Optical delay line in Fizeau type optical synthetic aperture imaging system

Abstract

The invention discloses an optical delay line in a Fizeau type optical synthetic aperture imaging system. The Fizeau type optical synthetic aperture imaging system comprises a simulation light source subsystem, a sub-aperture variable baseline subsystem, a light combination imaging delay line, a light combination imaging subsystem, a light combination imaging variable baseline subsystem, a first optical path detection subsystem, a second optical path detection subsystem and the like. Wherein optical delay lines in the first optical path detection subsystem and the second optical path detection subsystem are consistent in structure, composition, function and performance, are symmetrically arranged on two sides of the system, and form an angle of + 49.1 degrees / -49.1 degrees with the horizontal plane; the optical delay line is applied to an optical path detection subsystem in a Fizeau type optical synthetic aperture imaging system composed of four sub-apertures, and is obliquely arranged relative to the horizontal plane, so that each optical path detection telescope can measure three optical path detection light beams at the same time; two sets of symmetrically arranged optical path detection subsystems are set up in the system, so that four-beam optical path difference detection can be realized, and the detection efficiency is high.

Description

Technical Field

[0001] The invention relates to the technical field of astronomical observation, and in particular to an optical delay line in a Fizeau type optical synthetic aperture imaging system. Background Art

[0002] Optical synthetic aperture technology is a technology that precisely arranges multiple optical elements or optical systems of smaller apertures so that the light beams passing through each sub-aperture can achieve coherent superposition of the light field on the focal plane, and after image restoration processing, achieve a diffraction-limited resolution equivalent to that of a single large-aperture system. Depending on whether the combined light path in the optical synthetic aperture imaging system is constrained, it can be distinguished into Fizeau type, Michelson type, and Hyper telescope type. The Fizeau type interference imaging system has the advantages of instantaneous imaging, high imaging efficiency, and a large field of view, but the technical requirements for its implementation are also higher. The entrance pupil baseline of the Fizeau type interference imaging system forms a similar polygon to the combined light imaging baseline, and the reduction ratio is the magnification of the sub-aperture. At the same time, there is a consistency requirement for the magnification of each sub-aperture, which is related to the imaging field of the system. The larger the field of view, the higher the consistency requirement. It is also required that each light beam interferes and superimposes with equal phase (i.e., zero optical path difference) on the image plane. ‌ The existing methods and means are as follows: 1. The CHARA array telescope at the Mount Wilson Observatory in California, USA, consists of six 1m telescopes with a baseline range from 34m to 331m. Its delay line is a horizontal motion stage with a cat's eye reflector. The motion stage performs large-stroke motion. The light beam passes through the cat's eye structure to ensure that the directions of the incident light and the reflected light are consistent. The optical delay line is arranged horizontally, so no mass balance mechanism is required.

[0003] 2. The wide-field imaging interferometry (WIIT) device established by NASA contains two 25mm sub-apertures installed at both ends of a horizontally placed linear air-floating translation stage. The baseline range is from 25mm to 250mm. Its optical delay line is arranged horizontally, so no mass balance mechanism is required.

[0004] 3. The National Astronomical Observatory of the Chinese Academy of Sciences designed and built a Fizeau imaging interferometer test device (FIIT), which includes three 100mm sub-apertures in a Golay-3 distribution (equilateral triangle). The baseline is fixed and cannot be adjusted. The optical delay line in the combined light beam is arranged horizontally and includes four reflectors. No mass balance mechanism is required. The optical delay line in the optical path detection subsystem has an angle of 30° with the horizontal plane and includes a beam splitter prism. However, since the optical delay line in the optical path detection subsystem uses a piezoelectric inertial drive translation stage instead of an air-floating translation stage, a mass balance device is not required.

[0005] 4. Harbin Institute of Technology has designed an antenna gravity unloading device. The load antenna is driven by a drive mechanism and a two-axis turntable to simulate earth observation and tracking movements. When the load antenna moves horizontally, the linear motor of the suspension mechanism drives the air flotation system to follow; when the load antenna moves vertically, the electric cylinder of the suspension mechanism is extended and retracted to complete the vertical following movement. Since the antenna experimental area is large and there is sufficient space, a horizontal motion guide rail and an electric cylinder can be set above the antenna, and a balancing mass block can be used to form a gravity unloading device. When the antenna moves or pitches, the horizontal air flotation guide rail and the electric cylinder will be displaced accordingly to balance the changing gravity position and torque of the antenna in real time.

