RU147304U1 - DEVICE FOR CONFIGURING AND CHECKING STATIC WIDER-FIELD CORNER MEASURING INFRARED INSTRUMENTS FOR EARTH ORIENTATION - Google Patents

Abstract

1. Device for tuning and checking static wide-field angle-measuring infrared orientation devices on the Earth, containing heated and cooled emitters located in the field of view of the device placed in a multi-axis suspension, characterized in that the emitters are made in the form of concentric spherical cups of a double-walled structure, the cavity of each of which is equipped with a temperature-controlled medium, and a cooled radiator located along the beam behind a heated radiator, with a concave surface facing m axial suspension, has a central hole corresponding to the angular size of the simulated Earth. 2. The device according to claim 1, characterized in that the heated and cooled radiators are made with the possibility of their joint movement along the optical axis of the device. The device according to claim 1, characterized in that a partition is arranged in the cavity of the heated radiator for separating the thermally controlled media. The device according to claim 1, characterized in that the radiator to be cooled is made in the form of a set of radiators that differ from each other in the size of the central hole. The device according to claim 1, characterized in that a collimating lens is located behind the cooled emitter along the beam. The device according to claim 1, characterized in that the multi-axis suspension has three rotation axes.

Description

The proposed model relates to the field of measurement technology, and more specifically to devices for tuning and checking angle-measuring infrared (IR) instruments for orienting spacecraft (SC) over the Earth.

A device (analogue) is known for setting up and checking angle-measuring infrared instruments for orientation of the spacecraft on the Earth, containing heated emitters simulating the Earth, cooled emitters emulating space, a mirror parabolic torus with a flat mirror, collimating the radiation of the simulated Earth-to-space boundary located in the field view of the device placed in a two-stage suspension (see Fedoseev VI, Kolosov MP, “Optoelectronic devices for orienting and navigating spacecraft”: - M .: Logos, 2007. - 247 s, Fig. 6.3, p. 228).

This device, which simulates the angular fields and the temperature contrast between the Earth and space, corresponding to the geostationary orbit in the spectral range Δλ = 8 μm ... 20 μm, is designed to configure and verify scanning optical-electronic angle-measuring infrared measuring instruments for orienting the spacecraft of the secant type with instantaneous fields about several degrees.

The purpose of these devices is to determine the angular coordinates of the deviation of the axis of sight of the device from the local vertical (direction to the center of the Earth).

In this device, the presence of a mirror torus that collimates the radiation of the simulated Earth-to-space boundary minimizes the effect of image defocusing in the tested scanning devices, which usually contain long-focus lenses. Joint vertical movement of the emitters provides a change in the simulated angular size of the Earth.

The accuracy characteristics of the device are checked using a known device by tilting the device installed in a two-stage suspension to a fixed angle (using angle sensors) and comparing this angle with the vertical angle coordinate (direction to the center of the simulated Earth) measured directly by the device.

The disadvantage of the analogue is the complexity of its design, which includes several heated and cooled radiators, a parabolic torus, a flat mirror, mechanical components and their mounts. This set of features is due to the need to create a device for testing scanning devices secant type with long-focus lenses. In addition, the device complicates the need to equalize the temperatures of heated and respectively cooled emitters. Obviously, the creation of such a device is associated with great technological difficulties and cost.

Another disadvantage of this technical solution is the insignificant range of variation of the simulated angular size of the Earth - only ± 25 ′ (for simulating flight heights H = 33796 km and H = 37796 km). Since the change in the angular size of the Earth is ensured by the joint vertical movement of the emitters, the features of the parabolic torus and the geometry of the device as a whole, to simulate another angular size of the Earth, which is necessary for testing instruments operating at lower altitudes, it is necessary to create a new device that will differ from the existing parameters of the parabolic torus, the dimensions and dimensions of the emitters, fasteners, which leads to high cost costs. It should also be noted that the development and manufacture of a parabolic torus that simulates the large angular dimensions of the Earth is an extremely complex technological task.

