A long-focus telephoto type television wide-temperature optical axis stability passive compensation mechanism

Abstract

The application relates to the technical field of precise optical machine system design, in particular to a long-focus telephoto type television wide-temperature optical axis stability passive compensation mechanism, which comprises an optical machine lens assembly, the optical machine lens assembly is externally sleeved with an integrated support matched with the optical machine lens assembly, the integrated support is fixedly arranged on a mounting bottom plate, and the rear end of the optical machine lens assembly is fixedly connected with a detector assembly; the front end of the integrated support is fixedly connected with the optical machine lens assembly, the rear end of the integrated support is slidably connected with the optical machine lens assembly, and a reserved gap is arranged between the rear end surface of the integrated support and the front end surface of the detector assembly; the compensation mechanism is applied to a television camera, axial deformation stress between the optical machine lens assembly and the integrated support caused by structural mechanical characteristic differences of the long-focus telephoto type television under a wide-temperature range can be effectively offset, and the wide-temperature optical axis stability is improved.

Description

Technical Field

[0001] This invention relates to the field of precision optomechanical system design technology, and in particular to a passive compensation mechanism for wide-temperature optical axis stability for long-focal-length telephoto televisions. Background Technology

[0002] As the core sensing component of a high-precision stabilization system, the optical axis stability of a television camera directly affects the pointing accuracy of the stabilization system. In practical applications, traditional television cameras have their lens barrels fixed to the mounting base via flanges at the front and rear, respectively, before being connected to the optical bench of the stabilization system. The optical axis stability of these cameras is affected by changes in the internal ambient temperature. Especially in complex application scenarios such as outdoor, high-altitude, or industrial sites, the ambient temperature can fluctuate significantly between high and low temperatures. This wide temperature range variation causes changes in the spatial position and surface shape of optical elements and their mounting structures under the influence of thermo-structural coupling stress, resulting in optical axis misalignment and severely affecting the accuracy of target observation and positioning. Particularly for telephoto television cameras, whose main lens barrels are typically elongated structures with a larger front and smaller rear, the traditional method of fixing them with front and rear flanges to the base plate restricts the axial extension and contraction freedom of the elongated main lens barrel. After temperature changes, the main lens barrel is prone to deformation, causing changes in the spatial position and surface shape of the internally mounted front positive lens group and rear negative lens group, thus resulting in optical axis misalignment. Therefore, in order to ensure that the television optical axis maintains good stability over a wide temperature range, effective compensation measures must be taken to suppress or eliminate this thermally induced offset.

[0003] Currently, most existing optical axis stability compensation measures employ active compensation mechanisms. For example, Chinese Patent Publication No. CN115933097A, entitled "A Lightweight, High-Precision Two-Dimensional Flexible Optical Axis Compensation Mechanism and Method," discloses a scheme that uses two one-dimensional linear transmission mechanisms respectively mounted in the horizontal and vertical directions of a flexible compensation mechanism. Micro-motion in the horizontal and vertical directions is achieved through a flexible compensation base, and position telemetry feedback is provided by two angle sensors, thereby realizing optical axis offset compensation. However, such active compensation mechanisms typically require drive motors, sensors, and complex control systems, resulting in problems such as complex structure, high cost, reliance on external control commands, and significant impact on system reliability from electronic components and the control system.

[0004] Therefore, there is an urgent need to design a passive mechanical structure that enables telephoto televisions to adapt to wide temperature range changes and maintain optical axis stability without the need for external energy and complex control. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a passive compensation mechanism for the optical axis stability of long-telephoto televisions with a wide temperature range. It has a simple structure, requires no external power, and has high reliability. It can solve the technical problem that the optical axis of long-telephoto televisions is offset due to the thermal deformation difference between optical elements and mounting structure components in a wide temperature range, which in turn reduces the pointing accuracy of high-precision stabilization systems.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention proposes a passive compensation mechanism for wide-temperature optical axis stability in telephoto televisions, comprising an optical-mechanical lens assembly. An integrated bracket is fitted around the optical-mechanical lens assembly and is fixedly mounted on a mounting base. The rear end of the optical-mechanical lens assembly is fixedly connected to a detector assembly. The front end of the integrated bracket is fixedly connected to the optical-mechanical lens assembly, and the rear end is slidably connected to the optical-mechanical lens assembly. A pre-reserved gap is provided between the rear end face of the integrated bracket and the front end face of the detector assembly.