[0006] 5. Shanghai Jiao Tong University has designed a ground adaptive gravity compensation system for large-scale deployable space structures based on suspended air cushions. The air-floating gravity compensation device is connected to the antenna plate to compensate for the gravity of the antenna plate. It floats above the ground and is affected by the unevenness of the ground. The force change has the characteristics of time-varying and uncertainty. Fuzzy PID control strategy and multi-point force-position separation coordination control strategy are proposed. The support points are interconnected and independently adjustable to jointly maintain the constant force compensation system of the antenna plate. Since there is sufficient space under the large-scale deployable space structure, an air-floating gravity compensation system with a control system can be designed.

[0007] Disadvantages of existing technology: (1) At present, the optical delay lines of the aperture of existing optical synthetic aperture imaging systems at home and abroad are mostly arranged horizontally, and do not require a mass balancing mechanism. Even if there are inclined optical path detection optical delay lines in some systems, they mostly use piezoelectric inertial drive translation stages or mechanical motion stages, which also do not require a mass balancing mechanism.

[0008] (2) Systems and devices involving mass balancing mechanisms in other fields are mostly large equipment with ample space. Active motion mechanisms can be designed to balance the gravity of the equipment and the torque generated by gravity. However, mass balancing mechanisms that include active motion mechanisms have disadvantages such as complex structure, high cost, large space occupied, and complex control.

[0009] (3) There is no precedent for the use of an inclined air-floating guide in the optical delay line of the optical path detection subsystem in the existing Fizeau type optical synthetic aperture imaging system. Correspondingly, there is no precedent for the use of a follow-up mass balance mechanism for the inclined air-floating guide in the optical delay line of the optical path detection subsystem.

[0010] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to those skilled in the art. Summary of the invention

[0011] In view of the problems existing in the prior art, the purpose of the present invention is to provide an optical delay line in a Fizeau type optical synthetic aperture imaging system. The system includes four sub-apertures, and correspondingly has four combined light imaging beams. The interference superposition of the four combined light imaging beams at equal phase (i.e., zero optical path difference) on the image plane is crucial to the imaging effect of the Fizeau type interference imaging system. Since the Fizeau type interference imaging system involved in the present invention includes four combined light imaging beams, two sets of three-beam optical path detection subsystems with consistent structure, function and performance are designed to realize fast and efficient detection of the optical path difference of the four combined light beams. The two sets of optical path detection subsystems are symmetrically arranged on both sides of the system. In order to meet the relationship of 1:2 between the center distances of the three optical path detection beams, the two sets of optical path detection subsystems need to be arranged at an angle of +49.1° / -49.1° to the horizontal plane. When the combined light imaging baseline length changes, the three optical path detection beams in the optical path detection subsystem also need to meet the equal optical path condition, and the dispersion fringes generated by the three beams after passing through the AMICI prism have a good degree of overlap.

[0012] In order to achieve the above object, the present invention adopts the following technical solutions: An optical delay line in a Fizeau type optical synthetic aperture imaging system, the Fizeau type optical synthetic aperture imaging system comprising: an analog light source subsystem, a subaperture variable baseline subsystem, a combined light imaging delay line, a combined light imaging subsystem, a combined light imaging variable baseline subsystem, a first optical path detection subsystem and a second optical path detection subsystem; wherein, The optical delay lines in the first optical path detection subsystem and the second optical path detection subsystem have the same structure, composition, function and performance, and are symmetrically arranged on both sides of the system, with an angle of +49.1° / -49.1° to the horizontal plane; the combined imaging beam, the combined imaging beam, the combined imaging beam and the combined imaging beam enter the first optical path detection subsystem and the second optical path detection subsystem after passing through the beam splitting prism, among which three combined imaging beams enter the first optical path detection subsystem, the three combined imaging beams interfere with each other after passing through the AMICI prism and the optical path detection telescope, and the three combined imaging beams enter the second optical path detection subsystem, and the three combined imaging beams interfere with each other after passing through the AMICI prism and the optical path detection telescope.

