A method for adjusting the axial spacing between lenses of a zoom infrared lens

Abstract

A method for adjusting the axial spacing between lenses in a zoom infrared lens is disclosed. This method utilizes a tooling glass and measures the spacing between the tooling lenses using a depth micrometer to determine the distance between the mounting surfaces of adjacent lenses. Based on the measurement results, shims are adjusted to ensure the required axial spacing of the optical system. This disclosure achieves high-precision adjustment of the axial spacing between infrared lens lenses, and the operation is simple and convenient. The tooling glass is made entirely of flat glass, which is simple to process and has high dimensional accuracy.

Description

Technical Field

[0001] This invention relates to the fields of mechanical and optical technologies, and in particular to a method for adjusting the axial spacing between lenses in a zoom infrared lens. Background Technology

[0002] With the development of science and technology, infrared imaging technology has been widely used in national defense, industry, medicine and other fields. Infrared detection has a certain ability to penetrate smoke, fog, haze and snow, as well as the ability to identify camouflage. It is not blinded by strong battlefield light or flashes, and can achieve long-distance, all-weather observation. It is especially suitable for target detection at night and under adverse weather conditions.

[0003] In complex environments, focal length can be affected by various factors, leading to unclear imaging and affecting the normal operation of the detector. For example, the axial spacing between lenses in an optical system is a crucial indicator affecting the system. If the axial spacing of the lenses does not meet the requirements of the optical system during assembly, it will significantly reduce the optical imaging quality, resulting in blurry images, decreased contrast, and ultimately affecting imaging performance.

[0004] Therefore, how to easily and efficiently adjust the axial spacing between lens elements is a problem that needs to be explored in depth in this field at present. Summary of the Invention

[0005] This disclosure provides a method for adjusting the axial spacing between lenses in a zoom infrared lens, which can simply and efficiently adjust the axial spacing between lenses.

[0006] The zoom infrared lens disclosed herein includes: a front lens barrel (1), a main lens barrel (2), a focusing cam (3), a zoom lens frame (4), a zoom centering carriage assembly (5), a compensation lens frame (6), a compensation centering carriage assembly (7), a rear main lens barrel (8), a focusing cam (9), and other structural components. Inside the lens barrel, along the direction of light incidence, there are sequentially arranged a front lens (10), a zoom lens (11), a compensation lens (12), a rear fixed lens (13), and a focusing lens (14).

[0007] During installation, the front lens (10) is installed into the front lens barrel (1) using a centering process; the zoom lens (11) is installed into the zoom lens frame (4) using a centering process; the compensation lens (12) is installed into the compensation lens frame (6) using a centering process; the rear fixed lens (13) is installed into the rear main lens barrel (8) using a centering process; the focusing lens (14) is installed into the rear main lens barrel (8) using a centering process; and the zoom lens frame (4) is installed into the guide rail of the main lens barrel (2) using guide pins. The compensation lens frame (5) is installed in the guide rail groove of the main lens barrel (2) and the guide rail groove of the focusing cam (3) through the guide pin assembly. The focusing group lens (14) is installed in the guide rail groove of the rear main lens barrel (8) and the guide rail groove of the focusing cam (9) through the guide pin assembly. Through the rotational movement of the focusing cam (3) and the focusing cam (9), the zoom lens (11), the compensation lens (12) and the focusing group lens (14) are driven to make linear movement, thereby realizing the zoom function of the infrared lens.

[0008] Among them, except for the focusing lens (14), the axial spacing of the other adjacent lenses has high precision requirements, including: between the front lens (10) and the zoom lens (11), between the zoom lens (11) and the compensation lens (12), and between the compensation lens (12) and the rear fixed lens (13).

[0009] To address the axial spacing design requirements of these optical systems, this disclosure, taking into account the assembly manufacturability of optical components, proposes a method for assembling and adjusting zoom lenses. Specifically, it includes the following steps:

[0010] S1: Process the corresponding tooling glass according to the size and shape of the front lens (10), the zoom lens (11), the compensation lens (12), and the rear fixed lens (13);

[0011] S2: Install each piece of tooling glass into the corresponding lens mounting position in turn, and measure the distance from the front end face of the front lens to the front end face of each tooling glass.

[0012] S3: Based on these distance values ​​and the thickness of each tooling glass, calculate the actual interval between the corresponding lenses;

[0013] S4: Compare the measured interval with the theoretical value and adjust the thickness of the lens spacer that does not meet the requirements; the theoretical value is the theoretical value of the interval between the mounting surfaces of each lens, obtained according to the axial interval index requirements of adjacent lenses, the structure of the optical system and the measured value of the lens itself.

[0014] S5: Install the lens and gasket in sequence to complete the assembly.

