RU1785054C - Device for semiconductor plates and structures defectiveness determining - Google Patents

Abstract

The invention relates to optical electronic instrumentation and can be used in meteorology and navigation. The device comprises a laser with a control unit, a transceiver optical system, a reference pulse sensor optically coupled to a laser, a counter, a counting pulse generator that starts the counter, three code comparison circuits, three memory registers, a photodetector optically coupled to a transceiver optical system , a logarithmic amplifier at the output of the photodetector, two controlled integrators, two memory blocks that store the output signals of the controlled integrators, a subtraction circuit, three digital a log converter (DAC), at the outputs of the corresponding memory registers, three logarithmic amplifiers connected to the output of the corresponding DACs, a quadrator connected to the output of the subtraction circuit, two adders, two integrators, five multipliers, an analog-to-digital converter, and a reference signal source. 1 ill. $

Description

The invention relates to optical electronic instrumentation and can be used in meteorology and navigation.

A patent application for measuring optical transparency is known, comprising a light source and a transmitting optical system in series, a reflector optically coupled to a transmitting optical system, a receiving optical system coupled to a reflector in series, a photodetector and an electronic processing unit.

The disadvantages of this device stem from the need to use a reflector in it. Such a disadvantage is the bulkiness of the structure, the limited range of applications, the long preparation time associated with the installation of the reflector and the orientation of the transceiver in the direction of the reflector.

A device is known for determining the transparency of an optical medium, taken as a prototype, comprising serially connected a master oscillator, a radiation source, a transmitting optical system and two corner reflectors mounted at the boundaries of the studied section of the optical medium, sequentially connected to a receiving optical system that is optically coupled to corners with reflectors, a photodetector and a switch, to the outputs of which two integrators are connected, as well as a division circuit connected by inputs to the outputs ntegratorov and a delay line connected to the control inputs of the two integrators.

The presence of corner reflectors in the prototype leads to the bulkiness of the structure, a limited range of heights

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application, the duration of the preparatory work associated with the installation of reflectors at predetermined distances and the orientation of the transceiver in the direction of the reflectors.

The aim of the invention is to simplify the design associated with the exclusion of corner reflectors from the device.

This goal is achieved by the fact that in the device containing a laser connected in series with the control unit and a transmitting optical system, series-connected receiving optical system and a photodetector, the corresponding blocks and nodes are introduced, allowing meteorological range to be estimated by changing the backscatter power visibility. The operation of the device according to this invention is based on the equation of the laser location of the scattering medium, which for a horizontal path takes the form:

P (D) s ...

Po J / n / PR o to exp (- 2 e D) /

/D2.(1)

where P (D) is the power of the received pulse signal of single scattering from the distance D from the laser; - Po is the power of the probe pulsed laser radiation;

Avkh - the area of the entrance pupil of the receiving device;

y-speed of light:. ...., -,.

t / c radiation pulse duration;

. tyn, t / pr is the transmittance of the optical systems of the transmitter and receiver, respectively;

a is the dispersion index;

k is the modulus of the scattering indicatrix vector for an angle of 180 °; ,

Ј o + a is an indicator of attenuation; a is a measure of the absorption of laser radiation in the atmosphere.

Since the current range D is related to time t by the relation

 , fa)

then equation (1) can be converted to

P (t) 2P0 Avkh

- J / np ff to exp (- s with t) / 4 (3)

The signal S (t) at the output of the photodetector with integrated sensitivity y is described by the expression:

S (exp (- e s t)

(4)

where u Avkh / n Vnp ak with

The logarithmic transformation of expression (4) gives

lnS (tHnk-2lnt-set (5)

If the samples of the information signal (5) are taken not at separate time instants, but at separate intervals q, rz and t2,13, then the obtained samples will be averaged, which

causes a decrease in the fluctuation of the component and an increase in accuracy. Counts Ji and Ja in the intervals ti.tz and t2, ta are characterized by the relations

 m

V)

1

, lnS (t) dt (t2-ti) lnK + 2 (t2-ti-t2lnt2 + tilnti) -.

