SU1035419A1 - Optical electronic device for measubring linear displacements - Google Patents

Description

I The invention relates to a measurement technique and can be used to measure displacements of monitored objects, in particular, to measure angular oscillations, for example, in the vibration tests of products. An optical-electronic device is known for measuring the linear dimensions of parts J containing an interferometer with a carriage, an interference modulator with a source of modulating oscillations, an additional light source-. plate, two target diaphragms, two photoelectric converters, two AC amplifiers, two phase demodulators, a reversible counter and an interpolator of the G1 interference band. The drawback of the device is the use of two channels of signal processing, which imposes high requirements on tuning and leads to a decrease in the measurement accuracy, and also complicates the measurement of the angular oscillations of the object. The closest to the proposed technical entity is an opto-electronic device for measuring linear displacements, which contains an optical system for forming interference or moire bands, a discrete phototransducer optically connected to the system for forming interference or moire bands, sequentially connected to a block of drivers, A counting unit and a display unit 2 connected to a discrete phototransducer. A disadvantage of the known device is the difficulty of measuring angular oscillations. Because of the presence of angular displacements of the object, there is a divergence of the reference and signal beams at the output of the system to form interference fringes, for example, an interferometer at an angle equal to the angle of rotation of the object. This leads to a change in the spatial frequency of the following interferential or moiro OX bands 5, which leads to contact with the photosensitive layer of the discrete photoconverter not one, but several interference or moire bands, whose width may vary and complicate their calculation. The purpose of the invention is to expand the functionality by providing measurement of angular displacements. This goal is achieved by the fact that in an optical-electronic device for measuring linear displacements containing an optical system for forming interference or moire bands, a discrete photo-converter is optically coupled to the system. the formation of interference or moire bands, a series-connected block of drivers, connected to a discrete phototransducer, a block of bills and an indie block The shaper unit is made with two outputs and consists of the amplifier node of the switch and element I, connected in series to the clock generator and the control node, the outputs of the amplifier node and the main outputs of the control node are connected to the switch, the output of which is connected to the first input of the element And and the input of the node control, the first additional output of which is connected to the second input of the element AND, and the second is the second output of the block of drivers and connected to the second input of the counting block, the output of the generator such as are for. "pulse is coupled to the third input of AND gate whose output is the first output of the block and is connected to the first input of the counting unit. The drawing shows a block diagram of the proposed device. The device consists of an optical system 1 for forming interference or moire bands 5 connected in series, a discrete phototransducer 2, a block 3 of formers, a counting block k, and a display unit 5. The driver unit is made in the form of an amplifier unit 6 connected in series, switch 7 and element 8 I, clock generator 9 and control unit 10 connected to it. The device works as follows. The discrete phototransducer 2 serves to convert the optical signal into an electrical one and contains a system of parallel electrically isolated photodetectors, the width of one photosensitive layer being selected less than the width of the interference or moire band at the maximum frequency. If there are angular displacements of the object, the reference and signal beams diverge at the output of the optical system 1 to form interference or moire fringes by an angle equal to the angle of rotation of the object. The divergence of the beams leads to a change in the width of the interference or moire bands by an amount equal to 2Bini where b is the width of one interference or moire band; L is the wavelength of the source of monochromatic radiation; i is the angle between the reference and signal beams. By fixing the width of the interference or moire fringes falling on a discrete photoconverter., It is possible to uniquely determine the angular oscillations of an object:, R X-. 1 where d is the angle of deviation of the surface of the test object from the vertical plane normal to the beam incident on it; radius of a circle created from the output of a monochromatic radiator; the distance from the controlled object to the plane on which the experimental and signal beam converge. In addition, the angular oscillations of the surface of the object being monitored occur in one, for example, a vertical plane, in the initial state, when the plane of the object being monitored is normal, to the beam incident on it, from the output of the monochromatic radiator, two bands (with a maximum and minimum illumination), which are projected onto the receiving part of the discrete photoconverter 2, whose width is equal to the width of the selection of the bands. At normal displacements of the object, the boundary between the two interference fringes moves along the photosensitive surface of the discrete photoconverter 2, while the width of the interference fringes remains unchanged. If the object under test has angular oscillations of its surface, then the spatial frequency of the following interference fringes changes, i.e. their width changes. From the output of the discrete photoconverter 2, electrical signals are removed, which are fed to the input of the amplifier unit 6, from which either O or 1 is removed, depending on whether; As the band is currently on the photosensitive surface of the photodetector of the discrete phototransducer 2, the amplifier unit 6 may consist, for example, of analog signal amplifiers and comparators with a predetermined trigger threshold. The clock pulse generator 9 generates a sequence of square-wave pulses, which alternately through control 10 and switch J, interrogate the state of the photodetectors of the discrete phototransducer 2. At the output of the switch 7, a sequence of pulses is formed whose width determines the width of the interference or moire bands , projected onto discrete photoconverter 2. Pulses from the output of switch 7 are fed to the first input of element 8 I, and at the moment of their transition from state O to state 1 there is a resolution on the first input of the element 8 I, which enables the passage of pulses from the generator 9 clock pulses through the element 8 AND to the input of the counting unit. At the moment when the impulse from the output of switch 7 goes from state 1 to state O, a inhibit impulse is generated through the control node TH, which is fed to the second input of element 8 I, and thus blocks the passage of pulses from the generator output 9 clocks to the input of the counting block k, until the interrogation of all photodetectors of the discrete photoconverter 2 in the given polling period is completed. At the end of each survey cycle from the second additional output of node 10 control S10

No short pulse is generated which is fed to the counting block i, and. the information from the account block A is entered into the injection block 5. The node 10 of the controls also forms at the end of each polling cycle a resolution impulse sent to the second input of element 8 I.

The frequency of the pulses from the generator output of 9 clock pulses is chosen not less than twice the maximum frequency of interfering OHHbix or moirés, and the width of one photosensitive layer of the phototransmitter of the discrete converter 2 must be no more than the narrowest interference or moire band produced by the object. At 3TOjM, the magnitude of the angle by which object 5 is displaced relative to its vert 19, b

tical plane can be determined from the expression

arcsi n

IT-K

where 0 is the angle by which it shifts

an object;

7 is the wavelength of the monochromatic radiation source; T is the period of the following pulses. With the output of the generator of clock pulses;

k the number of pulses recorded by the display unit. Thus, due to the proposed execution of the block of formers, it is possible to measure the angular deviations of the object under study.

Claims (1)

OPTICAL-ELECTRONIC DEVICE FOR MEASURING LINEAR MOVEMENTS, containing an optical system for forming interference or moire fringes, a discrete photoconverter, optically coupled to a system for forming interference or moire fringes, series-connected block of formers, connected to a discrete Photoconverter, counting unit and an indication unit that, in order to expand the functionality by providing measurement of angular displacements, the block of formers flnn with two outputs and consists of an amplifier unit, a switch and an And element connected in series with a clock generator and a control unit, the outputs of the amplifier unit and the main outputs of the control unit are connected to a switch, the output of which is connected to the first input of the And element and the input of the control unit, the first the additional output of which Qth is connected to the second input of the And element, and the second is the second output of the shaper unit and connected to the second input of the counting unit, the output of the clock generator is connected to tim input AND gate whose output is the first output of the block and is connected to the first input of the counting unit. <