Nonlinear cam curve measurement method and system based on variable magnification beam expander

Abstract

This invention relates to the field of optical technology, and discloses a method and system for measuring nonlinear cam curves based on a zoom beam expander, in order to screen out accurate and reliable zoom beam expanders. The method includes: recording the initial size of the focused spot in a beam quality analyzer when the measurement system is not equipped with the zoom beam expander; deploying the zoom beam expander to be measured between a laser source and a focusing lens; when the zoom beam expander is adjusted to the sampling scale line, recording the actual size of the focused spot in the beam quality analyzer, and then calculating a first difference between the actual size and the expected size; adjusting the zoom beam expander until the ratio of the size of the focused spot to the unit size in the beam quality analyzer meets the expected target, and recording a second difference between the actual scale line and the expected scale line; and obtaining the final measurement result of the nonlinear cam curve of the zoom beam expander based on the focal length of the focusing lens, the initial size, the unit size, and the first and second differences of a series of sampling points.

Description

Technical Field

[0001] This invention relates to the field of optical technology, and in particular to a method and system for measuring nonlinear cam curves based on a variable magnification beam expander. Background Technology

[0002] The nonlinear cam curve zoom beam expander is an optical system that achieves continuous, high-precision, and high-stability zooming by using a precision mechanical cam mechanism to realize the nonlinear relative displacement of the optical lens group. Its core value lies in using a customized nonlinear cam curve to perfectly compensate for optical aberrations during the zooming process, ensuring excellent beam quality throughout the entire zoom range. Although complex to design and manufacture and costly, it is an indispensable key component in industrial laser processing, high-end scientific research, and precision measurement fields where beam quality, accuracy, stability, and continuous zooming capabilities are extremely demanding.

[0003] The basic structure of a nonlinear cam curve variable magnification beam expander typically includes:

[0004] Two sets of lenses: an input lens group closer to the input beam and an output lens group closer to the output beam. The most common are Galilean (no real focal point, using a negative-positive lens group) or Keplerian (real focal point, using a positive-positive lens group, with an aperture stop that can be added in the middle).

[0005] A precision-machined cam whose profile curve has been optimized through a combination of optical and mechanical methods.

[0006] Two followers (such as precision bearings or sliders) are connected to the input and output lens groups respectively and are in close contact with the cam profile.

[0007] A rotary adjustment mechanism (such as a knob or motor drive) is used to drive the cam to rotate.

[0008] During operation: When the user rotates the adjustment mechanism, the cam rotates accordingly. The non-linear profile curve on the cam, through contact with the two followers, converts the cam's rotation angle into a precise relative displacement between the input and output lens groups. This displacement is calculated based on the optical design, ensuring that the lens group spacing at each rotation angle produces the required beam expansion ratio, and that the aberrations of the optical system (mainly spherical aberration, coma, and astigmatism) are effectively controlled throughout the zoom range. This maintains the high quality of the output beam (low divergence angle, low wavefront error) and the stability of the beam shape. Therefore, a smoothly rotating cam can achieve continuous, stepless changes in the beam expansion ratio.

[0009] In the process of developing system-level products, different manufacturers need to conduct sample tests on the variable magnification beam expanders with different nonlinear cam curve structures they purchase, and then select the best high-matching components that are universally applicable to their self-developed series of system-level products. Summary of the Invention

[0010] The purpose of this invention is to disclose a nonlinear cam curve measurement method and system based on a variable magnification beam expander, so as to screen out accurate and reliable variable magnification beam expanders.

[0011] To achieve the above objectives, the present invention discloses a nonlinear cam curve measurement method based on a variable magnification beam expander, comprising:

[0012] Step S1: Deploy the measurement system, which includes a laser source, a focusing lens, a beam quality analyzer for acquiring focal plane imaging information of the focusing lens, and a control host connected to the quality analyzer;

[0013] Step S2: The control host records the initial size of the focused spot in the beam quality analyzer when the measurement system is not equipped with a zoom beam expander;

[0014] Step S3: Deploy the variable magnification beam expander based on the nonlinear cam curve to be tested between the laser source and the focusing lens;

[0015] Step S4: When the zoom beam expander is adjusted to the sampling scale line, the actual size of the focused spot in the beam quality analyzer is recorded by the control host. Then, the first difference between the actual size and the expected size is calculated. The expected size is the product of the multiple shown by the scale line and the unit size. The unit size is the actual size corresponding to 1 scale line on the focal plane of the focusing lens.

