RU2667335C1 - Two-beam interferometer (variants) - Google Patents

Abstract

FIELD: physics.SUBSTANCE: group of inventions refers to optical holography and is designed to form periodic interference patterns, which are used for recording holographic diffraction gratings, creating periodic structures of various dimensions (one-, two-, and three-dimensional) in photosensitive materials. Two-beam interferometer of the first variant and the second variant comprises a source of collimated light beam, a movable mirror with a rotation axis, a beamsplitter element dividing the original beam into two partial light beams sequentially located along the beam path, two mirrors that guide these beams at a certain angle of convergence to each other, and a photosensitive element. In the first and second embodiment of the interferometer the beam splitter element, the two mirrors and the photosensitive member are fixedly fixed to the base and form a jointly mirror-symmetric system with respect to the plane of the beam splitter mirror built into the beam splitter element. However, in the first embodiment, the source is also fixed immovably on the same base. Movable mirror directs the collimated light beam to the beam splitter element, and its angular and linear movements leading to a change in the angle of convergence are mutually consistent in such a way that the center of the overlapping region of the partial beams is positioned near the photosensitive member, moving within the range small compared to the size of this region along the plane of the beam splitter. In the second variant, the source equipped with the axis of rotation directs the collimated light beam to the beam splitter element, the angular and linear displacement of the source leading to a change in the convergence angle are mutually consistent, so that the center of the overlapping region of the partial beams is positioned near the photosensitive member, moving within a segment that is small in comparison with the size of this region along the plane of the beam splitter.EFFECT: possibility of combining two or three interferometers into a system for recording two- or three-dimensional periodic structures, ensuring high vibration resistance of both the interferometer itself and the combination of several interferometers, as well as the expansion of the arsenal of means for this purpose.6 cl, 5 dwg

Description

The claimed invention relates to optical holography and is intended for the formation of periodic interference patterns, which are used, for example, to record holographic diffraction gratings, flat and corrugated, to create periodic structures of various dimensions (one-, two- and three-dimensional), including photonic crystals of various crystalline systems, implementation of static Fourier spectrometers used in spectral analysis to create Bragg mirrors, frequency and polarization filters in optical fibers and waveguides, for controlling the frequency of generation of lasers with distributed feedback, for the purpose of encoding, decoding and storing information, in photolithography and in other fields.

A technical solution is known that is implemented in the manufacture of an optical diffraction grating with variable spatial frequency (patent DE 1285763 "Verfahren zur Herstellung optischer Beugungsgitter", IPC G02B 5/18, G02B 5/32, published December 19, 1968), in which the collimated light beam is directed to a translucent mirror splitting this beam into two partial light beams; a second mirror is installed on the path of the partial light beam passing through the translucent mirror; both mirrors are oriented in such a way that the partial light beams reflected from them intersect on the photographic plate and interfere on it, forming equidistant bands on the photosensitive layer. The spatial frequency of the bands is changed by changing the angle of convergence of the partial beams by turning the mirrors, and this change is accompanied by a movement of the region of mutual overlap of the partial light beams.

The disadvantages of the known technical solution are the fatal difference in the optical path lengths of the partial light beams, which requires a high temporal coherence of the collimated light beam, the need to move the photographic plate after moving the region of intersection of the partial light beams, and high sensitivity to vibrations due to the presence of two adjustable mirrors.

A technical solution is known that is implemented in the manufacture of a three-dimensional diffraction grating (US Pat. No. 3507564, “Method of making a tree-dimensional diffraction grating”, IPC G02B 5/18, published April 21, 1970), consisting in the fact that the collimated beam of monochromatic light is directed to an inclined beam splitting plate splitting this beam into transmitted and reflected partial light beams, two mirrors are installed in the path of these beams, directing them to a block of photosensitive material, where the partial light beams mutually overlap, forming an extra Three of the block equidistant fringes. The interval between the bands varies by changing the angle of convergence of the partial light beams, rotating two mirrors in mutually opposite directions around axes perpendicular to the plane of incidence. When the angle of convergence changes, the position of the block is adjusted so that the partial light beams intersect again inside it.

The disadvantages of the known technical solution are the difficulty in operation, due to the fact that the convergence angle is set by mutually independent alignment of two mirrors and additionally align the optical paths of the partial light beams, and the block of photosensitive material is moved in accordance with the change in the convergence angle, the impossibility of simultaneous recording of diffraction arrays in all three dimensions, high sensitivity of the interferometer to vibrations due to the presence of adjustable mirrors.

A technical solution is known, presented in a two-beam interferometer, described in [Shelkovnikov V.V., Vasiliev E.V., Gerasimova T.N., Pen E.F., Plekhanov A.I. The dynamics of pulsed recording of holographic diffraction gratings in photopolymer material. Optics and Spectroscopy, T. 99, No. 5, p. 838-847 (2005)] and widely used in practice. It contains a collimated light beam source sequentially located along the beam, a beam splitting element dividing the collimated light beam into two partial light beams, two mirrors that reflect the partial light beams incident on them towards each other at a given angle of convergence, and a photosensitive element. The convergence angle is changed by mutually independent alignment of each of the two mirrors, and a change in this angle is accompanied by a movement of the region of mutual overlap of the partial light beams. The photosensitive element is combined with this overlapping region; when switching from one value of the convergence angle to another, the photosensitive element is reinstalled so that it is compatible with the new position of the overlapping region of the partial light beams. When varying the angle of convergence, an uncontrolled change in the length of the optical paths of these beams occurs, therefore, a number of measuring and adjustment operations are performed to align the mentioned lengths. As a result, each change in the convergence angle is accompanied by adjustment and measurement work, which complicates the operation of the interferometer and makes it impossible to continuously adjust the convergence angle, however, the presence of adjustable mirrors increases the sensitivity of the interferometer to vibrations.

The disadvantages of the known technical solution is the high sensitivity of the interferometer to vibrations, as well as the difficulty in operation.

A known technical solution implemented in a diffraction grating with a variable period [Mikerin SL, Ugozhaev VD Tunable holographic interferometer with fixed mirrors, AUTOMETRY, t. 48, No. 4, p. 20-32 (2012)]. The technical solution is carried out by splitting a collimated light beam into two partial light beams by a beam splitting cube and then reducing these beams using two mirrors on a photosensitive element at a variable angle of convergence. Two mirrors are mounted motionlessly and mirror-symmetrically with respect to the plane of the beam splitting mirror on the path of partial light beams emerging from the beam splitting cube, owing to which these partial light beams themselves and the region of their mutual overlap also appear mirror-symmetric with respect to the indicated plane. The photosensitive element is placed in the specified area of overlap with the possibility of movement. The convergence angle of these beams is continuously tuned by changing the angle of incidence of the collimated light beam on the input surface of the beam splitter cube, which is accomplished by joint rotation of the beam splitter cube, two mirrors, and a photosensitive element about an axis perpendicular to the plane of incidence of the collimated light beam on the beam splitter mirror. In the entire range of changes in the angle of convergence, exact equality of the optical lengths of the partial light beams along their axes along the path from the point of their formation on the beam splitting mirror to the point of mutual overlap is fulfilled. The axis of rotation is located at the entrance surface of the beam splitter cube so as to maintain the width of the entrance pupil near its possible maximum. With this position of this axis, the convergence of the convergence angle is accompanied by a movement of the said overlapping region along the plane of the beam splitter mirror, which requires a corresponding movement of the photosensitive element.