In addition, the disadvantages of this device (in relation to the verification of static infrared devices for orientation of the spacecraft on the Earth based on a bolometric matrix as a radiation receiver) include the presence of some mechanical assemblies for attaching the elements of the device to the base of the stand, for example, mounting a flat mirror. When checking a secant type scanning device with an instantaneous field of the order of several degrees, this mount does not impede the passage of working beams. However, when testing static matrix devices, for which a complete simulation of the Earth’s disk and space is required to ensure measurements within significant fields of view, this mount will be in the field of view of the device, reducing the accuracy of determining the energy center of the simulated Earth and limiting the angular field of measurements.

The closest in technical essence to the claimed object is a device for tuning and checking angle-measuring infrared instruments for orientation of the spacecraft on the Earth, selected as a prototype, containing flat cooled and heated emitters installed along the beam located in the field of view of the device placed in a two-stage suspension (see Fedoseev VI, Kolosov MP Optoelectronic devices for orientation and navigation of spacecraft: - M .: Logos, 2007. - 247 s, Fig. 6.5 on page 230).

In this device, shown in figure 1, a flat heated emitter 1 simulates the radiation of the Earth, and a flat cooled emitter 2 simulates the radiation of space.

During the test, the device under test is installed in a two-stage suspension at a finite distance from the emitters. In the focal plane of the device, an image of the simulated Earth and space is formed, according to which the device is tuned.

The purpose of these devices is to determine the angular coordinates of the deviation of the axis of sight of the device from the local vertical (direction to the center of the Earth).

Checking the device is carried out in the same way as in the case of the analogue.

The simulated angular size of the Earth 2ω ₃ Earth is determined by the diameter of the heated emitter D _{Izl. 1} and its distance L ₁ to the entrance pupil of the tested device. The magnitude ω of the _Earth , D _Izl . ₁ and L ₁ as follows from FIG. 1, are related by the dependence tgω of the _Earth = D _{outl. 1/2} L ₁ .

The angular size of the simulated cosmos 2ω _cosmos should cover the entire angular field of the device under test, which is always larger than the angular size of the Earth, to ensure its capture, i.e. 2ω _cosmos ≥2ω of the _device . The simulated angular size of the cosmos 2ω _cosmos is determined by the diameter of the cooled emitter D _{Izl. 2} and its distance L ₂ to the entrance pupil of the tested device. The magnitudes 2ω of the _earth , D _vl . ₂ and L ₂ , as follows from FIG. 1, are related by the dependence tgω _cosmos = D _outl . ₂ / 2L ₂ . For preliminary calculations, we can take L ₁ = L ₂ and then tgω _space = D _{Iz. 2} / 2L ₁ .

Due to the location of emitters 1, 2 at a finite distance from the lens of the device under test, defocusing occurs in the focal plane of the lens, which can reduce the quality of the generated image of the simulated Earth-to-space boundary and, consequently, the accuracy of the device, which will not correspond to the actual flight conditions . However, when the heated radiator is removed from the entrance pupil of the device L ₁ by an amount of the order of several tens of the focal lengths of the device or more (depending on the relative aperture of the lens of the device), the image quality change due to defocusing will be minimal.

Such a construction of the device is most optimal for testing static IR devices based on bolometric matrix radiation detectors having small focal lengths of the lenses of the order of several millimeters and angular fields of the order of several tens of degrees. In this case, the dimensions of the device D and L will be quite real for practical implementation.

In this device, in contrast to the analogue, the required simulated angular dimensions of the Earth and space of small and medium sizes with fairly compact dimensions are quite simply implemented.

Simulation of various angular dimensions of the Earth (with a constant angular size of the simulated space) can be achieved by installing heated emitters 1 of the desired diameter.