[0008] Furthermore, the width of the reserved gap △X≥△X1+△X2, where △X1=|X1-X2|; △X2=|X3-X4|, X1 and X2 are the axial changes of the optical-mechanical lens assembly and the integrated bracket at the highest operating temperature, and X3 and X4 are the axial changes of the optical-mechanical lens assembly and the integrated bracket at the lowest operating temperature.

[0009] Furthermore, 1.05×(△X1+△X2)≤△X≤1.3×(△X1+△X2).

[0010] Furthermore, the width of the reserved gap is calculated through optomechanical-thermal joint simulation.

[0011] Furthermore, the front end of the integrated bracket is engaged with the optical engine lens assembly through a shaft hole, and the engagement point between the front end of the integrated bracket and the optical engine lens assembly is fixed with a first fastener.

[0012] Furthermore, the rear end of the integrated bracket is fitted with the optical engine lens assembly via a shaft hole.

[0013] Furthermore, the rear end of the optical-mechanical lens assembly is connected to the detector assembly via a shaft hole, and the mating point between the optical-mechanical lens assembly and the detector assembly is fixed with a second fastener.

[0014] Furthermore, the operating temperature of the compensation mechanism is -43℃ to 70℃.

[0015] Furthermore, the mounting base and integrated bracket are made of the same material as the lens barrel in the optical engine lens assembly.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] (1) In this invention, the optical-mechanical lens assembly is fixed on the mounting base plate by an integrated bracket. The integrated bracket is fitted onto the optical-mechanical lens assembly, with the front end fixedly connected to the optical-mechanical lens assembly and the rear end not fixedly connected to the optical-mechanical lens assembly. The rear end face of the optical-mechanical lens assembly is fixedly connected to the detection component. A reserved gap is provided between the rear end face of the integrated bracket and the front end face of the detection component. Compared with the traditional installation method of the lens assembly, this invention has a simple structure, low cost, and high reliability. Without relying on motors, sensors, or complex control systems, the lens barrel can be freely released in the axial direction without being constrained by its installation structure. The reserved gap can effectively offset the axial deformation stress between the optical-mechanical lens assembly and the integrated bracket caused by the difference in structural mechanical characteristics under a wide temperature range.

[0018] (2) The optical-mechanical lens assembly and the integrated bracket of the present invention are fitted with shaft holes at both the front and rear. The rear end face of the optical-mechanical lens assembly and the detection component are also fitted with shaft holes. This effectively limits the radial change of the optical-mechanical lens assembly relative to the integrated bracket, avoids the lens barrel from bending and deforming due to axial stress, and ensures the radial stiffness and stability of the optical axis. This effectively guarantees the dual stability of the optical axis in both the radial and axial directions, and reduces the axial deformation factors that cause optical axis deviation from the source.

[0019] (3) The present invention calculates the width △X of the preset gap based on the optical-mechanical-thermal joint simulation, with high compensation accuracy. This ensures that the gap value can not suppress deformation under extreme high and low temperatures, and will not introduce unnecessary assembly errors or shaking due to excessive gap. This accurately ensures the stability of the optical axis of the optical-mechanical lens assembly in the full temperature range. Through experimental verification, it can achieve a high-precision index of optical axis offset of less than 5 pixels (X and Y directions).