[0016] Step S5: Adjust the zoom beam expander until the ratio of the size of the focused spot in the beam quality analyzer to the unit size meets the expected target, and record the second difference between the actual scale line and the expected scale line based on the control host.

[0017] Step S6: The control host obtains the final measurement result of the nonlinear cam curve of the zoom beam expander based on the focal length of the focusing lens, the initial size, the unit size, and the first and second differences obtained in steps S4 and S5 for each corresponding sampling point.

[0018] Preferably, step S6 includes:

[0019] When the ratio of the offset between the initial size and the unit size to the focal length of the focusing lens meets the first threshold range, the ratio of the first difference between each sampling point to the focal length of the focusing lens meets the second threshold range, and the ratio of the second difference between each sampling point to the focal length of the focusing lens meets the third threshold range, the control host determines that the final measurement result of the nonlinear cam curve of the zoom beam expander is qualified; otherwise, it is determined to be unqualified.

[0020] Preferably, the method of the present invention further includes:

[0021] Step S7: When the final measurement results of the nonlinear cam curves of at least two of the zoom beam expanders are qualified, the control host records the unique identification code information of each zoom beam expander, and first calculates the first deviation coefficient, the second deviation coefficient, and the third deviation coefficient of the nonlinear cam curve of any zoom beam expander; the first deviation coefficient is the result of dividing the standard deviation by the mean in the sequence composed of the first differences of each sampling point; the second deviation coefficient is the result of dividing the standard deviation by the mean in the sequence composed of the second differences of each sampling point; the third deviation coefficient is the result of dividing the absolute value of the offset between the initial size and the unit size by the focal length of the focusing lens.

[0022] Step S8: The control host multiplies the first deviation coefficient, the second deviation coefficient, and the third deviation coefficient corresponding to the nonlinear cam curve of each of the variable magnification beam expanders, and sorts them in ascending order according to the final product result and the corresponding identity code information.

[0023] To achieve the above objectives, the present invention also discloses a nonlinear cam curve measurement system based on a variable magnification beam expander, comprising a laser source, a focusing lens, a beam quality analyzer for acquiring focal plane imaging information of the focusing lens, and a control host connected to the quality analyzer; the control host includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement some of the related steps in the above method.

[0024] The present invention has the following beneficial effects:

[0025] The system can analyze the performance of the focusing lens from three dimensions: the deviation between the initial size and the unit size, the first difference distribution of a series of sampling points, and the second difference distribution of a series of sampling points. There are subtle relationships between these three dimensions, with both complementary and independent parts. Thus, the overall performance of the zoom beam expander can be obtained through comprehensive analysis. Moreover, the measurement system is simple and convenient to deploy, making it easy to promote and implement.

[0026] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0027] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0028] Figure 1This is a schematic flowchart of the nonlinear cam curve measurement method based on a variable magnification beam expander disclosed in an embodiment of the present invention.

[0029] Figure 2 This is a block diagram of the measurement system disclosed in an embodiment of the present invention. Detailed Implementation

[0030] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0031] Example 1

[0032] This embodiment discloses a nonlinear cam curve measurement method based on a variable magnification beam expander, such as... Figure 1 As shown, it includes the following steps:

[0033] Step S1: Deploy the measurement system.

[0034] The measurement system for this step, such as Figure 2 As shown, it includes a laser source 1, a zoom beam expander 2, a focusing lens 3, a beam quality analyzer 4 for acquiring focal plane imaging information of the focusing lens, and a control host 5 connected to the quality analyzer.

[0035] Step S2: The host control records the initial size of the focused spot in the beam quality analyzer when the measurement system is not using a variable magnification beam expander.

[0036] Step S3: Deploy the variable magnification beam expander based on the nonlinear cam curve to be tested between the laser source and the focusing lens.

