SU1037063A1 - Interferometric device for measuring distance and for changing distances - Google Patents

Abstract

The measuring device uses a monochromatic light source beam splitting elements, relectors and a photodetector together with devices for frequency or amplitude modulation of the light from the source. An afocal optical system is positioned in the path of both the measuring beam and the reference beam, each with an associated matt surfaced disc. One of the discs lies in the focal plane of a projection lens for projecting it onto the photodetector, while the other is projected via two cooperating lenses onto the reflector attached to the object. Pref. the photodetector has a matrix of photodetector cells, connected via a common capacitive coupling element with a common line.

Description

2. The device according to p. 1, r and t and h ay with the fact that, both in the course of the comparison beams, and in the hoi measuring beams, there are located the most common beams of afocapture optical systems 12,13

.14,15 and the matte glasses 16 and 17 related to them, and in the focal plane from the source of the light one pinna projects matte glass 17 onto the photoelectric receiver 19, and the other lens projects the second matte glass 1b onto the light reflector 2 connected to the object.

3. The device according to PP.1 and 2, tl and that the optoacoustic cell 8 or another electro-optical element for splitting the light beam 9 coming from the light source 7 into the light beam of the O-th pore is located during illuminating rays. For and a beam of light of the 1st order 10 and 11, at. than the beam of the 0th order 10 is provided for the course of measuring beams, and the beam of the 1st order of 11 - for the course of beams of comparison.

4. Device pop. l, attributed to the fact that the light beam 42 in the course of measuring rays is focused on the measured length f. , while the aperture of the retroreflector 42 has such parameters that the non-parallelism of the interfered fronts does not exceed / 8, and the amplitude-modulation cell 47 is located during the measuring beams.

5. The device according to claim 1, such that the reflector 62 associated with the object has a convex reflective surface.

6. The device according to paragraphs. 1-5, that is, since the photoelectric receiver 19 has a crossed raster photoactive layer 26, the individual photoactive elements 28 of which are connected to the common conductor 30 by a common capacitive binding element 29, and the photoelectric receiver 19 is tuned to certain incident frequencies radiation.

The invention relates to interferometric devices for measuring distances or changing the distances of an object to a fixation point, in particular, dp precision measuring instruments.

An interferometric device, dp, determining the distance of an object to a certain position (described in BEOS 12/20/94), is known based on the use of radiation emitted from a light source, which, after interacting with the object along with radiation passing a reference beam, is directed to a photoelectric detector . The radiation emitted by the light source changes the frequency around an average value.

The interferometric device has a reflector in one of the two branches, which is rigidly connected to the object. The radiation is polarized and, in at least one of the branches, the device contains one L / 4 - ppastine.

However, measuring the distance of an object to a certain position is possible

only if this position lies on the optical axis or in the immediate vicinity of the lever that encircles the course of the measuring beams. If a certain position lies outside the optical axis, which, as a rule, takes place with such measurements, then these interferometric measurements cannot be made.

The aim of the invention is to extend the capabilities of interferometric devices. distance measurements and distance changes.

The invention is based on the task of creating an interferometric device for measuring distances and changing the distance between an object displaced in any direction from the optical axis and a fixing point.