The disadvantages of the known technical solutions are the change in position of the photosensitive element during rotation of the interferometer, which may complicate its operation, low vibration resistance due to the mobility of the photosensitive element.

Known technical solution implemented in a diffraction grating with a variable period [Ugozhaev V.D. RF patent for the invention No. 2626062, "Two-beam interferometer", IPC G02B 5/18, G02B 5/32, published July 21, 2017], selected as a prototype. The technical solution is carried out in the form of a two-beam interferometer, which is mounted on the base with the possibility of rotational motion and contains a beam splitting element, a first mirror, a second mirror and a photosensitive element fixed motionless and optically connected to a collimated light beam source. As a possible embodiment of a beam splitting element, a beam splitting cube composed of two 90-degree prisms tightly connected by their flat hypotenuse surfaces is considered. On the hypotenuse surface of one of these prisms, a beam splitting mirror is preliminarily applied, which as a result is diagonally integrated into the beam splitting cube. Due to its mirror symmetry with respect to the plane of the beam splitting mirror, the output surfaces are mirror symmetrically relative to this plane. The first mirror and the second mirror are also installed mutually symmetrically with respect to the indicated plane. As a result, the two-beam interferometer is a rigid mirror-symmetric design, providing its high vibration resistance.

The collimated light beam is directed to the input surface of the beam splitting cube and, having refracted on it, is divided by the beam splitting mirror into the first partial light beam, which passes through the beam splitting mirror, and the second partial light beam, which is reflected from the beam splitting mirror. The first mirror and the second mirror are installed on the path of the first partial light beam and the second partial light beam emerging from the beam splitting cube, respectively. After reflection from the mirrors, the first partial light beam and the second partial light beam mutually overlap at a given angle of convergence. Due to the mirror symmetry of the two-beam interferometer, both partial light beams are also mutually symmetrical. As a result, the periodic interference pattern formed in the region of their mutual overlap is also symmetrical with respect to the plane of the beam splitter, and the optical lengths of the first and second partial light beams along their axes from the point of separation of the collimated light beam in the beam splitter mirror to the point of mutual intersection are equal for any angle of convergence. The photosensitive element is placed inside said overlap area.

Rotational motion of the base is accompanied by a change in the angle of incidence of the collimated light beam on the input surface of the beam splitter cube and a corresponding change in the angle of convergence of the first and second partial light beams. The axis of rotation is oriented perpendicular to the plane of incidence of the collimated light beam on the beam splitter mirror and is located behind the beam splitter cube along the first and second partial light beams. This position is set so that the rotational motion of the base and the associated movement of the collimated light beam through the beam splitter mirror ensures the movement of the interference pattern relative to the photosensitive element within a segment small compared to its length along the plane of the beam splitter mirror. The rotation of the base is carried out by a rotational motion drive, which is controlled by signals generated by the control unit.

The disadvantages of the known technical solutions are, firstly, the complexity of its operation, due to the rotation of the interferometer and the associated change in the position of the photosensitive element relative to the equipment interacting with the interferometer located outside the rotating base, and secondly, the inability to combine such interferometers into a system designed for simultaneous recording multidimensional periodic structures on a photosensitive element common to all interferometers.

The authors were tasked with developing a two-beam interferometer with a tunable angle of convergence of partial beams with a collimated light beam source and a photosensitive element stationary relative to it, in order to be able to combine two or three such interferometers into a system designed to simultaneously record two or three-dimensional periodic structures in a photosensitive material with mutually independent restructuring of the period of a given structure in each of its dimensions.

The problem is solved in that, according to the first embodiment, a two-beam interferometer including a collimated light beam source, a base with a fixed beam splitting element fixed to it with a beam splitting mirror separating the collimated light beam into the first partial light beam and the second partial light beam, the first mirror , a second mirror, a photosensitive element optically coupled to a collimated light source, the first mirror and the second mirror The first partial light beam and the second partial light beam reflected from them in the direction to each other until they intersect on the photosensitive element are oriented by guides, the angular displacement sensor, the control unit is additionally equipped with a movable mirror with an axis of rotation, designed to direct the collimated light beam to the beam splitter a mirror of the beam splitting element, while the axis of rotation is made providing simultaneous angular movement of the movable mirror, I change its angle of incidence of the collimated light beam on the beam splitting mirror of the beam splitting element, and the linear movement of the movable mirror, changing the position of the collimated light beam on the beam splitting mirror of the beam splitting element, the matching unit, while the control unit is configured to generate control signals for the matching unit performing angular and linear axis movements rotation, and matching them together, according to the formula

where W is the linear movement of the axis of rotation relative to the initial position, in which M = G / 2, G is the length of the beam splitting mirror in the plane of incidence of the collimated light beam, M is the distance from the position of the axial beam of the collimated light beam on the beam splitting mirror to its edge, closest to the photosensitive element, χ is the angle of incidence of the collimated light beam on the beam splitter mirror, T is the distance from the axis of rotation to the input surface of the beam splitter element, ϕ is the angle of rotation of the axis of rotation relates in relation to the initial position, in which χ = 45 °, and the collimated light beam source is fixed fixed on the base, while the beam splitting element with a beam splitting mirror is made with output faces of the beam splitting element symmetrical with respect to the plane of this beam splitting mirror, then the first mirror and the second mirror are made arranged mutually symmetrically with respect to the plane of the beam splitting mirror.

According to the second embodiment, a two-beam interferometer including a collimated light beam source, a base with a fixed beam splitting element fixed to it with a beam splitting mirror separating the collimated light beam into a first partial light beam and a second partial light beam, a first mirror, a second mirror, a photosensitive element, optically coupled to a collimated light beam source, wherein the first mirror and the second mirror are oriented by reflection guides the first partial light beam and the second partial light beam directed to each other until they intersect on the photosensitive element, the angular displacement sensor, control unit is additionally equipped with a rotation axis, which provides simultaneous angular displacement of the source, which changes the angle of incidence of the collimated light beam to the beam splitting mirror of the beam splitting element, and the linear movement of the source, changing the position of the collimated light beam to light dividing mirror of the beam-splitting element, matching unit, while the control unit is configured to generate control signals for matching unit performing angular and linear movements of the axis of rotation, and matching them together, according to the formula

where W is the displacement of the axis of rotation relative to the initial position, in which M = G / 2, G is the length of the beam splitting mirror in the plane of incidence of the collimated light beam, M is the distance from the position of the axial beam of the collimated light beam on the beam splitting mirror to its edge, near to the photosensitive element, χ is the angle of incidence of the collimated light beam on the beam splitter, T is the distance from the axis of rotation to the input surface of the beam splitter, ϕ is the angle of rotation of the axis of rotation relative to the initial th position in which χ = 45 °, wherein the beam splitter with the beam-splitting mirror configured to output facets beam-splitting element, symmetrical about the plane of the beam-splitting mirror, then a first mirror and a second mirror formed mutually symmetrically disposed with respect to beam-splitting mirror plane.

