A method for measuring and eliminating the deviation angle between the optical axis and the mechanical axis of a laser alignment system

Abstract

The present invention relates to the field of laser spectrum alignment and adjustment, and specifically to a method for measuring and eliminating the deflection angle between the optical axis and the mechanical axis of a laser alignment system. The method comprises the following steps: determining the spatial position of the laser alignment system's output beam using a pinhole diaphragm, measuring the pinhole diaphragm's spatial coordinates and the laser alignment system's mechanical axis using a three-dimensional coordinate measuring machine, calculating the spatial angle between the two axes, and compensating for the angle using a wedge. This method can achieve miniaturization of the laser spectrum detection system. The method is simple and reliable, with simple steps, and can be widely used for coaxial adjustment of various laser spectrum detection systems, improving assembly and adjustment efficiency.

Description

Technical Field

[0001] The present invention relates to the field of laser spectrum collimation adjustment, and in particular to a method for measuring and eliminating the deflection angle between an optical axis and a mechanical axis of a laser collimation system. Background Art

[0002] The laser field, especially multi-pass cell laser absorption spectroscopy technology, has very high requirements for the incident collimation of the laser. Most of the existing laser diode packaging forms and assembly methods will cause an angle deviation between the light output axis and the assembly mechanical axis. After a very small angle is amplified by multiple reflections, a large light spot offset will be formed at the receiving end. This offset will seriously affect the test results and the normal operation of the equipment. The traditional method is for the tester or assembler to continuously adjust the optical path to the ideal state and then solidify the adjusted laser diode package position. This method has a long dimming time and poor accuracy, which places high demands on the tester or assembler and is inefficient. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for measuring and eliminating the deviation angle between the optical axis and the mechanical axis of a laser alignment system, aiming to overcome the defects of the existing technology and solve the two major problems of low adjustment efficiency and poor accuracy mentioned in the above background technology.

[0004] To this end, the present invention proposes a method for measuring and eliminating the deviation angle between the optical axis and the mechanical axis of a laser alignment system, comprising the following steps:

[0005] S100: Determine the spatial position of the output beam of the laser collimation assembly through the pinhole aperture and the optical power meter;

[0006] S200: Use a three-dimensional coordinate measuring machine to measure the spatial coordinates of the pinhole aperture;

[0007] S300: Measuring the mechanical axes of laser alignment components using a coordinate measuring machine;

[0008] S400: Calculating the spatial angle between the optical axis and the mechanical axis;

[0009] S500: Use wedges to compensate for spatial angles.

[0010] As a preferred technical solution of the present application, S100 specifically includes the following steps:

[0011] S110: Fix the laser collimator assembly, power on the laser diode of the laser collimator assembly through the laser driver assembly, and adjust the parameters to a normal working state;

[0012] S120: Place the optical power meter at the far end and adjust the laser collimation assembly to maximize the optical power meter reading.

[0013] S130: Place the pinhole diaphragm 1 at the near end of the laser collimation assembly and adjust the position of the pinhole to maximize the optical power meter reading.

[0014] S140: Place the second pinhole aperture near the optical power meter and adjust the position of the pinhole to maximize the reading on the optical power meter.

[0015] As a preferred technical solution of the present application, S200 specifically includes the following steps:

[0016] S210: Using a three-dimensional coordinate measuring instrument probe, select at least three measuring points on the back disc of the pinhole stop 1, form a circle with the multiple measuring points, and find the coordinates of the center of the circle, which are the coordinates of the center point of the pinhole stop 1;

[0017] S220: Repeat the step of S210 to measure the second pinhole stop and find the coordinates of the center point of the second pinhole stop;

[0018] S230: Fitting a line connecting the center of the first pinhole stop and the center of the second pinhole stop to obtain the propagation path of the light, which is the optical axis, and obtaining the spatial normal vector (X1, Y1, Z1) of the optical axis.

[0019] As a preferred technical solution of the present application, in S210, a three-coordinate measuring instrument probe is used to measure a point every 30° on the back wafer of the aperture stop, and a total of 7 measuring points are set within a range of 180°.

[0020] As a preferred technical solution of this application, S300 specifically includes the following steps:

[0021] S310: Use the three-dimensional coordinate measuring instrument probe to measure five points on the reference plane of the laser collimator assembly. The plane formed by the measured points is the normal plane of the mechanical axis of the laser collimator assembly.