[0013] Furthermore, the first optical path detection subsystem or the second optical path detection subsystem includes a 40mm voice coil displacement stage, a 24mm voice coil displacement stage, a first piezoelectric displacement stage, a second piezoelectric displacement stage, a first two-mirror structure, a second two-mirror structure, a third two-mirror structure, a 40mm voice coil displacement stage follow-up mass balance device, a 24mm voice coil displacement stage follow-up mass balance device, a 40mm voice coil displacement stage support mechanism, and a 24mm voice coil displacement stage support mechanism.

[0014] Furthermore, the 40mm voice coil displacement platform follow-up mass balance device includes a counterweight hook, a counterweight rope, a counterweight block and a slideway; the 24mm voice coil displacement platform follow-up mass balance device includes a counterweight hook, a counterweight rope, a counterweight block and a limit groove.

[0015] Furthermore, the first optical path detection subsystem and the second optical path detection subsystem are respectively installed on two linear air-floating displacement platforms with an angle of +30° / -30° with the horizontal plane; the 40mm voice coil displacement platform is connected to the linear air-floating displacement platform through a 40mm voice coil displacement platform support mechanism, the 24mm voice coil displacement platform is connected to the same linear air-floating displacement platform through a 24mm voice coil displacement platform support mechanism, and the second two-mirror structure is installed on another linear air-floating displacement platform; the 40mm voice coil displacement platform, the 24mm voice coil displacement platform, and the second two-mirror structure as a whole move simultaneously with the linear air-floating displacement platform light-combining imaging variable baseline movement.

[0016] Further, the first piezoelectric displacement stage is installed on the 40mm voice coil displacement stage, and the second piezoelectric displacement stage is installed on the 24mm voice coil displacement stage. After the linear air floating displacement stage performs the light combining imaging variable baseline movement, the 40mm voice coil displacement stage and the 24mm voice coil displacement stage perform the optical path adjustment movement of the large-stroke optical path detection branch along + / -49.1° with the horizontal plane. At this time, the first piezoelectric displacement stage and the second piezoelectric displacement stage follow up. After the movement of the 40mm voice coil displacement stage and the 24mm voice coil displacement stage stops, the first piezoelectric displacement stage and the second piezoelectric displacement stage perform the optical path detection branch equal optical path real-time closed-loop operation.

[0017] By adopting the above technical solution, the present invention has the following beneficial effects: The optical delay line involved in the present invention is applied to the optical path detection subsystem of the optical delay line in a Fizeau type optical synthetic aperture imaging system composed of four sub-apertures. The arrangement inclined with respect to the horizontal plane can enable each optical path detection telescope to measure three optical path detection beams at the same time. Two sets of symmetrically arranged optical path detection subsystems are built in the system to realize the detection of the optical path difference of four beams, and the detection efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is an overall structural diagram of the optical delay line in the Fizeau type optical synthetic aperture imaging system of the present invention.

[0020] Figure 2 This is a layout diagram of the optical path detection subsystem of the present invention.

[0021] Figure 3 This is a structural diagram of an optical delay line in an optical path detection subsystem of the present invention.

[0022] Figure 4 This is a schematic diagram of the principle of adjusting the optical path difference compensation of three light beams by the large and small voice coil displacement stages of the present invention.

[0023] Figure 5 It is a force diagram of the follow-up mass balance device of the voice coil displacement platform of the present invention. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0026] Combination Figure 1-3 As shown, an optical delay line in a Fizeau type optical synthetic aperture imaging system proposed by the present invention is characterized in that the Fizeau type optical synthetic aperture imaging system comprises: an analog light source subsystem 1, a subaperture variable baseline subsystem 2, a combined light imaging delay line 3, a combined light imaging subsystem 4, a combined light imaging variable baseline subsystem 5, a first optical path detection subsystem 6 and a second optical path detection subsystem 7; wherein, The optical delay lines in the first optical path detection subsystem 6 and the second optical path detection subsystem 7 have the same structure, composition, function and performance, and are symmetrically arranged on both sides of the system, with an angle of +49.1° / -49.1° to the horizontal plane; the combined imaging beams 8, 9, 10 and 11 enter the first optical path detection subsystem 6 and the second optical path detection subsystem 7 after passing through the beam splitter prism, wherein the combined imaging beams 8, 9 and 10 enter the first optical path detection subsystem 6, and the combined imaging beams 8, 9 and 10 interfere with each other after passing through the AMICI prism and the optical path detection telescope support, and the combined imaging beams 8, 9 and 11 enter the second optical path detection subsystem 7, and the combined imaging beams 8, 9 and 11 interfere with each other after passing through the AMICI prism and the optical path detection telescope support. After the four combined imaging beams 8-11 pass through six beam splitter prisms, the six reflected lights enter the two sets of optical path detection subsystems as optical path detection branches.