The disadvantages of the prototype include the impossibility of simulating the large angular dimensions of the Earth and space due to the unrealistic linear dimensions of flat emitters 1 and 2, which does not allow for the adjustment and verification of wide-field static matrix orientation devices of spacecraft operating also at low altitudes. As an example, let us determine the dimensions of emitters 1 and 2, which are necessary for testing an instrument with an angular field of 2ω = 176 ° for a flight altitude of 500 km (2ω of the _Earth = 136 °, 2ω of _space ≥176 °) with a focal length of the lens f '= 4.9 mm and pupil diameter ⌀ _sp = 2.45 mm (see, for example, Gebgart A.Ya., Shatova A.Ya., Medvedev VV, “Optical types of some types of wide-angle IR lenses”, Optical Journal, 2013 , v. 80, No. 2, pp. 48-51).

When L ₁ = 189 mm (L \ f '= 42), the diameters of the emitters 1 and 2, as follows from the above expressions, should be D _ex.1 = _93.5.5 mm, D _ex.2 = 10824.5 mm that is almost impossible to implement.

Also, the disadvantage of this device is getting into the field of the device structural elements necessary to ensure the heating of the emitter 1.

In addition, when using flat emitters to simulate the large angular dimensions of the Earth, there is a significant unevenness of illumination in the entrance pupil of the device under test for different points of the field, due to different distances of the emitter points from the pupil, as well as different energy brightness of the emitter for different tilt angles, which leads to inaccurate settings and verification of the device under test.

The task to which the utility model is directed is to create a device (stand) that provides tuning and precision tests of static wide-field angle-measuring infrared instruments for orientation of the spacecraft over the Earth, providing simulation of any range of simulated angular dimensions of the Earth and space with high uniformity of illumination and without getting into Field of view of the device.

This problem is solved due to the fact that in the device for tuning and checking angle-measuring infrared instruments of orientation on the Earth, containing heated and cooled radiators located in the field of view of the device placed in a multiaxial suspension, the radiators are made in the form of concentric spherical cups of a double-walled structure, the cavity of each of which is equipped with a thermo-controlled medium, and a replaceable cooled radiator located along the beam behind the heated radiator, with a concave surface facing multiaxial mu suspension, has a Central hole corresponding to the angular size of the simulated Earth.

In this case, it is necessary to take into account the development and refinement of the totality of the above features of the utility model, namely:

- installation of heated and cooled radiators with the possibility of their joint movement along the optical axis of the device;

- placement in the cavity of the heated radiator of the partition to separate the thermally controlled environments;

- the implementation of the cooled emitter in the form of a set of emitters that differ from each other in the size of the Central hole corresponding to the angular size of the simulated Earth;

- placement behind a cooled emitter along the beam of a collimating lens;

- The choice of multi-axis suspension with three axes of rotation.

This utility model is characterized by a combination of features, expressed in the presence of new ones in comparison with the prototype of structural solutions, such as:

- the form of the heated and cooled radiators having substantially smaller linear dimensions compared to the prototype due to its spherical surface, which allows to simulate any angular dimensions of the Earth and space;

- the implementation of the cooled emitter with a hole and its location along the beam behind the heated emitter, which provides a complete simulation of the Earth’s disk and space without any structural elements falling into the field of view of the device under test;

- the spherical shape of concentric emitters, the center of curvature of which is located near the entrance pupil of the device under test, which ensures the propagation of the axes of the beams entering the lens of the device along the normals to the surfaces of the emitters, and, therefore, a high uniformity of illumination in the region of the entrance pupil of the device. This property is especially important for testing devices with lenses having angular fields of the order of 180 ° and an almost uniform distribution of illumination over the field.

In addition, the indicated development and refinement of the features of the utility model given in the independent paragraphs relate to:

- the possibility of implementing the joint movement of the emitters along the optical axis to provide simulations of the atmospheric layer and changes in simulated angular dimensions within small limits;

- the presence in the cavity of the heated emitter of a partition for separating thermally controlled media, which allows, if necessary, to create different temperatures in the cavities of the emitter and provide different temperature contrasts on opposite sides of the simulated Earth;

- installation of spherical cooled emitters from a set with a diameter of the central hole corresponding to the required angular size of the Earth, to simulate any other angular dimensions of the Earth;

- the presence of a collimating lens, the focal plane of which is aligned with the Earth-space interface, which eliminates the influence of linear displacements of the device in a plane perpendicular to the optical axis of the device, which can introduce additional angular errors in determining the center of the simulated Earth. Moreover, a certain departure from the concentricity of the surfaces of spherical emitters does not practically affect the uniformity of illumination in the pupil;

- the presence of the third axis of the suspension, directed along the axis of the device, which allows you to implement the coordinate system necessary for inspections (spherical or polar) and to ensure the determination and compensation of such errors, such as, for example, the parallel line of sight of the device and the normal to its landing plane.