[0022] S320: Find the intersection of the normal plane of the mechanical axis in step S310 and the straight line in step S230. A straight line passing through this point and perpendicular to the normal plane in step S310 is the mechanical axis of the laser collimation assembly, and obtain the spatial normal vector (X2, Y2, Z2) of the mechanical axis.

[0023] As a preferred technical solution of the present application, S400 specifically includes the following steps:

[0024] S410: Calculate the angle ∆x between the optical axis and the mechanical axis along the X direction;

[0025] Δx=A1-A2= arcSinX1- arcSinX2, (1)

[0026] S420: Calculate the angle ∆z between the optical axis and the mechanical axis along the Z direction;

[0027] Δz=B1-B2= arcSinZ1- arcSinZ2 (2).

[0028] As a preferred technical solution of the present application, in step S400, A1 and A2 are the angles between the optical axis space normal vector, the mechanical axis space normal vector and the YZ plane, and X1 and X2 are the distances between the optical axis space normal vector, the mechanical axis space normal vector and the YZ plane; B1 and B2 are the angles between the optical axis space normal vector, the mechanical axis space normal vector and the XY plane, and Z1 and Z2 are the distances between the optical axis space normal vector, the mechanical axis space normal vector and the XY plane.

[0029] As a preferred technical solution of the present application, S500 specifically includes the following steps:

[0030] S510: Design a cross section with reference to the reference plane of the laser collimator assembly, and stretch the cross section to obtain an initial wedge;

[0031] S520: Using the wedge to compensate in the X direction, the initial normal line 22 of the wedge reference surface is deflected along the X direction by -∆x to obtain the X-direction deflected normal line 23 of the compensation surface along the X direction;

[0032] S530: Using the wedge to compensate for the Z direction, the X-direction deflection normal line 23 obtained in step S520 is deflected along the Z direction -Δz to obtain the Z-direction deflection normal line 24 of the wedge compensation surface;

[0033] S540: Use the Z-direction deflection normal 24 to draw a compensation surface, and use the compensation surface to cut the wedge to form a wedge compensation surface. The wedge compensation surface is aligned with the reference surface, and the other surface of the wedge is aligned with the mating surface.

[0034] The method for measuring and eliminating the deviation angle between the optical axis and the mechanical axis of the laser alignment system provided by the present invention is simple and reliable, with simple steps. It can be widely used for coaxial adjustment of various laser spectrum detection systems to improve the installation efficiency; it solves the two major problems mentioned in the prior art: low installation efficiency and poor accuracy.

[0035] In addition to the above-described purposes, features and advantages, the present application also has other purposes, features and advantages. The present application will be further described in detail below with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings that constitute part of this application are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation on this application. In the drawings:

[0037] Figure 1 Schematic diagram of the structure of the laser alignment system of the present invention;

[0038] Figure 2A simplified diagram of the measurement process of the method for measuring and eliminating the angle between the optical axis and the mechanical axis of the laser alignment system of the present invention;

[0039] Figure 3 Schematic diagram of the pinhole aperture measuring point in the method for measuring and eliminating the deviation angle between the optical axis and the mechanical axis of the laser alignment system of the present invention;

[0040] Figure 4 Schematic diagram of the measuring points of the laser alignment component in the method for measuring and eliminating the deflection angle between the optical axis and the mechanical axis of the laser alignment system of the present invention;

[0041] Figure 5 Schematic diagram of the optical axis deflection along the X direction in the method for measuring and eliminating the deflection between the optical axis and the mechanical axis of the laser alignment system of the present invention;

[0042] Figure 6 Schematic diagram of ∆x calculation in the method for measuring and eliminating the deviation angle between the optical axis and the mechanical axis of the laser alignment system of the present invention;

[0043] Figure 7 Schematic diagram of the optical axis deflection along the Z direction in the method for measuring and eliminating the deflection between the optical axis and the mechanical axis of the laser alignment system of the present invention;

[0044] Figure 8 Schematic diagram of ∆z calculation in the method for measuring and eliminating the deviation angle between the optical axis and the mechanical axis of the laser alignment system of the present invention;

[0045] Figure 9 Schematic diagram of the deflection of the initial axis of the wedge along the X direction in the method for measuring and eliminating the deflection angle between the optical axis and the mechanical axis of the laser alignment system of the present invention;