[0015] Furthermore, the tooling glass is processed using flat glass.

[0016] Further, step S2 specifically includes:

[0017] S21: Assemble the front lens barrel (1) and the front lens fixture glass (15), record the thickness of the front lens fixture glass (15) as c1, and measure the distance δ1 from the front end face of the front lens to the front end face of the front lens fixture glass (15).

[0018] S22: Remove the front lens fixture glass (15), assemble the front lens barrel (1), main lens barrel (2), focusing cam (3), zoom lens frame (4), and zoom lens fixture glass (16), rotate the focusing cam (3) to the left limit position, record the thickness of the zoom lens fixture glass (16) as c2, and measure the distance δ2 from the front end face of the front lens to the front end face of the zoom lens fixture glass (16).

[0019] S23: Remove the zoom lens frame (4) and zoom lens fixture glass (15), install the compensation lens frame (5) and compensation lens fixture glass (17), record the thickness of the compensation lens fixture glass (17) as c3, and measure the distance δ3 from the front end face of the front lens to the front end face of the compensation lens fixture glass (17).

[0020] S24: Remove the compensating frame (5) and the compensating lens fixture glass (17), install the rear main lens barrel (8) and the rear fixed lens fixture glass (18), record the thickness of the rear fixed lens fixture glass (18) as c3, and measure the distance δ4 from the front end face of the front lens to the front end face of the rear fixed lens fixture glass (18).

[0021] Furthermore, a depth micrometer was used to measure the distance from the front end face of the front lens group to the front end face of each tooling glass.

[0022] Furthermore, step S3 specifically includes:

[0023] Calculations were made based on the obtained measurement data:

[0024] Distance between the mounting surface of the front lens and the mounting surface of the zoom lens: L1=δ2-δ1-c1+c2;

[0025] Distance between the mounting surface of the zoom lens and the mounting surface of the compensation lens: L2=δ3-δ2-c2;

[0026] Distance between the mounting surface of the compensating lens and the mounting surface of the rear fixed lens: L3=δ4-δ3+c4.

[0027] Furthermore, in step S4, adjusting the thickness of the gasket includes:

[0028] The adjustment value of the lens shim to be installed later is determined based on the difference between the measured value and the theoretical value.

[0029] Adjust the shim thickness by replacing it with a thicker one or by polishing it, according to the adjustment value.

[0030] In this calculation, the accuracy of the data source for each set of data values ​​is higher than 0.01 mm, and the calculation results are reliable.

[0031] This disclosure uses tooling glass and directly measures the spacing between tooling lenses to obtain the distance between the mounting surfaces of two adjacent lenses. Based on the measurement results, the shims are adjusted to ensure the axial spacing requirements of the optical system. Compared with the prior art, the beneficial effects of this disclosure are: (1) it achieves high-precision assembly and adjustment of the axial spacing between infrared lens lenses; (2) it is simple and convenient to operate; (3) the tooling glass is all made of flat glass, which is simple to process and has high dimensional accuracy. Attached Figure Description

[0032] The above and other objects, features and advantages of this disclosure will become more apparent from the more detailed description of exemplary embodiments of this disclosure taken in conjunction with the accompanying drawings, in which the same reference numerals generally represent the same components.

[0033] Figure 1 A schematic diagram of a zoom infrared lens to which this disclosure applies;

[0034] Figure 2 This diagram illustrates the axial spacing requirements between lenses in an optical system.

[0035] Figure 3 This is a schematic diagram of the measurement.

[0036] Figure 4 This is a diagram illustrating the relevant parameters of the lens;

[0037] Figure 5 Here is a flowchart of the assembly and adjustment method according to this disclosure;

[0038] Among them, 1-front lens barrel, 2-main lens barrel, 3-focusing cam, 4-zoom lens frame, 5-zoom centering carriage assembly, 6-compensation lens frame, 7-compensation centering carriage assembly, 8-rear main lens barrel, 9-focusing cam, 10-front lens, 11-zoom lens, 12-compensation lens, 13-rear fixed lens and 14-focusing lens, 15-front lens fixture glass, 16-zoom lens fixture glass, 17-compensation lens fixture glass, 18-rear fixed lens fixture glass, 19-zoom adjustment pad, 20-compensation adjustment pad, 21-rear fixed group adjustment pad. Detailed Implementation

[0039] Preferred embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0040] As attached Figure 1 As shown, this is a zoom infrared lens designed in this disclosure, including a front lens barrel (1), a main lens barrel (2), a focusing cam (3), a zoom lens frame (4), a zoom centering carriage assembly (5), a compensation lens frame (6), a compensation centering carriage assembly (7), a rear main lens barrel (8), a focusing cam (9), and other structural components. Inside the lens barrel, along the light incident direction, there are sequentially arranged a front lens (10), a zoom lens (11), a compensation lens (12), a rear fixed lens (13), and a focusing lens (14).

