SU1017980A1 - Interferential band boundary determination device - Google Patents

Abstract

USRRSY STVr for DETERMINING LIMITS YNTERF RENTSSHNNYH POLSS comprising successive slit diafrashu, double-arm interferometer antiphase adjustment, bounding the aperture and photodetector of t n and h and w u her to the fact that, in order to increase accuracy, it introduced disposed between the slit diaphragm and interferometer pentaprism, one & of the reflecting faces of which is semi-proe: rachna, and the entrance face is parallel to the slit diaphragm, and two optically coupled flat mirrors, one of which is located directly behind the exit face of the pentapriz “under 45®” to it, and the other is parallel to the semi-transparent face of the pentaprise, while the optical the axes of the interferometer arms are mixed one relative to the other by an amount not exceeding the third part of the size of the slit diaphragm, and the size of the restrictive aperture does not exceed two “L third dimensions of the slit diaphragm. --J "00

Description

The invention relates to technical physics and can be used to determine the boundaries between the bright and dark fields of image elements. -. :

A device for determining the fringes of the rim, which contains, a differential diaphragm, a system for the confinement of light fluxes, consisting of deflecting and translucent mirrors, and a photodetector, is known.

However, in this device, the accuracy of determining the boundaries of the interference fringes is influenced by the relative shift of the slits of the diaphragm in the scanning direction and the blurring of the interfaces between the bright and dark edges of the image. In addition, the device does not allow detecting the boundaries of interference fringes having small dimensions in the scanning direction.

The closest to the invention is an interference device in which contains successively arranged slit diaphragms, a two-arm interferometer q in antiphase tuning, a limiting diaphragm and a photodetector.

However, the accuracy of determination of the band edge by this device is limited and determined by the length of the triangular luminous impulse fronts (whose top corresponds to the boundary of the axial line strip of the slit diaphragm), which depends on the scanning direction and is equal to half of the target aperture.

The aim of the invention is to improve the accuracy of determining the boundaries of image elements. . The specified goal is achieved by the fact. What is in the device containing nd the sequentially located slit diaphragm, two shoulders interferometer. with antiphase tuning, a restricting diaphragm and a photodetector, are inserted between the optical diaphragm and the pentaprim interferometer, one of the reflected faces of which is translucent, and the input face is parallel to the slit diaphragm, and two optically coupled flat mirrors. One of which is located directly behind the output face. pentaprism at an angle, and the other in parallel, the translucent face of the pentaprism, while the optical axes of the interferometer arms are shifted one, relative to the other one. a value not exceeding the third part of the size of the slit diaphragm, and the size of the restrictive aperture does not exceed two-thirds the size of the slit diaphragm.

FIG. Figure 1 shows the optical layout of the device proposed;

in fig. 2 - diaphragm of variation of the resultant light flux depending on the position of the border. scanned image element relative to the slit diaphragm.

The device contains a silken diaphragm 1, a pentaprism 2 with one translucent reflective face, flat mirrors 3 and 4, a two-armed interferometer 5 consisting of beamer b, flat mirrors 7 and 8 and a translucent mirror 9, a restricting diaphragm 10 and a photodetector

.eleven.; .V /: -:::.

Aperture 1 is located in the plane of the scanned image formed by a scaled coherent monochromatic light flux. Behind diaphragm 1 is located pentaprism 2. s; one translucent reflective edge in such a way that its entrance is perpendicular to the light flux passing through the diaphragm. A flat, mirror 3 is located at an angle of 45. to the output edge of the penta.prism 2, and mirror 4 is parallel to its semi-transparent face. The interferometer B of the Interferometer 5 is located on the path of the Luminous flux, passing through a translucent, reflecting face of the pentaprism; 2, at an angle of 45 ° 1.

Plane; mirrors 7 and 8 are installed parallel to the beam splitter b On the path of the light beam passing through the beam splitter and reflected from it. These mirrors match the flows on the semitransparent mirror 9, and the difference in their travel is equal to an odd number of half-waves of the coherent monochromatic light used. The optical axes of the shoulders of the interferometer 5 are shifted one relative to the other by the value of dX by moving the same distance by a straight line, mirrors 7 along the optical axis of the corresponding shoulder, as a result of which the light fluxes combined on the translucent mirror 9 form the resulting light. . The flux spreads out in the same direction and has a slit, displaced relative to the root by a value. The lithium diaphragm 10 is installed behind the interferometer 5 in the path of the resulting luminous flux, and its width is 2 „less than the width S of the slit diaphragm 1 (in the scanning direction) by the magnitude dX of the linear displacement of the cross sections of the luminous fluxes combined by a semi-transparent mirror 9. The photoreceiver 11 is located behind the orifice plate 10.