[0020] (4) The detector assembly and the optomechanical lens assembly of the present invention are fixedly connected by fasteners at the joint, so that the two deform synchronously in the temperature field and become a thermally coupled whole. This greatly reduces the impact of temperature fluctuations on the back focus of the optical system, ensures the stability of the relative position of the imaging target surface and the optical image surface, and thus makes the imaging quality of the system stable over a wide operating temperature range. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the compensation mechanism of the present invention;

[0022] Figure 2 This is an exploded view of the compensation mechanism of the present invention;

[0023] Figure 3 This is a schematic diagram showing the connections between the various components of the compensation mechanism of the present invention;

[0024] Figure 4 for Figure 3 A magnified view of a section at point A in the middle;

[0025] Figure 5 This is a schematic diagram illustrating the calculation principle of △X in this invention;

[0026] Figure 6 This is a schematic diagram of the optical axis offset of the optical-mechanical lens assembly;

[0027] Figure 7 Images showing the optical axis shift of television camera A at different temperatures;

[0028] Figure 8 Photos showing the optical axis shift of television camera B at different temperatures;

[0029] Reference numerals: 1. Optical-mechanical lens assembly; 101. Lens barrel; 102. Front positive lens group; 103. Rear negative lens group; 2. Integrated bracket; 3. Detector assembly; 301. Target surface; 4. Mounting base plate; 5. First fastener; 6. Second fastener; 7. Third fastener; 8. Optical axis before the shift; 9. Optical axis after the shift. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the protection scope of the present invention.

[0031] Example

[0032] refer to Figures 1 to 4This embodiment proposes a passive compensation mechanism for wide-temperature optical axis stability in telephoto televisions, including an optical-mechanical lens assembly 1. An integrated bracket 2 is fitted around the optical-mechanical lens assembly 1 and cooperates with it. The integrated bracket 2 is fixedly mounted on a mounting base plate 4 by a third fastener 7. The mounting base plate 4 is fixedly mounted on the optical bench of the aiming system. The rear end of the optical-mechanical lens assembly 1 is fixedly connected to a detector assembly 3. The optical-mechanical lens assembly 1 includes a lens barrel 101. The integrated bracket 2 is fitted onto the lens barrel 101. The lens barrel 101 cooperates with the integrated bracket 2 and the detector assembly 3. Inside the lens barrel 101, a front positive lens group 102 and a rear negative lens group 103 are fixedly arranged according to optical relationships. In this embodiment, the focal length of the optical-mechanical lens assembly 1 is 480mm. During operation, the optical axis passes through the front positive lens group 102 and the rear negative lens group 103 and reaches the target surface of the detector assembly 3. In traditional television cameras, the optical axis is located at the exact center of the target surface at room temperature (20℃). However, with temperature variations over a wide temperature range, the spatial position and surface shape of the optical elements and their mounting structures change under the influence of thermal-structural coupling stress, causing the optical axis to shift. This severely affects the accuracy of target observation and positioning. A schematic diagram of the optical axis shift can be found here. Figure 6 Before the shift, the optical axis 8 is located at the center of the target surface 301. After the shift, the optical axis 9 will deviate from the center of the target surface 301. In this embodiment, the front end of the integrated bracket 2 is fixedly connected to the optical-mechanical lens assembly 1, and the rear end is slidably connected to the optical-mechanical lens assembly 1. A reserved gap is provided between the rear end face of the integrated bracket 2 and the front end face of the detector assembly 3. This allows the optical-mechanical lens assembly 1 to be unconstrained by the integrated bracket 2 in the axial direction and to be freely released, effectively offsetting the axial deformation stress between the optical-mechanical lens assembly 1 and the integrated bracket 2 caused by differences in structural mechanical characteristics under a wide temperature range. In this embodiment, the optical-mechanical lens assembly 1 is also fixedly connected to the detector assembly 3 to minimize the impact of temperature fluctuations on the back focus of the optical system and ensure stable imaging quality of the television camera over a wide operating temperature range.

