Filter wheel mechanism for coronagraph

Abstract

The invention relates to the technical field of space optical load optical-mechanical structures, in particular to a filter wheel mechanism for coronagraph, which comprises a focal plane mounting plate, a filter wheel frame, a filter wheel and a filter wheel axle system, the filter wheel frame is a complete machine mounting foundation, the focal plane mounting plate and the filter wheel axle system are both connected with the filter wheel frame, and the filter wheel frame is connected with the filter wheel. The filter wheel shaft system outputs motor input through a gear pair, the filter wheel is installed on an output shaft of the filter wheel shaft system, the filter wheel is provided with different functional lenses such as an optical filter, a polaroid and a full-strength sheet, and the functional lenses used for observation are switched through transmission of the filter wheel shaft system. According to the invention, rapid switching of multiple observation channels can be realized, and the device has the advantages of high switching positioning precision, high switching speed, compact structure, long service life and the like.

Description

Technical Field

[0001] The invention relates to the technical field of optical-mechanical structures of space optical loads, and in particular provides a filter wheel mechanism for a coronagraph. Background Art

[0002] A coronagraph is a special space optical telescope that can block the sun's light and observe the hot, thin outermost corona of a burning star. In order to capture polarized light waves in a specific direction and observe the corona from different wavelengths, different filters, polarizers or other optical elements are needed to achieve this, thereby providing scientists with important research data. However, the process of reassembling different lenses according to different observation needs each time is rather cumbersome and troublesome, and frequent assembly adjustments can easily affect the observation optical path. Therefore, there is an urgent need for a mechanism used in a coronagraph that can quickly switch observation channels without the need for optical assembly each time. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a filter wheel mechanism for a coronagraph, which can realize rapid switching of six different observation channels, avoiding the reassembly of different lenses according to different observation requirements, and the mechanism has the advantages of high switching positioning accuracy, fast switching speed, and long service life.

[0004] The filter wheel mechanism for a coronagraph provided by the present invention comprises: a housing formed by connecting a focal plane mounting plate and a filter wheel frame, a filter wheel, and a filter wheel shaft system;

[0005] Wherein, a group of observation holes with corresponding positions are provided on the focal plane mounting plate and the filter wheel frame;

[0006] The filter wheel is arranged in the housing, and comprises a wheel disc and a plurality of groups of lenses with different functions arranged along the circumference of the wheel disc;

[0007] The filter wheel shaft system is connected to the filter wheel frame. The filter wheel shaft system includes a first gear driven by a power mechanism, a filter wheel shaft, and a second gear fixed on the filter wheel shaft. The first gear meshes with the second gear, and the wheel disc is sleeved on the filter wheel shaft.

[0008] Preferably, the observation hole on the focal plane mounting plate is connected to the focal plane device of the coronagraph, and the observation hole on the filter wheel frame is connected to the optical system.

[0009] Preferably, three filters, two polarizers and one full-intensity filter are evenly arranged on the wheel.

[0010] Preferably, the functional lens is fixed on the wheel disc through a mounting assembly, the mounting assembly includes a lens seat, a pressure ring, and an adjustment gasket, the functional lens is pressed into the lens seat through the pressure ring, and the adjustment gasket is padded between the lens seat and the wheel disc.

[0011] Preferably, the mirror base has a plurality of stress unloading grooves along the circumference.

[0012] Preferably, the filter wheel frame is provided with a power unit mounting hole and a filter wheel shaft mounting hole, and coplanar power unit mounting surfaces, shaft system mounting surfaces and optical system mounting surfaces are provided on the outside of the power unit mounting hole, the outside of the filter wheel shaft mounting hole and the observation hole on the filter wheel frame.

[0013] Preferably, the power mechanism is a stepper motor, and the stepper motor is mounted on the power unit mounting surface via a motor pad.

[0014] Preferably, the gear ratio between the first gear and the second gear is 1:3.

[0015] Preferably, the filter wheel shaft system further comprises a shaft system support cylinder mounted on the shaft system mounting surface, and the filter wheel shaft is arranged in the shaft system support cylinder via an angular contact bearing.

[0016] Preferably, a photoelectric encoder for recording the output of the second gear is also provided at the rear end of the filter wheel shaft.

