RU2790198C1 - Optical system for shaping and guidance of a laser radiation beam - Google Patents

Abstract

FIELD: laser technology.

SUBSTANCE: optical system includes a laser fibre module with a fibre-optic terminal including optic fibre. At the output of the optical system, a beam reflected from a secondary mirror is incident on the main optical mirror structurally linked with a pre-guidance apparatus, from the reflecting surface whereof, made in a concave off-axis parabolic shape with a focus F of a complete parabola, a low-divergence laser beam incident on the image plane exits. The output optical axis is parallel to the central optical axis of the rectilinear optical fibre segment distanced from the axis of the complete parabola. The emitting end of the fibre optic terminal core is distanced by L from the point of intersection of the central optical axis with the reflecting plane of the secondary mirror. An additional secondary mirror is added. The main optical mirror is structurally linked with a scanning apparatus.

EFFECT: creation of a compact telescopic optical system based on fibre lasers and increase in the directivity of the created beam due to the increase in the accuracy of adjustment and scanning.

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Description

The invention relates to the field of creating systems for remote transmission of laser radiation energy to air and space objects and laser location guidance systems with high accuracy of a laser channel for transmitting energy to a receiver-converter based on semiconductor photoelectric converters (PVC) for converting electromagnetic energy of high-density laser radiation. The areas of application of such a transformation are wireless systems for remote power supply of air or space objects [V.A. Griliches, P.P. Orlov, L.B. Popov. Solar energy and space flights. M.: Nauka, 1984, p. 199].

In space technology, a number of new directions based on the use of laser radiation have been determined. Among them, a very promising direction should be considered the transfer of energy to spacecraft (SC) using laser power transmission systems (LTTS) based on high-power fiber lasers, followed by conversion into electricity in receiver-converters. Fiber lasers, which are currently being intensively developed, combine the properties of radiation generators themselves (laser diodes), radiation amplifiers, and high-performance optical fibers [V.I. Kishko, V.F. Matyukhin. Principles of constructing adaptive repeaters for stratospheric power transmission systems // Avtometriya. 2012. V. 48, No. 2, p. 59-66].

Currently, each spacecraft is equipped with its own power generation system. However, there is an alternative method of energy supply, which involves the use of centralized power plants and the transfer of energy to consumer spacecraft using electromagnetic radiation (EMR). For example, the transfer of energy using a laser between an orbital space station, which has an optical-mechanical system for forming and guiding a laser beam, and a spacecraft, which has a photodetector of an optical-electronic converter. In this case, it is possible to implement a centralized power supply scheme for both individual spacecraft and their groups, which expands their functionality and increases their resource.

Compared to other radiation sources, lasers have the highest degree of coherence. This property of lasers is used in optical systems for transmitting and receiving information and in other cases. The use of lasers as radiation sources requires the development of optical systems that serve to convert laser radiation. With the help of such systems, the following problems can be solved: concentration of laser radiation into a small spot (focusing); conversion of a laser beam into a beam with a small angle of divergence (collimation); formation of a laser beam into a beam with the necessary parameters for matching with the subsequent optical system (matching) [N.P. Zakaznov, S.I. Kiryushin, V.N. Kuzichev. Theory of optical systems. 3rd ed. M: Mashinostroenie, 1992. p. 318-319]. To successfully implement the transmission of laser radiation to a consumer object, it is necessary to create an optical system that effectively forms a narrowly directed laser beam in order to concentrate laser radiation on a remote photodetector.

Known laser-optical system for the formation of high-power laser beams on long paths with specified characteristics.

So in the invention proposed in [Patent No. 2117322. Published 08/10/1998. G02B 27/48 (2006.01)] shows a device for forming light beams. The device contains a source of coherent optical radiation and a concave main mirror, a wavefront conjugation device with a beam splitter at the input, and two auxiliary optical systems that ensure self-projection of the main mirror onto itself. The main mirror and elements of both auxiliary systems are located coaxially. The beam splitter is made in the form of a translucent mirror deposited on the surface of the lens element of one of the auxiliary systems. The first auxiliary system can be made in the form of a concave mirror, a lens component and a meniscus facing the main mirror with its convex surface. It should be noted that auxiliary optical systems must have a high optical quality. When using the proposed optical system as a collimator, a significant disadvantage is that the auxiliary systems contain a large number of optical surfaces, the errors of which affect the accuracy of the formed wave front.

соответственно. Причем главная оптическая ось асферической линзы перпендикулярна плоскости торца сердцевины соответствующего оптоволоконного вывода и проходит через его центр, размещенный в переднем фокусе f_a. Сумматор единичных лазерных пучков состоит из n светоделительных элементов, выполненных в виде дихроичных пластин, через геометрический центр каждой из которых проходит под углом 45° главная оптическая ось соответствующей асферической линзы коллиматора. Главные оптические оси асферических линз параллельны и лежат в одной плоскости, а упомянутые дихроичные пластины установлены параллельно между собой так, что через их геометрические центры под углом 45° проходит главная оптическая ось подвижной линзы перпендикулярная главным оптическим осям асферических линз. При этом подвижная линза установлена на микропозиционере трехкоординатного блока сканирования и выполнена асферической, с передним и задним фокусными расстояниями f_c и

, соответственно. Главная оптическая ось подвижной линзы проходит через фокус F зеркала через его геометрический центр, через который проходит оптическая ось параболического зеркала, параллельная или совпадающая с оптической осью его полной параболы. При этом упомянутый фокус F совпадает с задним фокусом

подвижной линзы. Одним из основных недостатков данной оптической системы формирования и наведения лазерного излучения является конструктивное исполнение ЛСПЭ для формирования результирующего лазерного пучка. В данном техническом предложении рассматриваемая конструкция устройства основана на пространственном некогерентном сложении отдельных излучателей и не позволяет получать на выходе пучки дифракционного качества с постоянным однородным и неизменным распределением плотности мощности по сечению пучка на протяженных трассах. Другим недостатком предложенного устройства, затрудняющим его эксплуатацию, является то, что оптическая система содержат большое количество оптических поверхностей, погрешности которых сказываются на точности формируемого волнового фронта.In the invention proposed in [Patent RU 2663121, published 08/07/2018, bul. No. 22, IPC: G01S 17/88 (2006.01), F41G 3/22 (2006.01)] an optical system for the formation and guidance of laser radiation is considered, which includes: a transmitting laser complex of n-laser modules, each of which contains a fiber optic output with a core , the end of the core of which is a source of radiation that creates a single laser beam; beam-splitting element; a three-coordinate scanning element made in the form of a movable lens. At the output of the optical system, the total laser beam of rays falls on a concave parabolic mirror, which is structurally connected with the "coarse" pointing device, and is reflected in the form of a low-divergent beam of rays. The optical system includes n collimators, an adder of single laser beams and a three-coordinate scanning unit, and each i-th laser module, where i=1, 2, ... n, is equipped with a fiber optic output with a numerical aperture NA _i and a core diameter d _i , from the end the core of which the divergent laser beam enters the mentioned i-th collimator on the aspherical lens contained in it with front and rear focal lengths f _a and

respectively. Moreover, the main optical axis of the aspherical lens is perpendicular to the plane of the end face of the core of the corresponding fiber optic output and passes through its center, located in the front focus f _a . The summator of single laser beams consists of n beam-splitting elements made in the form of dichroic plates, through the geometric center of each of which the main optical axis of the corresponding aspherical lens of the collimator passes at an angle of 45°. The main optical axes of the aspherical lenses are parallel and lie in the same plane, and the mentioned dichroic plates are installed parallel to each other so that the main optical axis of the movable lens passes through their geometric centers at an angle of 45° and is perpendicular to the main optical axes of the aspherical lenses. At the same time, the movable lens is installed on the micropositioner of the three-coordinate scanning unit and is made aspherical, with front and rear focal lengths f _c and

, respectively. The main optical axis of the movable lens passes through the focus F of the mirror through its geometric center, through which the optical axis of the parabolic mirror passes, parallel or coinciding with the optical axis of its full parabola. In this case, the mentioned focus F coincides with the back focus

moving lens. One of the main disadvantages of this optical system for the formation and guidance of laser radiation is the design of the LSPE for the formation of the resulting laser beam. In this technical proposal, the design of the device under consideration is based on the spatial incoherent addition of individual emitters and does not allow obtaining beams of diffraction quality at the output with a constant uniform and unchanged power density distribution over the beam cross section along long paths. Another disadvantage of the proposed device, which complicates its operation, is that the optical system contains a large number of optical surfaces, the errors of which affect the accuracy of the formed wave front.