The technical effect of the claimed device is to simplify the setup of the interferometer, to increase the accuracy of the period of the interference pattern, to increase the productivity of the process of recording one- and multidimensional periodic structures in a photosensitive material; in reducing sensitivity to vibration, as well as in expanding the arsenal of funds for this purpose.

In FIG. 1 is a diagram of a two-beam interferometer according to the first embodiment, where 1 is a source, 2 is a collimated light beam, 3 is a movable mirror, 4 is a beam splitter, 5 is a beam splitter, 6 is a first mirror, 7 is a second mirror, 8 is a photosensitive element, 9 - base, 10 - axis of rotation, 11 - direction of angular movement, 12 - direction of linear movement, 13 - matching unit, 14 - control unit, 15 - sensor of angular movement, 16 - first partial light beam, 17 - second partial light beam , 18 - initial set Ie.

In FIG. 2 is a diagram of one of the possible mechanisms of the unit for matching angular and linear displacements of the axis of rotation according to the first embodiment, where 2 is a collimated light beam, 3 is a movable mirror, 10 is an axis of rotation, 11 is a direction of angular displacement, 12 is a direction of linear displacement, 19 is case, 20 - platform, 21 - the frame of the movable mirror, 22 - the lever, 23 - the guide, 24 - the elastic element, 25 - support, 26 - the displaced position.

In FIG. 3 is a diagram of a two-beam interferometer according to the second embodiment, where 1 is a source, 2 is a collimated light beam, 4 is a beam splitter, 5 is a beam splitter, 6 is a first mirror, 7 is a second mirror, 8 is a photosensitive element, 9 is a base, 10 - axis of rotation, 11 - direction of angular displacement, 12 - direction of linear displacement, 13 - matching unit, 14 - control unit, 15 - angular displacement sensor, 16 - first partial light beam, 17 - second partial light beam, 18 - initial position .

In FIG. 4 shows a diagram of one of the possible mechanisms of the unit for matching angular and linear displacements of the axis of rotation according to the second embodiment, where 1 is the source, 2 is the collimated light beam, 10 is the axis of rotation, 11 is the direction of angular movement, 12 is the direction of linear movement, 19 is the body , 20 - platform, 22 - lever, 23 - guide, 24 - elastic element, 25 - support, 26 - offset position, 27 - source frame.

, расстоянии от оси вращения до входной поверхности светоделительного элемента

, угле наклона направляющей в механизме узла согласования η=8°, диаметре коллимированного светового пучка

где 28 - коэффициент смещения, 29 - метка на низшем значении угла падения, 30 - метка на высшем значении угла падения, 31 - низший уровень коэффициента смещения, 32 - высший уровень коэффициента смещения.In FIG. 5 is a graph of the dependence of the displacement coefficient k _{s of the} center of symmetry О of the interference pattern relative to the photosensitive element on the angle of incidence θ of the collimated light beam on the input surface in the two-beam interferometer according to the first and second options at a distance between the first mirror and the second mirror H = 1.03G, the angle of inclination of the first and the second mirror ξ = -15 °, the distance from the photosensitive element to the edge of the beam splitter near to it

, the distance from the axis of rotation to the input surface of the beam splitting element

, the angle of inclination of the guide in the mechanism of the matching unit η = 8 °, the diameter of the collimated light beam

where 28 is the displacement coefficient, 29 is the mark at the lowest value of the angle of incidence, 30 is the mark at the highest value of the angle of incidence, 31 is the lowest level of the displacement coefficient, 32 is the highest level of the displacement coefficient.

The inventive two-beam interferometer according to the first embodiment works as follows. A double-beam interferometer, the circuit of which is shown in FIG. 1 includes an optically coupled source of collimated light beam 2, a beam splitter 4 with a beam splitter 5, a first mirror 6, a second mirror 7 and a photosensitive element 8, as well as a movable mirror 3, which is additionally equipped with a two-beam interferometer.

где А - длина ребра кубика. На гипотенузной поверхности одной из 90-градусных призм предварительно наносится светоделительное зеркало 5, которое в результате оказывается встроенным в светоделительный кубик. Благодаря его зеркальной симметрии относительно диагональной поверхности С₁С₂ выходные поверхности С₂С₃ и С₂С₄ располагаются зеркально-симметрично относительно светоделительного зеркала 5. Первое зеркало 6 и второе зеркало 7 устанавливаются также взаимно симметрично относительно светоделительного зеркала 5 на расстоянии Н друг от друга и под углом наклона ξ к указанной плоскости (на фиг. 1 ξ>0). Поэтому плоскость светоделительного зеркала 5 является плоскостью зеркальной симметрии (далее плоскость симметрии) собственно интерферометра, включающего в себя светоделительный элемент 4 со светоделительным зеркалом 5, первое зеркало 6 и второе зеркало 7.The source 1, the beam splitting element 4, the first mirror 6, the second mirror 7 and the photosensitive element 8 are fixedly mounted on the base 9. As a beam splitting element 4, for example, a beam splitting cube made up of two identical 90-degree prisms, tightly connected by their flat hypotenous surfaces forming its diagonal surface With ₁ With ₂ length

where A is the length of the edge of the cube. On the hypotenous surface of one of the 90-degree prisms, a beam splitting mirror 5 is preliminarily applied, which, as a result, is built into the beam splitting cube. Due to its mirror symmetry with respect to the diagonal surface C ₁ C _{2, the} output surfaces C ₂ C ₃ and C ₂ C ₄ are mirror-symmetrical with respect to the beam splitter mirror 5. The first mirror 6 and the second mirror 7 are also installed mutually symmetrically with respect to the beam splitter mirror 5 at a distance H of from a friend and at an angle of inclination ξ to the indicated plane (in Fig. 1 ξ> 0). Therefore, the plane of the beam splitting mirror 5 is a plane of mirror symmetry (hereinafter the plane of symmetry) of the interferometer itself, including a beam splitting element 4 with a beam splitting mirror 5, a first mirror 6 and a second mirror 7.

The movable mirror 3 is equipped with a rotation axis 10, which provides this mirror with two movements simultaneously: angular - (shown by the arrow of the direction of angular movement 11), characterized by the angle of rotation ϕ, and linear, determined by the offset W and directed parallel to the surface C ₁ C _{4 of the} beam splitting element 4, and also perpendicular to its ribs C ₁ -C ₄ (shown by the arrow of the direction of linear movement 12). The axis of rotation 10 is located at a distance T from the same surface With ₁ With ₄ and oriented parallel to the ribs With ₁ -C ₄ . Both movements are carried out by the coordination unit 13 and are mutually coordinated through it. The control unit 14 generates control signals for the matching unit 13. The two-beam interferometer is also equipped with an angular displacement sensor 15, designed to monitor the current characteristics of the two-beam interferometer during its operation.