[0017] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0018] The present invention is applied to the rapid switching of the observation channels of the coronagraph. The filter wheel is driven to rotate by a motor and a transmission gear pair to realize the rapid switching of lenses with different functions. The motor output is subdivided and decelerated by the transmission gear pair, and a photoelectric encoder is provided to count the output, thereby effectively improving the switching positioning accuracy. The filter wheel mechanism of the present invention has a compact structure, and the size and weight of the whole machine are both small. The envelope size of the prepared prototype is only 240mm×230mm×100mm, and the total weight is 2Kg.

[0019] The present invention mounts lenses with different functions on a wheel disc via a lens holder, and a stress unloading groove is provided on the lens holder, thereby reducing the influence of temperature load on the surface shape of the functional lens.

[0020] The filter wheel shaft system of the present invention adopts P4 grade precision bearing for transmission, the small gear material is 40Cr, the large gear material is tin bronze, the stepping motor and the photoelectric encoder are both customized aerospace grade products, which effectively improves the on-orbit service life of the whole machine and can meet the long-life requirement of 5 years of on-orbit operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a structural diagram of a filter wheel mechanism provided according to an embodiment of the present invention;

[0022] Figure 2 is a general appearance diagram of a filter wheel mechanism provided according to an embodiment of the present invention;

[0023] Figure 3 is a schematic diagram of the inner and outer sides of a filter wheel frame provided according to an embodiment of the present invention;

[0024] Figure 4 is a structural diagram of a filter wheel shaft system according to an embodiment of the present invention;

[0025] Figure 5 is a general appearance diagram of a filter wheel shaft system provided according to an embodiment of the present invention;

[0026] Figure 6 is a structural diagram of a filter wheel provided according to an embodiment of the present invention;

[0027] Figure 7 is a cross-sectional view of a filter assembly provided according to an embodiment of the present invention;

[0028] Figure 8 is a structural diagram of a mirror holder provided according to an embodiment of the present invention.

[0029] Reference numerals include:

[0030] Filter wheel 100, filter wheel shaft system 200, focal plane mounting plate 300, filter wheel frame 400, wheel disc 1, filter assembly 2, polarizing plate assembly 3, full-intensity plate assembly 4;

[0031] Mirror base 11, pressing ring 12, filter 13, adjusting gasket 14;

[0032] The second gear 21, the shaft support tube 22, the filter wheel shaft 23, the angular contact bearing 24, the first gear 25, the gear block 26, the motor pad 27, the stepping motor 28, the bearing spacer 29, the bearing outer ring pressure ring 30, the bearing inner ring pressure ring 31, the encoder retaining ring 32, the photoelectric encoder 33, and the encoder seat 34;

[0033] Observation hole 40, power unit mounting surface 41, shaft system mounting surface 42, optical system mounting surface 43, focal plane mounting surface 44, outrigger mounting surface 45;

[0034] The filter wheel shaft mounting surface 50 and the stress unloading groove 51 . DETAILED DESCRIPTION

[0035] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same modules are represented by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, the detailed description thereof will not be repeated.

[0036] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0037] Please see Figure 1 and Figure 2 In one embodiment of the present invention, a filter wheel mechanism for a coronagraph is provided, and its structure mainly includes: a filter wheel 100, a filter wheel shaft system 200, a focal plane mounting plate 300 and a filter wheel frame 400, wherein the filter wheel frame 400 is the installation base of the entire mechanism, and the focal plane mounting plate 300 and the filter wheel frame 400 constitute the shell of the entire mechanism. The focal plane mounting plate 300 and the filter wheel frame 400 are overall in the shape of an arch, and the focal plane mounting plate 300 and the filter wheel frame 400 are connected along the edge by screws. A group of observation holes 40 corresponding in position are provided on the focal plane mounting plate 300 and the filter wheel frame 400, and a focal plane device mounting surface is ground on the outer side of the observation hole 40 on the focal plane mounting plate 300, and the focal plane device of the coronagraph is connected to the focal plane device mounting surface by screws. Please see for details. Figure 3 The outer side of the observation hole 40 on the filter wheel frame 400 is also ground to form an optical system mounting surface 43, and the optical system at the front end is connected to the optical system mounting surface 43 by screws. In addition, a power unit mounting hole and a filter wheel shaft mounting hole are also opened on the filter wheel frame 400, and a power unit mounting surface 41 and a shaft system mounting surface 42 are correspondingly provided on the outer side of the power unit mounting hole and the outer side of the filter wheel shaft mounting hole. The power unit mounting surface 41, the shaft system mounting surface 42 and the optical system mounting surface 43 are installed using three surfaces with a common reference. The coplanar design is conducive to grinding and ensuring the accuracy requirements. The inner side of the filter wheel frame 400 is ground to form a focus plate mounting surface 44 and a leg mounting surface 45. The focus plate mounting surface 44 is directly in contact with and connected to the focus plane mounting plate 300, and the leg mounting surface 45 is used to install the legs, thereby fixing the filter wheel mechanism.