[0027] The first optical path detection subsystem 6 or the second optical path detection subsystem 7 includes a 40mm voice coil displacement stage 12, a 24mm voice coil displacement stage 13, a first piezoelectric displacement stage 14, a second piezoelectric displacement stage 15, a first two-mirror structure 16, a second two-mirror structure 17, a third two-mirror structure 18, a 40mm voice coil displacement stage follow-up mass balance device 19, a 24mm voice coil displacement stage follow-up mass balance device 24, a 40mm voice coil displacement stage support mechanism 29 and a 24mm voice coil displacement stage support mechanism 30. The 40mm voice coil displacement stage follow-up mass balance device 19 includes a counterweight hook 20, a counterweight rope 21, a counterweight block 22 and a slide 23; the 24mm voice coil displacement stage follow-up mass balance device 24 includes a counterweight hook 25, a counterweight rope 26, a counterweight block 27 and a limit groove 28.

[0028] The force and moment of the load of the 40mm voice coil displacement stage are balanced by the follow-up mass balance device 19 of the 40mm voice coil displacement stage. The counterweight hook 20 is installed on the 40mm voice coil displacement stage support mechanism 29. One end of the counterweight rope 21 is connected to the load of the voice coil displacement stage, and the other end is connected to the counterweight block 22. The counterweight block 22 is placed on the slideway 23 for sliding, and the sliding direction is consistent with the movement direction of the voice coil displacement stage, parallel and opposite. The force and moment of the load of the 24mm voice coil displacement stage are balanced by the follow-up mass balance device 24 of the 24mm voice coil displacement stage. The counterweight hook 25 is installed on the 24mm voice coil displacement stage support mechanism 30. One end of the counterweight rope 26 is connected to the load of the voice coil displacement stage, and the other end is connected to the counterweight block 27. The counterweight block 27 is placed in the vertical limit groove 28 for sliding, and the sliding direction is vertical. The follow-up mass balance device 19 of the 40mm voice coil displacement stage and the follow-up mass balance device 24 of the 24mm voice coil displacement stage are unpowered devices, which follow the extension and retraction of the movement axes of the 40mm voice coil displacement stage 12 and the 24mm voice coil displacement stage 13 respectively.

[0029] In this embodiment, the first optical path detection subsystem 6 and the second optical path detection subsystem 7 are respectively installed on two linear air-floating displacement platforms with an angle of +30° / -30° with the horizontal plane; the 40mm voice coil displacement stage 12 is connected to the linear air-floating displacement stage through the 40mm voice coil displacement stage support mechanism 29, the 24mm voice coil displacement stage 13 is connected to the same linear air-floating displacement stage through the 24mm voice coil displacement stage support mechanism 30, and the second two-mirror structure 17 is installed on another linear air-floating displacement stage; the 40mm voice coil displacement stage 12, the 24mm voice coil displacement stage 13, and the second two-mirror structure 17 move as a whole simultaneously with the linear air-floating displacement stage light-combining imaging variable baseline movement.

[0030] The first piezoelectric displacement stage 14 is installed on the 40mm voice coil displacement stage 12, and the second piezoelectric displacement stage 15 is installed on the 24mm voice coil displacement stage 13. After the linear air floating displacement stage performs the light combining imaging variable baseline movement, the 40mm voice coil displacement stage 12 and the 24mm voice coil displacement stage 13 perform the long-stroke optical path detection branch equal optical path adjustment movement along the horizontal plane + / -49.1°. At this time, the first piezoelectric displacement stage 14 and the second piezoelectric displacement stage 15 follow-up. After the movement of the 40mm voice coil displacement stage 12 and the 24mm voice coil displacement stage 13 stops, the first piezoelectric displacement stage 14 and the second piezoelectric displacement stage 15 perform the optical path detection branch equal optical path real-time closed-loop work.

