SU1413415A1 - Method of determining diameter of holes - Google Patents

Abstract

The invention relates to instrumentation engineering, in particular, to carry out fetoelectric methods for controlling the diameter of the holes. The aim of the invention is to improve the accuracy of the measurement of the diameter by eliminating the effect on accurate measurements. diameter values. To do this, illuminate the object with a controlled hole by a collimated monochromatic radiation beam and behind the hole along the beam propagation axis, coordinates are fixed along this axis of three consecutive central minima to the intensity in the diffraction pattern obtained by diffraction of light on the hole. Based on the recorded values of the coordinates, the diameter of the test hole is calculated. 1 il. (/)

Description

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The invention relates to a control measurement technique, in particular to photoelectric methods for controlling the diameter and shape of the holes.

The purpose of the invention is to improve the accuracy of measuring the diameter by eliminating the influence on the accuracy of measuring the magnitude of the diameter of the holes (ensuring the invariance of the method to the size of the diameter of the holes)

The drawing shows the optical layout of the device for carrying out the method.

The optical scheme contains a laser 1, a first beam splitter 2, a first collimator 3, an object mounting unit 4 with a controlled aperture, a lens 5, a first diaphragm 6, a first photocell 7, a prism 8, a second collimator 9, a second beam splitter 10 a reflector 11 a reference, a reflector 12 measuring, the carriage 13, the second 14 and the third 15 of the diaphragm, the second 16 and the third 17 of the photocells and the electronic unit 18.

The method is carried out as follows.

The light beam from the coherent monochromatic source - laser 1 is directed to the first beam splitter 2, which divides the incoming beam into two secondary mutually perpendicular beams of equal intensity. Then one of the secondary beams is directed to the first collimator 3, an expanded parallel beam of light is obtained, during which an object of control is installed in the attachment unit (a part with an aperture. As a result of diffraction of the laser beam on the aperture, diffraction images are formed one after the other on its axis object with minimum intensity in the center. These diffraction images are enlarged by lens 5 and projected onto the plane of the first circular aperture 6 which cuts the center the zone “First photocell 7 registers the illumination of the central zone of each diffraction image of the aperture on the diaphragm 6.

Another secondary beam of light, to which the direction perpendicular to the first is specified by means of a prism 8, is expanded by a second collimator 9 and enters the interferometer.

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 The following optical elements assembled according to the Michelson scheme: the second beam splitter 10, the reflector 11 of the reference beam, the reflector 12 of the measuring element mounted on the carriage 13, the second 14 and the third 15 of the slit diaphragms shifted one relative to

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The second 16 and third 17 photocells electrically connected to the electronic unit 18 By moving the carriage 13 and the lens 5, the diaphragm 6 and the photocell 7 mounted on it, using a non-contact electromagnetic actuator in the direction of the hole 4 that is monitored the hole projected by lens 3 onto the plane of the first aperture 6, which is recorded by the first photocell 7 electrically connected to the electronic unit 18. At the same time Electrical signals from the second 16 and third 17 photoelectric interferometric transducer of linear displacements arrive at the electronic unit, at which the distance lx is measured by the first photocell 7 intensity minima of the diffraction patterns in the electronic unit and 4xi passed by the carriage 13, that adequate to the linear distance between the first, second, and third diffraction images of the aperture with intensity minima at the center. Then calculate the diameter d of the hole by the formula

d 2 .l-2J.5lil5jlJ.2jL d M (Lx, - / 1x) 2

where D is the wavelength of the laser radiation.

Claims (1)

Invention Formula The method of determining the diameter of the holes, which consists in illuminating a monitored monochromatic radiation beam controlled hole, register the radiation intensity in the diffraction pattern behind the hole and determine the diameter of the hole, which differs by measuring the intensity of the axis 14134154 Along the beam axis, they fix the beams in the diffraction pattern, and the coordinates of three consecutive center-diameter holes are determined taking into account the intensity minima of the detected coordinates. 7-1I / j 71 mnt; / 4 16 18 P 1 JO Lx / 3 12 15 17