.w

ta -.,:

 nS (t) dt (t3-t2) lnk + 2 (t3-t2-t3lnt3 + t2lnt2) -

) with

If the duration of the intervals t2-ti t3-, then the signal difference

Ji-J2 e c (At) 2 + 2tilnti + 2t3lnt3-4t2lnt2 (8)

It is known that the meteorological visibility range DM is defined as the distance at which a standard observer, under conditions of sufficient illumination, can still distinguish an object of sufficient size, the contrast of which relative to the background is unity. By standard observation is meant an observer capable of perceiving an image with some minimal contrast. The DM value for the horizontal path can be found from the equation: :: :: -: - :::; -: -: -.- h. ;; Y -; - .: L. : -; ... DMHn (1 / Ko) / e;:,:,: -; g (9) Usually, the contrast is set to 0.02. . Thus, determining from the expression

(8) the value Ј, from the expression (9) you can find the meteorological range of visibility DM. The described algorithm is implemented in the proposed device ..; ; ; x

;. The drawing shows a functional diagram of the meter meteorological visibility range. : v

The device comprises a laser 1 with a control unit 2, a transceiver optical system 3, a reference pulse sensor 4 optically coupled to a laser, a counter 5, resetting of which is performed by the pulses of the sensor 4, a counter pulse generator 6, which starts the counter 5, three circuits 7, 8 and 9 code comparisons, three

memory registers 10, 11 and 12, a photodetector 13 optically coupled to a receiving optical system, a logarithmic amplifier 14, converting the output signal of the photodetector 13, two controlled integrators 15 and 16, two memory blocks 17 and 18, which are stored in predetermined points in time, the output signals of the controlled integrators 15 and 16, the subtraction circuit 19 ,. three digital-to-analog converters 20, 21 and 22, converting the output signals of the memory registers 10. 11 and 12, respectively, three logarithmic amplifiers 23,24 and 25, connected to the output of the corresponding digital-to-analog converters 20, 21 and 22, a quadrator 26 connected to the output subtraction circuits 19, five multipliers 27, 28, 29, 30 and 31, two adders 32 and 33, two integrators 34 and 35, an analog-to-digital converter 36, and a reference signal source 37.

The device operates as follows.

Laser 1, under the action of an ignition pulse generated in the control unit 2, generates an optical pulse, which is transmitted through the transceiving optical system 3 to the atmosphere along a horizontal path. At the time of the laser 1 radiation, the sensor 4 generates a reference pulse, which nullifies the counter 5. The counting pulses generated by the generator 6 are supplied to the counting input of the counter 5 and change its state. The current digital code generated by counter 5 and carrying information about the time since the laser pulses the optical pulse is simultaneously fed to three schemes for comparing codes 7.8 and 9 and to three memory registers 10, 11 and 12.

The backscattered optical radiation is transmitted through a transceiving optical system 3 to a photodetector 13, in which it is converted into an electrical signal (4). The logarithmic amplifier 14 converts the signal S (t) to form (5).

Let ti be the point in time after the emission of the optical pulse corresponds to the digital code Ni, t2 be the point in time after the emission of the optical pulse corresponds to the digital code N2. a t3 - the time after the emission of the optical pulse corresponds to digital code N3. Then, at time ti, the code comparison circuit 7 generates a pulse that simultaneously arrives at the control input of the memory register 10 and at the first control input of the controlled integrator 15. By

a digital code corresponding to time ti is written to this signal in register 10, and controlled integrator 15 will integrate the output signal of logarithmic amplifier 14. After some time Д t, the digital code generated by counter 5 will coincide with digital code N2 At the time match codes circuit 8 generates a pulse

0 comparison, by which a digital code is entered in register 11, corresponding to time t2 after receiving an optical pulse, and controlled integrator 15 will complete the integration of the information signal 5. The arrival of the output signal to the control input of the memory unit 17 will lead to the fact that it will contain the signal Jt (formula 6) generated in the integrator 15. The arrival of this signal to the first control input of the controlled integrator 16 will lead to that from time ti, the integrator 16 will integrate the output of the logarithmic amplifier 14.

5 At the end of time 2 At a digital code. generated by the counter 5, will coincide with the digital code Ms corresponding to time ta. At the moment of coincidence of codes, circuit 9 generates

0 pulse, by which the integrator 16 completes the integration of the information signal, and a digital code corresponding to the time ts after the emission of the optical pulse is entered into register 12. The arrival of the output signal of the comparison circuit 9 to the control input of the memory unit 18 will lead to storing in it the signal J2 (formula 7) generated in the controlled integrator 16. The construction of the controlled integrator is based, for example, on the use of an operational amplifier the input circuit of which includes a resistor and an electronic key, and a capacitor in the feedback circuit. Electronic control,

The 5th key is implemented by the output pulses of the code comparison circuit. Sample storage devices may be used as memory blocks 17 and 18.