The closest technical solution adopted for the prototype is the optical system for the formation and guidance of the laser beam, discussed in [Patent No. 2715083, publ. 25.02.2020, bul. No. 6, IPC: G02B 27/09 (2006.01), G02B 17/06 (2006.01), G01S 7/481 (2006.01); SPK: G02B 27/0977 (2019.08), G02B 17/0621 (2019.08), G01S 7/4814 (2019.08)] and including a laser fiber module with a fiber optic output, including an optical fiber consisting of an optical cladding containing a core, through the radiating end of which with a numerical aperture NA, a beam with a central beam exits, and at the exit from the optical system, the beam reflected from the reflecting plane of the secondary mirror, with a central axis, falls on the main optical mirror, which is structurally connected with the "coarse" pointing device, from the reflecting surface of which, made concave off-axis parabolic with a focus F of a full parabola, a low-divergent laser beam comes out incident on the image plane, and the previously mentioned central axis of the beam coincides with the focal radius vector of a point on the full parabola, the output optical axis of the beam passes through this point, coinciding with the diameter of the full parabola, in this case, the diameter forms, at the intersection with the tangent plane to the reflecting its surface at this point, angle β, and the reflecting plane of the secondary mirror is parallel to the tangent plane, while the output optical axis is parallel to the central optical axis of the rectilinear segment of the fiber, spaced from the axis of the full parabola at a distance h, and the emitting end of the core of the fiber optic output is spaced at a distance L from the point of intersection of the central optical axis with the reflective plane of the secondary mirror, which forms an angle β ₁ at the intersection, where β ₁ =β. It should be noted that the proposed layout of the optical system does not allow to more effectively solve the problem of further improving the image quality, increasing the optical characteristics and improving the design of optical devices, reducing their size and weight, and achieving compactness.

The objective of the invention is to improve the design of the optical system for the formation and guidance of the laser beam. The technical result of the invention are:

- creation of a compact optical system of a telescopic type for remote transmission of laser radiation energy based on fiber lasers;

increasing the directivity of the generated laser radiation beam by increasing the accuracy of alignment and scanning.

The technical result is achieved by the fact that the optical system for the formation and guidance of a laser beam, including a laser fiber module with a fiber optic output, including an optical fiber, consisting of an optical sheath with a diameter of δ _O , enclosing a core with a diameter of δ _C , through the radiating end of which with a numerical aperture NA the beam exits with a central beam, and at the exit from the optical system, the beam reflected from the reflecting plane of the secondary mirror, with a central axis, falls on the main optical mirror, structurally connected with the "coarse" pointing device, from the reflecting surface of which, made of a concave off-axis parabolic with focus F of a full parabola, a low-divergent laser beam comes out incident on the image plane, and the previously mentioned central axis of the beam coincides with the focal radius vector of a point on the full parabola, the output optical axis of the beam passes through this point, coinciding with the diameter of the full parabola, while dia the meter forms, at the intersection with the tangent plane to the reflecting surface at this point, the angle β, and the reflecting plane of the secondary mirror is parallel to the tangent plane, while the output optical axis is parallel to the central optical axis of the rectilinear segment of the fiber, spaced from the axis of the full parabola at a distance h, and the radiating end of the core of the fiber optic output is spaced at a distance L from the point of intersection of the central optical axis with the reflective plane of the secondary mirror, which forms an angle β ₁ when crossing, where β ₁ =β, while an additional secondary mirror is introduced, with a reflective plane, located in the beam expander unit with a mechanism for moving along the central optical axis, while the reflecting plane is made in the form of a circle, with a diameter of d ₂ , perpendicular to the central optical axis passing through its geometric center, spaced at a distance L ₁ from the point of intersection of the central optical axis with the reflecting plane of the secondary mirrors, as well as a block connector, which consists of a secondary mirror and an optical connector with a thermal control system, the secondary mirror is made in the form of a truncated circular cylinder, with a diameter d ₁ , with a beveled plane forming the reflective plane of the secondary mirror, inside which the through channel, with the axis coinciding with the axis of the truncated circular cylinder of the secondary mirror and with the central optical axis, with an optical connector enclosed in it, terminating the fiber optic output, which includes a straight cable segment fixed in the optical connector, straight segments of the buffer shell and an open fiber optic segment fixed in bushing axisymmetrically placed in the optical connector, and a segment of the buffer shell with an outer diameter d _B is fixed by a bushing, with an inner diameter d _B and an outer diameter D _B , where d _B =d _B , and in the end part of the bushing, made in the form of a truncated straight cone, with base diameter d _K \u003d D _B , with a base diameter of the truncated part δ _K and with an angle β ₂ <β ₁ between the generatrix of the cone and height, in its axisymmetric channel, with an axis coinciding with the central optical axis, with a diameter δ _B \u003d δ _O -δ _K , an open segment of the optical fiber is fixed, and the base of the truncated part of the straight cone of the end part of the sleeve, the end of the optical shell, the emitting end, through which the radiation beam exits to the additional secondary mirror, lie in one plane passing perpendicular to the central optical axis through the point of intersection of it with the reflecting plane secondary mirror, while the main optical mirror is structurally connected with the scanning device, and the parameters of the optical system correspond to the following relations:

а

- минимально допустимое расстояние, при выбранном h, отражающей плоскости дополнительного вторичного зеркала от точки пересечения центральной оптической оси с отражающей плоскостью вторичного зеркала;Where

A

- the minimum allowable distance, for a selected h, of the reflecting plane of the additional secondary mirror from the point of intersection of the central optical axis with the reflecting plane of the secondary mirror;

α is the angle between the central optical axis of the straight fiber segment and one of the limiting aperture beams that form a light cone at the exit from the core;

P is the focal parameter of a complete parabola formed by the intersection of the YOX plane with a paraboloid of revolution with the coordinate axis OX and forming a concave reflective surface of the main optical mirror;

D _lp is the diameter of the laser beam at the output of the optical system.

The essence of the invention is illustrated in Fig. 1-4, where the following designations are accepted:

1 - laser fiber module;

2 - fiber optic output;

3 - optical fiber (rectilinear segment of optical fiber);

4 - optical fiber cladding 3;

5 - fiber core 3;

6 - radiating end of the core 5 of the optical fiber 3;

7 - the central beam of the beam emerging through the radiating end 6;

8 - reflecting plane of the secondary mirror 9;

9 - secondary mirror (in the form of a truncated circular cylinder);

10 is the central axis of the beam reflected from the secondary mirror 9;

11 - main optical mirror;

12 - reflective surface of the main optical mirror 11;

13 - complete parabola;

14 - image plane;

15 - output optical axis;

16 - diameter of the full parabola 13;

17 - tangent plane to the reflecting surface 12 of the main optical mirror 11 (tangent to the full parabola 13);

18 - the Central optical axis of the rectilinear segment of the optical fiber 3;

19 - axis of the complete parabola 13;

20 - additional secondary mirror;

21 - reflecting plane of the additional secondary mirror 20;

22 - beam expander block;

23 - mechanism for moving the additional secondary mirror 20;

24 - block connector;

25 - optical connector of fiber optic output 2;

26 - thermal control system of the optical connector 25;

27 - through channel in the secondary mirror 9;

28 - axis of the through channel 27, made in the secondary mirror 9;

29 - axis of the secondary mirror, made in the form of a truncated circular cylinder;

30 - piece of fiber-optic output cable 2;

31 - segment of the buffer shell;

32 - open piece of fiber 3

33 - sleeve;

34 - axisymmetric channel in the end part of the sleeve 33;

35 - axis of the axisymmetric channel 34;

36 - the plane of placement of the base of the truncated part of the straight cone of the end part of the sleeve 33, the end of the optical shell 4 and the radiating end 6;

37 - scanning device;

38, 39 - extreme rays reflected from the reflecting plane 8 of the secondary mirror 9;

40, 41 - extreme rays reflected from the reflective surface 12 of the main optical mirror 11;

42, 43 - limiting aperture rays of the beam emerging through the radiating end 6;

44, 45 - extreme rays reflected from the reflecting plane 21 of the additional secondary mirror 20.

In FIG. Figure 1 shows a schematic diagram of the optical system for the formation and guidance of a laser beam. In FIG. 1 marked: F focus of the full parabola 13; points M, M ₁ , M ₂ focal radius vectors at these points on the complete parabola 13; d ₁ - diameter of the reflecting plane 8 of the secondary mirror 9; d ₂ - diameter of the reflecting plane 21 of the additional secondary mirror 20; D _lp is the diameter of the laser beam at the output of the optical system; α is the angle between the central optical axis 18 of the rectilinear segment of the optical fiber 3 and the limiting aperture beam 42, 43, forming a light cone at the exit from the core 5; β is the angle formed at the intersection of the diameter 16 of the full parabola 13 with the tangent plane 17 to the reflecting surface 12 of the main optical mirror 11 in the YOX plane; β ₁ - the angle formed at the intersection of the Central optical axis 18 with the reflective plane 8 of the secondary mirror 9 in the YOX plane; x ₀ , y ₀ , x ₁ , y ₁ , x ₂ , y ₂ - coordinates of the points M, M ₁ , M ₂ , respectively, on the complete parabola 13 in the YOX plane; M ₃ - point, with coordinates x ₃ , y ₃ , the intersection of the Central optical axis 18 with the reflective plane 8 of the secondary mirror 9 in the YOX plane; L ₁ - distance from the reflective plane 21 of the additional secondary mirror 20 to the point of intersection of the central optical axis 18 with the reflective plane 8 of the secondary mirror 9; X, Y, Z - coordinates of the position of the elements of the optical system; O - origin and vertex of the complete parabola 13; h is the distance of the Central optical axis 18 of the straight segment of the optical fiber 3 from the axis 19 of the complete parabola 13; T is the point of intersection with the OX axis of the tangent plane 17 to the reflecting surface 12 of the main optical mirror 11 in the YOX plane, t is the point of intersection of the vertical passing through the point M3 with the X axis. m is the point of intersection with the OY axis of the continuation of the focal radius vector of the point M of the full parabolas 13; x _D - point of intersection of the focal radius vector of the point M ₂ with the straight line y=h+d ₂ /2 in the YOX plane. View A is shown in Fig. 2.