The technical result implemented by the given set of features is to provide simulations of any angular dimensions of the Earth and space, increase the uniformity of illumination on the entrance pupil of the tested device and prevent the structural elements from getting into the field of view of the tested device, which allows tuning and checking the accuracy characteristics of static wide-field IR orientation devices Spacecraft on Earth operating in a wide range of flight altitudes.

Thus, the claimed technical solution has significant differences, allowing to obtain a new positive effect.

The essence of the utility model is illustrated by drawings, where

in FIG. 1 shows the optical scheme of the closest analogue - prototype;

in FIG. 2 shows an optical diagram of the proposed device;

in FIG. 3 shows an optical diagram of the proposed device with a collimating lens.

The proposed device (Fig. 2) contains: a heated emitter 1 and a cooled emitter 2 with a central hole 3, made in the form of concentric spherical bowls of a double-walled structure, as well as a triaxial suspension (not shown in the drawing) with axes I, II, III, with installed on it with a verified device. The cavity of each of the emitter is equipped with a temperature-controlled environment. The concave spherical surfaces of the emitters 1, 2 are facing the suspension, while the centers of their curvature are located near the center of the pupil of the device at the intersection of the axes of rotation I, II, III. The cooled emitter 2 is provided with a central hole 3. In the cavity of the heated emitter, a partition 4 can be placed to separate the thermally controlled media. Emitters have the possibility of joint movement along the optical axis. The stand also includes a collimating lens 5 (see Fig. 3). This device provides simulated angular fields and temperature contrast between the Earth and space in the spectral range Δλ = 8 μm ... 20 μm, which allows you to configure and verify the accuracy of the tested devices.

The double-walled design of the emitter can be made by extruding two spherical surfaces and then welding them with each other with a gap to form a cavity, for example, from AMg6 alloy having a high thermal conductivity. A sharp edge around the perimeter of hole 3 in the cooled emitter (to form the Earth-space boundary) can be made as a separate insert also from the AMg6 alloy welded to the emitter. The partition 4 in the heated emitter 1 can be made in the form of a welded structure. The temperature-controlled medium is a liquid of the required temperature, placed in the cavity of the emitters. The specified liquid may be water, antifreeze, etc. The fluid flow in a closed circuit is carried out using the inlet and outlet hoses connected to the inlet and outlet openings of the cavity, and the desired temperature is ensured by a thermostat. Thus, the proposed implementation examples confirm the feasibility of the claimed technical solution.

The device operates as follows.

The device under test is installed in a three-stage suspension with axes I, II, III at a finite distance from the emitters. The entrance pupil of the device is located in the center of curvature of the surfaces of the emitters 1 and 2 at the intersection of the axes of rotation I, II, III. The spherical cooled emitter 2 simulates the radiation of space, and the spherical heated emitter 1 through the central hole 3 of the emitter 2 simulates the radiation of the Earth. A sharp edge around the perimeter of the hole 3 in the cooled emitter 2 forms an imitation of the Earth-space boundary. In the focal plane of the device, an image of the simulated Earth is formed, according to which the device is tuned. This device provides simulated angular fields and temperature contrast between the Earth and space in the spectral range Δλ≈8 μm ... 20 μm.

Checking the accuracy of the device is also carried out, as in the prototype, by tilting the device in a suspension to a fixed angle (using angle sensors) and comparing this angle with the vertical angle coordinate (direction to the center of the simulated Earth), measured directly by the device.