[0037] In this step, the optical axes between the zoom and expander endoscope groups are aligned with the optical axes of the external measurement system during deployment.

[0038] Step S4: When the zoom beam expander is adjusted to the sampling scale line, the actual size of the focused spot in the beam quality analyzer is recorded by the control host. Then, the first difference between the actual size and the expected size is calculated. The expected size is the product of the multiple shown on the scale line and the unit size. The unit size is the actual size corresponding to 1 scale line on the focal plane of the focusing lens.

[0039] In this step, referring to the background art for the structural description of the nonlinear cam curve variable magnification expander, the scale line is the mark made by the manufacturer to indicate to the user how to achieve a quantitative expansion ratio by smoothly rotating the cam.

[0040] It is worth noting that the sampling points in this step do not include cases where the beam expansion ratio is 1, in order to avoid data duplication in subsequent steps during the selection and sorting process, which would affect the accuracy of the results.

[0041] Step S5: Adjust the zoom beam expander until the ratio of the size of the focused spot in the beam quality analyzer to the unit size meets the expected target. Record the second difference between the actual scale line and the expected scale line based on the control host.

[0042] In this step, since the unit size itself is regarded as the reference target for other sampling points, and there are cases where the unit size is larger than the initial size mentioned above, the case where the beam expansion ratio is 1 is not included as a sampling point.

[0043] In the two steps above, the "expected" in "expected size" and "expected target" essentially refers to the ideal spot effect obtained from the perspective of the quality analyzer, with the unit size of the focused spot as a reference, ignoring the initial size in step S2 and assuming no interference from design and assembly errors.

[0044] Step S6: The control host obtains the final measurement result of the nonlinear cam curve of the zoom beam expander based on the focal length, initial size, unit size, and corresponding sampling points of the focusing lens, using the first difference and second difference obtained in steps S4 and S5.

[0045] In the above steps, the spot size quantification of each step and each sampling point adopts a unified standard, which is an existing technology well known to those skilled in the art and will not be elaborated upon.

[0046] Preferably, in step S6, when the ratio of the initial size offset relative to the unit size to the focal length of the focusing lens meets the first threshold range, the ratio of the first difference of each sampling point to the focal length of the focusing lens meets the second threshold range, and the ratio of the second difference of each sampling point to the focal length of the focusing lens meets the third threshold range, the control host determines that the final measurement result of the nonlinear cam curve of the zoom beam expander is qualified; otherwise, it is determined to be unqualified. The first, second, and third thresholds can be flexibly set by the system-level product in-house manufacturer according to its own needs, and can be regarded as internal standards of the enterprise.

[0047] Furthermore, the method of the present invention also includes:

[0048] Step S7: When the final measurement results of the nonlinear cam curves of at least two zoom beam expanders are qualified, the control host records the unique identification code information of each zoom beam expander. First, calculate the first deviation coefficient, the second deviation coefficient, and the third deviation coefficient of the nonlinear cam curve of any zoom beam expander. The first deviation coefficient is the result of dividing the standard deviation of the sequence composed of the first differences of each sampling point by the mean. The second deviation coefficient is the result of dividing the standard deviation of the sequence composed of the second differences of each sampling point by the mean. The third deviation coefficient is the result of dividing the absolute value of the offset between the initial size and the unit size by the focal length of the focusing lens.

[0049] Step S8: The control host multiplies the first deviation coefficient, the second deviation coefficient, and the third deviation coefficient corresponding to the nonlinear cam curve of each zoom beam expander, and sorts them in ascending order according to the final product result and the corresponding identity code information.

[0050] Based on the above steps S7 and S8, multiple independent measurement systems with the same measurement principle but different parameters and selections of specific components can be compared and ranked according to the same standard. Moreover, its logical settings are reasonable and scientific, which can ensure the reliability of the comparison and ranking results. This makes it convenient for system-level product manufacturers to select the best-performing variable magnification beam expander (the higher the ranking, the better the performance), thereby ensuring the system performance of the corresponding system-level products.