[0046] Figure 10 Schematic diagram of the wedge deflection axis along the Z direction in the method for measuring and eliminating the deflection angle between the optical axis and the mechanical axis of the laser alignment system of the present invention;

[0047] Figure 11 Schematic diagram of the structure of the wedge in the method for measuring and eliminating the angle between the optical axis and the mechanical axis of the laser alignment system of the present invention;

[0048] Figure 12 A flowchart of the steps of the method for measuring and eliminating the deviation angle between the optical axis and the mechanical axis of the laser alignment system of the present invention;

[0049] Explanation of reference numerals: 1. Mounting barrel; 2. Laser pressure ring; 3. Laser mounting base; 4. Beam waist adjustment washer; 5. Lens mounting base; 6. Laser heat sink; 7. Laser diode; 8. Collimating lens; 9. Lens pressure ring;

[0050] 10. Laser alignment assembly; 11. Laser drive assembly; 12. Optical power meter; 13. Pinhole diaphragm 1; 14. Pinhole diaphragm 2; 15. Coordinate measuring instrument probe; 16. Optical axis spatial normal vector; 17. Mechanical axis spatial normal vector; 18. Wedge; 19. Base; 20. Reference plane; 21. Mating surface; 22. Reference plane initial normal; 23. X-axis deflection normal; 24. Z-axis deflection normal; 25. Wedge compensation surface. DETAILED DESCRIPTION

[0051] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0052] like Figure 1~Figure 2 As shown, the present invention discloses a laser collimation assembly, which specifically includes a mounting barrel 1, a laser pressure ring 2, a laser mounting seat 3, a beam waist adjustment washer 4, a lens mounting seat 5, a laser heat sink 6, a laser diode 7, a collimating lens 8 and a lens pressure ring 9.

[0053] Among them, the lens pressure ring 9, the collimating lens 8, the lens mounting seat 5, the beam waist adjustment gasket 4, and the laser mounting seat 3 are installed in sequence from the inside to the outside in the mounting barrel 1. The laser diode 7 is installed on the laser mounting seat 3 and is tightened and fixed by the laser pressure ring 2. At the same time, the rear end of the laser diode 7 is connected to a laser heat sink 6 for conducting heat to the laser diode 7 and improving its service life.

[0054] Combine Figures 2 to 12 , and the laser alignment assembly disclosed above, the present invention also discloses a method for measuring and eliminating the deviation angle between the optical axis and the mechanical axis of the laser alignment system, the steps of which are as follows:

[0055] S100: determining the spatial position of the output beam of the laser collimation assembly through a pinhole aperture;

[0056] S200: Use a three-dimensional coordinate measuring machine to measure the spatial coordinates of the pinhole aperture;

[0057] S300: Measuring the mechanical axes of laser alignment components using a coordinate measuring machine;

[0058] S400: Calculating the spatial angle between the optical axis and the mechanical axis;

[0059] S500: Make wedges according to the spatial angle to compensate for the laser collimation component.

[0060] Furthermore, in step S100, determining the spatial position of the output beam of the laser collimation assembly by the pinhole aperture specifically includes the following steps:

[0061] S110: Fix the laser collimation assembly 10, power on the laser diode 7 through the laser driving assembly 11, and adjust the parameters to a normal working state;

[0062] S120: placing the optical power meter 12 at the far end and adjusting the laser collimation assembly 10 so that the optical power meter 12 shows the maximum value;

[0063] S130: Place the pinhole diaphragm 13 at the proximal end of the laser collimation assembly 10 and adjust the position of the pinhole so that the optical power meter 12 shows the maximum value;

[0064] S140: Place the pinhole aperture 2 14 near the optical power meter 12, and adjust the position of the pinhole so that the optical power meter 12 shows the maximum value.

[0065] Furthermore, in step S200, the spatial coordinates of the pinhole stop are measured using a three-dimensional coordinate measuring machine, which specifically includes the following steps:

[0066] S210: Using the three-dimensional coordinate measuring instrument probe 15, select at least three measuring points on the back surface of the pinhole stop 13. The three-dimensional coordinate measuring instrument probe 15 forms a circle with the three measuring points, and finds the coordinates of the center of the circle, which are the coordinates of the center point of the pinhole stop 13.