The source 1 generates a collimated light beam 2 of diameter D, which is oriented parallel to the aforementioned surface C ₁ C ₄ (hereinafter the input surface) along the direction of linear movement 12, and after reflection from the movable mirror 3 is reoriented to this surface at an incidence angle θ in the plane perpendicular to the edges C ₁ -C ₄ . The position of the collimated light beam 2 on the input surface is determined by the distance Q from the trace of the axial beam of this beam on it to the edge C _{1 of the} beam splitter mirror 5, which is close to the axis of rotation 10. Next, the collimated light beam 2 enters the beam splitter 4 at a refraction angle ψ, falls on beamsplitting mirror 5 at an angle χ, and its axial beam misses the point F at a distance from the edge of the M ₂ C-splitting mirror 5 near to the photosensitive member 8. This beam splitter is split into two mirror 5 Partsa cial light beams 16 and 17. The first partial beam 16 passes through beam splitter mirror 5 as if continuing a collimated light beam 2 leaves the beam splitter 4 via the exit surface C ₂ C ₃ and is directed to the first mirror 6, the axial ray trace E a first partial light beam 16 on the surface remote from the edge _C2-splitting mirror 5 by a distance B. The second partial beam 17 is reflected from the beam-splitting mirror 5, leaves the beam splitter 4 through vyho hydrochloric surface C ₂ C ₄ partial symmetrically to the first light beam 16 and directed to the second mirror 7. The partial light beams 16 and 17 reflected from the first mirror 6 and second mirror 7, respectively, overlap each other at an angle of convergence 2α. Due to the symmetry of the interferometer, these partial light beams are also mirror symmetric to each other with respect to the plane of symmetry. Therefore, the region of their mutual overlap highlighted in FIG. 1 is gray, has the same symmetry, and the point O of the intersection of their axial rays, remote at a distance L (hereinafter, the convergence length) from the edge C _{2 of the} beam splitter mirror 5 closest to the photosensitive element 8 lies on the indicated plane, is the center of symmetry of the periodic interference patterns formed in this area and is characterized by a zero order of interference. The difference in travel along the axes of the first partial light beam 16 and the second partial light beam 17 from the point F of their formation on the beam splitting mirror 5 to point O due to their mutual symmetry is zero at any angle of convergence. The photosensitive element 8 is placed inside the aforementioned overlapping region at a distance L ₀ from the edge C _{2 of the} beam splitting mirror 5.

The period Λ of the interference pattern is uniquely related to the convergence angle 2α by the formula Λ = λ / 2sinα, where λ is the wavelength of the radiation generated by the source 1. Therefore, one of the possibilities to control this period is to change the convergence angle. In turn, in the considered two-beam interferometer, the half convergence angle α is determined through the angle of incidence θ by the relation

if the value of θ is assigned a sign in accordance with the direction of angular displacement 11. In this case, an increase in the angle θ is accompanied by an increase in the angle α and vice versa, since according to (1) their increments are equal to: δθ = δα. As a result, the period Λ can be controlled by changing the angle of incidence θ.

The output parameters of the interferometer, α and L, are expressed through the input parameters, θ and Q, by the basic formula of a symmetric two-beam interferometer with fixed mirrors:

derived by the rules of geometric optics, where

and

since the angle of refraction is ψ = arcsin [(sinθ) / n], where n is the refractive index of the material from which the beam splitting element is made.

If we fix the convergence length according to the condition L = L ₀ , that is, so that the center O of the interference pattern is located exactly on the photosensitive element 8, then from (2) and (3) we can obtain a formula describing the law of matching the distance Q with the half convergence angle α or according to formula (1) with an angle of incidence θ:

The dependence Q (θ) extracted from (5) is close to linear with a positive slope, if the sign of the increment of the value of Q corresponds to the sign of the direction of linear displacement 12, therefore, increasing the angle of incidence θ requires an almost proportional increase in the distance Q. Therefore, the problem of constructing a two-beam interferometer with a fixed photosensitive element is solved by coordinated rotation of the collimated light beam 2 and its linear movement along the input surface according to a law close to linear dependence.

. Следует отметить, что при повороте подвижного зеркала 3 на угол ϕ значение угла падения θ изменяется на величину, вдвое большую угла поворота: θ=θ₀+2ϕ. С учетом принятого значения θ₀ получается равенство:The parameters generated by the matching unit 13, the angle of incidence θ and the distance Q _W, are determined through the corresponding parameters of the rotation axis 10 of the movable mirror 3: rotation angle ϕ and linear shift W. The latter are counted from the rotation axis 10 in the initial position 18 of the movable mirror 3 ( is shown by dashed lines), in which the initial value of the angle of incidence θ ₀ = 0 °, and the initial position Q _{0 of the} axial beam trace of the collimated light beam 2 is located in the center of symmetry of the input surface

. It should be noted that when the movable mirror 3 is rotated through an angle ϕ, the value of the angle of incidence θ changes by an amount twice the angle of rotation: θ = θ ₀ + 2ϕ. Given the accepted value of θ _{0, we} obtain the equality:

If at the same time the axial beam of the collimated light beam 2 intersects the axis of rotation 10, as shown in FIG. 1, then the interdependence of the geometric parameters of the matching node 13 is expressed by the following formula:

in which the signs θ and W correspond to the signs of the directions of the arrows 11 and 12, respectively. From (7) follows the dependence Q _W (θ):

In (7) and (8), the approximation θ << 1, at which tgθ≈θ, is accepted. The dependence Q _W (θ), expressed by formula (8), should be close to linear, as well as the dependence Q (θ) according to (5), due to the requirement L = L ₀ . Therefore, the required form of the matching function W (θ) generated by the matching unit 13 under the action of control signals from the control unit 14 should also be linear or close to that. This is the basis for the approach to the construction of the coordination node 13.

In FIG. 2 shows a diagram of one of the possible variants of the mechanism of the coordination node 13, which implements the required type of coordination. The mechanism is placed in the housing 19, fixedly mounted on the base 9. The mechanism includes a platform 20, which can move relative to the housing 19 and, as a result, relative to the beam splitting element 4 along the zz axis in the direction of linear movement 12. This axis intersects the axis of rotation 10 , designated as Z, and is aligned with the axial beam of the collimated light beam 2 incident on the movable mirror 3. It is mounted in the frame of the movable mirror 21, which, like the axis of rotation 10, is rigidly fixed to the lever 22. Lednov arranged to perform a rotation about the axis of rotation 10 in the direction of the angular displacement 11. It is shown in a position corresponding to the starting position 18 (see. FIG. 1) of the movable mirror 3. As shown in FIG. 2, the lever 22 in this position, with its edge opposite the axis of rotation 10, contacts without a gap at a point K belonging to the z-z axis with a straight guide 23 inclined to this axis at an angle η. A segment ZK of length R is the shoulder of the lever 22. The specified contact is provided by the pressing created by the elastic element 24, for example, a spring, which abuts against the support 25, rigidly connected to the platform 20, and the lever 22 with the other.

When the platform 20 is moved to a distance W, the lever 22 is rotated through an angle ϕ about the axis of rotation 10 due to the sliding of its edge K along the inclined guide 23. As a result, the lever 22 is in an offset position 26 (shown by dashed lines), the axis of rotation is positioned at the point Z _W , and the point of contact of the lever 22 with the guide 23 is at the point K _W. From the triangle Z _W K _W K in the approximation of small angles ϕ and η, the law of motion of the described mechanism is found:

Taking into account (6), we obtain the required linear dependence W (θ):

therefore, the dependence Q _W (θ) according to formula (8) is also linear.