[0038] Please see Figure 4 and Figure 5The filter wheel shaft system 200 is composed of a power mechanism and a rotating shaft structure, wherein the power mechanism adopts a customized aerospace-grade stepper motor 28 to improve the service life of the filter wheel mechanism. The stepper motor 28 is the power source for the filter wheel mechanism to switch channels. A motor pad 27 is fixed on the stepper motor 28. The stepper motor 28 is fixed on the power unit mounting surface 41 of the filter wheel frame 400 through the motor pad 27. The position of the motor pad 27 can be adjusted up and down to adjust the center distance between the first gear 25 and the second gear 21. The gear stopper 26 and the first gear 25 are coaxially mounted on the output shaft of the stepper motor 28 in sequence, and the first gear 25 is fixed by a flat-end top screw. The shaft structure mainly includes a second gear 21, a shaft support cylinder 22, a filter wheel shaft 23, an angular contact bearing 24, a photoelectric encoder 33 and an encoder seat 34. The shaft structure is installed on the shaft support cylinder 22, and the shaft support cylinder 22 is fixed to the shaft installation surface 42 of the filter wheel frame 400 by screws. Two angular contact bearings 24 are also installed back to back in the shaft support cylinder 22. The model of the two angular contact bearings 24 is 7005AC, and its precision is P4 level. A bearing spacer 29 is installed between the two angular contact bearings 24, and the filter wheel shaft 23 is coaxially installed on the inner ring of the angular contact bearing 24. The front end and the rear end of the shaft support tube 22 are respectively provided with a bearing outer ring pressure ring 30 and a bearing inner ring pressure ring 31. The bearing outer ring pressure ring 30 and the bearing inner ring pressure ring 31 are connected to the shaft support tube 22 through threads to press and position the two angular contact bearings 24, and the preload force of the angular contact bearing 24 can be adjusted through the bearing inner ring pressure ring 31 to achieve precise rotation of the bearing. The rear end of the filter wheel shaft 23 is coaxially installed with an encoder seat 34 and a photoelectric encoder 33 in sequence. The outer ring fixed end of the photoelectric encoder 33 is connected to the encoder seat 34, and the inner ring rotating shaft of the photoelectric encoder 33 is connected to the filter wheel shaft 23 through the encoder retaining ring 32. The photoelectric encoder 33 can be used to record the rotation amount of the filter wheel shaft 23. The second gear 21 is fixed to the front end of the filter wheel shaft 23 by a flat-end top screw. The second gear 21 has more teeth than the first gear 25. The output of the stepper motor 28 is decelerated by the gear pair formed by the first gear 25 and the second gear 21, thereby improving the switching accuracy of the whole machine. In the embodiment of the present invention, the gear ratio of the first gear 25 to the second gear 21 is 1:3, that is, the reduction ratio of the gear pair is 1:3. The material for preparing the first gear 25 is preferably 40Cr, and the material for preparing the second gear 21 is preferably tin bronze.

[0039] In addition, the filter wheel 100 is coaxially mounted on the front end of the filter wheel shaft 23, and the filter wheel 100 is driven to rotate by the rotation of the filter wheel shaft 23 to switch the observation channel. Figure 6The filter wheel 100 mainly includes a wheel disc 1 and a plurality of groups of different functional lenses. A through hole is provided at the center of the wheel disc 1, and a filter wheel shaft mounting surface 50 is provided at the edge of the through hole. The wheel disc 1 is mounted on the front end of the filter wheel shaft 23 by screws.

[0040] According to the observation requirements of the coronagraph, in this embodiment, three filter assemblies 2, two polarizer assemblies 3 and one full-strength plate assembly 4 are evenly arranged along the circumference of the wheel 1. The lenses in the three filter assemblies 2 have different filtering bands, the lenses in the two polarizer assemblies 3 have different polarization directions, and the angle between adjacent functional lenses is 60 degrees. Except for the functional lenses, the mounting components of the filter assemblies 2, polarizer assemblies 3 and full-strength plate assembly 4 all adopt the same structure. The following only takes the structure of the filter assembly 2 as an example to describe the structure of the mounting components of each functional lens. For details, please refer to Figure 7 The mounting assembly includes a lens seat 11, a pressure ring 12 and an adjusting gasket 14. The lens seat 11 is annular, and one end opening of the lens seat 11 is designed as a stepped slot structure. The filter 13 is coaxially mounted in the lens seat 11, and the filter 13 is pressed tightly in the lens seat 11 by applying threaded glue to the pressure ring 12, and an adjusting gasket 14 is arranged at the mounting position of the lens seat 11 and the wheel 1. The adjusting gasket 14 is arranged between the lens seat 11 and the wheel 1. The position of the filter 13 can be adjusted by adjusting the gasket 14 during installation. After adjustment, the filter assembly 2 is fixed to the corresponding position of the wheel 1 by screws and pins.