[0033] refer to Figure 5 , Figure 5In the diagram, (a) shows the relative positions of the optical-mechanical lens assembly 1 and the integrated bracket 2 at room temperature; (b) shows the relative positions of the optical-mechanical lens assembly 1 and the integrated bracket 2 at the highest operating temperature; and (c) shows the relative positions of the optical-mechanical lens assembly 1 and the integrated bracket 2 at the lowest operating temperature. The width of the reserved gap, ΔX, is ≥ ΔX1 + ΔX2, where ΔX1 = |X1 - X2| and ΔX2 = |X3 - X4|. X1 represents the axial change of the optical-mechanical lens assembly 1 at the highest operating temperature, X2 represents the axial change of the integrated bracket 2 at the highest operating temperature, X3 represents the axial change of the optical-mechanical lens assembly 1 at the lowest operating temperature, and X4 represents the axial change of the integrated bracket 2 at the lowest operating temperature. The width of the reserved gap, ΔX, is preferably calculated through a combined optical-mechanical-thermal simulation. ΔX is scientifically quantified to ensure that the design of the compensation mechanism meets the needs of actual application scenarios. For convenience, during the calculation, it can be assumed that the rear end face of the optical-mechanical lens assembly 1 is flush with the rear end face of the integrated bracket 2 at room temperature.

[0034] The value of △X is preferably 1.05 to 1.3 times the sum of △X1 and △X2. This ensures that deformation is not suppressed under extreme high and low temperatures, and avoids unnecessary assembly errors or shaking due to excessive gaps, thus accurately guaranteeing the stability of the optical axis of the optical-mechanical lens assembly 1 in the entire temperature range.

[0035] To further ensure the reliability of the compensation mechanism, the preferred operating temperature of the compensation mechanism in this embodiment is -43℃ to 70℃, that is, the minimum operating temperature is -43℃ and the maximum operating temperature is 70℃. The mounting base 4, integrated bracket 2, and lens barrel 101 can be made of the same material or different materials. In this embodiment, the mounting base 4, integrated bracket 2, and lens barrel 101 are all made of 7075 aviation aluminum. Through optomechanical-thermal joint simulation calculations, ΔX1 = 0.37mm and ΔX2 = 0.42mm were obtained, and ΔX was set to 0.85mm.

[0036] To effectively ensure the dual stability of the optical axis of the optical-mechanical lens assembly 1 in both the radial and axial directions, in the above embodiment, the front and rear ends of the integrated bracket 2 are respectively engaged with the optical-mechanical lens assembly 1 through shaft holes, and the rear end of the optical-mechanical lens assembly 1 is also connected to the detector assembly 3 through a shaft hole. Furthermore, the engagement point between the front end of the integrated bracket 2 and the optical-mechanical lens assembly 1 is fixed with a first fastener 5, and the engagement point between the optical-mechanical lens assembly 1 and the detector assembly 3 is fixed with a second fastener 6, while the engagement point between the rear end of the integrated bracket 2 and the optical-mechanical lens assembly 1 is not fixed. The shaft hole engagement ensures both the radial stability of the optical-mechanical lens assembly 1 and its free axial release.

[0037] To minimize the impact of the integrated bracket 2 on the optical axis stability, the integrated bracket 2 can be set as follows: Figure 2 The hollow structure shown minimizes the impact of changes in the axial direction of the integrated bracket 2 on the stability of the optical axis.

[0038] In this embodiment, the first fastener 5, the second fastener 6, and the third fastener 7 can all be screws, or other fasteners available on the market that meet the usage requirements.

[0039] To better illustrate the beneficial effects of the present invention, the inventors tested the optical axis stability of the television camera A equipped with the above embodiment 1, and also tested the optical axis stability of a conventional television camera B. The only difference between television camera B and television camera A is that television camera B does not contain an integrated bracket 2; the front and rear parts of the optical engine lens assembly 1 are directly fixedly connected to the mounting base plate 4 via flanges. The specific test method is as follows:

[0040] The television camera under test was placed in a high and low temperature test chamber with an optical window. The camera was pointed through the optical window at a collimator outside the chamber, and the optical axis (pointing to the crosshair) of the camera was aligned with the crosshair of the collimator. The optical axis deviation at room temperature was recorded as (0, 0). The temperature inside the high and low temperature test chamber was adjusted to the preset temperature and maintained at that temperature for one hour. The deviation between the optical axis (pointing to the crosshair) of the camera and the crosshair of the collimator was observed and recorded. The test results are shown in Table 1.