Соответствующие значения угла падения, θ₁ или θ₂, находятся из уравнений, построенных на основе формулы (5) путем подстановки в ее левую часть вместо Q принятых значений Q₁ или Q₂, а в правую - вместо переменной α выражения θ₁+2ξ+45° или θ₂+2ξ+45° согласно (1). При этом θ₁ оказывается минимальным, а θ₂ - максимальным возможными значениями угла падения, а соответствующие им значения половинного угла схождения α₁ и α₂ - нижним и верхним граничными значениями диапазона перестройки этого угла, который можно реализовать в рассматриваемом интерферометре с заданными геометрическими параметрами Н и ξ.Formulas (8) and (10) allow you to bind the geometric parameters T, R and η, characterizing the described mechanism of the matching node 13, to the required dependence Q (θ) according to (5). For such a procedure, you can assign two points with coordinates, (Q ₁ , θ ₁ ) and (Q ₂ , θ ₂ ), which belong to both dependencies, (5) and (8). Let these points determine the extreme possible positions of the trace of the axial beam of the collimated light beam 2 on the input surface C ₁ C _{4 of the} beam splitting element 4 - Q ₁ = Q _W1 = 0 or

The corresponding values of the angle of incidence, θ ₁ or θ ₂ , are found from the equations constructed on the basis of formula (5) by substituting the accepted values Q ₁ or Q ₂ instead of Q on its left side, and the expression θ ₁ + 2ξ instead of the variable α + 45 ° or θ ₂ + 2ξ + 45 ° according to (1). Moreover, θ ₁ is the minimum, and θ ₂ - the maximum possible values of the angle of incidence, and the corresponding values of the half angle of convergence α ₁ and α ₂ - the lower and upper boundary values of the adjustment range of this angle, which can be implemented in the considered interferometer with given geometric parameters H and ξ.

From formula (10), the values W ₁ = θ ₁ R / (2η) and W ₂ = θ ₂ R / (2η) are calculated, bounding the segment of the zz axis, within which the axis of rotation 10 can be displaced, with a length

where Δα = α ₂ -α ₁ = θ ₂ -θ ₁ is the width of the adjustment range of the half angle of convergence according to (1). W _Σ represents the full stroke of linear displacement in the matching mechanism under consideration. Equality (11) allows us to express the ratio of its geometric parameters in terms of Δα:

The distance T from the axis of rotation 10 to the input surface C ₁ C ₄ is found from (8) by substituting Q _W -Q ₁ or Q ₂ instead of WW ₁ or W ₂ and instead of θ-θ ₁ or θ _2, respectively:

If the distance T is taken as the base size, then according to (13) it uniquely determines the required full stroke of the linear movement:

As an example, we can present the characteristics of an interferometer with the following parameters: the length of the beam of the beam splitter 4 A = 20 mm, which gives the length of the beam splitter 5 G = 28.3 mm, the distance between the mirrors H = 29.1 mm (in the general case, H = 1.0298 G), the angle of the mirrors ξ = -15 °, the distance to the photosensitive element 8 L ₀ = 80 mm At the initial position of the collimated light beam 2 (θ ₀ = 0 °, Q ₀ = 10 mm), the corresponding half angle of convergence is α ₀ = 15 °. In the extreme positions of the axial beam of the collimated light beam 2: Q ₁ = 0 mm and Q ₂ = 20 mm, the angle of incidence is calculated from (5) and is θ ₁ = -5.3 ° and θ ₂ = 5.3 °, respectively. This makes it possible, using (1), to determine the boundaries of the permissible interval of variation of the half angle of convergence: α ₁ = 9.7 ° and α ₂ = 20.3 °, as well as the width of this interval Δα = 10.6 °.

Such an acceptable interval can be provided by the mechanism of the matching unit 13, in which the zz axis is removed from the input surface С ₁ С ₄ by a distance T = 35 mm, which sets the required total linear travel W _Σ = 26.5 mm according to (14). From (12) the lever arm 22 R = 40 mm is determined if the angle of inclination of the guide 23 η = 8 °.

In a real device, the diameter D of the collimated light beam 2 should be taken into account: so that it does not go beyond the input surface, the extreme positions of its axial beam are specified by the condition that this beam touches the boundaries C ₁ or C ₄ :

The index D means that these extreme positions are selected taking into account the diameter. The values of θ _D1 or θ _D2 are found from (5) when substituting Q _D1 or Q _D2 in the left side instead of Q and the expressions θ _D1 + 2ξ + 45 ° or θ _D2 + 2ξ + 45 ° in the right side instead of a. In the above example, D = 5 mm, hence the extreme positions of the axial beam Q _D1 = 2.51 mm and Q _D2 = 17.49 mm, the extreme values of the angle of incidence θ _D1 = -3.96 ° and Q _D2 = 3.96 °; the corresponding values of the half angle of convergence are α _D1 = 11.04 ° and α _D2 = 18.96 °, and Δα _D = 7.92 °. To calculate the full stroke of linear displacement, it is necessary to replace formula (14) with the following equality:

or its shortened version:

where ΔQ _D = Q _D2 -Q _D1 . With the same parameters of the matching mechanism: T = 35 mm, η = 8 ° and R = 40 mm, the required linear travel is slightly reduced: W _DΣ = 19.83 mm.

The correlated dependences: Q (θ), due to the requirement L = L ₀ and expressed by formula (5), as well as Q _W (θ), formed by the mechanism of matching node 13 and described by formula (8), slightly differ, therefore, the center of symmetry pattern (see Fig. 1) is shifted relative to the photosensitive element 8 by

which is zero only at the anchor points discussed above. To maintain a high contrast of the interference pattern, the displacement δL should be small compared to its length

along the plane of symmetry. The displacement is conveniently estimated by the corresponding coefficient k _s equal to the ratio of δL to half the length S:

The geometric meaning of this coefficient is that the difference 1- | k _s | indicates what proportion of full width

the interference pattern across the plane of symmetry falls on the photosensitive element 8. The interference pattern is completely outside it if the mentioned difference reaches zero, therefore it is necessary that the inequality

The diagram in FIG. 5 shows the dependence of the displacement coefficient 28 on the angle of incidence θ of the collimated light beam 2 on the input surface - k _s (θ) - for the above example of the inventive two-beam interferometer. Labels at the lowest value of the angle of incidence 29 θ _D1 = -3.96 ° and at the highest value of the angle of incidence 30 θ _D2 = 3.96 ° limit the allowable interval of variation of the angle of incidence, and the lowest level of the displacement coefficient 31 k _s ≈ -0.0023 and the highest level of the bias coefficient 32 k _s ≈0.0023 is determined by the segment within which the center of symmetry O shifts relative to the photosensitive element 8 in the process of changing the convergence angle, the offset δL does not go beyond the interval from -0.15 to 0.15 mm. Such small displacements practically do not affect the contrast of the interference pattern.