In FIG. 2, view A shows a section of the block connector 24, including a secondary mirror 9, made in the form of a truncated circular cylinder, with an axis 28 coinciding with the central optical axis 18, with a beveled plane forming a reflective plane 8 of the secondary mirror 9, and an optical connector 25 terminating fiber optic lead 2. FIG. 2 denoted by: α - angle between the central optical axis 18 of the rectilinear segment of the optical fiber 3 and the maximum aperture beam 42 or 43, forming a light cone at the exit from the core 5; β is the angle formed at the intersection of the central optical axis 18 with the reflecting plane 8 of the secondary mirror 9 in the YOX plane.

In FIG. 3 partially shows the block connector 24 and the secondary mirror 9, inside which a through channel 27 is made axisymmetrically, with the axis 28 coinciding with the axis 29 of the truncated circular cylinder of the secondary mirror 9 and with the central optical axis 18. FIG. 3 marked: d _B - outer diameter of the segment of the buffer shell 31; d _B - inner diameter of the sleeve 33; δ _B is the diameter of the axisymmetric channel 34 in the end part of the sleeve 33; δ _C , δ _O are the diameters of the core 5 and the optical sheath 4, respectively, of the rectilinear segment of the optical fiber 3; D _B - outer diameter of the sleeve 33; D _K - diameter of the base of a truncated straight cone in the end part of the sleeve 33, where D _K =D _B ; δ _K - diameter of the base of the truncated part of the truncated straight cone in the end part of the sleeve 33, where δ _K =δ _B =δ _O ; view B is shown in Fig. 4.

In FIG. 4 (view B) partially shows the secondary mirror 9, in which the through channel 27 is axisymmetrically made with the axis 28 coinciding with the axis 29 of the truncated circular cylinder of the secondary mirror 9, inside which the end part of the sleeve 33 is partially shown, made in the form of a truncated right cone. In its axisymmetric channel 34, with axis 35 coinciding with the central optical axis 18, an open segment 32 of fiber 3 is fixed. lie in one plane 36 passing perpendicular to the central optical axis 18 through the point of its intersection with the reflecting plane 8 of the secondary mirror 9. In FIG. 4 marked: M ₃ - the point of intersection of the Central optical axis 18 with the reflecting plane 8 of the secondary mirror 9; S* - point source of light; S - imaginary image of the point S*; r is the distance from the point S to the radiating end 6; δ _B is the diameter of the axisymmetric channel 34 in the end part of the sleeve 33; δ _C , δ _O are the diameters of the core 5 and the optical shell 4, respectively, of the rectilinear segment of the optical fiber 3; δ _K - diameter of the base of the truncated part of the truncated straight cone in the end part of the sleeve 33, where δ _K =δ _B =δ _O ; β ₁ - the angle formed at the intersection of the Central optical axis 18 with the reflective plane 8 of the secondary mirror 9 in the YOX plane; β ₂ - the angle between the height and generatrix of the truncated straight cone of the end part of the sleeve 33, where β ₂ <β ₁ ; α is the angle between the central optical axis 18 of the rectilinear segment of the optical fiber 3 and one of the limiting aperture beams 42 or 43, forming a light cone at the exit from the core 5; L is the distance from the emitting end 6 of the core 5 of the fiber optic lead 2 to the point of intersection of the central optical axis 18 with the reflecting plane 8 of the secondary mirror 9.

An optical system for the formation and guidance of a laser beam, including a laser fiber module 1 with a fiber optic output 2, including an optical fiber 3, consisting of an optical cladding 4 with a diameter of 80, enclosing a core 5 with a diameter of bs, through the emitting end 6 of which with a numerical aperture NA a beam with a central beam 7, and at the output of the optical system, the beam reflected from the reflecting plane 8 of the secondary mirror 9, with a central axis 10, falls on the main optical mirror 11, which is structurally connected with the "coarse" pointing device, from the reflecting surface 12 of which, made by a concave off-axis parabolic with focus F of the full parabola 13, a low-divergent laser beam comes out incident on the image plane 14. Moreover, the previously mentioned central axis 10 of the beam coincides with the focal radius vector of the point on the full parabola 13, the output optical axis 15 of the beam passes through this point, coinciding with the diameter 16 of the complete parabola 13. In this case, di meter 16 forms, at the intersection with the tangent plane 17 to the reflecting surface 12 at this point, the angle P, and the reflecting plane 8 of the secondary mirror 9 is parallel to the tangent plane 17. In this case, the output optical axis 15 is parallel to the central optical axis 18 of the rectilinear segment of the optical fiber 3, spaced from the axis 19 of the full parabola 13 at a distance h. Moreover, the radiating end 6 of the core 5 of the fiber optic output 2 is spaced at a distance L from the point of intersection of the central optical axis 18 with the reflective plane 8 of the secondary mirror 9, which forms an angle β ₁ at the intersection, where β ₁ =β. At the same time, an additional secondary mirror 20 is introduced into the optical system, with a reflecting plane 21, placed in the beam expander block 22 with a mechanism for moving 23 along the central optical axis 18. In this case, the reflecting plane 21 is made in the form of a circle, with a diameter d ₂ , perpendicular to the central optical axis 18 passing through its geometric center is spaced at a distance L ₁ from the point of intersection of the central optical axis 18 with the reflecting plane 8 of the secondary mirror 9. The optical system also includes a block connector 24, which consists of a secondary mirror 9 and an optical connector 25 with the system thermal control 26. Moreover, the secondary mirror 9 is made in the form of a truncated circular cylinder, with a diameter d ₁ , with a beveled plane forming a reflective plane 8 of the secondary mirror 9, inside which a through channel 27 is axisymmetrically made, with axis 28 coinciding with the axis 29 of the truncated circular cylinder of the secondary mirror 9 and with the central optical axis 18, with enclosed in it by an optical connector 25 terminating the fiber optic output 2, which includes a straight segment of the cable 30, fixed in the optical connector 25, straight segments of the buffer shell 31 and an open segment 32 of the fiber 3, fixed in the sleeve 33 axisymmetrically placed in the optical connector 25. Moreover, the segment of the buffer shell 31 with outer diameter d _B is fixed by sleeve 33, with inner diameter d _B and outer diameter D _B , where d _B =d _B . And in the end part of the sleeve 33, made in the form of a truncated straight cone, with a base diameter D _K =D _B , a base diameter of the truncated part δ _K and with an angle β ₂ <β ₁ between the generatrix of the cone and the height, in its axisymmetric channel 34, with axis 35 coinciding with the central optical axis 18, with a diameter δ _B = δ _O = δ _K , an open segment 32 of the fiber 3 is fixed. the radiation beam onto the additional secondary mirror 20 lie in the same plane 36 passing perpendicular to the central optical axis 18 through the point of intersection with the reflecting plane 8 of the secondary mirror 9. In this case, the main optical mirror 11 is structurally connected with the scanning device 37, and the parameters of the optical system correspond to ratios:

d ₁ =(4 L ₁ ⋅tgα⋅tgβ+δ _C ⋅tgβ+δ _O ⋅tgα)/(tgβ-tgα);

d ₂ =δ _C +2⋅tgα⋅L ₁ +δ _O ⋅tgα⋅ctgβ;

D _lp =P {[l+cos(2β-α)]/sin(2β-α)-[1+cos(2β+α)]/sin(2β+α)};

h/(2 L ₁ +0.5⋅δ _С /tgα+0.5⋅δ _О /tgβ)=sin(l80°-2β),

а

- минимально допустимое расстояние, при выбранном h, отражающей плоскости 21 дополнительного вторичного зеркала 20 от точки пересечения центральной оптической оси 18 с отражающей плоскостью 8 вторичного зеркала 9;Where

A

- the minimum allowable distance, with selected h, the reflecting plane 21 of the additional secondary mirror 20 from the point of intersection of the central optical axis 18 with the reflecting plane 8 of the secondary mirror 9;

α is the angle between the central optical axis 18 of the rectilinear segment of the optical fiber 3 and the limiting aperture beam 42 or 43, forming a light cone at the exit from the core 5;

P is the focal parameter of the complete parabola 13 formed by the intersection of the YOX plane with a paraboloid of revolution with the coordinate axis OX and forming a concave reflective surface 12 of the main optical mirror 11;

D _lp is the diameter of the laser beam at the output of the optical system.