[0041] Table 1. Test results of optical axis stability of television cameras

[0042]

[0043] Figure 7 (a) is a photograph showing the optical axis shift of television camera A at 20°C; (b) is a photograph showing the optical axis shift of television camera A at -43°C; and (c) is a photograph showing the optical axis shift of television camera A at 70°C. Figure 8 (a) is a photograph showing the optical axis shift of television camera B at 20°C; (b) is a photograph showing the optical axis shift of television camera B at -43°C; and (c) is a photograph showing the optical axis shift of television camera B at 70°C. (See reference.) Figure 7 , Figure 8 As shown in Table 1, the television camera equipped with the compensation structure proposed in this invention exhibits good stability of the optical axis across the entire operating temperature range, achieving a high-precision specification of less than 5 pixels (in both the X and Y directions) for optical axis offset.

[0044] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0045] It should be understood that the present invention is not limited to the content already described above, and modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A passive compensation mechanism for wide-temperature optical axis stability in long-focal-length telephoto televisions, characterized in that, The system includes an optical-mechanical lens assembly (1), which is fitted with an integrated bracket (2) that cooperates with it. The integrated bracket (2) is fixedly mounted on the mounting base plate (4). The rear end of the optical-mechanical lens assembly (1) is fixedly connected to the detector assembly (3). The front end of the integrated bracket (2) is fixedly connected to the optical-mechanical lens assembly (1), and the rear end is slidably connected to the optical-mechanical lens assembly (1). A reserved gap is provided between the rear end face of the integrated bracket (2) and the front end face of the detector assembly (3).

2. The passive compensation mechanism for wide-temperature optical axis stability of long-focal-length telephoto televisions according to claim 1, characterized in that, The width of the reserved gap △X≥△X1+△X2, where △X1=|X1-X2|; △X2=|X3-X4|, X1 and X2 are the axial changes of the optical-mechanical lens assembly (1) and the integrated bracket (2) at the highest operating temperature, and X3 and X4 are the axial changes of the optical-mechanical lens assembly (1) and the integrated bracket (2) at the lowest operating temperature.

3. The passive compensation mechanism for wide-temperature optical axis stability of long-focal-length telephoto televisions according to claim 2, characterized in that, 1.05×(△X1+△X2)≤△X≤1.3×(△X1+△X2).

4. The passive compensation mechanism for wide-temperature optical axis stability of long-focal-length telephoto televisions according to claim 1, characterized in that, The width of the reserved gap was calculated through a combined optical-mechanical-thermal simulation.

5. The passive compensation mechanism for wide-temperature optical axis stability of long-focal-length telephoto televisions according to claim 1, characterized in that, The front end of the integrated bracket (2) is engaged with the optical-mechanical lens assembly (1) through a shaft hole, and the engagement point between the front end of the integrated bracket (2) and the optical-mechanical lens assembly (1) is fixed by a first fastener (5).

6. The passive compensation mechanism for wide-temperature optical axis stability of long-focal-length telephoto televisions according to claim 1, characterized in that, The rear end of the integrated bracket (2) is engaged with the optical engine lens assembly (1) through a shaft hole.

7. The passive compensation mechanism for wide-temperature optical axis stability of long-focal-length telephoto televisions according to claim 1, characterized in that, The rear end of the optical-mechanical lens assembly (1) is connected to the detector assembly (3) through a shaft hole, and the joint between the optical-mechanical lens assembly (1) and the detector assembly (3) is fixed by a second fastener (6).

8. The passive compensation mechanism for wide-temperature optical axis stability of long-focal-length telephoto televisions according to claim 1, characterized in that, The operating temperature of the compensation mechanism is -43℃ to 70℃.

9. The passive compensation mechanism for wide-temperature optical axis stability of long-focal-length telephoto televisions according to claim 1, characterized in that, The materials of the mounting base plate (4) and the integrated bracket (2) are the same as those of the lens barrel (101) in the optical engine lens assembly (1).

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