The law of matching (5) of the angle of incidence θ of the collimated light beam 2 on the input surface and its position on this surface, determined by the distance Q, can be represented as the law of matching the angle of incidence χ of the collimated light beam 2 on the beam splitting surface 5 and its position on it, determined by the distance M. From FIG. 1 it follows that

Relation (22) allows us to express χ as a function of θ, using the law of refraction:

From (23) we obtain the dependence χ (α), if (1) is used, or a more convenient dependence θ (χ), which gives a reference to the input parameters of the collimated light beam 2:

The distance B can be connected with the variables χX and M by solving the triangle FEC ₂ , the sides of which are formed by the distances B, M and the segment FE of the axis of the first partial light beam 16 from point F on the beam splitter mirror 5 to the point E of its exit on the surface C ₂ C ₃ beam splitter item 4:

Formulas (2) and (25) allow us to express the distance M in terms of the interferometer parameters: the distance H between the first mirror 6 and the second mirror 7, the tilt angle ξ of these mirrors and the distance L ₀ from the edge C _{2 of the} beam splitter mirror 5 to the photosensitive element 8:

The angle α in (26) is also a function of χ, which is found by substituting (24) in (1). Using another substitution (25) in (3), we can derive the dependence of the distance Q on χ and M:

The combination of (7) and (27) gives the desired law that describes the coordination of linear and angular movements of the axis of rotation 10:

- угол поворота подвижного зеркала 3 относительно начального положения 18, в котором χ=45°.where W is the displacement of the axis of rotation 10 of the movable mirror 3 relative to the initial position 18, in which M = G / 2, G is the length of the beam splitting mirror 5 along the plane of incidence of the collimated light beam 2, M is the distance from the position F of the axial beam of the collimated light beam 2 on the beam splitter mirror 5 to its edge C ₂ , closest to the photosensitive element 9 and expressed by the formula (26), χ is the angle of incidence of the collimated light beam 2 on the beam splitter mirror 4 and expressed by the formula (23), T is the distance from the rotation axis 10 to input overhnosti C ₁ C ₄ beam-splitting element 4,

- the angle of rotation of the movable mirror 3 relative to the initial position 18, in which χ = 45 °.

The technical effect of the claimed device, which consists in simplifying the adjustment of the interferometer and possibly due to this simplification, increasing the accuracy of the period of the interference pattern, in increasing the productivity of the recording process of one- and multidimensional periodic structures in a photosensitive material; in reducing the sensitivity to vibrations, as well as in expanding the arsenal of means for this purpose, it is achieved due to the fact that the collimated light beam source, the beam splitter, the first and second mirrors and the photosensitive element are mutually immovable, and the coordination of the angle of incidence of the collimated light beam on the beam splitter mirror element with the movement of this beam along this beam splitting mirror, necessary to stabilize the position of the region of mutual overlapping of partial beams on a photosensitive element, is provided by mutually coordinated angular and linear movements of the axis of rotation of the rotary mirror, directing the collimated light beam to the beam splitting element, according to the law (28) in accordance with the control signals for the matching unit formed by the control unit.

The inventive two-beam interferometer according to the second embodiment works as follows. A double-beam interferometer, the scheme of which is shown in FIG. 3, includes a collimated light beam 2, an optically coupled source 1, a beam splitting element 4 with a beam splitting mirror 5, a first mirror 6, a second mirror 7 and a photosensitive element 8.

где А - длина ребра кубика, светоделительным зеркалом 5. Светоделительный кубик зеркально симметричен относительно этой диагональной поверхности, поэтому выходные поверхности С₂С₃ и С₂С₄ расположены зеркально-симметрично относительно светоделительного зеркала 5. Первое зеркало 6 и второе зеркало 7 устанавливаются также взаимно симметрично относительно светоделительного зеркала 5 на расстоянии Н друг от друга и под углом наклона ξ (на фиг. 3 ξ>0). Поэтому плоскость светоделительного зеркала 5 является плоскостью зеркальной симметрии (далее плоскость симметрии) собственно интерферометра, составленного из светоделительного элемента 4 со светоделительным зеркалом 5, первого зеркала 6 и второго зеркала 7.A beam splitting element 4 with a beam splitting mirror 5, a first mirror 6, a second mirror 7 and a photosensitive element 8 are fixedly mounted on the base 9. As a beam splitting element 4, for example, a beam splitting cube with a length C ₁ C ₂ embedded along its diagonal surface

where A is the length of the edge of the cube by the beam splitting mirror 5. The beam splitting cube is mirror symmetric with respect to this diagonal surface; therefore, the output surfaces C ₂ C ₃ and C ₂ C ₄ are mirror symmetric with respect to the beam splitting mirror 5. The first mirror 6 and the second mirror 7 are also installed mutually symmetrical with respect to the beam splitting mirror 5 at a distance H from each other and at an angle of inclination ξ (in Fig. 3 ξ> 0). Therefore, the plane of the beam splitter mirror 5 is a plane of mirror symmetry (hereinafter the plane of symmetry) of the interferometer itself, composed of a beam splitter element 4 with a beam splitter mirror 5, a first mirror 6 and a second mirror 7.

The source 1 is connected to the axis of rotation 10 so that it intersects with the continuation of the axial beam of the collimated light beam 2, and the axis of rotation 10 simultaneously performs two movements: angular (shown by arrow 11), characterized by an angle of rotation ϕ, and linear (shown by arrow 12), defined by the displacement W and directed parallel to the surface C ₁ C _{4 of the} beam splitting element 4 (hereinafter the input surface), as well as perpendicular to its ribs C ₁ -C ₄ . The axis of rotation 10 is located at a distance T from the input surface and is oriented parallel to the ribs C ₁ -C ₄ . Both movements are carried out using the coordination node 13 and are mutually coordinated through it. The control unit 14 generates control signals to the matching unit 13. The two-beam interferometer is also equipped with an angular displacement sensor 15, designed to monitor the current characteristics of the two-beam interferometer during its operation.

Source 1 generates a collimated light beam 2 of diameter D, which is sent directly to the input surface at an incidence angle θ in a plane perpendicular to the ribs C ₁ -C ₄ . The position of this beam on the input surface is determined by the distance Q from the trace of its axial beam on this surface to the edge C _{1 of the} beam splitting mirror 5, which is closest to the source 1. Next, the collimated light beam 2 enters the beam splitter 4 at a refraction angle ψ and falls onto the beam splitter mirror 5 angle χ, and its axial beam misses the point f at a distance from the edge of the M ₂ C-splitting mirror 5 near to the photosensitive member 8. This beam splitter mirror 5 is divided into two partial light n PFA: 16 and 17. The first partial beam 16 passes through beam splitter mirror 5 and leaves the beam splitter 4 via the exit surface C ₂ C _3, the mark on the surface E of the axial ray of this beam is determined by the distance from the edge in C ₂ 5-splitting mirror. The second partial beam 17 is reflected from the beam-splitting mirror 5 and leaves the beam splitter 4 via the exit surface C ₂ C ₄ partial symmetrically to the first light beam 16. The two partial light beams 16 and 17 reflected on the first mirror 6 and second mirror 7, respectively, overlap each other at an angle of convergence 2α. Due to the symmetry of the interferometer, these partial light beams are also mutually mirror symmetric with respect to the plane of symmetry. Therefore, the region of their mutual overlap highlighted in FIG. 3 is gray, has the same symmetry, and the point O of the intersection of their axial rays, remote at a distance L (hereinafter, the convergence length) from the edge C _{2 of the} beam splitter mirror 5 closest to the photosensitive element 8, lies on the indicated plane, is the center of symmetry of the periodic interference patterns formed in this area and is characterized by a zero order of interference. The path difference along the axes of the partial light beams 16 and 17 from the point F on the beam splitter mirror 5 to the point O of intersection of their axial rays is zero at any angle of convergence. The photosensitive element 8 is placed inside the aforementioned overlapping region at a distance L ₀ from the edge C _{2 of the} beam splitting mirror 5.

