RU2558269C1 - Method of holographic control of nonflatness of annular surfaces - Google Patents

Abstract

FIELD: instrument engineering.

SUBSTANCE: in the method of holographic control, a first reference beam is formed using the beam splitter and mirrors, and an object beam comprising a projection lens, a working area and a recording unit of the hologram. In addition, a second reference beam is formed, by introducing an optically interconnected system of mirrors, the shielding shutter is added, having a hole in the centre, and is located with the ability of output from the object beam, an opaque shutter is located in the first reference beam, the system of mirrors of the second reference beam is located between the working area and the recording unit of the hologram, the shielding shutter is placed between the projection lens and the working area, and the opaque shutter is placed perpendicular to the optical axis between the beam splitter and the mirror of the first reference beam with the ability of its output from the first reference beam when recording the hologram.

EFFECT: control of value of nonflatness of polished metal and graphite surfaces of the parts.

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Description

The invention relates to the field of modern optical instrument engineering and can be used for technological measuring purposes to control the non-flatness of annular surfaces, as well as to control the non-flatness of the surface of polished metal and graphite products, such as bushings, rings, etc. The invention can also find effective application in the control of non-flatness of the annular surfaces of contact seal parts in an aircraft engine and in engine building, in metal optics and in other fields. There is a real opportunity, for the first time in practice, to control the surfaces of parts with various reinforcing types of coatings: chromium-molybdenum, nitrided and others, as well as the most complex scattering surfaces of annular graphite products.

A known control method (see. Optical production control. - M.: Mechanical Engineering, 1985, under the editorship of D. Malakara, p. 43 - analogue), which uses a quasi-monochromatic radiation source, a beam splitter and mirrors, through which form the reference and the object branch, the lens in the object branch between the beam splitter and the controlled area and the observation area of the interferogram.

The holographic control method is known (see Optical production control. - M .: Mechanical Engineering, 1985, under the editorship of D. Malakara, p. 299 - prototype), in which a coherent radiation source (laser) is used, a beam splitter, through which reference and object branches, a system of mirrors in the reference branch, a lens in the object branch between the beam splitter and the controlled zone (part) and the hologram assembly.

The disadvantage of the first control method is that due to the limited temporal coherence of the radiation source in practice, it is very difficult to apply it to control the non-flatness of the surfaces of metal and graphite products. The disadvantage of the holographic control method is that when obtaining a holographic interferogram of the controlled surface, a reference hologram is used and illuminated at the stage of restoration of the wave fronts by both the reference wave and the object wave reflected from the controlled surface. Due to this, the technique of optical control is complicated, and also when implementing the method in practice, compensation for the aberrations of the optical system is not achieved. In this embodiment, it is very difficult to implement this method to control the non-flatness of the surfaces having an annular shape.

However, in practice, it is of great interest to create a method of holographic control of non-flatness of annular surfaces, in which a two-exposure method of recording a hologram would be implemented and there would be a real opportunity to control the non-flatness of annular scattering surfaces, the control of which is impossible using known methods and devices.

The objective of the invention is to expand the technological capabilities of the method of holographic control of non-flatness of the annular surfaces of parts made of metal and graphite materials, as well as surfaces having various types of hardening coatings used in the manufacture of ring seals for various purposes.

The technical result is achieved by the fact that in the method of holographic control of the non-flatness of the annular surfaces by forming the first reference beam by means of a beam splitter and a mirror and an object beam including a projection lens, a working area, and a hologram recording unit, characterized in that the second reference beam is formed by introducing optically interconnected mirror systems, introduce a screening curtain having a hole in the center, and place opaque with the possibility of output from the object beam the shutter is placed in the first reference beam, the mirror system of the second reference beam is installed between the working area and the hologram registration unit, the screening shutter is installed between the projection lens and the working area, and the opaque curtain is installed perpendicular to the optical axis between the beam splitter and the mirror of the first reference beam with the possibility of its output from the first reference beam when registering a hologram, and the diameter of the mirror of the second reference beam is chosen equal to the diameter of the opening of the shielding curtain, ion lens is mounted with the possibility of constructing an image of the component to diffuse in the opposite course to the surface of the light rays size equal to the diameter of the second reference beam and the diameter of the opaque shutter is selected equal to the diameter of the first mirror of the reference beam.

The invention is illustrated in the drawing (Fig. 1), which shows a schematic diagram of the optical system of a holographic interferometer that implements the proposed control method.

The numbers in the drawing indicate:

1 - laser;

2 - collimator;

3 - a beam splitter;

4 - projection lens of the object branch;

5 - curtain with a hole in the center of the object branch;

6 - controlled surface with a hole in the center of the object branch W _about ;

7 - the first mirror of the second supporting branch W _op2 ;

8 - the second mirror of the second supporting branch W _op2 ;

9 - the third mirror of the second supporting branch W _op2 ;

10 - hologram registration unit;

11 - opaque curtain of the first support branch W _op1 ;

12 is a mirror of the first supporting branch.