The optical system for the formation and guidance of the laser beam operates as follows. With the help of a special search, tracking and guidance system (PSN) (not shown in Figs. 1-4), search, capture and retention of a laser radiation receiver installed on air or space objects equipped, for example, with photoelectric receiving panels (Fig. 1-4 not shown), converting the coherent electromagnetic radiation generated by the laser fiber module 1 with fiber optic output 2 into electric current. Determining the coordinates of the center and tracking the center of the laser radiation receiver, the PSN system conducts using, for example, reference sources (not shown in Fig. 1-4) and outputs data to the power and control system (SPU) (not shown in Fig. 1-4 ), which generates commands to provide a "rough" pointing of the optical system with the main optical mirror 11, for example, using a turntable (not shown in Fig. 1-4), on which the structure with the main optical mirror 11 is installed. laser beam so that the output optical axis 15 of the beam was directed normally to the geometric center, for example, photovoltaic panels (not shown in Fig. 1-4) of the receiver-converter. To facilitate the detection of the receiver-converter by the commands and signals of the power and control system (SPU) when pointing, for example, corner reflectors (not shown in Fig. 1-4) mounted on the receiver-converter can be used. After capturing and holding the receiver of laser radiation, a signal from the STC sends a control command to supply power to the laser fiber module 1, made in the form of a radiation generator with a certain wavelength λ, with a fiber optic output 2. The fiber optic output 2 is terminated by an optical connector 25, the designs of which are considered , for example, in [Patent No. 2480797. IPC: G02B 6/36 (2006.01) Method and attachment of an optical connector in a fiber laser collimating device. Published 04/27/2013. Bull. #12], [JIK/YLR-Series. User guide. NTO IRE POLYUS, 2015, Optical fiber cable output. Devices with connector, p. 17], [David Bailey, Edwin Wright. Fiber optics. Theory and practice. Section 5.4. Connectors. http://izmer-ls.ru/w/v60.html#:~:text=], [QBH cable for high power fiber lasers from Lightel. https://sphotonics.ru/news/2018/41086/]. The STC, by means of electrical signals and commands, controls the operation of the laser power transmission system (LETS), and also provides power supply and a given thermal regime for the entire system and its components. The laser fiber module 1 generates coherent electromagnetic waves with a radiation wavelength λ, transmitted via fiber optic output 2 to the optical system for the formation and precise guidance of a low-divergent laser beam, with an output optical axis 15 and with extreme beams 40 and 41 reflected from the reflecting surface 12 of the main optical mirror 11 incident on the image plane 14 (Fig. 1), aligning it with the plane of the laser radiation receiver, for example, with panels of photoelectric converters (PVCs). With the beginning of work and during the operation of the laser fiber module 1 from the state diagnostic system (not shown in Fig. 1-4) LSPE, information is sent to the SPU about the state of the elements of the optical system, in particular, on temperature parameters from the thermal control system 26 of the optical connector 25, and issuance of information signals about the readiness, failure or abnormal operation of the optical system for the development and acceptance of control commands. Coherent electromagnetic radiation of the optical range, generated by the laser fiber module 1, propagates through the optical fiber 3, consisting of an optical cladding 4, with a diameter of δ _O , containing a core 5, with a diameter of δ _C , due to the phenomenon of total internal reflection at the interface of dielectric media (the core 5 is optical shell 4). For optical fiber 3, the refractive index n ₁ of the core 5, corresponding to the radiation wavelength λ of the laser fiber module 1, usually has a value slightly larger than the refractive index n ₂ of the optical cladding 4. Therefore, light waves propagating in the core 5 at an angle not exceeding the critical value, undergo total internal reflection from the optical cladding 4. By multiple re-reflections from the optical cladding 4, these waves propagate along the fiber optic terminal 2 and exit the core 5 through the radiating end 6, with a numerical aperture NA, in the form of a conical beam with a central beam 7 into the medium (air or outer space) with a refractive index n ₀ <n ₁ [Special fiber light guides: textbook. allowance / D.B. Shumkova, A.E. Levchenko. - Perm: Publishing House of Perm. nat. research polytechnics, un-ta, 2011, p. 9]. In this case, powerful electromagnetic radiation emanating from the core 5 of the rectilinear segment of the fiber 3, as from a point source S (Fig. 4) of laser radiation on the central optical axis 18 of the core 5 of the fiber 3, falls on the plane of the radiating end 6 of the fiber 3. Electromagnetic waves at the boundary two media (the plane of the radiating end 6), getting from a denser medium (core material 5, with a refractive index n ₁ ) into a less dense one (air or outer space) with a refractive index n ₀ , where n ₁ >n ₀ , experience refraction, caused by the fact that the speeds of wave propagation in these media are different. The continuation of the rays (determining the position of the spherical front of the refracted wave) of the diverging beam intersect at the point S, at a distance r from the radiating end 6, which is an imaginary image of the point S*. A divergent beam of laser radiation, with the central beam of the beam 7 and the angle α between the central optical axis 18 of the rectilinear segment of the fiber 3 and the limiting aperture beam 42 or 43, forming a light cone, leaves the core 5 and falls through the radiating end 6 onto the additional secondary mirror 20. The reflecting plane 21 of the additional secondary mirror 20 is made in the form of a circle with a diameter d ₂ perpendicular to the central optical axis 18 passing through its geometric center. Moreover, an additional secondary mirror 20, with a mechanism for moving it 23 along the central optical axis 18, is located in the beam expander block 22. mirror 20 also divergent spherical front with extreme beams 44, 45 and falls on the reflective plane 8 of the secondary mirror 9, placed in the block connector 24. Moreover, the reflective plane 21 of the additional secondary mirror 20 is spaced at a distance L ₁ from the intersection point of the central optical axis 18 with the reflecting plane 8 of the secondary mirror 9. Further, the beam is reflected from the reflecting plane 8 of the secondary mirror 9, with the central axis 10 and the extreme rays 38, 39, and falls on the main optical mirror 11, which is structurally connected with the "coarse" pointing device (not shown in the figures). shown). At the output of the optical system from the reflecting surface 12 of the main optical mirror 11, made of a concave off-axis parabolic full parabola 13 with focus F, a low-divergent laser beam emerges, with an output optical axis 15 and extreme beams 40, 41, and falls on the image plane 14. Moreover, in the considered optical system, mentioned earlier, the central axis 10 of the beam coincides with the focal radius vector of a point on the full parabola 13. Through this point, the output optical axis 15 of the beam passes, coinciding with the diameter 16 of the full parabola 13. In this case, the diameter 16 forms, at the intersection with a tangent plane 17 to the reflecting surface 12 at this point, angle β, and the reflecting plane 8 of the secondary mirror 9 is installed in the optical system parallel to the tangent plane 17. In this case, the output optical axis 15 is parallel to the central optical axis 18 of the rectilinear segment of the optical fiber 3, spaced from the axis 19 full parabola 13 at a distance h, and radiating th end 6 of the core 5 of the fiber optic output 2 is spaced at a distance L from the point of intersection of the central optical axis 18 with the reflective plane 8 of the secondary mirror 9, which forms an angle β ₁ at the intersection, where β ₁ =β. The block connector 24 consists of a secondary mirror 9 and an optical connector 25 with a thermal control system 26. Moreover, the secondary mirror 9 is made in the form of a truncated circular cylinder, with a diameter d ₁ with a beveled plane forming a reflective plane 8 of the secondary mirror 9, inside which a through channel is made axisymmetrically 27, with axis 28 coinciding with axis 29 of the truncated circular cylinder of the secondary mirror 9 and with the central optical axis 18, with an optical connector 25 enclosed in it, terminating the fiber optic output 2. The fiber optic output 2 includes a straight piece of cable 30 fixed in the optical connector 25, and rectilinear segments of the buffer shell 31 and an open segment 32 of the optical fiber 3, fixed in the sleeve 33 axisymmetrically placed in the optical connector 25. Moreover, the segment of the buffer shell 31 with an outer diameter dB is fixed by the sleeve 33, with an inner diameter d _B and an outer diameter D _B , where d _B \u003d d _B , and in the end part of the sleeve 33, made in the de truncated right cone, with a base diameter D _K =D _B , a base diameter of the truncated part δ _K and with an angle β ₂ <β ₁ between the generatrix of the cone and the height, in its axisymmetric channel 34, with the axis 35 coinciding with the central optical axis 18, with a diameter δ _B = δ _O = δ _K , an open segment 32 of the optical fiber 3 is fixed. secondary mirror 20, lay in the same plane 36 passing perpendicular to the central optical axis 18 through the point of intersection with the reflecting plane 8 of the secondary mirror 9. the image of the point S, after reflection from the parabolic reflecting surface 12 of the main optical mirror 11 are parallel to each other the circles with the extreme beams 40, 41 and the output optical axis 15 of the beam do not intersect or, as they say, intersect at infinity. After "rough" pointing, precise pointing of a low-divergent laser beam is performed, combining the image plane 14 with the plane, for example, of photovoltaic panels of the receiver-converter by internal displacement of radiation in the considered optical system for forming and pointing the laser beam. The image plane 14 can be made in the form of a receiver-converter, where laser radiation can be efficiently converted into electricity using photoelectric converters (PVCs) based on semiconductor heterostructures [V.A. Griliches, P.P. Orlov, L.B. Popov. Solar energy and space flights. M: Nauka, 1984, p. 110]. By controlling the deviation of the beam at the output of the optical system from the initial (zero) position, the low-divergent laser beam is precisely aimed, i.e. focusing and scanning in the image plane 14, according to commands and control signals from the STC system, coming respectively to the beam expander unit 22 and the scanning device 37, with which the main optical mirror 11 is structurally connected. Using the mechanism for moving the reflecting plane 23 23 of the additional secondary mirror 20 along the central optical axis 18 (along the X coordinate), the image of the object, which is the luminous point S, is focused in the image plane 14. The SPU ensures the operation of the movement mechanism 23 and controls the position of the reflecting plane 21 of the additional secondary mirror 20 using the built-in movement mechanism 23 displacement sensors (not shown in Figs. 1-4). Moreover, the movement mechanism 23 can be made on the basis of a precision stepping single-coordinate piezo positioner, including software that allows you to manage and control the main parameters of the movement of the piezo positioner [Piezo positioner for nanofocusing. http://www.eurotek-general.com], [Linear piezo platforms. http://www.innfocus.ru/ru/catalog/photonics_c/pozicionery/physik-instrumente-pi/lineinye-pezoplatformy/]. The main optical mirror 11 is structurally connected with the scanning device 37 and can be performed, for example, on the basis of a motorized two-axis kinematic piezoelectric nanopositioner [Motorized two-axis (XY) kinematic piezoelectric nanopositioner QNP2-100-XYA, http://www.phcloud.ru, manufacturer: Aerotech, Inc.]. Using the scanning device 37, which includes a movable piezoelectric platform with the main optical mirror 11, the platform is tilted along the angles ϕz and ϕy, as shown in Fig. 1. Thus, the one-coordinate movement (X) of the reflecting plane 21 in the beam expander block 22 and the movement of the movable main optical mirror 11 in two transverse directions (Z, Y) allow, respectively, accurate focusing and scanning of a low-divergent laser beam in the image plane 14. When In this case, the parameters of the optical system correspond to the relations:

d ₁ =(4 L ₁ ⋅tgα⋅tgβ+δ _C ⋅tgβ+δ _O ⋅tgα)/(tgβ-tgα);

d ₂ =δ _C +2⋅tgα⋅L ₁ +δ _O ⋅tgα⋅ctgβ;

D _lp =P {[1+cos(2β-α)]/sin(2β-α)-[1+cos(2β+α)]/sin(2β+α)};

h/(2 L ₁ +0.5⋅δ _С /tgα+0.5⋅δ _О /tgβ)=sin(l80°-2β),

а

- минимально допустимое расстояние, при выбранном h, отражающей плоскости 21 дополнительного вторичного зеркала 20 от точки пересечения центральной оптической оси 18 с отражающей плоскостью 8 вторичного зеркала 9;Where

A

- the minimum allowable distance, with selected h, the reflecting plane 21 of the additional secondary mirror 20 from the point of intersection of the central optical axis 18 with the reflecting plane 8 of the secondary mirror 9;

α is the angle between the central optical axis 18 of the rectilinear segment of the optical fiber 3 and the limiting aperture beam 42 or 43, forming a light cone at the exit from the core 5;

P is the focal parameter of the complete parabola 13 formed by the intersection of the YOX plane with a paraboloid of revolution with the coordinate axis OX and forming a concave reflective surface 12 of the main optical mirror 11;

D _lp is the diameter of the laser beam at the output of the optical system.

Let us give a calculation example of the design of an optical system for the formation and guidance of a laser beam, based on high-power fiber lasers that combine the properties of the radiation generators themselves (laser diodes), radiation amplifiers and high-performance optical fibers.