[0031] The working principle of the present invention is as follows: Combination Figure 4-5 As shown in the figure, after the linear air-floating displacement stage performs the variable baseline movement for combined light imaging in the Fizeau interferometric imaging system, the equal optical path conditions of the three beams in the optical path detection subsystem are destroyed. The three beams can be adjusted to the equal optical path after the large-stroke movement of the 40mm and 24mm voice coil displacement stages. After that, the piezoelectric displacement stage can overcome the environmental disturbance through real-time closed-loop adjustment to achieve real-time equal optical path conditions for the three beams.

[0032] The adjustment stroke of the 40mm and 24mm voice coil translation stages is related to the variable baseline motion stroke of the linear air-floating translation stage for combined light imaging. The calculation process is as follows: Points a, b, and c represent the beam splitters on the three combined imaging beams in the same optical path detection subsystem. The three beams after passing through the beam splitter prism are the optical path detection branches, which are recorded as 9, 8, and 11. After the combined imaging beam changes its baseline length, the beam splitter prism position becomes a', b', and c', and the corresponding three beam optical path detection branches are recorded as 9', 8', and 11'. The principle of the combined imaging beam after the baseline is changed is the same as the former, so beams 9, 8, and 11 are taken as examples for calculation. Since the beam splitter prism b is closer to the AMICI prism, the optical path of beam 8 is shorter, so it is necessary to move it through the voice coil translation stage so that the optical path of beams 9 and 11 to the AMICI prism is consistent with that of beam 8.

[0033] Long-stroke voice coil stage travel: L 大 =L ac cos30°cos49.1° / 2 Small stroke voice coil stage movement: L 大 =L ac sin0°sin49.1° / 2 Where, L ac It is the baseline length of the combined imaging beam, which is also the sub-aperture baseline length / sub-aperture angle magnification.

[0034] The control parameters of the real-time closed-loop control of the piezoelectric translation stage are derived from the real-time detection of the three-beam dispersion interference fringes by the optical path detection camera and the real-time calculation of the three-beam optical path difference by the computer. Since the voice coil translation stage has modulated the three-beam optical path difference close to 0 and the linear air-floating translation stage has completed the variable baseline movement at this time, the piezoelectric translation stage only needs to compensate for the three-beam optical path difference caused by environmental disturbance in real time.

[0035] The follow-up mass balance device of the large and small stroke voice coil stage is the key to ensure that the air-floating axis of the voice coil stage can perform telescopic movement, and at the same time, it is required to ensure that the pitch angle error of the movement is small enough to achieve the overlap of the three-beam dispersion interference fringes. The design process of the follow-up mass balance device is as follows: The component F of the gravity of the shaft and its load along the axis of motion 分 =G×sin49.1° The shaft and its load gravity G are known. The distance d from the centroid of the sleeve to the centroid of the shaft is known. Shaft torque T = G × cos49.1° × d Axis travel S, known The vertical distance L from the contact point between the counterweight rope and the shaft to the centroid of the sleeve is known to be Assume that the torque provided by the cable is equal to the torque of the shaft and its load when the shaft is extended to the maximum and minimum, respectively: The tension on the weight rope F 拉 =G×sin49.1° / cosθ The angle between the weight rope and the axis movement direction is θ = arcsin (T / F 拉 / L) The vertical distance from the pull point to the pulley when the shaft is extended to the longest (to ensure that the torque provided by the pull rope is equal when the extension is the longest and shortest) X = tanθ1×S / (sinθ2-tanθ1) When the vertical height between the wheel and the pulling point is h=0.025: Assume that the vertical distance from the contact point of the counterweight rope and the shaft to the pulley (the longest extension of the shaft) is X=0.025 At this time, the angle between the counterweight rope and the direction of shaft movement (h is the median of the height when the shaft is extended to the minimum and maximum) θ = arctan(0.004374 / (X+S) At this time, the torque provided by the counterweight rope is T'=F 拉 ×sinθ×L The component F of the pulling force in the direction of the motion axis 拉分 = F 拉 ×cosθ Overcoming residual F 分 Required voice coil motor thrust F 推 =F 分 -F拉分 <Voice coil motor rated thrust F 额 .

[0036] The theoretical values ​​of θ, X and F can be obtained through the above calculations. However, in the above theoretical analysis, it is assumed that the centroid of the sleeve is the axis and the rotation center of its load remains unchanged. Therefore, in the actual follow-up mass balancing device, it is necessary to design manually adjustable degree and millimeter margins for θ and X values ​​to adapt to the theoretical calculation errors caused by the assumptions.