The holographic interferometer, through which the proposed control method is implemented, contains optically coupled laser 1, a collimator 2, a beam splitter 3 for the formation of the object and support branches, a projection lens 4 of the object branch, a shutter with a hole in the center 5 of the object branch, a working area 6 for installing the controlled part , a system of mirrors of the second reference branch, consisting of the first mirror 7, second 8 and third 9 mirrors, an opaque curtain 11 of the first reference branch and a mirror 12 of the first reference branch.

The difference of the proposed control method is that the projection lens 4 is installed with the possibility of constructing an image of the part 6 in the reverse stroke of scattered light rays with a diameter equal to the diameter of the second reference beam.

In the object beam, a shutter 5 is installed with a hole in the center and is configured to output it from the object beam.

Between the working area 6 and the registration unit of the hologram 10 establish a system of mirrors 7, 8 and 9, forming a second reference branch.

Between the beam splitter 3 and the mirror 12 of the first supporting branch, an opaque curtain 11 is installed with the possibility of withdrawing it from the reference beam, and the diameter of the curtain 11 is chosen equal to the diameter of the mirror 12.

The principle of operation of the invention is as follows. Coherent radiation from the laser 1 is introduced into the collimator 2. At the output of the collimator, a collimated beam of light rays is formed. Using a beam splitter plate 3, the beam is divided into a reference W _op and an object W _about beams, respectively. These beams arrive at the object and reference branches of the interferometer. The sheaf of the support branch will be called the first support sheaf W _op1 . The beam of the object branch of the interferometer is W _{about the} beam.

The object beam W _{about is} sent to the lens 4 and illuminate the controlled annular surface 6. In this case, an opaque curtain 5 with a hole in the center is removed from the object beam. The light rays reflected from the surface 6 in the reverse stroke enter the aperture of the lens 4, which builds the image in the plane of the hologram 10 with the desired image scale.

The second part of the light beam of the object branch, passing through the hole of the annular surface, is sent to the plane of registration of the hologram 10 using a system of mirrors 7, 8 and 9. This beam acts as the second reference beam W _op2 . In shape, the beam W _op2 can be slightly _divergent or collimated by a light beam. To obtain a collimated beam, an lens is additionally introduced, the front focal plane of which is combined with the rear focal plane of the lens 4. The projection lens 4 constructs an image of the part in the hologram recording plane with a size equal to the diameter of the second reference beam W _op2 .

The first reference beam W _op1 (when the shutter 11 is removed from the beam) enters the mirror 12 and, reflected from it, enters the registration plane of the hologram 10.

To control the flatness of the annular surfaces in the present invention, a hologram is obtained by a two-exposure method.

During the first exposure in the first reference branch of the interferometer, the opaque curtain 11 is removed from the reference beam W _op1 . The object W beam _{about the} shutter 5 with the hole in the center to establish a controlled part 6. In this arrangement, the shutters 11 and 5 in the recording plane 10 interfere with two of the reference beam W W _OP1 and _OP2.

During the second exposure in the first supporting branch, the curtain 11 is installed in front of the mirror 12. In the object branch, the curtain 5 with an opening in the center is taken out of the object branch. Moreover, in the registration plane 10, the object beams W _ob and the second reference W _op2 light beams.

When reconstructing wave fronts from a hologram, it is illuminated only by the second reference beam W _op2 incident on the hologram at an angle 6 equal to the holography angle. Recovered W _'OP1 and W' _about the sheaves upon application to form a holographic interferogram characterizing flatness annular surface.

The implementation in the proposed invention of a two-exposure method of recording a hologram while monitoring non-flatness of annular surfaces made of various materials (metal, graphite, etc.) and having various coatings preserves the main advantages of the holographic interferometry method: compensation of aberrations of the optical system and elimination of the influence of local defects of optical elements on quality of the controlled wavefront.

Experimental testing by the proposed control method and a holographic interferometer based on it showed its performance.

In FIG. 2 shows the interferogram of a controlled metal part (seal ring). Figure 3 illustrates the topogram of its wave surface.

Thus, the effectiveness of the invention is confirmed.

Claims (1)

A method of holographic control of non-flatness of annular surfaces by forming the first reference beam using a beam splitter and mirrors and an object beam including a projection lens and a working area, and a hologram recording unit, characterized in that the second reference beam is formed by introducing an optically coupled mirror system, a shielding curtain is introduced, having a hole in the center, and placed with the possibility of output from the object beam, an opaque curtain is placed in the first reference beam, the system mirrors of the second reference beam are installed between the working area and the hologram recording unit, a screening curtain is installed between the projection lens and the working area, and an opaque curtain is installed perpendicular to the optical axis between the beam splitter and the mirror of the first reference beam with the possibility of outputting it from the first reference beam when registering the hologram, the diameter of the mirror of the second reference beam is chosen equal to the diameter of the opening of the shielding curtain, the projection lens is installed with the possibility of the image structure of the controlled part in the reverse stroke of light rays scattered on its surface with a size equal to the diameter of the second reference beam, and the diameter of the opaque curtain is chosen equal to the diameter of the mirror of the first reference beam.

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