[0051] Example 2

[0052] This embodiment discloses a nonlinear cam curve measurement system based on a variable magnification beam expander, including a laser source, a focusing lens, a beam quality analyzer for acquiring focal plane imaging information of the focusing lens, and a control host connected to the quality analyzer; the control host includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor executes the computer program to implement some of the steps associated with the above embodiment 1.

[0053] In summary, the nonlinear cam curve measurement method and system based on a variable magnification beam expander disclosed in the embodiments of the present invention have at least the following beneficial effects:

[0054] The system can analyze the performance of the focusing lens from three dimensions: the deviation between the initial size and the unit size, the first difference distribution of a series of sampling points, and the second difference distribution of a series of sampling points. There are subtle relationships between these three dimensions, with both complementary and independent parts. Thus, the overall performance of the zoom beam expander can be obtained through comprehensive analysis. Moreover, the measurement system is simple and convenient to deploy, making it easy to promote and implement.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for measuring nonlinear cam curves based on a variable magnification beam expander, characterized in that, include: Step S1: Deploy the measurement system, which includes a laser source, a focusing lens, a beam quality analyzer for acquiring focal plane imaging information of the focusing lens, and a control host connected to the quality analyzer; Step S2: The control host records the initial size of the focused spot in the beam quality analyzer when the measurement system is not equipped with a zoom beam expander; Step S3: Deploy the variable magnification beam expander based on the nonlinear cam curve to be tested between the laser source and the focusing lens; Step S4: When the zoom beam expander is adjusted to the sampling scale line, the actual size of the focused spot in the beam quality analyzer is recorded by the control host. Then, the first difference between the actual size and the expected size is calculated. The expected size is the product of the multiple shown by the scale line and the unit size. The unit size is the actual size corresponding to 1 scale line on the focal plane of the focusing lens. Step S5: Adjust the zoom beam expander until the ratio of the size of the focused spot in the beam quality analyzer to the unit size meets the expected target, and record the second difference between the actual scale line and the expected scale line based on the control host. Step S6: The control host obtains the final measurement result of the nonlinear cam curve of the zoom beam expander based on the focal length of the focusing lens, the initial size, the unit size, and the first and second differences obtained in steps S4 and S5 for each corresponding sampling point.

2. The method for measuring nonlinear cam curves based on a variable magnification beam expander according to claim 1, characterized in that, Step S6 includes: When the ratio of the offset between the initial size and the unit size to the focal length of the focusing lens meets the first threshold range, the ratio of the first difference between each sampling point to the focal length of the focusing lens meets the second threshold range, and the ratio of the second difference between each sampling point to the focal length of the focusing lens meets the third threshold range, the control host determines that the final measurement result of the nonlinear cam curve of the zoom beam expander is qualified; otherwise, it is determined to be unqualified.

3. The method for measuring nonlinear cam curves based on a variable magnification beam expander according to claim 2, characterized in that, Also includes: Step S7: When the final measurement results of the nonlinear cam curves of at least two of the zoom beam expanders are qualified, the control host records the unique identification code information of each zoom beam expander, and first calculates the first deviation coefficient, the second deviation coefficient, and the third deviation coefficient of the nonlinear cam curve of any zoom beam expander; the first deviation coefficient is the result of dividing the standard deviation by the mean in the sequence composed of the first differences of each sampling point, and the second deviation coefficient is the result of dividing the standard deviation by the mean in the sequence composed of the second differences of each sampling point; The third deviation coefficient is the absolute value of the offset between the initial size and the unit size, divided by the calculated focal length of the focusing lens; Step S8: The control host multiplies the first deviation coefficient, the second deviation coefficient, and the third deviation coefficient corresponding to the nonlinear cam curve of each of the variable magnification beam expanders, and sorts them in ascending order according to the final product result and the corresponding identity code information.

4. A nonlinear cam curve measurement system based on a variable magnification beam expander, characterized in that, The method includes a laser source, a focusing lens, a beam quality analyzer for acquiring focal plane imaging information of the focusing lens, and a control host connected to the beam quality analyzer; the control host includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the associated steps of any of the methods described in claims 1 to 3.

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