The device works as follows.

When moving along the X-axis of the image element boundary in the direction of the slit diaphragm 1, a luminous flux is formed behind it, in the cross section of which the image of the boundary, the light and dark fields is swept. This luminous flux enters the pentaprism 2 and its translucent reflecting face is divided into two beams, one of which spreads beyond the pentaprism, and the other, having undergone another reflection at the verge of pentaprism 2, is directed to the first perpenthoradio rio.

Ze | In steps 3 and 4, this beam is directed to the translucent from: the razhaimtsuyu face of the pentaprism 2, where it is combined with the first beam, ppp, 15 that goes through a prism through the 31st face. Thus, a prism 2 is formed behind the prism 2, in the cross section of which an opposite movement of the border of the light and dark fields 20 of the scanned slit diagamy 1 is observed, from the ampoule. Entering the interferometer 5, the atom stream is amplitude divided into two streams, combined in antiphase with a linear displacement of their cross sections by 25 times dX on a translucent mirror

 .-.-. . . . :: Thus, in the simple case, on a semi-transparent mirror 9, four coherent monochromatic tear beams are combined and intherfer each other. 1 The resulting luminous flux, which is obtained through the restrictive aperture, enters

on photoperiod 11, which implements its photoelectric conversion. The 5th Result1 luminous flux behind the limited diaphragm is the flux, cross section; which belongs to one light four light beams, its. Forward:, -40 -; Ras, 4btr. various stages of movement; Along the ray X, the boundaries of the section of the light and dark fields of the image from the yoy slit.

1 and the size of the resulting light is 45 BqronpTOjta, falling at the same time

on photoprinter 11.

;) Aet) eMem (HHH of the interface along, dagafragmy 1 on translucent 3eipK irie Si, a counter CQ is observed. Movement of flieyx pairs of images of this border, shifted from each pair on and K 6 to each pair. Up to its point at the point., Just from Equally zero on the lx, the resultant; the total current flow, which is set in at the front end, increases along the linear axis (Fig. 2), since from zero to

2dh gwe; The magnitude of the sections of its cross section is checked, from which the light beams A and 60 fall onto the photographic 11

V.:.: The further movement of the boundary in relation to the alternating diaphragm 1 leads to the fact that there appear on the translucent mirror of € 9 there are areas where 65

the images of the element formed by the light fluxes A and A, B and B are combined and integrate in pairs with each other. Due to the interphase-frequency tuning of the interferometer 5. The intensity of those sections, the cross sections of the resulting light flux. A, where the pairs do not overlap the images formed by the streams A and A, B, and B (zero-beam interference) are zero. PratRMu in the area of movement X, -X2 border. of the scanned pixel, the magnitude of the resulting light flux remains constant. The position of the X2 point on the X axis is determined by the moment of meeting on the semi-mirror 9 images formed by the light fluxes A and B.

Moving the border of the element from point X 2 to point Xs, which coincides; with the axial line of the diaphragm 1, leads to the appearance of a section of the cross section of the resulting light flux j on which the rays A and B interfere with each other. The size of this area varies from zero to EM and, as the internality of the pulsating light stream, varnish is zero due to the difference in the path of the interfering beams equal to the odd number of half-waves of the light used, the resulting light beam falling on the photodetector 11 varies linearly from maximum value to zero. So, as on a translucent mirror 9 there is a counter-motion of images of an element of the monitored element, a change in the size of the section of interference of rays A and B from zero to dX corresponds to a linear movement of the boundary of the element relative to the diaphragm i naiX / 2 (Tie. 2). The minimum value of the resulting luminous flux reaches into THAT a methylene, the code on the translucent mirror 9 encounters images of the element boundary, formed by the rays A. and c. Moving the boundary of the element with respect to diaphragm 1 from Xj to X leads to the appearance of sections of the cross section of the resulting flow with a three-beam,: interference. The light beams A, Au and B interfere with each other non a section of the resultant flux and A, vi in another part of it. The total light flux linearly increases from zero to maximum when the scientific research institute reaches the element boundary of the X ray due to interference of three rays, and the front of its growth equals X / 2. The maximum value of the light flux on the photocurrent 11 corresponds to the moment of seeing on the translucent mirror 9 of The battles formed by the rays A and

