SU838323A1 - Device for contactless measuring of surface geometric parameters - Google Patents

Description

(54) DEVICE FOR CONTACTLESS MEASUREMENT OF GEOMETRIC PARAMETERS OF SURFACES

one

The invention relates to a measurement technique and can be applied in instrumentation, for example, to control the shape and profile of parts.

Contactless devices for monitoring the profile of parts are known, based on an analysis of the defocusing of radiation projected on a controlled surface, containing a radiation source, an optical receiving-transforming system, a photodetector, and a recording device 1J.

The disadvantage of these devices is a small measurement range.

The closest to the invention in technical essence and the achieved result is a device for contactless measurement of geometrical parameters of surfaces, containing sequentially installed radiation source, a beam splitter and a focusing lens, a receiving lens optically coupled to a controlled surface through a beam splitter and a focusing lens, a point-controlled diaphragm installed in the focal plane of the receiving lens with the ability to move along the optical axis, phot receiver mounted for

a pinhole, and an electronic measuring system connected to the photoreceiver output, containing a series-connected amplifier, a phase-sensitive detector, a display and recording unit, a voltage generator connected to the second input of the phase-sensitive detector, and an optical-electronic circuit for normalizing the amplitude of the output signal connected by the output to display and registration unit 2.

A disadvantage of the known device is that it allows you to control only the profile of parts having small angles of change in the profile and a uniform material structure, since a large deflection of the reflected beam from the normal and a change in the structure of the material and its color (for example, tinge color), as well as microscopic irregularities leads to a change in the output signal of the photodetector.

The purpose of the invention is to increase the measurement accuracy and expand the range of monitored surfaces.

The goal is achieved by the fact that the device is equipped with an additional beam splitter,

installed between the receiver lens and a pinhole, and forming a compensating channel, successively installed an additional pinhole and a photodetector, and the amplifier is made differential and connected to the second input with the output of the additional photodetector.

The drawing shows a diagram of the device.

The device contains a radiation source 1 (for example, a laser), a beam splitter 2, a focusing lens 3, a receiving lens 4 receiving radiation from a test surface 5. The focus of the lens 4 is a point aperture 6 with a drive made in the form of a modulator 7 excited in a ring pattern including an inductive transducer 8, a phase shifter 9, an amplifier 10, an exciter (not shown). A photodetector 11 is installed behind the diaphragm 6. A beam splitter is installed in the form of a beam-splitting cube 12 between the receiving lens 4 and the pinhole 6 located in the focus of the receiving lens 4, and the photodetector 14 forms a compensation channel. The outputs of the photodetectors 11 and 14 are connected to the inputs of the differential amplifier 15, the output of which is connected to one of the inputs of the synchronous detector 16. The optical-electronic circuit for normalizing the amplitude of the output signal is formed sequentially by the installed splitter 17, the lens 18, the photoreceiver 19 and the operational amplifier 20. The device also contains phase shifter 21, a dial indicator 22 connected to the output of the synchronous detector 16, to the second output of which a matching device 23 is connected, an electronic meter 24 ratios, electronic zero-body 25, analog-to-digital converter 26 and digital indicator 27.

The device works as follows.

The luminous flux from the radiator 1 is reflected by the controlled surface 5 and is focused in the planes of the point diaphragms 6 and 13. The amplitude of the signal at the output of the photodetector 11, modulated with the oscillation frequency of the point diaphragm 6, depends not only on the position of the controlled surface 5, but also on its structure, processing qualities, colors, etc. Changes in the luminous flux incident on the photodetector 14 depend only on the reflective properties of the material. Therefore, the signal at the output of the differential amplifier 15 depends only on the position of the monitored surface 5. The output signal of the differential amplifier 15 is fed to the input of the synchronous detector 16, the reference voltage for which is removed from the inductive converter 8 and the modulator 7 through the phase shifter 21. At the output of the synchronous detector 16 an arrow indicator 22 is turned on. The output signal of the synchronous detector 16 is fed through a matching device 23

on the electronic meter 24 otnosheny as a dividend. The signal divider is formed by an amplitude ration scheme. The output signal of the ratio meter 24 controls the electronic zero-body 25 and is fed to an analog-to-digital converter 26 with a digital indicator 27.

Supplying the device with additional elements, made and installed in the manner described above, makes it possible to increase the measurement accuracy due to

that the result does not depend on dynamic factors, and to expand the range of controlled surfaces.

Claims (2)

1. Vorontsov L.N. Photoelectric 5 systems of control of linear quantities. M., “Mashinostroenie, 1965, p. 192-200. 2. US patent number 3506839, cl. 250-222, 1970 (prototype).