The period Λ of the interference pattern is related to the half-convergence angle by the formula Λ = λ / 2sinα, where λ is the wavelength of the radiation generated by the source 1. Therefore, one of the possibilities to control this period is to change the angle of convergence. In turn, it follows from formula (1) that the period Λ can be controlled by changing the angle of incidence θ.

The output parameters of the interferometer: the half convergence angle α and the convergence length L - are connected with the input parameters: the angle of incidence θ and the distance Q - through formula (2). If we fix the convergence length so that the interference pattern appears on the photosensitive element 8, i.e. satisfy the condition L = L ₀ , then in this case the required distance Q is expressed by formula (5). It gives a dependence Q (θ) close to linear. The latter is a guide for constructing a two-beam interferometer with a fixed photosensitive element 8.

Взаимозависимость геометрических параметров узла согласования 13 выражается формулами (7) и (8), учитывающих приближение tgθ≈θ по условию малости θ<<1. Из (8) следует, что приемлемое совмещение выражаемой ею зависимости Q_W(θ) с требуемой зависимостью Q(θ) согласно (5) возможно в случае, если и функция W(θ), вырабатываемая узлом согласования 13, также близка к линейной. Это условие определяет выбор механизма, закладываемого в основу конструкции данного узла.The parameters produced by the matching unit 13, the angle of incidence θ and the distance Q _W, are determined through the corresponding parameters of the position of source 1: the angle of rotation ϕ equal to the angle of incidence θ and the linear shift W. Both last parameters are counted from the position of the axis of rotation 10 corresponding to the initial position 18 of the source 1 (shown by dashed lines), in which the collimated light beam 2 normally falls on the input surface (the initial value of the angle of incidence θ ₀ = 0 °), and the initial distance Q ₀ is equal to half the total width of the input surface C ₁ C ₄ :

The interdependence of the geometric parameters of the matching node 13 is expressed by formulas (7) and (8), taking into account the approximation tgθ≈θ by the condition of smallness θ << 1. It follows from (8) that an acceptable combination of the dependence Q _W (θ) expressed by it with the required dependence Q (θ) according to (5) is possible if the function W (θ) generated by the matching node 13 is also close to linear. This condition determines the choice of the mechanism laid in the basis of the design of this node.

In FIG. 4 shows a diagram of one of the possible options for such a mechanism. It is mounted in a housing 19 fixedly mounted on the base 9 and includes a platform 20 that can move relative to the housing 19 and, as a result, relative to the beam splitting element 4 in the direction of linear movement 12 along the zz axis parallel to the input surface and intersecting with the axis of rotation 10, denoted as Z. The source 1 is placed in the frame of the source 27, which, like the axis of rotation 10, is rigidly fixed to the lever 22. The latter is mounted with the ability to rotate around the axis of rotation 10 in a directional ju angular displacement 11 and is depicted in the position corresponding to the initial position 18 (see Fig. 3) of the source 1. In FIG. 4, the lever 22 itself in this position, with its edge opposite the axis of rotation 10, is in contact without a gap at a point K belonging to the z-z axis with a straight guide 23 inclined to this axis at an angle η. A segment ZK of length R is the shoulder of the lever 22. The specified contact is provided by the pressing created by the elastic element 24, for example, a spring, which abuts against the support 25, rigidly connected to the platform 20, and the lever 22 with the other.

When the platform 20 is moved to a distance W, the lever 22 is rotated through an angle ϕ about the axis of rotation 10 due to the sliding of its edge K along the guide 23. As a result, the lever 22 occupies an offset position 26 (shown by dashed lines), the axis of rotation is shifted to the point Z _W , and the point the contact of the lever 22 with the guide 23 to the point K _W. From the triangle Z _W K _W K in the approximation of small angles ϕ and η, we obtain the law of motion of the described mechanism:

similar to (9), which, given the equality ϕ = θ, gives the required linear dependence W (θ):

and, as a consequence, the linear dependence Q _W (θ) according to (8).

Using formulas (8) and (30), the parameters T, R, and η are linked to the dependence Q (θ), which is required according to (5). For this, it is convenient to choose the two extreme points of this dependence, (θ _D1 , Q _D1 ) or (θ _D2 , Q _D2 ), which are determined by the condition that the collimated light beam 2 with diameter D of the boundaries C ₁ or C _{4 of the} input surface touches, respectively (see Fig. 3), and the coordinates in each pair are interconnected by formulas (15). The index D means that these extreme positions are selected taking into account the diameter of the beam. The dependence Q _W (θ), bound to Q (θ), must also pass through these points. The values of θ _D1 or θ _D2 can be found from (5) if we substitute Q = Q _D1 or Q _D2 from (15) in the left side and α = θ _D1 + 2ξ + 45 ° or θ _D2 + 2ξ + 45 in the right °. With D = 5 mm, the extreme positions are Q _D1 = 2.51 mm and Q _D2 = 17.49 mm, the extreme values of the angle of incidence are θ _D1 = -3.96 ° and θ _D2 = 3.96 °; the corresponding values of the half angle of convergence are α _D1 = 11.04 ° and α _D2 = 18.96 °, and Δα _D = 7.92 °.

The full stroke of the linear displacement W _DΣ in the matching mechanism in FIG. 4 can be found by formula (17); in it, W _DΣ = W _D2 -W _D1 , ΔQ _D = Q _D2 -Q _D1 and Δα _D = α _D2 -α _D1 = θ _D2 -θ _D1 . If the zz axis is removed from the input surface C ₁ C ₄ (see Fig. 3) by a distance T = 35 mm, then the required linear travel is W _DΣ = 19.83 mm. The extreme positions of linear displacement, limiting the segment of the zz axis, within which the source 1 is shifted, are calculated by the formula (30): W _D1 = θ _D1 R / η and W _D2 = θ _D2 R / η, so that the ratio of the remaining two parameters of the mechanism is obtained coordination:

As a result, when the angle of inclination η = 8 ° of the guide 23 is equal to that in the inventive two-beam interferometer according to the first embodiment, the length of the arm of the lever 22 is half as much: R = 20 mm.

The discrepancy between the mutually linked dependences Q _W (θ) and Q (θ) is determined by the displacement δL of the center of symmetry О of the interference pattern relative to the photosensitive element 8 according to (18). Obviously, at the anchor points considered above, δL = 0. To maintain a high contrast of the interference pattern, this displacement should be small in comparison with its length S along the plane of symmetry expressed by formula (19). The smallness of the displacement δL is estimated using the displacement coefficient k _s defined by formula (19) and modulo not exceeding 1: | k _s | ≤1.