With further mixing of the boundary, at diaphragm 1 to the point Xj of re-emulation, the flux remains constant, since there are four truncates in the central part of its cross section. the interference and intensity of the luminous flux at all points of this region will become zero. The size of the section with four-beam interference increases (at a constant value of the size of the sections with three-beam interference) until the image of the element border formed by the rays of A and B is outside the boundary of the aperture 10. Moving the element border relative to the aperture 1 beyond point Xd the cross section of the resultant flux with a four-beam interference is due to the reduction of the portions with the radiation radiation; therefore, the resultant flux falling on the phototop At the time of the boundary of the element beyond the scanning diaphragm 1 (point Xg), this output goes beyond the cross section of the resultant flow limited by the diaphragm 10 to the image of the element formed by the rays A and B. segment Xj-X (, HH ..

Thus, the luminous flux / incident on the photodetector changes according to a complex law when scanning the boundary of the monitored element, the image of the slit OI diadragm 1, and its change when passing the boundary near the centerline of the dia, the fragments have a triangular shape. The minimum value of the flux corresponds to the scanning of the boundary of the element by the axial line of the diaphragm. The top of the triangular electric pulse from the photodetector 11 can be determined / by any known method.

Maxima / ibHoe offset dX dc optical axes of the arms of the interferoment5 one relative to the other should not exceed a third part of the size S

slit 1 aperture 1, i.e. max i, since in this case the change in the resultant luminous flux occurs in such a way that its maximum value coincides with the maximum value from zero to maximum (,) with the maximum value as it decreases from maximum to zero (Y. 2 -Xj). With this plots

X-X are zero. Then legitimate EA max 5

LETTER T

At the same time

MOIKC W "t.C votKC 3

Therefore 2

I.

those. the size of the restrictive diaphragm 10 must not exceed two-thirds the size of the slit diaphragm 1,

In the proposed device, the duration of the front of the ns growth and decay of a triangular electric pulse is equal to half the value of DX of the optical axis of the PLR interferometer.

The magnitude of this displacement can be selected within the previously specified limits. Therefore, the duration of the front of the resultant signal can be made much shorter than the length of the front of the resultant signal obtained with the help of a known device, since in it the length of the front is equal to half the width of the scanning slit-shaped diaphragm. As a result, the steepness of the pulses received on the proposed device is greater than the steepness of the triangular signals and the output from the known device. In this connection, impulse noise and noise also have less influence on the selection of the apex of a triangular pulse.

Thus, the introduction of new elements and their connections makes it possible to increase the accuracy of determining the boundaries of image elements by 2.5 times in comparison with known devices.

The proposed device can be widely used in monitoring the topology of such plane-parallel objects, such as aerial photographs, in graphic information processing devices. In particular, its use in enterprises of the electronics industry for the automated control of linear dimensions and coordinates of elements (in microchips and photo patterns allows us to quickly and more accurately carry out objective quality control of their manufacture at various stages of the technological process, to increase the percentage of production of suitable products, improve the conditions and labor productivity of controllers by reducing the share of manual labor.

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Claims (1)

A DEVICE FOR DETERMINING THE BOUNDARIES OF INTERFERENCE POLYSSES, containing a sequentially located slit diaphragm, a two-arm interferometer with antiphase adjustment, a limiting diaphragm and a photodetector, in order to increase the accuracy, they are inserted between the slit intorferometrom pentaprism diaphragm and one of which poluprozg rachna reflective facets and parallel to the front face 'slotted aperture and the two optically coupled flat mirrors, one of which _parts is arranged neposreds just beyond the exit face of the pentaprism at an angle of 45 ° to it, and the other parallel to the translucent face of the pentaprism, while the optical axes of the interferometer arms are offset relative to each other by an amount not exceeding the third part of the size of the slotted diaphragm, and the size of the limiting diaphragm does not exceed two-thirds slotted diaphragm. .SU „1017980 1017980.