It should be noted that this technical solution considers an off-axis optical scheme with three power components, three mirrors and an off-axis beam path. Namely, an off-axis aspherical mirror is used, in the form of a paraboloid of revolution - the main mirror 11, and two flat mirrors - a deflecting secondary mirror 9 and an additional secondary mirror 20. Mirror schemes provide diffractive image quality and do not introduce chromatic aberrations. In addition, the advantage of mirrors, in comparison with prisms and lenses, is: less weight, simplicity of design, lower value of introduced aberrations (including the absence of chromatism in mirrors with external reflection), the exclusion of requirements for a number of quality indicators of the material of mirrors with external reflection, as well as the possibility of creating large mirrors [S.M. Latiev. Designing precise (optical) instruments. Chapter 8, paragraph 8.4. MIRRORS, p. 354-364, https://ozlib.com/813864/tehnika/zerkala]. The use of non-spherical surfaces in optical systems makes it possible to more effectively solve the problem of further improving image quality, increasing optical characteristics and improving the design of optical devices, reducing their size and weight, and achieving compactness. It is known, for example, that a parabolic mirror forms a near-ideal image of an infinitely distant axial point [N.P. Zakaznov, S.I. Kiryushin, V.N. Kuzichev. Theory of optical systems. 3rd ed. M.: Mashinostroenie, 1992, p. 357]. Moreover, as can be seen from Fig. 1, the proposed technical solution considers the off-axis placement of mirrors - the optical scheme of a brachite. The positive qualities of brachites include the absence of shielding, which has a positive effect on the clarity and contrast of the image [Chapter Four. COMPLEX TELESCOPES. http://www.old.astronomer.ru/data/library/books/sikoruk/glava4/4_1.htm], [Reflector (telescope), https://ru.wikipedia.org/wiki/]. Of all types of aspherical reflectors, it is off-axis parabolic mirrors that are devoid of spherical aberrations; therefore, they project a point source to infinity and can be effectively used in devices for expanding a laser beam. In addition, the use of such an optical scheme reduces the size and weight of the optical system, and also allows the use of mirrors of both wedge-shaped and equal-thickness configurations [TYDEX: Off-axis parabolic mirrors http://www.tydexoptics.com/en/products/spectroscopy/oap_mirrors/ ]. For example, we design an optical system including a laser fiber module 1 with a fiber optic output 2 based on a laser module (LM) of the LK-1000 ytterbium fiber laser type, manufacturer IPG Photonics (Russia) [https://www.stankoff.ru/product/11234/ itterbievyiy-volokonnyiy-lazer-lk-1000]. Let us assume that the ytterbium fiber laser generates infrared radiation with a wavelength of λ=1070 nm and is made with a fiber optic output 2, the design of which is discussed, for example, in [Patent No. 2480797. G02B 6/36 (2006.01) Method and assembly for mounting an optical connector in a fiber laser collimator. Published 04/27/2013. Bull. No. 12], [LC/YLR-Series. User guide. NTO IRE POLYUS, 2015, Optical fiber cable output. Devices with connector, p. 17], [David Bailey, Edwin Wright. fiber optics. Theory and practice. Section 5.4. Connectors. http://izmer-ls.ru/w/v60.html#:~:text=]. Let us assume that the fiber optic lead 2 includes a fiber 3 consisting of an optical cladding 4 with a diameter of δ _O =0.125 mm, enclosing a core 5 with a diameter of 5 δ _C =0.02 mm, through the emitting end 6 of which a beam exits with a numerical aperture NA= 0.06. Let us assume that the radiation output is made through the optical connector 25 located in the block connector 24, terminating the fiber optic output 2, as shown in Fig. 1-4. The design of the block connector 24 includes a secondary mirror 9 and an optical connector 25 with a thermal control system 26. The secondary mirror 9 is made in the form of a truncated circular cylinder, with a diameter d ₁ with a beveled plane forming a reflective plane 8 of the secondary mirror 9, inside which a through channel 27 is axisymmetrically made , with the axis 28 coinciding with the axis 29 of the truncated circular cylinder of the secondary mirror 9 and with the central optical axis 18, with the optical connector 25 enclosed in it, ending the straight section of the fiber optic output 2 with the central optical axis 18. The optical connector 25 includes a straight section of the cable 30, fixed in the optical connector 25, and the straight segments of the buffer shell 31 and the open segment 32 of the fiber 3, fixed in the sleeve 33 axisymmetrically placed in the optical connector 25. The optical fiber 3 has an additional protective sheath around the optical sheath 4. The protective sheath, which is one or more polymer layers, one of the layers is a buffer layer (buffer shell), protects the core 5 and the optical cladding 4 from influences that may affect their optical properties, protects the optical fiber 3 from breaks due to surface irregularities; determines the environmental operating conditions of the fiber: temperature range, radiation level, vacuum, chemical exposure and minimum bend radius. The protective sheath does not affect the process of light propagation along the fiber, but only protects against impacts [Special fiber light guides: textbook. allowance / D.B. Shumkova, A.E. Levchenko. - Perm: Publishing House of Perm. nat. research polytechnic un-ta, 2011, p. 58], [Fiber components for Avantes spectrometric measurements, https://in-science.ru/library/article_post/volokonnye-komponenty-dlya-spektrometricheskih-izmerenij-avantes]. Moreover, a segment of the buffer shell 31 with an outer diameter, let's put d _B =6 mm, is fixed by a sleeve 33, with an inner diameter d _B and an outer diameter D _B , let's put D _B = 8 mm, where d _B = d _B = 6 mm, and in the end part of the sleeve 33, made in the form of a truncated straight cone, with a base diameter D _K \u003d D _B \u003d 8 mm, a base diameter of the truncated part δ _K , let's put δ _K \u003d 0.125 mm and with an angle β between the generatrix of the cone and the height, we take β ₂ =45°, in its axisymmetric channel 34, with axis 35 coinciding with the central optical axis 18, with a diameter δ _B =δ _O =δ _K =0.125 mm, we fix the open segment 32 of the optical fiber 3. Moreover, the base of the truncated part of the straight cone of the end part of the sleeve 33, the end of the optical shell 4, the emitting end 6, through which the radiation beam exits to the additional secondary mirror 20, is set so that they lie in the same plane 36 passing perpendicular to the central optical axis 18 through the point of intersection of it with the reflecting plane 8 of the secondary mirror 9 Hairstyle m, the designed optical system is designed so that the previously mentioned central axis 10 of the beam coincides with the focal radius vector of a point on the full parabola 13, the output optical axis 15 of the beam passes through this point, coinciding with the diameter 16 of the full parabola 13. In this case, the diameter 16 forms, at the intersection with the tangent plane 17 to the reflective surface 12 at this point, the angle β. At the same time, we design the optical system so that the output optical axis 15 is parallel to the central optical axis 18 of the rectilinear segment of the fiber 3, spaced from the axis 19 of the complete parabola 13 at a distance h (in this calculation example, we take h=60 mm). The secondary mirror 9 in the optical system is installed so that its reflecting plane 8 is parallel to the tangent plane ₁₇ . β ₁ =β. The end part of the sleeve 33 is made in the form of a truncated right cone with an angle β ₂ so that the condition β ₂ <β ₁ is satisfied. Let us assume that the designed optical system is made with a focal parameter P=2F=820 mm of a full parabola 13 formed by the intersection of the YOX plane with a paraboloid of revolution with the coordinate axis OX and forming a concave reflective surface 12 of the main optical mirror 11. The main optical mirror 11 with a reflective surface 12 we perform, for example, from a material representing the composite AKK "Skeleton" (diamond / silicon carbide (AKC), obtained in a vacuum furnace from industrial grades of diamond powders impregnated with liquid silicon) [S.M. Latiev. Designing precise (optical) instruments. Chapter 8, paragraph 8.4. MIRRORS, p. 354-364 https://ozlib.com/813864/tehnika/zerkala]. It should be noted that, unlike traditional materials such as optical glass, for example, brand LK-7 [Physical quantities. Handbook, ed. I.S. Grigorieva, E.Z. Meilikhov. Moscow: Energoatomizdat, 1991, p. 770], ACC "Skeleton" in terms of specific rigidity is inferior only to diamond single crystals, and high thermal conductivity (650 W/(m K)), higher than that of copper, and thermal diffusivity (320 m ² /s) ensure uniformity of temperature fields in mirrors and its fast thermal relaxation, which allows it to have the temperature stability of the best ultra-slowly expanding materials. These characteristics make it possible to create mirrors with qualitatively new service properties from this material. On the working surface of the mirror, special structural coatings (glass, copper, nickel, chromium, etc.) are applied, which are then brought and polished to optical quality.

Powerful electromagnetic radiation emanating from the core 5 of the rectilinear segment of the fiber 3, as from a point source S* (Fig. 4) of laser radiation on the central optical axis 18 of the core 5 of the fiber 3, falls on the plane of the radiating end 6 of the fiber 3. Electromagnetic waves at the boundary of two media (the plane of the radiating end 6), getting from a denser medium (core material 5, with a refractive index n ₁ ) into a less dense one (air or outer space) with a refractive index n ₀ , where n ₁ >n ₀ , experience refraction caused by the fact that the speeds of wave propagation in these media are different. The continuation of the rays (determining the position of the spherical front of the refracted wave) of the diverging beam intersect at the point S, at a distance r from the radiating end 6, which is an imaginary image of the point S*.

We accept that the numerical aperture of the fiber 3 is determined by the ratio NA=n ₀ ⋅sinα, where n ₀ =1 is the refractive index of air, α is the angle between the central optical axis 18 of the rectilinear segment of the fiber 3 and the limiting aperture beam 42 or 43, forming a light cone on exit from core 5 [V.A. Dyakov, L.V. Tarasov. Optical coherent radiation. M.: Soviet radio, 1974, p. 117], and the greater NA, the higher the degree of divergence of the laser beam emerging through the emitting end 6 of the core 5 of the fiber 3. shown in FIG. 4, in the first approximation can be determined as r=0.5⋅δ _c /tgα. For small angles α one can take

r=0.5⋅δ _С /sinα=0.5⋅δС _{/NA=0.5⋅0.02/0.06=0.17} mm.

The divergent beam of laser radiation, with the central beam of the beam 7 and the angle α between the central optical axis 18 of the rectilinear segment of the fiber 3 and the limiting aperture beam 42 or 43, forming a light cone, as from a point source S (Fig. 4), leaves the core 5 through the radiating end 6 in total passes the distance L ₁ +r+L and falls on the reflecting plane 21 of the additional secondary mirror 20, where L ₁ is the distance from the reflecting plane 21 of the additional secondary mirror 20 to the point of intersection of the central optical axis 18 with the reflecting plane 8 of the secondary mirror 9 ; r is the distance from the point S to the radiating end 6; L is the distance from the radiating end 6 of the core 5 of the fiber optic lead 2 to the point of intersection of the central optical axis 18 with the reflective plane 8 of the secondary mirror 9. The additional secondary mirror 20 is made in the form of a circle with a diameter d ₂ perpendicular to the central optical axis 18 passing through its geometric center, spaced at a distance L ₁ (for the designed optical system, we take L ₁ = 88 mm) from the point of intersection of the central optical axis 18 with the reflecting plane 8 of the secondary mirror 9. An additional secondary mirror 20 is placed in the beam expander unit 22 with a mechanism for moving 23 along the central optical axis 18. The movement mechanism 23 can be made on the basis of a precision stepping single-coordinate piezo positioner, including software that allows you to manage and control the main parameters of the movement of the piezo positioner [Piezo positioner for nanofocusing. http://www.eurotek-general.coml, [Linear piezo platforms. http://www.innfocus.ru/ru/catalog/photonics_c/pozicionery/physik-instrumente-pi/linejnye-pezoplatformy/]. Further, the laser radiation beam is reflected from the reflecting plane 21 of the additional secondary mirror 20 also by a divergent spherical front and falls on the reflecting plane 8 of the secondary mirror 9 placed in the block connector 24. ”, similar to that discussed above for the main optical mirror 11 with a special structural coating on the reflecting plane 8 and the reflecting plane 21, similarly to the main optical mirror 11. Angle α in FIG. 1-4 are determined from the above ratio NA=n ₀ ⋅sinα, where n ₀ =1: α=Arcsin NA=Arcsin 0.06=3.44°.

The distance L of the end face 6 of the core 5 of the fiber optic lead 2 from the point of intersection of the central optical axis 18 with the reflecting plane 8 of the secondary mirror 11, forming an angle β 1 at the intersection, where β ₁ =β, is chosen to be minimal so that the ends of the core ₅ and the optical cladding 4, lying in the same plane 36 did not go beyond the reflecting plane 8 of the secondary mirror 9. Let us determine L, as follows from FIG. 4, according to the ratio

L/(0.5⋅δ _О )=tg(90°-β ₁ )=ctg β ₁ , given that β ₁ =β, we get L= L/(0.5⋅δ _О ⋅ctg β=0.5⋅δ _О /tg β.