According to the invention, this task in such a device, including a monochromatic light source, separating the beam elements, one stroke of measuring rays and one stroke of comparison rays, as well as a photoelectric detector, is solved by the fact that optical elements are provided during the measuring beams The formation of a diverging beam of light in the surround of the object, and in the course of the comparison beams, the imaging and control optical elements to form the comparison beam equivalent in aperture and direction reflected from the object chku light provided comprising separate photoactive el & P1YUSKY cops and repressor moieties DC photoelectric light receiver. It is preferable that both the measuring beams and the matching beams provide for the expansion beams of afocal optical systems and matte glasses related to them, and these matte glasses are located on the side of the light source in the focal plane of the lenses, one of which projects one is frosted glass on a photoelectric receiver, and a friend is designing a second frosted glass in the direction of a photoelectric mirror connected to the object. In this case, during the illumination beams, an optoacoustic cell or another electro-optical element is located to split the outgoing beam from the light source into beams of the 0th and 1st order, with the 0th order beam being provided for the measuring beam and the 1st beam order is for the path of the beams of comparison. The retroreflector during the measuring beams focuses on half of the average measured length of 1W-, and the aperture of the retroreflector has such parameters that the non-parallelness of the interfering wave fronts does not exceed L / 8, and the retroreflective modulating light reflector connected to the object has the optic transducer having an optic 1rub optic). reflective surface. To register similar distances and changes in the signal distance, the photoelectric receiver has a photoactive layer (in the form of a raster with crossing lines) I whose individual photoactive elements are connected to a common conductor, npi, than the photoelectric receiver is configured at certain frequencies of incident radiation. Such an interferometric device has the advantage that it provides for measuring the distance between the object and the point of fixation and if the object is displaced in the direction, i.e. lies outside the optical axis of the measuring beams. Thus, there is no need in the presence of mechanical and adjusting means, with the help of which it would be necessary to produce an orientation of the course of the measuring beams on the object in the off-axis position. In addition, the field of application of such devices is expanding. FIG. 1 shows the path of the beams of the ferometric device, extended from HOIX) in the form of a Dopper double-beam interferometer with an optical quantum generator; in fig. 2 - schematic diagram of a photoelectric receiver; in fig. 3 - receiver design; in fig. 4 shows the signal flow during processing; in fig. 5 - small size and filling device; Fig. 6 shows a device with a convex retroreflector. The interferometric device (Fig. 1) consists of a fixed base 1 of a double-beam interferometer and connected to an object (not shown) of the retroreflector 2, the main elements of which are a concave mirror and a lens. (C is the measured distance between the main points 3 and 4 of lenses 5 and 6). In such a device, a light source 7, made in the form of an optical quantum generator, illuminates an optoacoustic cell 8, which beam 9 of light diffracts into a certain number of diffracted diode beams, of which order beam 010 is provided for measuring beams, and beam 1 Order is for the path of the beams of comparison. Since the 0th order beam has the largest fraction of energy, it serves to illuminate the area of the object and has an oscillation frequency V generated by the light source 7. Beam frequency 11 of the 1st order is modulated by sound energy induced into an optoacoustic cell (carrier frequency -fy). It corresponds in this way to V-H. Two afocal optical systems 12, 13 and 14, 15 represented by lenses expand the beams 10 and 11. The light-scattering elements in the form of 1x glass 16 and 17 that are connected to the afocal systems give the beams 10 and 11 necessary for subsequent {Effective optics divergence For a better understanding, opaque glass 16 and 17 are located behind the afocal systems 12,13 and, 15. If they are laid out in front of afocapal systems, then their operation is more advanced. A beam splitter 18 guides the beam of a 10 0 order to the lens 5 serving as a measuring lens, which, when the surface element of the frosted glass 16 is imaged, scatters light at infinity in the object area. The beam 10 assembled by the retroreflector 2 is directed in itself back and with the help of lens 5 to the photoelectric receiver 19. During the course of comparison with beam 11, the 1st order lens 2 and beam splitter 21 project light onto the photoelectric receiver 19, and the beam of the beam 11 in the aperture and direction coincides with the light reflected by the retro-reflector 2. Both beams 10 and 11 interfere. At the location of the image of the interference pattern, the photoelectric receiver 19 receives the induced carrier frequency y and the Doppler frequency d proportional to the displacement. Receiver 19 is insensitive with respect to the components of permanent light (figures 2 and 3). The photoelectric receiver 19 (Fig. 2) has a photoactive pad 26 on the substrate 25, which is divided into many separate elements 28 through zones 27 in the form of a raster with intersecting edges, which are connected to common wiring 30 by means of capacitive connecting elements 29. the capacitance resistance of the connecting elements 29 suppresses the components of the constant light, the signals of the same light, on the frequency of which the capacitance is tuned, are directed to the output of the conductor 30, and moreover if they originate only from individual The elements 28 of the photoactive layer 26 of the receiver 19. Elements 28, which are affected by the components of the constant light, are opposed to. In this case, an electrical signal is not supplied to the conductor 30. In the receiver 19 (Fig. 3), as the conductor of the RO, it is provided, for example, a glass plate covered with a passing metal layer. The plate has an applied dielectric layer 31, the thickness of which is matched with the required capacitance determined by the size of the individual elements 28 and the carrier frequency fy. The elements of the receiver can be built on the basis of integrated circuits using matched oscillatory circuits. The signal flow diagram 10636 (Fig. 4) schematically shows the processing associated with the carrier frequency f. Drapler frequency -, the result of which is to receive the signal further processed. It also shows a generator of 35 sinusoidal oscillations and a mixer 36. Here, the Dopper frequency f d is separated from the carrier frequency y. A carrier-free signal with a Doppler frequency can be fed to a pulse counter (not shown) for further processing to determine the position of the object. The Doppler double-beam interferometer with an optical quantum generator (Fig. 5) has a basis 41 and a retro-reflector 42, which is connected to the object. A beam of light emanating from a light source (not shown) passes the aperture 43 and by means of a splitter 44 the beam is divided into a path of measuring beams and a path of comparison beams. The reference beam falls on the slightly reflecting reference 45 and through the splitter 44 is directed to a photoelectric receiver. 46. The measuring plug passes an amplitude-modulating cell 47 and by means of a measuring lens 48 in the form of spherical waves is diffused into the area of the object. In the device, the light in the course of the measuring beams and the course of the rays of the medium has the same frequency 1Г. One part of the scattered light in the course of the measuring beams falls on the unfocused light reflector 42. It is focused on the focal distance -t / 2, and ff is the average length measured. The aperture of the retroreflector 42 has such parameters that the non-parallelism of the interfering wave fronts does not exceed L / 8, where is the wavelength of the light. The measuring beam returns back to itself and due to movement the retroreflector acquires a Doppler shift V - p. After the second passage of the cell 47, a complete amplitude modulation is achieved. The frequency does not change. On the surface of the splitter beam 44, the interference of the measuring and comparing beams occurs. The receiver 46 receives, at the location where the combined HHTejxj of the rotated beam hits, the amplitude-modulated radiation of the carrier frequency y. The signal generated by the receiver 46 is fed to a signal processing device dp to obtain a similar value corresponding to the measured distance, Measured distance. (Fig. 5) is the distance between the focus 49 of the measuring pivza 48 and the main point 50 of the light transducer 42. The distance measurement with the help of the light fluorescence depends on the shift in space. However, there are feed motions that are produced when several axles are rotated around a single shaft and exclude the use of these light reflectors. In this case, it is preferable to use spherical reflecting convex reflecting surface of reflectors (FIG. V6). Along with insensitivity to rotation, they have the advantage that by choosing the radius of the reflecting surface the measured point can be transferred to the desired planes, axes And points, so that The influence of errors of the rotation of the object-reflector system is reduced. In addition, this kind of device used in the technique of measuring flow. The main devices of the device (Fig. 6) are the basis 61 and the spherical refpector 62.-Is1 skype1-monochromatic light The light source 7 forms with the help of a weakly reflecting radiation splitter 63 the course of the measuring beams and the course of the beams 64 and 65 of the comparison. Electro-optical element 66 biases the radiation frequency of the measuring beam 64 to V + y. By means of the lens 67, the light of the stroke of the measuring beams 64 is scattered and deflected by the prism 68 so that the imaginary origin of the spherical waves lies at the main point 3 of the lens 5 from the side of the object. One part of the light reflected from the reflector 62 is displayed by a lens 5 in the form of a circle scattered on the receiver 19. The light of the stroke of the measuring beams 64 in connection with the displacement of the object has a frequency at this point (y + fy ± fj). In the course of the comparison beams 65, the lens 69 and the prism 70 light up the light in such a way that it seems as if the light comes from the head 4 of the light lines 71. The objective of the lens 72 and the reflector 73 is to form comparison beams that coincide with the movement Measure the lions of the x-ray 64 in direction, type of image, and aperture. The light of the course of measuring the rays and the course of the rays. 64 and 65 comparisons interfere with the fragrance 63. Receiver 19 npHtffiMaeT beat frequency y + f jj. Obtaining a frequency with the frequency i t ™ of determining directions and speeds is performed (Fig. 4) using a mixer. The invention makes it possible to expand the capabilities of devices for interferometer measurement of distances and distances of distance. It is recognized as an invention according to the results of the examination carried out by the Office for the Invention of the German Democratic Republic.