[0067] S220: Repeat the step of S210 to measure the second pinhole stop 14 and find the coordinates of the center point of the second pinhole stop 14;

[0068] S230: Fit the line connecting the center of the pinhole aperture 13 and the center of the pinhole aperture 2 14 as the propagation path of the light, and the light is the optical axis, and obtain the optical axis space normal vector (X1, Y1, Z1). The starting point of the optical axis space normal vector 16 is the output starting point of the laser diode 7 (such as Figure 2 shown).

[0069] In step S210, the three-dimensional coordinate measuring instrument probe 15 is used to measure a point every 30 degrees on the back surface of the aperture diaphragm 13, and a total of 7 measuring points (P1-1 to P1-7) are set within a range of 180 degrees. This step uses 7 measuring points to determine the plane (such as Figure 3 ), takes the existence of measurement errors into account. Theoretically, three points can determine a plane in space. However, due to the existence of measurement errors, there is a certain difference between the measured plane and the theoretical plane measured by three measuring points. The plane fitted by seven measuring points and the three-coordinate measuring instrument's own software algorithm is closer to the theoretical plane.

[0070] Furthermore, in step S300, the mechanical axis of the laser alignment system is measured using a three-dimensional coordinate measuring machine as follows:

[0071] S310: Using the coordinate measuring instrument probe 15, measure five points on the reference plane of the laser collimator assembly 1. A plane formed by the measured points is the normal plane of the mechanical axis of the laser collimator assembly 1.

[0072] S320: Find the intersection of the normal plane of the mechanical axis in step S310 and the straight line of the optical axis in step S230. A straight line passing through this point and perpendicular to the normal plane in step S310 is the mechanical axis of the laser collimation assembly, and obtain the mechanical axis space normal vector (X2, Y2, Z2).

[0073] Similarly, this step uses 5 measuring points to determine the plane (such as Figure 4 ), takes the existence of measurement errors into account. Theoretically, three points can determine a plane in space. However, due to the existence of measurement errors, there is a certain difference between the measured plane and the theoretical plane measured by the three measuring points. The plane fitted by five measuring points (P2-1 to P2-5) and the three-coordinate measuring machine's own software algorithm is closer to the theoretical plane, and the mechanical axis space normal vector 17 is further obtained.

[0074] Furthermore, in step S400, the spatial angle between the optical axis and the mechanical axis is calculated as follows:

[0075] S410: Calculate the angle ∆x between the optical axis and the mechanical axis along the X direction;

[0076] Δx=A1-A2= arcSinX1- arcSinX2 (1)

[0077] S420: Calculate the angle ∆z between the optical axis and the mechanical axis along the Z direction;

[0078] Δz=B1-B2= arcSinZ1- arcSinZ2 (2).

[0079] like Figure 5 As shown in the figure, A1 and A2 are the angles between the optical axis space normal vector, the mechanical axis space normal vector and the YZ plane, and X1 and X2 are the distances between the optical axis space normal vector, the mechanical axis space normal vector and the YZ plane. The specific calculation process includes: SinA1=X1, A1=arcSinX1, SinA2=X2, A2=arcSinX2, so ∆x=A1-A2=arcSinX1-arcSinX2.

[0080] like Figure 6As shown in the figure, B1 and B2 are the angles between the optical axis space normal vector, the mechanical axis space normal vector and the XY plane, and Z1 and Z2 are the distances between the optical axis space normal vector, the mechanical axis space normal vector and the XY plane. The specific calculation process includes: SinB1=Z1, B1=arcSinZ1, SinB2=Z2, B2=arcSinZ2, so ∆z=B1-B2=arcSinZ1-arcSinZ2.

[0081] Furthermore, in step S500, the space angle is compensated using a wedge as follows:

[0082] S510: Design a cross section with reference to the reference plane of the laser collimator assembly, and stretch the cross section to obtain an initial wedge;

[0083] S520: Using the wedge 18 to compensate in the X direction, the initial normal line 22 of the reference surface of the wedge is deflected along the X direction by -∆x to obtain the X-direction deflected normal line 23 of the compensation surface along the X direction;

[0084] S530: Using the wedge to compensate for the Z direction, the X-direction deflection normal line 23 obtained in step S520 is deflected along the Z direction -Δz to obtain the Z-direction deflection normal line 24 of the wedge compensation surface;

[0085] S540: Use the Z-direction deflection normal 24 to draw a compensation surface, and use the compensation surface to cut off the wedge block. The cross section formed is the wedge block compensation surface, and the remaining geometric body after cutting is the wedge block. The wedge block has a spatial dihedral angle feature. The wedge block compensation surface 25 is aligned with the reference surface 20, and the other surface of the wedge block is aligned with the mating surface 21 of the base 19.