[0037] The working process of the present invention is as follows: Taking one optical path detection subsystem as an example, the working process of another subsystem is the same.

[0038] 1) After the four sub-apertures perform variable baseline movement, the corresponding four combined light imaging beams perform variable baseline movement, and the stroke is the change amount of the entrance pupil baseline of the four sub-apertures / sub-aperture angle magnification. The combined light imaging baseline and the entrance pupil baseline form a similar rectangle; 3) When the 4-beam combined imaging beams move with variable baselines, the linear air-floating displacement stage will drive the delay line in the optical path detection subsystem to move, which will destroy the equal optical path conditions of the 3-beam optical path detection branches. At this time, 2 beams (upper and lower beams) of the 3-beam optical path detection branches will be driven by their respective voice coil displacement stages through the two-mirror mechanism to adjust the 3-beam optical path detection branches to equal optical path. The equal optical path adjustment of the upper beam is achieved by the 40mm voice coil displacement stage, while the equal optical path adjustment of the lower beam is achieved by the 24mm voice coil displacement stage. The specific movement amount is obtained from the above calculation results.

[0039] 4) At the same time, with the assistance of the follow-up mass balance device, the dispersion interference fringes of the three optical path detection branches after passing through the AMICI prism are ensured to remain overlapped on the optical path detection camera; 5) Afterwards, the optical path difference is calculated in real time using the interference fringes on the optical path detection camera, and the piezoelectric displacement stage is controlled in real time through an automatic control program to compensate for the unequal optical path of the three micrometer-level optical path detection branches caused by environmental fluctuations.

[0040] In summary, compared with the prior art, the present invention has the following innovative features: 1) The optical delay line of the present invention is applied to the optical path detection subsystem of the optical delay line in the Fizeau type optical synthetic aperture imaging system composed of four sub-apertures. The arrangement inclined with respect to the horizontal plane enables each optical path detection telescope to measure three optical path detection beams at the same time. Two sets of symmetrically arranged optical path detection subsystems are built in the system to realize the detection of the optical path difference of four beams, and the detection efficiency is high. 2) The optical delay line involved in the present invention is composed of a large-stroke voice coil air-floating displacement stage (low frequency and low speed) and a small-stroke piezoelectric displacement stage (high frequency and high speed), which can solve the problem of unequal optical paths of the three optical path detection beams caused by changes in the combined light imaging baseline, and can also solve the problem of unequal optical paths of the three optical path detection beams caused by environmental and system fluctuations; 3) The voice coil air-floating displacement stage used in the optical delay line of the present invention is matched with a follow-up mass balance device, which can simultaneously achieve the advantages of long travel, high resolution, high positioning accuracy, and low pitch angle error, and can meet the equal optical path conditions of the three optical path detection beams while also meeting the overlap conditions of the dispersion interference fringes after passing through the AMICI prism; 4) The follow-up mass balance device of the optical delay line involved in the present invention occupies less space, has a simple structure, and uses mature components. It does not require an active motion mechanism and a complex control system to meet the functional and performance requirements of the optical delay line, saving space, cost, and difficulty.