Digital codes removed from the registers

The 0.11 and 12 in the digital-to-analog converters are converted into analog signals, which are then fed to the logarithmic amplifiers 23, 24 and 25, respectively. Gain Amplifiers 23 and 25

5 is twice the gain of the logarithmic amplifier 14, and the gain of the logarithmic amplifier 24 is four times. The signals generated by the logarithmic amplifiers 23, 24 and 25 are fed to the frontier residents 27, 28 and 29, respectively. The signals of the respective memory registers 10, 11, and 12 are fed to the other input of these multipliers. The output signals of the multipliers 27, 28, and 29, together with the signals contained in the memory blocks If and 18, are fed to the adder 32, where they are implemented algebraic summation in accordance with the formula:

U i-J2-2tiInti + 4t2lnt2-2t2lrm e c (At) 2. (10)

Digital codes I removed from registers 11 and 12 also go to subtraction circuit 19, where you generate Guy Graznost At t3-t2 t2-ti. The found value of At is supplied to the quadrator 26 and then fed to the first input of the multiplier 30, the feedback of which Ubc is supplied to the second input of which. A multiplier zo, an adder 32 and an integrator 34 are included; (: BstS of the automatic control loop. Therefore, the mismatch signal, which is the output signal of the adder 32, is processed by this circuit. If the mismatch signal is zero, the voltage Uoc at the output of the integrator 34 will have some constant value, after multiplying about in the life expectancy 30 on (At) 2 it will be obtained from the ignal corresponding to the value of Ui Therefore, after processing the mismatch signal, the following relation takes place:

;. (At) 2, from which it follows:

 Uoc4Ji / (At) 2. .(eleven)

Comparing relations (11) and (10), we conclude that

 .(12)

The generated feedback voltage, proportional to the attenuation, in the analog-to-digital converter 36 is digitized and fed to the first input of the multiplier 31, to the other input of which a signal Ua is supplied. A multiplier 31, an adder 33 and an integrator 35 are included in the automatic control loop. Therefore, the error signal, which is the output signal of adder 33, where the output signal of the multiplier h31 is compared with the reference signal with ln (1 / k0) generated by the source 37, is processed by this circuit. For values of the mismatch signal equal to zero, the voltage U-jj at the output of the integrator. 35 will have some constant value, after multiplication

which in the multiplier 31 of us will receive a signal; corresponding to the reference value with In (1 / k0). Therefore, after processing the mismatch signal

we have:

cln (1 / ko) Un-e-c, from which it follows

(1 / k0) / e, (13)

that is, it coincides with formula (9) and means that the signal Uо corresponds to the meteorological visibility range.

Multipliers 27.28, 29.30 and 31 can be made using a digital-to-analog converter.

 It follows from the foregoing that for the operation of the proposed device, angular reflectors are not needed. And this means that the proposed technical solution will have a more compact compact solution;

and it contains a transceiver with an electronics unit that performs the above functions. However, the proposed device can measure the meteorological range of visibility

on a horizontal track in a wide range of not heights and requires a significant reduction in preparatory work.

Formula and zobreet n and:

Measure the meteorological range of cf and visibility, containing a laser with a control unit, optically coupled to a transceiver optical system and a reference pulse sensor, a photodetector optically coupled to a transceiver optical system, and two integrators, isolated the fact that, in order to simplify the design, two controlled integrators, two memory blocks, each of which is connected to the output of the integrator integrator, two sums, a source of the reference signal, are additionally introduced into the meter. ala, posloDvatolno generators connected p SChoGyyh: iShulsov and counter set input connected to the sensor output of the reference pulse, three parallel circuits serially connected memory registers, a digital to analog

a converter, a logarithmic amplifier and a multiplier, the second input of which is connected to the output of the corresponding Memory register, and the output - to the corresponding input of the first adder, the fourth

the logarithmic gain is connected by BHODO.M to the output of the photodetector, and the output to the information inputs of the managed Integrators, three code comparison circuits, each of which is connected to the counter output by the input, and the ic to the control input of the corresponding memory register, each output which is connected by an information input to the counter output, wherein the output of the first comparison circuit is connected to the first control input of the first controlled integrator, the output of the second comparison circuit is connected to the second control input to the first controlled integrator, to the first control input of the second controlled integrator and to the control input of the first memory block, the output of the third comparison circuit is connected to the second input of the second controlled integrator and to the control input of the second memory block subtraction, two inputs of which are connected to

0

the outputs of the second and third memory registers, a quadrator and a fourth multiplier connected to the fourth input of the first adder, the fifth and sixth inputs of which are connected to output-1. memory blocks, and the output — With the input of the first integrator, connected by the output to the second input of the fourth integrator, serially connected analog-to-digital converter connected by the input to the output of the first integrator, and the fifth multiplier, the output of which is connected to the input of the second adder, the second the input of which is connected to the output of the source of the reference signal, and the output is connected to the input of the second integrator, the output of which is the output of the meter and connected to the second input of the fifth multiplier.