Let us determine the angle β from the transcendental equation (5), which can be solved approximately [Bronshtein I.N., Semendyaev K.A. Handbook of mathematics for engineers and students of higher educational institutions. Ed. recycled. Edited by G. Grosche and W. Ziegler. Joint publication. Teubner Publishing House Leipzig, Moscow Nauka, Ch. ed. Phys.-Math. lit., 1981, p. 147], or as in this calculation example, by analyzing equation (5). Based on the adopted optical scheme, as can be seen from Fig. 1, the angle β ₁ is limited to 45°<β ₁ <90°. Whence it follows that for the diameter of the optical shell adopted in this example 4 δ _O =0.125 mm, the third term on the left side of equation (5) for L=0.5⋅δ _O /tg β is limited to the interval 0<L<0.0625.

Thus, considering the known parameters h, L ₁ δ _С , δ _О , α, and bearing in mind the relation 0<L<0.0625, we determine the angle β from equation (5):

h/(2⋅L ₁ +0.5⋅δ _c /tgα+0.5⋅δ _О / tgβ)=sin(180°-2β) or

60/(2⋅88+0.5⋅0.02/0.06+0.5⋅0.125/tgβ)=sin(180°-2β)

or 60/(176+0.167+0.5⋅0.125/tgβ)=sin(180°-2β), i.e. the third term is negligible in comparison with the first two terms and can be neglected in the first approximation.

From where we define β as β=90°-0.5⋅Arcsin[h/(2 L ₁ +0.5⋅δ _С /tgα)]=90°-0.5⋅Arcsin[60/(2⋅88+0 .5⋅0.02/0.06)]=80.04°.

As a result of the approximate solution, we obtain β=80.04°, which corresponds to the condition β ₂ <β ₁ =β.

Let us determine the distance L of the end face 6 of the core 5 of the fiber optic lead 2 from the point of intersection of the central optical axis 18 with the reflecting plane 8 of the secondary mirror 11:

L=0.5⋅δ _О ⋅ctg β=0.5⋅0.125⋅ctg 80.04°=0.011 mm.

The diameter d ₁ of the reflecting plane 8 of the secondary mirror 9, the diameter d ₂ of the reflecting plane 21 of the additional secondary mirror 20, as well as the diameter of the laser beam D _lp at the output of the optical system, will be determined from relations (1-3).

d ₁ =(4⋅L ₁ ⋅tgα⋅tgβ+δ _C ⋅tg β+δ _O ⋅tgα)/(tgβ-tgα)= =(4⋅88⋅tg 3.44°⋅tg 80.04°+0 .02⋅tg 80.04°+0.125⋅tg 3.44°)/(tg 80.04°-tg 3.44°)==21 mm;

d ₂ =δ _С +2⋅tgα⋅L ₁ +δ _О ⋅tgα⋅ctg β=0.02+2⋅tg 3.44°⋅88+0.125⋅tg 3.44°⋅ctg 80.04°=11 mm;

D _lp =P⋅{[1+cos(2⋅β-α)]/sin(2⋅β-a)-[1+cos(2⋅β+α)]/sin(2⋅β+α)} =820 {[1+cos(2⋅80.04°-3.44°)]/sin(2⋅80.04°-3.44°)-[1+cos(2⋅80.04°+3 .44°)]/sin(2⋅80.04°+3.44°)}=51 mm.

Let's determine the minimum allowable distance L ₁ ^min , with the chosen h, according to the relation (4)

что удовлетворяет условию

=

which satisfies the condition

We present the derivation of expressions (1-5), which determine the main geometric relationships and technical characteristics necessary for the design study of the designed optical system for the formation and guidance of a laser beam.

When deriving relations (1-5), we assume that the radiation comes from the core 5 through the radiating end 6 from a point source of radiation (point S), as shown in Fig. 4, placed at a distance r from the radiating end 6 on the central optical axis 18 of a straight piece of fiber 3 installed in the optical connector 25 terminating the fiber optic output 2 of the laser fiber module 1.

The derivation of relations (1-5) follows from the laws of reflection and refraction of light, as well as the definition and basic properties of a complete parabola 13 formed by the intersection of the YOX plane with a paraboloid of revolution with the coordinate axis OX and forming a concave reflective surface 12 of the main optical mirror 11 [Bronstein I. N., Semendyaev K.A. Handbook of mathematics for engineers and students of higher educational institutions. Ed. recycled. Edited by G. Grosche and W. Ziegler. Joint publication. Teubner Publishing House Leipzig, Moscow Nauka, Ch. ed. Phys.-Math. lit., 1981, p. 244].

As shown in FIG. 1, the reflecting surface 12 of the main optical mirror 11, which is part of the paraboloid of revolution of the full parabola 13, is made concave, off-axis with focus F. Moreover, as can be seen from FIG. 1, the tangent plane 17 at point M to the reflecting surface 12 of the main optical mirror 11 in the YOX plane forms a tangent 17 to the complete parabola 13 at point M. The tangent 17 and the normal to the complete parabola 13 are the bisectors of the angles between the focal radius vector of the point M of the complete parabola 13 and a diameter 16 passing through the same point M, while the diameter 16 forms, at the intersection with the tangent 17 at this point, the angle β. And the secondary mirror 9 is installed in the optical system so that its reflective plane 8 is parallel to the tangent plane 17 to the reflecting surface 12 of the main optical mirror 11 at point M.

In this case, we assume that the numerical aperture of the optical fiber is determined by the ratio NA=n ₀ ⋅sinα, where n ₀ =1 is the refractive index of air, α is the angle between the central optical axis 18 of the rectilinear segment of the optical fiber 3 and the limiting aperture beam 42 or 43, forming a light cone at the exit from the core 5 [V.A. Dyakov, L.V. Tarasov. Optical coherent radiation. M.: Soviet radio, 1974, p. 117], and the greater NA, the higher the degree of divergence of the laser beam emerging through the radiating end 6 of the core 5 of the fiber optic output 2. From the relation NA=n ₀ ⋅sinα, where n ₀ =1, we determine the angle α (Fig. 1-4) , i.e.

The distance r of the point source of radiation (point S) from the emitting end 6 on the central optical axis 18 of the core 5 of the fiber optic lead 2, as shown in FIG. 4 can be defined as a first approximation as

For small angles a, one can take

The distance L from the end face 6 of the core 5 of the fiber optic lead 2 to the point of intersection of the central optical axis 18 with the reflecting plane 8 of the secondary mirror 11, forming an angle β 1 at the intersection, where β ₁ =β, is chosen to _be minimal so that the ends of the core 5 and the optical cladding 4 , lying in the same plane 36, did not go beyond the reflecting plane 8 of the secondary mirror 9. Let us determine L, as follows from FIG. 4, according to the ratio

L/(0.5⋅δ _o )=tg(90°-β ₁ )=ctgβ ₁ , given that β ₁ =β, we get

The angle β formed at the intersection of the diameter 16 of the full parabola 13 with the tangent plane 17 to the reflecting surface 12 of the main optical mirror 11 in the YOX plane and the angle β ₁ equal to it formed at the intersection of the central optical axis 18 with the reflecting plane 8 of the secondary mirror 9 in the plane YOX, for the adopted constructive solution of the considered optical system, taking into account relations (7) and (9), we determine, for example, from the triangle ΔtM ₃ F (Fig. 1)

In relation (10) M ₃ t=h, where, as can be seen from FIG. 1, h is the distance of the central optical axis 18 of the rectilinear segment of the optical fiber 3 from the axis 19 of the complete parabola 13. The hypotenuse M ₃ F, as can be seen from FIG. 1 and FIG. 4 is an imaginary segment of the focal radius vector of the point M on the full parabola 13, equal to the distance traveled by the central beam 7 of the radiation beam emanating from the core 5 through the radiating end 6, from the point source S, after reflection from the reflecting plane 21 of the additional secondary mirror 20, to the reflecting plane 8 of the secondary mirror 9. Whence in relation (10) M ₃ F=2 L ₁ +r+L.

Substituting into (10) the expressions for r and L from (7) and (9), we obtain for β the transcendental equation

which can be solved approximately [Bronstein I.N., Semendyaev K.A. Handbook of mathematics for engineers and students of higher educational institutions. Ed. recycled. Edited by G. Grosche and W. Ziegler. Joint publication. Teubner Publishing House Leipzig, Moscow Nauka, Ch. ed. Phys.-Math. lit., 1981, p. 147]. Whence, to determine β, we arrive at relation (5).

The diameter d ₂ of the reflecting plane 21 of the additional secondary mirror 20, as can be seen from FIG. 1 and FIG. 4, bearing in mind the law of reflection of rays incident on the reflecting plane 21 of the additional secondary mirror 20 and preliminarily assuming the known parameters α, δ _C , L ₁ , r and L, taking into account (7) and (9), can be determined from the relationship

0.5⋅d ₂ /(L ₁ +r+L)=tgα, from which we determine d ₂

d ₂ =δ _С +2⋅tgα⋅L ₁ +δ _О ⋅tgα⋅ctgβ, i.e. we arrive at relation (2).

