SU1416860A1 - Interferometer for measuring displacement of objects - Google Patents

Abstract

The invention relates to a measurement technique and can be used to accurately measure large linear movements of objects. The purpose of the invention, an increase in the measurement accuracy with an increase in the range of measured values, is achieved by stabilizing the contrast of the interference pattern when measuring large displacements. The beam of laser radiation 1, passed through a telescopic system 2, is divided by a beam splitter 3 into a measuring one in which mirror 4 is successively arranged and the reflector 6 and the reversing prism 7 and the reflector 8, which reflectors 8, 9 and 10 are sequentially arranged in front of each of which, besides the reflector 10, rhombic prisms 11 and 12, respectively, and the second wrapping prism 13 are installed. The reference and measuring beams, reflected from the reflectors 6, 8, 9 and 10, interfere with the beam splitter 3 and through the diaphragms 14 and 15 Respectively to detectors 16 and 17. The reflectors are made in the form of dihedral mirrors with an angle of 90 ° amp; between grandmas. When an object is moved by an amount larger than the calculated value S, the reference beam moves from one reflector 8 to another 9 using prisms 11 or 12 and so on, and the reflectors of the reference beam are located at a distance S from each other. By the number of interference fringes on the detectors 16 and 17, the displacement of the object is judged to be 5. 2 Il. F (L

Description

Ob 00

about:

The invention relates to meter; technology and can be used to accurately measure large linear: movements of objects.

The purpose of the invention is to increase the point j. i of measurement with an increase in the range of {measured values by stabilizing 1 the contrast of the interference pattern i when measuring large displacements. I FIG. Figure 1 shows the optical: interferometer circuit; in fig. 2 shows a section i A-A in FIG. one. .

i The interferometer contains a laser 1, successively along the laser radiation 1 i, a telescopic system 2 and a beam splitter 3, i dividing the beam into a measuring and reference beam. Along the course of the measuring beam, the mirror 4 is sequentially arranged and pre- assigned to be fixed on the object 5; reflector 6 and wrapping prism 7.

ten

varies, as a result, the interference fringes move in the plane of the slit diaphragms 14 and 15. The detectors 16 and 17 produce sinusoidal signals, which are then used to count the interference fringes, the amount of which determines the amount of movement of the object. For reverse counting of interference fringes, the slit diaphragms are shifted one relative to the other by a quarter of the band.

Due to the finite length L of the laser coherence, the amount of movement of the object 5 at a given band contrast

is equal to

0,8bVl - K

When the object 5 is moved by values larger than E, the reference beam moves with the help of the corresponding rhombic prism 12 to the next reflector 9. installed at a distance of

also at a distance S from the previous reflector 9, and so on. Thus, constant contrast is maintained. During the course of the reference beam,

Claims (1)

reflectors 8, 9 and 10 are placed before 20, from reflector 8, then each of which, besides reflector 10, has rhombic prisms 11 and 12 installed on the next reflector 10, respectively, with the possibility of moving perpendicular to the direction of propagation of the beam and the second wrap-jc the interference fringes, independent of the prism 13, placed between the laser coherence, the todel 3 and the last along the beam of rum reflected from the reflectors 8-10 —The formula of the invention is a biological prism 11. All reflectors 6- 10 are made in the form of dihedral mirrors; An interferometer for measuring displacements by an angle of 90 ° between the faces. Object objects containing a laser and each of the beams reflected from reflectively located along the beam. 6-10 dwellers and those who passed through a laser radiation dividing system telescopic system 3, a beam splitter is installed in series and in pairs, dividing the radiation beam slit diaphragms 14 and 15 and the detector on the measuring and reference, along the way 16 and 17. The measuring beam sequentially, the integrator operates as follows: a mirror and the first reflector are placed, With the purpose of fixing the radiation beam from the laser 1 onto the object, it is expanded with the telescopic system 2 and gets into the beam splitter 3, where it is divided into measuring and reference. The measuring beam, reflected from the mirror 4, falls on the reflector 6, reflects it back parallel to itself, passes the inverting prism 13 and returns again to the beam splitter 3. 40 In the course of the reference beam, there is a second reflector, along each of the radiation beams reflected from the reflectors and passing through the beam splitter, a slit diaphragm and detector are installed sequentially and in pairs, characterized in that in order to increase the measurement accuracy with increasing range of measured values, it is equipped with an additional reference beam passing through a rhombic j reflector mounted in support prism 11, it is displaced perpendicular to the point between the beam splitter and the reference beam reflector in series one after another at distances x, one from the other, where L is the coherence length of the laser radiation, and K is the specified contrast of the interference pattern, with rhombic prisms installed at the reference point in front of each of the additional reflectors with the ability to move perpendicular to the direction of propagation When the object is moved 5, the difference is 55, two reversing prisms, the measuring and reference beams are one of which is designed to set the beam to the value of its diameter aa and fall to ne The fixed fixed reflector 8 and, reflected from it, goes back parallel to itself through the prism 13 to the beam splitter 3. Both beams are again divided by a beam splitter 3, interfere and, creating two patterns of interference fringes in the plane of the diaphragms 14 and 15, pass to the detectors 16 and 17. . 0 varies, as a result, the interference fringes move in the plane of the slit diaphragms 14 and 15. The detectors 16 and 17 produce sinusoidal signals, which are then used to count the interference fringes, the amount of which determines the amount of movement of the object. For reverse counting of interference fringes, the slit diaphragms are shifted one relative to the other by a quarter of the band. Due to the finite length L of the laser coherence, the amount of movement of the object 5 at a given band contrast is equal to 0,8bVl - K When the object 5 is moved by values larger than E, the reference beam moves with the help of the corresponding rhombic prism 12 to the next reflector 9. installed at a distance of 0, from the reflector 8, then to the next reflector 10, the established c of the interference fringes, independent of the coherence length of the laser, also at a distance S from the previous reflector 9, and so on. Thus, the constant contrast S 0 is maintained, from the reflector 8, then to the next reflector 10, the set of interference fringes, independent of the coherence length of the laser, the Invention Formula 40 j 50 314168604 ki on the object behind the reflector, and the friend reflected from the reflector beam, and all placed in the reference beam between the light reflectors made in the form of dihedral the divider and the last prism along a 90 ° angle between the faces. / 2 / e / // d J2 70