This device is intended for tuning and testing static wide-field optical-electronic infrared devices for spacecraft orientation on the Earth based on matrix radiation detectors having small focal lengths of lenses of the order of several millimeters. In this case, the dimensions of the device D and L will be quite real for practical implementation:

или L₂=R≥(f'/N)²/2,44λ, где N - диафрагменное число. Например, для объектива прибора с фокусным расстоянием f'=4,9 мм, диаметром входного зрачка D=2,45 мм и длиной волны λ=12 мкм, расстояние от подогреваемого излучателя 1 до зрачка прибора и радиус кривизны поверхности охлаждаемого излучателя 2 составят L₂=R₂≥189 мм;- the distance from the cooled emitter 2 to the entrance pupil of the device L ₂ can be determined from the condition of minimizing the effect of defocusing in the lens of the device, arising from the location of the emitters at a finite distance from the device. The indicated defocus focus reduces the image quality of the simulated Earth-space boundary and, consequently, the instrument’s accuracy parameters that will not correspond to the actual flight conditions. If the center of curvature of the emitters 1 and 2 coincides with the center of the entrance pupil of the device L ₂ = R ₂ , where R ₂ is the radius of curvature of the surface of the cooled emitter 2 facing the device. The specified defocus focus reduces the image quality of the simulated Earth-space boundary and, therefore, the accuracy characteristics of the device, which will not correspond to the real ones. The value of defocusing in an angular measure (in radians) is determined by the well-known expression Δψ≈⌀ _sp. / L ₂ , where ⌀ _sp. - the diameter of the pupil of the lens of the device. To minimize the effect of defocusing, its value should be no larger than the diffraction scattering circle (Erie circle) of the test lens, the angular value of which is determined by the well-known expression γ = 2.44λ / ⌀ _sp , where λ is the working wavelength. Then from the condition Δψ≤γ we can obtain an expression for the distance L ₂ (R ₂ ), which will have the form

or L ₂ = R≥ (f '/ N) ² / 2.44λ, where N is the diaphragm number. For example, for a device lens with a focal length f '= 4.9 mm, an entrance pupil diameter D = 2.45 mm and a wavelength of λ = 12 μm, the distance from the heated emitter 1 to the pupil of the device and the radius of curvature of the surface of the cooled emitter 2 will be L ₂ = R ₂ ≥189 mm;

- the simulated angular size of the Earth 2ω of the _Earth is determined by the diameter of the hole of the cooled emitter D _{hole 2} , its distance L ₂ to the entrance pupil of the device under test and the radius of curvature of the surface of the cooled emitter 2 R ₂ . When the coincidence of the center of curvature of radiators 1 and 2 with the center of the entrance pupil, L ₂ = R _2, and the value ω _ground, D _otv.izl.2 and R _2, as follows from FIG. 2, are related by the dependence sinω of the _Earth = D _{resp. Ex} . ₂ / 2R ₂ . The diameter D _Izl. 1 of the heated emitter 1 should always be larger than the diameter of the hole in the cooled emitter 2;

- the simulated angular size of the cosmos 2ω _cosmos is determined by the diameter of the cooled emitter D _{vl. 2} , its distance L ₂ to the entrance pupil of the device under test, as well as the radius of curvature of the surface of the cooled emitter 2R. If the center of curvature of the emitters 1 and 2 coincides with the center of the entrance pupil of the device, L ₂ = R ₂ , and the magnitude ω is _cosmos , D _isl.2 and R ₂ , as follows from FIG. 2, are related by the dependence sinω _cosmos = D _outl . ₂ / 2R ₂ .

Obviously, when the angle tends to 2ω → 180 °, D _rad . → 2L ₂ = 2R _rad . ₂ (unlike the prototype, which has a flat shape of emitters and which, when the angle tends to 2ω → 180 °, D _rad . → ∞).

As an example, we can show: to test the device for a flight altitude of 500 km (2ω of the _Earth = 136 °, 2ω of _space ≥176 °), having a focal length of the lens f '= 4.9 mm, the diameter of the entrance pupil ⌀ _sp = 2.45 mm and located from the cooled emitter 2 to a distance L ₁ = 189 mm (to minimize defocusing) the diameters of the emitters will be D _{hole 2} = 350.5 mm, D ₂ = 378 mm (hemisphere). D _rad .1≥D _otv.izl.2.