The diameter d ₁ of the reflective plane 8, as can be seen from FIG. 1 and FIG. 4, bearing in mind the law of reflection of rays incident on the reflecting plane 8 of the secondary mirror 9, we find as the ordinate (y) the intersection point of the extreme beam 44, reflected from the reflecting plane 21 of the additional secondary mirror 20, with the reflecting plane 8, as a point on the reflecting plane 8 the most distant from the central optical axis 18, from the solution of the system of equations of the extreme beam 44 and the straight line formed from the intersection of the reflecting plane 8 with the YOX plane, moving the point of origin, for this particular case, to the point M ₃ :

Solving equations (12) and (13) together, we find the ordinate (y) of the point of intersection of the extreme beam 44 with the reflecting plane 8, as the point most distant from the central optical axis 18:

Substituting into (14) the expressions from (7) and (9) we determine the diameter d ₁ from the relation

d ₁ =2⋅у=(4 L ₁ ⋅tgα⋅tgβ+δ _С ⋅tgβ+δ _O ⋅tgα)/(tgβ-tgα), i.e. we arrive at relation (1).

The diameter D _lp of the laser beam at the exit from the optical system is defined as the difference between the ordinates of the points M ₁ and M ₂ on the full parabola 13 of the corresponding focal radius vectors, as can be seen from Fig. 1, having previously determined the ordinate of the point M on the full parabola 13.

By jointly solving the equation of the focal radius vector of the point M on the complete parabola 13, using the triangles in FIG. 1 ∆TMF and ∆OmF,

and the canonical equation of the parabola [Bronshtein I.N., Semendyaev K.A. Handbook of mathematics for engineers and students of higher educational institutions. Ed. recycled. Edited by G. Grosche and W. Ziegler. Joint publication. Teubner Publishing House Leipzig, Moscow Nauka, Ch. ed. Phys.-Math. lit., 1981, p. 244]

where P is the focal parameter of the complete parabola 13 formed by the intersection of the YOX plane with a paraboloid of revolution with the coordinate axis OX and forming a concave reflective surface 12 of the main optical mirror 11.

From the joint solution of equations (15) and (16) we find the ordinate of the point M(x ₀ , y ₀ )

Similarly, using the drawing in FIG. 1, we determine the ordinates of the points M ₁ and M ₂ on the full parabola 13, and the diameter D _lp of the laser beam at the exit from the optical system is determined as the difference between the ordinates of the points M ₁ and M ₂

D _lp =y ₁ -y ₂ =P⋅{[l+cos(2β-α)]/sin(2β-α)-[1+cos(2β+α)]/sin(2β+α)}, t .e. we arrive at relation (3).

, при выбранном h, отражающей плоскости 21 дополнительного вторичного зеркала 20 от точки (М₃) пересечения центральной оптической оси 18 с отражающей плоскостью 8 вторичного зеркала 9, чтобы сравнить с предварительно выбранным параметром L₁, при этом очевидно, как видно из фиг. 1, L₁ должно быть больше

.

определим как разность абсцисс точки М₃ и точки пересечения фокального радиуса-вектора точки М₂ с прямой у=h+d₂/2. Абсциссу х₃ точки М₃(х₃, у₃), где у₃=h, определим совместно решая уравнение (15) фокального радиуса-вектора точки М на полной параболе 13 с уравнением у=h. Откуда получаемDetermine the minimum allowable distance

, with selected h, the reflecting plane 21 of the additional secondary mirror 20 from the point (M ₃ ) of the intersection of the central optical axis 18 with the reflecting plane 8 of the secondary mirror 9, in order to compare with the pre-selected parameter L ₁ , while it is obvious, as can be seen from Fig. 1, L ₁ should be more

.

define as the difference between the abscissas of the point M ₃ and the point of intersection of the focal radius vector of the point M ₂ with the straight line y=h+d ₂ /2. The abscissa x ₃ of the point M ₃ (x ₃ , y ₃ ), where y ₃ =h, is determined by jointly solving the equation (15) of the focal radius vector of the point M on the full parabola 13 with the equation y=h. Where do we get

Similarly to (18), we obtain the abscissa (let's call it x _D ) of the point of intersection of the focal radius vector of the point M ₂ with the straight line y \u003d h + d ₂ /2, this point on the reflecting plane 21 of the additional secondary mirror 20 is the most distant from the central optical axis 18, where we get

при выбранном h, отражающей плоскости 21 дополнительного вторичного зеркала 20 от точки (М₃) пересечения центральной оптической оси 18 с отражающей плоскостью 8 вторичного зеркала 9, как

т.е. получаем соотношение (4).Where we determine the minimum allowable distance

when h is selected, the reflecting plane 21 of the additional secondary mirror 20 from the point (M ₃ ) of the intersection of the central optical axis 18 with the reflecting plane 8 of the secondary mirror 9, as

those. we obtain relation (4).

It should be noted that when applying the above ratios, it is necessary to take into account the design features of the frames in which the main optical mirror 11, the secondary mirror 9 and the additional secondary mirror 20 are located in the design of a real optical system.

Claims (6)

An optical system for the formation and guidance of a laser beam, including a laser fiber module with a fiber optic output, including an optical fiber, consisting of an optical cladding 4 with a diameter of δ _O , containing a core with a diameter of δ _C , through the emitting end of which with a numerical aperture NA a beam with a central beam exits, and at the exit from the optical system, the beam reflected from the reflecting plane of the secondary mirror, with a central axis, falls on the main optical mirror, which is structurally connected with the "coarse" pointing device, from the reflecting surface of which, made of a concave off-axis parabolic with a focus F of a full parabola, a slightly diverging a laser beam incident on the image plane, and the previously mentioned central axis of the beam coincides with the focal radius vector of a point on a full parabola, the output optical axis of the beam passes through this point, coinciding with the diameter of the full parabola, while the diameter forms, at the intersection with the tangent the reflecting plane to the reflecting surface at this point, angle β, and the reflecting plane of the secondary mirror is parallel to the tangent plane, while the output optical axis is parallel to the central optical axis of the rectilinear segment of the fiber, spaced from the axis of the full parabola at a distance h, and the emitting end of the core of the fiber optic output is spaced at a distance L from the point of intersection of the central optical axis with the reflecting plane of the secondary mirror, which forms an angle β ₁ when crossing, where β ₁ =β, characterized in that an additional secondary mirror is introduced, with a reflecting plane, placed in the beam expander unit with a mechanism for moving along the central optical axis, while the reflecting plane is made in the form of a circle with a diameter of d ₂ , perpendicular to the central optical axis passing through its geometric center, spaced at a distance L ₁ from the point of intersection of the central optical axis with the reflecting plane of the secondary mirror, and also introduced bl ok-connector, which consists of a secondary mirror and an optical connector with a thermal control system, the secondary mirror is made in the form of a truncated circular cylinder with a diameter d ₁ with a beveled plane forming the reflective plane of the secondary mirror, inside which a through channel is axisymmetrically made, with an axis coinciding with the axis of the truncated circular cylinder of the secondary mirror and with the central optical axis, with an optical connector enclosed in it, terminating the fiber optic output, which includes a straight cable section fixed in the optical connector, straight sections of the buffer shell and an open fiber section fixed in a sleeve, axisymmetrically placed in optical connector, and a segment of the buffer shell with an outer diameter d _B is fixed by a sleeve, with an inner diameter d _B and an outer diameter D _B , where d _B \u003d d _B , and in the end part of the sleeve, made in the form of a truncated straight cone, with a base diameter D _K \u003d D _B , diameter the base of the truncated part δ _K and with an angle β ₂ <β ₁ between the generatrix of the cone and the height, in its axisymmetric channel, with an axis coinciding with the central optical axis, with a diameter δ _B = δ _O = δ _K , an open segment of the fiber is fixed, and the base of the truncated part of the straight cone of the end part of the sleeve, the end of the optical shell, the emitting end, through which the radiation beam enters the additional secondary mirror, lie in the same plane passing perpendicular to the central optical axis through the point of intersection of it with the reflecting plane of the secondary mirror, while the main optical the mirror is structurally connected with the scanning device, and the parameters of the optical system correspond to the relations:

where L ₁ >L ₁ ^min , a L ₁ ^min - the minimum allowable distance, when selected h, the reflective plane of the additional secondary mirror from the point of intersection of the central optical axis with the reflective plane of the secondary mirror; α is the angle between the central optical axis of the straight fiber segment and one of the limiting aperture beams that form a light cone at the exit from the core; P is the focal parameter of a complete parabola formed by the intersection of the YOX plane with a paraboloid of revolution with the coordinate axis OX and forming a concave reflective surface of the main optical mirror; D _lp is the diameter of the laser beam at the output of the optical system.

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