,

g | (., X

x (t) y (t) - f, i.e. this particular case is reduced to subtracting the actual value of the dark current. In other words, the method of subtracting the dark current of the constant level is a special case in relation to

.

7 F 10

about-"

:

but

,

with- . niyu

to the proposed method. At the same time, an increase in registration accuracy is achieved even in this simplest case. Such accuracy is due to the fact that the dark current level is measured - just before the passage of the optical pulse and. The assessment of its level is higher in comparison with the known method. In addition, with the periodic supply of reference pulses, a constant component of the photocurrent is created, which significantly exceeds the level of dark current, which improves the stability of the characteristics of the photoelectronic device in comparison with the known method due to a decrease in the range of variation of the constant photocurrent photocurrent.

Claims (1)

Invention Formula A method of registering an optical pulse 25, which includes passing a detected pulse through the optical system and converting it into an electrical signal using a photoelectronic device, as well as smoothing the converted electrical signal during a lowpass filter, which, in order to increase the recording accuracy, To the input of the photoelectronic device prior to the beginning of the impedance 35 and immediately after its termination, a periodically repeating reference optical signal is supplied, the magnitude of which Based on the condition of obtaining the converted 40 signal in the middle of the linear section, the characteristics of the photoelectric conversion of the photoelectronic device are measured, the value of the smoothed electrical signal y (t) is measured at different instants of time t, the value of the smoothed electrical signal g at time t reference signal to a photoelectric device, the signal f after the reference signal 50 is turned off before the optical pulse begins, as well as the corresponding values of the signals g2.H f at the instant of time neither t after the end of the optical pulse, and the values of the detected optical .55 pulse x (t) are determined by the formula thirty 2 (t) K (t) f, - f-Ч-г («- t 2. - with ( at t, t "t where K (t) e 1 + 4. li. (.. tj-t, factor, teach-5 Awesome treason characteristics of photovoltaic: - the conversion of a photoelectronic device. f URO YUSHCHUV CUSHOAfJ TTY awox V513AD-865 (7DD Py