SU1388720A1 - Linear displacement comparator - Google Patents

Abstract

The invention relates to a measuring and measuring technique. The purpose of the invention is to improve the accuracy with the certification of position-sensitive photodetectors by transforming the movements of the carriage with a deflecting optical system into movements of the probing optical image and minimizing the transformation ratio. Optical system. made in the form of two mirrors 9 mounted on the carriage 7, deflects the light beam created by the illuminator 3 from the optical axis and directs it to the surface of the attested photodetector 17. The carriage 7 moves with a predetermined pitch along a direction 2 parallel to the optical axis Illuminator 3. At the same time, the deflecting optical system transforms the movement of the carriage 7 .-: to the movement of the probing optical image along the sensitive surface of the photodetector 17 with the transformation ratio K 2sin6, where 6 is the angle between the plane and mirror 9. The minimization of the transformation ratio K, reach alignment mirrors 9, provides a corresponding decrease in the effect of the displacement of the carriage 7 error on the accuracy of sensing. 2 Il. ate

Description

2178 ,, /

The invention relates to instrumentation engineering and can be used to certify position-sensitive photodetectors.

The purpose of the invention is to improve the accuracy of certification of position-sensitive photo receivers by transforming the movements of the carriage with a deflecting optical system into the movements of a probing optical image.

FIG. 1 shows a linear displacement comparator diagram; in fig. 2 is an optical diagram of a linear displacement comparator.

The linear displacement comparator contains a base 1 with a guide 2, an illuminator 3 consisting of a source 4 of light, a diaphragm 5 and an objective 6 mounted on the base 1 so that its optical axis is parallel to the guide 2, the carriage 7 mounted on the direction 2 can be moved along it and equipped with two racks 8, on which two mirrors 9 and a photodetector mounting unit 10 are rigidly fixed, designed to install a certified photodetector 17, a signal processing unit 11, the input of which is intended to be connected to the output of a certified photodetector, electric drive 12, kinematically connected with carriage 7 and intended for its movement, driver 13 signals of exemplary measure of length, consisting of a waiting tunable generator 14 of pulses of stabilized frequency and sensor 15 of speed of movement of the carriage 7, output connected to the input 1 generator 14, and the input connected to the carriage 7, and the control unit 16, the input I of which is connected to the output of the generator 14, the input II - to the output of the signal processing unit 11, the outputs I and II are connected to the corresponding vuyuschimi drive inputs 12 and III and IV - respectively to the inputs II and 14 HZ generator.

The mirrors 9 are mounted on the carriage 7 along the light beam produced by the illuminator 3, so that they form a deflecting optical system, and the photodetector mounting unit 10 is placed on the carriage 7 so that when the certified photo-receiver 17 is installed on it

the sensitive surface was oriented perpendicular to the optical axis of the illuminator 3 and the distance from the main plane of the lens 6 to a distance equal to

a -f (1 + v) -1 (sin2c (+ sih26) - (1 + v) -d sin26,

(one)

a the center of the photosensitive surface was offset relative to the optical axis of the lens 6 by an amount equal to

 {1 + v) -d3 (l-cos26) -, -I (cos2ot.-cos26),

(2)

where f is the focal distance of the illumination lens 6; V is the linear increase of the illumination lens 6; 1 is the distance between the traces of intersection of the optical axis of the lens 6 with mirrors 9; c1 is the angle between the optical axis of the lens 6 and the plane of the first along the rays from the mirrors 9;

6 is the angle between the planes of the first and second mirrors 9; d is the distance between the nodal point of the lens and the intersection of its optical axis with the plane of the first along the rays from the mirrors 9 in the middle position of the carriage 7.

The reflective surfaces of mirrors 9 have the following (minimum) dimensions:

first mirror

 f (H-v) -d 2f (1 + v)

second mirror:

f (H-v) - (d + l) 2f (l + v)

 sinc, (3)

nDjjg sin (o (+6),

(four)

20 25 30

50

55

where D p5 is the exit pupil of the lens.

The linear displacement comparator works in the following way.