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Claims (6)

1. INTERFEROMETRIC DEVICE FOR MEASURING DISTANCES AND CHANGING DISTANCES, having a source of monochromatic light, ray-splitting ephementes, one stroke of measuring rays and one stroke of comparison beams with reflectors and a photoelectric receiver, and, in addition, there are provided elements for frequency modulation or amplitudes for modulation radiation light source, characterized in that during the measuring rays optical elements are provided for receiving a diverging light beam in the region of the object, and during of comparison beams, displaying and scattering elements to obtain a reference beam equivalent in aperture and direction to the light beam reflected from the object, a planar photoelectric detector 19 consisting of individual photoactive elements 28 is provided and suppresses the constant light components. 2. The device according to π. 1, on the other hand, both in the course of the comparison rays and in the course of the measuring rays there are expanding beams and focal optical systems 12.13 and 14.15 and related frosted glasses 16 and 17, moreover, in the focal plane from the side of the light source, one lens projects the frosted glass 17 onto the photoelectric detector 19, and the other lens projects the second frosted glass 16 onto the retroreflector 2 connected to the object. 3. The device according to paragraphs. 1 and 2, γ t, in that an optical-acoustic cell 8 or other electro-optical element is located during the illuminating rays for splitting the light beam 9 coming from the light source 7 into an O-th order light beam and a first-order light beam of 10 and 11, whereby a beam of the 0th order 10 is provided for the course of the measuring beams, and a beam of the 1st order 11 for the course of the comparison beams. 4. The device according to p. Characterized by the fact that the retroreflector 42 during the measuring rays is focused on the measured length f '- Dp-, and the aperture of the retroreflector 42 has such parameters that the unparalleled interfering fronts does not exceed λ / 8, and during the measuring rays is located amplitude-modulating cell 47. 5. The device according to π. 1, due to the fact that the light reflector 62 connected to the object has a convex reflective surface. 6. The device according to paragraphs. 1-5, the reason being that the photoelectric detector 19 has a crossed raster photoactive junction 26, individual photoactive elements 28 of which are connected by a common capacitive coupling element 29 to a common conductor 30, the photoelectric receiver 19 being tuned to certain carrier frequencies of incident radiation.