The diagram in FIG. 5 shows the dependence k _s (θ) 28 for both variants of the inventive two-beam interferometer. Labels at the lowest value of the angle of incidence 29 θ _D1 = -3.96 ° and at the highest value of the angle of incidence 30 θ _D2 = 3.96 ° limit the allowable interval of variation of the angle of incidence, and the lowest level of the displacement coefficient 31 k _s ≈ -0.0023 and the highest level of the bias coefficient 32 k _s ≈0.0023 is determined by the segment within which the center of symmetry O is shifted relative to the photosensitive element 8 during the adjustment of the convergence angle, the offset δL does not go beyond the interval from -0.15 to 0.15 mm. Such small displacements practically do not affect the contrast of the interference pattern.

The law of matching (5) of the angle of incidence θ of the collimated light beam 2 on the input surface with its position on this surface, determined by the distance Q, can be converted into the corresponding law, which relates the angle of incidence χ of the collimated light beam 2 on the beam splitting surface 5 and its position on determined by the distance M. The ratio of the angles χ and ψ is determined from FIG. 3 by formula (22) and, taking into account the law of refraction, by formula (23). The distance B is expressed through variables χ and M by the formula (25), which is derived by solving the triangle FEC ₂ , the sides of which are formed by the distances 6, M and the segment FE of the axial beam of the first partial light beam 16 from point F to point E of its exit on the surface C ₂ C _{3 of the} beam splitting element 4. Formulas (2) and (25) allow you to create a formula (26) that displays the distance M through the parameters of the interferometer: the distance H between the first mirror 6 and the second mirror 7, the tilt angle ξ of these mirrors and the distance L ₀ from the edge With ₂ beam splitting mirrors 5 to the photosensitive element 8, and substituting into the formula (1) the expression for θ from (24), enter the angle χ in (26). Substituting (25) into (3), we can find the dependence of the distance Q on χ and M described by formula (27). Finally, the combination of (7) and (27), taking into account the equality θ = ϕ, gives the desired law that describes the matching of the linear and angular motions of source 1:

where W is the displacement of the axis of rotation 10 of the source 1 relative to the initial position 18, in which M = G / 2, G is the length of the beam splitter mirror 5 along the plane of incidence of the collimated light beam 2, M is the distance from the position F of the axial beam of the collimated light beam 2 on the beam splitting mirror 5 to its edge C ₂ , closest to the photosensitive element 9 and expressed by the formula (26), χ is the angle of incidence of the collimated light beam 2 on the beam splitting mirror 4 and expressed by the formula (23), T is the distance from the rotation axis 10 to the input superficially of the beam splitting element 4, ϕ is the angle of rotation of the axis of rotation 10 of the source 1 relative to the initial position 18, in which χ = 45 °.

The technical effect of the claimed device, which consists in simplifying the adjustment of the interferometer and possibly due to this simplification, increasing the accuracy of the period of the interference pattern, in increasing the productivity of the recording process of one- and multidimensional periodic structures in a photosensitive material; in reducing the sensitivity to vibration, as well as in expanding the arsenal of means for this purpose, it is achieved due to the fact that the matching of the angle of incidence of the collimated light beam on the beam splitting mirror of the beam splitting element with the movement of this beam along this beam splitting mirror, necessary to stabilize the position of the region of mutual overlapping of partial beams on the photosensitive element, provided by the direction of the collimated light beam to the beam splitting element by mutually Harmonization of angular and linear displacements of the axis of rotation under the law of the beam source (29) in accordance with the control signals for matching assembly formed by the control unit.

Claims (10)

1. A two-beam interferometer, which includes a collimated light beam source, a base with a fixed beam splitting element fixed to it with a beam splitting mirror, dividing the collimated light beam into a first partial light beam and a second partial light beam, a first mirror, a second mirror, a photosensitive element, optically coupled to a collimated light beam source, wherein the first mirror and the second mirror are oriented by guides reflected from them by the first a partial light beam and a second partial light beam towards each other until they intersect on the photosensitive element, an angular displacement sensor, a control unit, characterized in that it is additionally equipped with a movable mirror with an axis of rotation, made directing the collimated light beam to the beam splitter mirror element, while the axis of rotation is made providing simultaneous angular movement of the movable mirror, changing the angle of incidence of the collimated about the light beam to the beam splitting mirror of the beam splitting element, and linear movement of the movable mirror, changing the position of the collimated light beam on the beam splitting mirror of the beam splitting element, the matching unit, while the control unit is configured to generate control signals for the matching unit performing angular and linear movements of the axis of rotation, and matching them together, according to the formula

, where W is the linear movement of the axis of rotation relative to the initial position, in which M = G / 2, G is the length of the beam splitting mirror in the plane of incidence of the collimated light beam, M is the distance from the position of the axial beam of the collimated light beam on the beam splitting mirror to its edge, closest to the photosensitive element, X is the angle of incidence of the collimated light beam on the beam splitter mirror, T is the distance from the axis of rotation to the input surface of the beam splitter element, ϕ is the angle of rotation of the axis of rotation relates flax initial position, wherein X = 45 °, and the source of collimated light beam is made fixedly secured to the base. 2. A two-beam interferometer according to claim 1, characterized in that the beam splitting element with a beam splitting mirror is made with output faces of the beam splitting element symmetrical with respect to the plane of this beam splitting mirror. 3. A two-beam interferometer according to claim 1, characterized in that the first mirror and the second mirror are arranged mutually symmetrically with respect to the plane of the beam splitting mirror. 4. A two-beam interferometer, which includes a source of collimated light beam, a base with a fixed beam splitting element fixed to it with a beam splitting mirror, dividing the collimated light beam into the first partial light beam and the second partial light beam, the first mirror, the second mirror, and the photosensitive element, optically coupled to a collimated light beam source, wherein the first mirror and the second mirror are oriented by guides reflected from them by the first the partial light beam and the second partial light beam towards each other until they intersect on the photosensitive element, an angular displacement sensor, a control unit, characterized in that it is additionally equipped with a rotation axis, which provides simultaneous angular movement of the source, changing the angle of incidence of the collimated light beam to the beam splitting mirror of the beam splitting element, and linear movement of the source, changing the position of the collimated light beam by the beam splitting mirror of the beam splitting element, the matching unit, while the control unit is configured to generate control signals for the matching unit performing angular and linear movements of the axis of rotation, and matching them together, according to the formula

, where W is the displacement of the axis of rotation relative to the initial position, in which M = G / 2, G is the length of the beam splitting mirror in the plane of incidence of the collimated light beam, M is the distance from the position of the axial beam of the collimated light beam on the beam splitting mirror to its edge, near to the photosensitive element, X is the angle of incidence of the collimated light beam on the beam splitter mirror, T is the distance from the axis of rotation to the input surface of the beam splitter element, ϕ is the angle of rotation of the axis of rotation relative to the initial th position in which X = 45 °. 5. A two-beam interferometer according to claim 4, characterized in that the beam splitting element with a beam splitting mirror is made with output faces of the beam splitting element symmetrical with respect to the plane of this beam splitting mirror. 6. A two-beam interferometer according to claim 4, characterized in that the first mirror and the second mirror are arranged mutually symmetrically with respect to the plane of the beam splitting mirror.

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