Thus, the proposed device provides the ability to simulate any angular dimensions of the Earth and space with real sizes of spherical emitters (in contrast to the prototype, which does not simulate large angular fields due to the flat shape of the emitters), which is necessary to configure and verify wide-field static IR spacecraft orientation instruments.

In the proposed device, the cooled emitter 2, located in front of the tested device, covers the entire field of the device, so that all structural elements, including hoses for supplying fluid to the cavity of the emitters, can be placed on the inside of the emitters or at their end and do not fall into the angular field device (unlike the prototype, where these elements fall into the field of the device).

The spherical shape of concentric emitters, the center of curvature of which is located near the entrance pupil of the device under test, ensures the propagation of the axes of the beams entering the lens of the device along the normals to the surfaces of the emitters, and, therefore, high uniformity of illumination in the region of the entrance pupil of the device (unlike the prototype, where - due to the flat shape of the emitters, irregularity of illumination over the field occurs). This property is especially important for testing devices with lenses having angular fields of the order of 180 ° and an almost uniform distribution of illumination over the field.

The presence of the partition 4 in the heated radiator 1 allows, if necessary, to provide different temperatures in its cavity and create different temperature contrasts on opposite sides of the simulated Earth.

Simulation of various angular dimensions of the Earth is ensured by installing (from a set of emitters), spherical cooled emitters 2 different from each other with a central hole diameter 3 corresponding to the required angular size of the Earth, as well as due to the joint movement of emitters 1 and 2 within small limits.

Simulation of the atmospheric layer, the thickness of which for low orbits can reach values of the order of a degree, can be achieved due to some defocusing of the image of the Earth-space boundary. Defocusing is achieved due to the joint movement of the emitters 1 and 2 along the optical axis. Obviously, with small movements of the emitters, the positive properties of the device are preserved.

In some cases, when conducting precision checks of the device, it is possible to use a collimating lens 5, the focal plane of which is aligned with the Earth-space interface (Fig. 3). In this case, the influence of the linear displacements of the device in the plane perpendicular to the optical axis of the device, which can introduce additional angular errors in determining the center of the simulated Earth, is eliminated. Some departure from the concentricity of the surfaces of spherical emitters practically does not affect the uniformity of illumination in the pupil.

The presence of a triaxial suspension, in which one of the axes (axis III) coincides with the axis of the device, allows you to implement the coordinate system (spherical or polar) necessary for testing, and to ensure the determination and compensation of such errors, such as non-parallelism with the sight line of the device and the normal to its landing plane.

Thus, the proposed technical solution provides the setting and verification of static wide-field angle-measuring infrared instruments for orientation of the spacecraft on the Earth by simulating any range of angular dimensions of the Earth and space with high uniformity of illumination and without the presence of structural elements of the device in the field of view of the device under test.

Claims (6)

1. Device for tuning and checking static wide-field angle-measuring infrared orientation devices on the Earth, containing heated and cooled emitters located in the field of view of the device placed in a multi-axis suspension, characterized in that the emitters are made in the form of concentric spherical cups of a double-walled structure, the cavity of each of which is equipped with a temperature-controlled medium, and a cooled radiator located along the beam behind a heated radiator, with a concave surface facing m axial suspension, has a central hole corresponding to the angular size of the simulated Earth. 2. The device according to claim 1, characterized in that the heated and cooled radiators are made with the possibility of their joint movement along the optical axis of the device. 3. The device according to claim 1, characterized in that a partition is arranged in the cavity of the heated radiator for separating the thermally controlled media. 4. The device according to p. 1, characterized in that the cooled emitter is made in the form of a set of emitters, differing from each other by the size of the Central hole. 5. The device according to claim 1, characterized in that a collimating lens is located behind the cooled emitter along the beam. 6. The device according to claim 1, characterized in that the multiaxial suspension has three axes of rotation.

Images