The certified photodetector 17 is mounted on the photodetector mounting unit 10 and connected with an output to the input of the signal processing unit 11. The carriage 7 is in one of the extreme positions at which the image

31

diaphragm 5 is not obviously projected onto the surface of the photodetector 17. On the scale of the imaging unit of 13 signals of an exemplary measure of length, the frequency switch sets the nominal pulse frequency, pre-calculated from the condition of the nominal step of indicating the position of the carriage 7 and its speed, include sources of stabilized linear displacement voltage comparator ( not shown). In this case, the output from control unit 16 turns on the electric drive 6, which moves the carriage 7. In the process of movement of the carriage 7, the optical image of the diaphragm 5 moves along the sensitive layer of the photodetector 17, the output of which produces photoelectric signals entering the signal processing unit 11. In block 11 of signal processing, at the moment of the beginning of this signal, a pulse arrives at the input II of control unit 16, which generates. the reference pulse and sends it from output III to the input II of the waiting tunable generator 14 of a stabilized frequency. From this pulse, the generator 14 starts and begins to generate a sequence of pulses calibrated in time and amplitude with the above-mentioned nominal frequency. In the process of moving the carriage 7, the sensor 15 measures its speed. The signal corresponding to the speed of movement of the carriage 7 is fed to the input I of the generator 14 in accordance with the change in the speed of movement of the carriage 7. A sequence of short pulses from the output of the generator 14 of a stabilized frequency is fed to the input I of the control unit 16. At the end of the attestation, the control unit 16 generates a signal. The end of the measurement cycle, coming from the output IV of the control unit 16 to the input III of the generator 14 ,. and suspending the generation of pulses for the time required to replace the photodetector 17 on the photodetector mounting unit 10.

Each linear increment of the movement of the carriage 7, the value of which is determined by the frequency of the generator pulses 1.4 and the speed of movement of the carriage 7, corresponds to a proportional linear displacement

.-

image of diaphragm 5 over the surface of the position-sensitive photodetector 17, determined by

 sin &

(five)

S 6 Stroke

where S is the amount of movement of the optical image; the amount of movement of the carriage 7;

the angle between the reflective surfaces of the mirrors 9. S of the carriage is determined on the basis of the dimensions of the photodetector to be certified so that the center position of the carriage 7 is at a distance equal to the value of d included in formula (1).

The displacement transformation coefficient k is equal to the ratio of the S / S values included in formula (5):

25

 five,

(6)

and may vary within the limits defined by the inequality

thirty

0.k.2.

(7)

35

40

45

50.

55

Thus, by minimizing the transformation coefficient k, the influence on the accuracy of the probe beam movement is reduced by the error introduced by the inaccuracy of the step motion of the carriage 7. The limiting degree of minimization is determined by the quality of the adjustment of the mirrors 9.

Claims (1)

Invention Formula A linear displacement comparator comprising a base with a guide, a carriage mounted for movement along a guide, an electric drive kinematically connected to the carriage, a signal generator of an exemplary measure of length, consisting of a stand-alone tunable pulse generator of a stabilized frequency and a carriage speed sensor, the output of which connected to the first input of a standby tunable pulse generator of a stabilized frequency, and the input is connected to the carriage, control unit, the first input cat The first is connected to the output of a standby tunable pulse generator, stabilized frequency, the first and second outputs are connected to the corresponding inputs of the actuator, and the third and fourth outputs are connected respectively to the second and third inputs of a standby tunable pulse generator of a stabilized frequency, characterized in that, in order to increase accuracy certification of posed-sensitive photodetectors; it is equipped with an illuminator mounted on the base so that its optical axis is parallel to On the course of a light beam by an optical deflection system consisting of two racks mounted on a carriage and two flat mirrors rigidly mounted on the racks, while the reflecting surfaces of the mirrors are located at a predetermined angle to each other, and a photodetector mounting unit whose working plane is perpendicular The optical axis of the illuminator, as well as by the signal processing unit, the input of which is intended for connecting the output of the certified photodetector a to it, and the output are connected with the third input of the control unit. tpue.2