[0041] According to the optical system design requirements, the axial spacing between the front lens (10) and the zoom lens (11) is required to be 41.04±0.02 (mm), the axial spacing between the zoom lens (11) and the compensation lens (12) is required to be 44.02±0.02 (mm), the axial spacing between the compensation lens (12) and the rear fixed lens (13) is required to be 27.83±0.02 (mm), and the axial spacing between the rear fixed lens (13) and the focusing lens (14) is required to be 46.71 (mm). Except for the focusing lens (14), the axial spacing of the other adjacent lenses has high precision requirements. Figure 2 As shown.

[0042] According to the axial spacing adjustment method between infrared lens elements disclosed herein, such as Figure 5 As shown, the steps are as follows:

[0043] S101, according to the size and shape of the front lens (10), the zoom lens (11), the compensation lens (12), and the rear fixed lens (13), process the corresponding front lens fixture glass (15), zoom lens fixture glass (16), compensation lens fixture glass (17), and rear fixed lens fixture glass (18).

[0044] S102, Determination of theoretical values. This relates to the theoretical spacing of the structural design and the measured values ​​from the lens manufacturing process itself.

[0045] The theoretical values ​​of the distances between the mounting surfaces of the front lens and the zoom lens, the zoom lens and the compensating lens, and the compensating lens and the rear fixed lens are related to the measured values ​​of the rear end face sag of the front lens (10), the thickness of the zoom lens, and the thickness of the compensating lens, such as... Figure 4As shown. If the theoretical value of the sagitta of the rear end face of the front lens is 5.65mm, the theoretical value of the distance between the front lens mounting surface and the zoom lens mounting surface is 36.32mm. However, there will always be dimensional tolerances in the front lens. Let the measured value of the sagitta of the rear end face of the front lens be (5.65±a)mm, then the theoretical value of the distance between the front lens mounting surface and the zoom lens mounting surface is... Similarly, if the measured thickness of the zoom lens is (3.5±a) mm, then the theoretical distance between the mounting surface of the zoom lens and the mounting surface of the compensation lens is (46.2±a)±0.01 mm; similarly, if the measured thickness of the compensation lens is (5±a) mm, then the theoretical distance between the mounting surface of the zoom lens and the mounting surface of the compensation lens is (44.18±a)±0.01 mm.

[0046] S103, assemble the front lens barrel (1) and the front lens fixture glass (15), record the thickness of the front lens fixture glass (15) as c1, and measure the distance δ1 from the front end face of the front lens to the front end face of the front lens fixture glass (15) using a depth micrometer. Figure 3 As shown;

[0047] S104, remove the front lens fixture glass (15), assemble the front lens barrel (1), main lens barrel (2), focusing cam (3), zoom lens frame (4), and zoom lens fixture glass (16), rotate the focusing cam (3) to the left limit position, record the thickness of the zoom lens fixture glass (16) as c2, and measure the distance δ2 from the front end face of the front lens to the front end face of the zoom lens fixture glass (16) using a depth micrometer.

[0048] S105, remove the zoom lens frame (4) and zoom lens fixture glass (15), install the compensation lens frame (5) and compensation lens fixture glass (17), record the thickness of the compensation lens fixture glass (17) as c3, and use a depth micrometer to measure the distance δ3 from the front end face of the front lens group to the front end face of the compensation lens fixture glass (17).

[0049] S106, remove the compensating frame (5) and the compensating lens fixture glass (17), install the rear main lens barrel (8) and the rear fixed lens fixture glass (18), record the thickness of the rear fixed lens fixture glass (18) as c3, and use a depth micrometer to measure the distance δ4 from the front end face of the front lens to the front end face of the rear fixed lens fixture glass (18).

[0050] S107, the following calculations are made based on the measurement data from the above steps:

[0051] Distance between the mounting surface of the front lens and the mounting surface of the zoom lens: L1=δ2-δ1-c1+c2;

[0052] Distance between the mounting surface of the zoom lens and the mounting surface of the compensation lens: L2=δ3-δ2-c2;

[0053] Distance between the mounting surface of the compensating lens and the mounting surface of the rear fixed lens: L3=δ4-δ3+c4;

[0054] S108, compare the measured values ​​and theoretical values ​​of each distance obtained in step S107.

[0055] If the distance (L1) between the mounting surface of the front lens and the mounting surface of the zoom lens deviates from the theoretical value, the theoretical value of the distance between the mounting surface of the front lens and the mounting surface of the zoom lens can be ensured by grinding or replacing the thicker zoom adjustment shim (19).