[0041] Compared with the prior art, the present invention has the following outstanding technical effects: 1) The technology involved is relatively mature and easy to implement. At present, the manufacturing and application technology of piezoelectric displacement stage, voice coil motor and air floating guide rail is relatively mature at home and abroad, and the feasibility and reliability of this invention are relatively high; 2) Strong versatility. The invention is generally applicable to Fizeau-type spatially distributed synthetic aperture imaging systems or optical systems that require both long-stroke high precision and short-stroke high response for tilted delay lines or systems that require two-stage tilt motion; 3) Strong applicability. The invention can be extended to two-stage tilt motion systems that require both large stroke and high precision and small stroke and high response; 4) High cost performance. The invention can achieve its functions and performance by using mature parts, fewer motion mechanisms and devices, smaller space, lower cost and difficulty; 5) High precision. The tilting optical delay line with a follow-up mass balance device has a travel of up to 40mm, a resolution of up to 2nm, a positioning accuracy of up to 10nm, and a pitch angle error as low as tens of microradians; 6) High safety. The follow-up mass balance device follows the slow, large-stroke voice coil displacement stage and is not connected to the high-response piezoelectric displacement stage, which can avoid the disturbance caused by the high-frequency operation of the piezoelectric displacement stage and the impact on the optical path detection accuracy.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An optical delay line in a Fizeau type optical synthetic aperture imaging system, characterized in that: The Fizeau type optical synthetic aperture imaging system comprises: an analog light source subsystem (1), a subaperture variable baseline subsystem (2), a combined light imaging delay line (3), a combined light imaging subsystem (4), a combined light imaging variable baseline subsystem (5), a first optical path detection subsystem (6) and a second optical path detection subsystem (7); wherein: The optical delay lines in the first optical path detection subsystem (6) and the second optical path detection subsystem (7) have the same structure, composition, function and performance, and are symmetrically arranged on both sides of the system, with an angle of +49.1° / -49.1° with respect to the horizontal plane; the combined imaging beams (8), (9), (10) and (11) enter the first optical path detection subsystem (6) and the second optical path detection subsystem (7) after passing through the beam splitting prism, wherein the combined imaging beams (8), (9) and (10) enter the first optical path detection subsystem (6), and the combined imaging beams (8), (9) and (10) interfere with each other after passing through the AMICI prism and the optical path detection telescope; and the combined imaging beams (8), (9) and (11) enter the second optical path detection subsystem (7), and the combined imaging beams (8), (9) and (11) interfere with each other after passing through the AMICI prism and the optical path detection telescope.

2. The optical delay line in the Fizeau type optical synthetic aperture imaging system according to claim 1, characterized in that: The first optical path detection subsystem (6) or the second optical path detection subsystem (7) comprises a 40 mm voice coil displacement stage (12), a 24 mm voice coil displacement stage (13), a first piezoelectric displacement stage (14), a second piezoelectric displacement stage (15), a first two-mirror structure (16), a second two-mirror structure (17), a third two-mirror structure (18), a 40 mm voice coil displacement stage follow-up mass balance device (19), a 24 mm voice coil displacement stage follow-up mass balance device (24), a 40 mm voice coil displacement stage support mechanism (29), and a 24 mm voice coil displacement stage support mechanism (30).

3. The optical delay line in the Fizeau type optical synthetic aperture imaging system according to claim 2, characterized in that: The 40 mm voice coil displacement platform follow-up mass balance device (19) comprises a counterweight hook (20), a counterweight rope (21), a counterweight block (22) and a slideway (23); the 24 mm voice coil displacement platform follow-up mass balance device (24) comprises a counterweight hook (25), a counterweight rope (26), a counterweight block (27) and a limit groove (28).

4. The optical delay line in the Fizeau type optical synthetic aperture imaging system according to claim 2, characterized in that: The first optical path detection subsystem (6) and the second optical path detection subsystem (7) are respectively mounted on two linear air-floating displacement platforms with an angle of +30° / -30° to the horizontal plane; the 40mm voice coil displacement platform (12) is connected to the linear air-floating displacement platform via a 40mm voice coil displacement platform support mechanism (29); the 24mm voice coil displacement platform (13) is connected to the same linear air-floating displacement platform via a 24mm voice coil displacement platform support mechanism (30); and the second two-mirror structure (17) is mounted on another linear air-floating displacement platform; the 40mm voice coil displacement platform (12), the 24mm voice coil displacement platform (13), and the second two-mirror structure (17) move as a whole simultaneously with the linear air-floating displacement platform light-combining imaging variable baseline movement.

5. The optical delay line in the Fizeau type optical synthetic aperture imaging system according to claim 2, characterized in that: The first piezoelectric displacement stage (14) is installed on the 40mm voice coil displacement stage (12), and the second piezoelectric displacement stage (15) is installed on the 24mm voice coil displacement stage (13). After the linear air-floating displacement stage performs light-combination imaging variable baseline movement, the 40mm voice coil displacement stage (12) and the 24mm voice coil displacement stage (13) perform a long-stroke optical path detection branch equal optical path adjustment movement along an angle of + / -49.1° with the horizontal plane. At this time, the first piezoelectric displacement stage (14) and the second piezoelectric displacement stage (15) perform follow-up. After the 40mm voice coil displacement stage (12) and the 24mm voice coil displacement stage (13) stop moving, the first piezoelectric displacement stage (14) and the second piezoelectric displacement stage (15) perform an optical path detection branch equal optical path real-time closed-loop operation.

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