[0041] Please see Figure 8 As a preferred embodiment, the lens holder 11 has three strip-shaped stress unloading grooves 51 along the circumferential direction. The stress unloading grooves 51 can effectively reduce the influence of the temperature load on the surface shape of the functional lens in the lens holder 11.

[0042] During the coronagraph observation process, the filter wheel mechanism is arranged between the focal plane of the coronagraph and the front-end optical system. The stepper motor 28 drives the gear pair to switch the functional lens corresponding to the observation hole 40, thereby realizing the rapid switching of the observation channel. Specifically, each time the stepper motor 28 rotates, the filter wheel 100 is driven to rotate 60 degrees, thereby switching a group of functional lenses located at the observation hole 40 to meet different observation requirements. The process is simple to operate, has a fast switching speed, and a high switching positioning accuracy, and can fully meet the existing coronagraph observation requirements.

[0043] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

[0044] The above specific implementations of the present invention do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A filter wheel mechanism for a coronagraph, It is characterized in that include: A housing formed by connecting a focal plane mounting plate and a filter wheel frame, as well as a filter wheel and a filter wheel shaft system; Wherein, a group of observation holes with corresponding positions are provided on the focal plane mounting plate and the filter wheel frame; The filter wheel is arranged in the housing, and comprises a wheel disc and a plurality of groups of lenses with different functions arranged along the circumference of the wheel disc; The filter wheel shaft system is connected to the filter wheel frame, and the filter wheel shaft system includes a first gear driven by a power mechanism, a filter wheel shaft, and a second gear fixed on the filter wheel shaft, the first gear is meshed with the second gear, and the wheel disc is sleeved on the filter wheel shaft.

2. The filter wheel mechanism for a coronagraph as claimed in claim 1, It is characterized in that The observation hole on the focal plane mounting plate is communicated with the focal plane device of the coronagraph, and the observation hole on the filter wheel frame is communicated with the optical system.

3. The filter wheel mechanism for a coronagraph as claimed in claim 1, It is characterized in that The wheel is evenly arranged with three filters, two polarizing plates and a full-intensity plate.

4. The filter wheel mechanism for a coronagraph as claimed in claim 1, It is characterized in that The functional lens is fixed on the wheel disc through a mounting assembly, which includes a lens seat, a pressure ring, and an adjustment gasket. The functional lens is pressed into the lens seat through the pressure ring, and the adjustment gasket is padded between the lens seat and the wheel disc.

5. The filter wheel mechanism for a coronagraph as claimed in claim 4, It is characterized in that The mirror base has a plurality of stress unloading grooves formed along the circumference.

6. The filter wheel mechanism for a coronagraph as claimed in claim 1, It is characterized in that The filter wheel frame is provided with a power unit mounting hole and a filter wheel shaft mounting hole, and coplanar power unit mounting surfaces, shaft system mounting surfaces and optical system mounting surfaces are correspondingly provided on the outside of the power unit mounting hole, the outside of the filter wheel shaft mounting hole and the observation hole on the filter wheel frame.

7. The filter wheel mechanism for a coronagraph as claimed in claim 6, It is characterized in that The power mechanism is a stepper motor, which is mounted on the power unit mounting surface via a motor pad.

8. The filter wheel mechanism for a coronagraph as claimed in claim 1, It is characterized in that The gear ratio between the first gear and the second gear is 1:

3.

9. The filter wheel mechanism for a coronagraph as claimed in claim 6, It is characterized in that The filter wheel shaft system further comprises a shaft system support cylinder mounted on the shaft system mounting surface, and the filter wheel shaft is arranged in the shaft system support cylinder through an angular contact bearing.

10. The filter wheel mechanism for a coronagraph as claimed in claim 6, It is characterized in that The rear end of the filter wheel shaft is also provided with a photoelectric encoder for recording the output of the second gear.

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