[0056] If the distance (L2) between the mounting surface of the zoom lens and the mounting surface of the compensation lens deviates from the theoretical value, the theoretical value (46.2±a)±0.01mm of the distance between the mounting surface of the zoom lens and the mounting surface of the compensation lens can be ensured by grinding or replacing the thicker compensation adjustment shim (20).

[0057] If the distance (L3) between the mounting surface of the compensating lens and the mounting surface of the rear fixed lens deviates from the theoretical value, the theoretical value (44.18±a)±0.01mm of the distance between the mounting surface of the compensating lens and the mounting surface of the rear fixed lens can be ensured by grinding or replacing the thicker rear fixed assembly adjustment shim (21).

[0058] S109: Assemble the ground adjustment pads and each group of lenses according to the assembly drawings, and test the focal length of the infrared lens to ensure it meets the usage requirements.

[0059] The above technical solutions are merely exemplary embodiments of the present invention. For those skilled in the art, based on the application methods and principles disclosed in the present invention, it is easy to make various types of improvements or modifications, and not limited to the methods described in the specific embodiments of the present invention. Therefore, the methods described above are merely preferred and not restrictive.

Claims

1. A method for adjusting the axial spacing between lenses in a zoom infrared lens, the zoom infrared lens comprising a front lens barrel (1), a main lens barrel (2), a focusing cam (3), a zoom lens frame (4), a zoom centering carriage assembly (5), a compensation lens frame (6), a compensation centering carriage assembly (7), a rear main lens barrel (8), and a focusing cam (9), wherein the lens barrel is provided with a front lens (10), a zoom lens (11), a compensation lens (12), a rear fixed lens (13), and a focusing lens (14) sequentially along the light incident direction, characterized in that, Includes the following steps: S1: Process the corresponding tooling glass according to the size and shape of the front lens (10), the zoom lens (11), the compensation lens (12), and the rear fixed lens (13); S2: Install each piece of tooling glass into the corresponding lens mounting position in turn, and measure the distance from the front end face of the front lens to the front end face of each tooling glass. S3: Based on these distance values ​​and the thickness of each tooling glass, calculate the actual interval between the corresponding lenses; S4: Compare the measured interval with the theoretical value and adjust the thickness of the lens spacer that does not meet the requirements; the theoretical value is the theoretical value of the interval between the mounting surfaces of each lens, obtained according to the axial interval index requirements of adjacent lenses, the structure of the optical system and the measured value of the lens itself. S5: Install the lens and gasket into place in sequence to complete the assembly; The tooling glass is made of flat glass. Step S2 specifically includes: S21: Assemble the front lens barrel (1) and the front lens fixture glass (15), record the thickness of the front lens fixture glass (15) as c1, and measure the distance δ1 from the front end face of the front lens to the front end face of the front lens fixture glass (15). S22: Remove the front lens fixture glass (15), assemble the front lens barrel (1), main lens barrel (2), focusing cam (3), zoom lens frame (4), and zoom lens fixture glass (16), rotate the focusing cam (3) to the left limit position, record the thickness of the zoom lens fixture glass (16) as c2, and measure the distance δ2 from the front end face of the front lens to the front end face of the zoom lens fixture glass (16). S23: Remove the zoom lens frame (4) and zoom lens fixture glass (16), install the compensation lens frame (6) and compensation lens fixture glass (17), record the thickness of the compensation lens fixture glass (17) as c3, and measure the distance δ3 from the front end face of the front lens to the front end face of the compensation lens fixture glass (17). S24: Remove the compensating frame (6) and the compensating lens fixture glass (17), install the rear main lens barrel (8) and the rear fixed lens fixture glass (18), record the thickness of the rear fixed lens fixture glass (18) as c4, and measure the distance δ4 from the front end face of the front lens to the front end face of the rear fixed lens fixture glass (18).

2. The method according to claim 1, characterized in that, The distance from the front end face of the front lens group to the front end face of each tooling glass was measured using a depth micrometer.

3. The method according to claim 1, characterized in that, Step S3 specifically includes: Calculations were made based on the obtained measurement data: Distance between the mounting surface of the front lens and the mounting surface of the zoom lens: L1 = δ2 - δ1 - c1 + c2; Distance between the mounting surface of the zoom lens and the mounting surface of the compensation lens: L2 = δ3 - δ2 - c2; The distance between the mounting surface of the compensating lens and the mounting surface of the rear fixed lens is: L3 = δ4 - δ3 + c4.

4. The method according to claim 1, characterized in that, In step S4, adjusting the thickness of the gasket includes: The adjustment value of the lens shim to be installed later is determined based on the difference between the measured value and the theoretical value. Adjust the shim thickness by replacing it with a thicker one or by polishing it, according to the adjustment value.

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