[0086] The working principle and working process of the method for measuring and eliminating the deviation angle between the optical axis and the mechanical axis of the laser alignment system of the present invention are briefly described below.

[0087] First, place the optical power meter at the far end, adjust the laser collimation assembly, place pinhole diaphragm 1 at the near end of the laser collimation assembly, place pinhole diaphragm 2 at the near end of the optical power meter, and determine the spatial position of the output beam of the laser collimation assembly.

[0088] Secondly, use the three-dimensional coordinate measuring instrument probe to set 7 measuring points on the back disc of pinhole aperture 1 to find the coordinates of the center point of pinhole aperture 1; repeat the above steps to find the coordinates of the center point of pinhole aperture 2; fit the line connecting the center of pinhole aperture 1 and the center of pinhole aperture 2 to obtain the propagation path of the light, and obtain the spatial normal vector (X1, Y1, Z1) of the optical axis.

[0089] Then, five points are measured on the reference plane of the laser collimator assembly to obtain the normal plane of the mechanical axis of the laser collimator assembly. The intersection of the normal plane of the mechanical axis in step S310 and the straight line of the optical axis in step S230 is found. A straight line passing through this point and perpendicular to the normal plane in step S310 is the mechanical axis of the laser collimator assembly, and the spatial normal vector of the mechanical axis (X2, Y2, Z2) is obtained.

[0090] Then, calculate the angle ∆x between the optical axis and the mechanical axis along the X direction; calculate the angle ∆z between the optical axis and the mechanical axis along the Z direction; and obtain the spatial angle between the optical axis and the mechanical axis.

[0091] Finally, a cross-section is designed with reference to the reference plane of the laser alignment assembly, and the cross-section is stretched to obtain an initial wedge; the initial normal line 22 of the reference plane of the wedge is deflected along the X direction -∆x to obtain the X-direction deflection normal line 23 of the compensation surface along the X direction; the X-direction deflection normal line 23 obtained in step S520 is deflected along the Z direction -∆z to obtain the Z-direction deflection normal line 24 of the wedge compensation surface; a compensation surface is drawn using the Z-direction deflection normal line 24, and the wedge is cut out using the compensation surface. The cross-section formed is the wedge compensation surface, and the remaining geometric body after cutting out is the wedge. The wedge has a spatial dihedral angle feature, and the wedge compensation surface 25 is aligned with the reference plane 20, and the other surface of the wedge is aligned with the mating surface 21 of the base 19.

[0092] The method for measuring and eliminating the deviation angle between the optical axis and the mechanical axis of a laser collimation assembly provided by the present invention is simple and reliable, with simple steps. It can be widely used for coaxial adjustment of various laser spectrum detection systems to improve the efficiency of installation and adjustment. It solves the two major problems mentioned in the prior art: low installation and adjustment efficiency and poor accuracy.

[0093] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for measuring and eliminating the deviation angle between the optical axis and the mechanical axis of a laser alignment system, characterized in that The steps include: S100: Determine the spatial position of the output beam of the laser collimation assembly through the pinhole aperture and the optical power meter; S200: Use a three-dimensional coordinate measuring machine to measure the spatial coordinates of the pinhole aperture; S300: Measuring the mechanical axes of laser alignment components using a coordinate measuring machine; S400: Calculating the spatial angle between the optical axis and the mechanical axis; S500: Use wedges to compensate for spatial angles; S100 specifically includes the following steps: S110: Fix the laser collimator assembly, power on the laser diode of the laser collimator assembly through the laser driver assembly, and adjust the parameters to a normal working state; S120: Place the optical power meter at the far end and adjust the laser collimation assembly to maximize the optical power meter reading. S130: Place the pinhole diaphragm 1 at the near end of the laser collimation assembly and adjust the position of the pinhole to maximize the optical power meter reading. S140: Place the second pinhole aperture near the optical power meter and adjust the position of the pinhole to maximize the optical power meter reading. S200 specifically includes the following steps: S210: Using a three-dimensional coordinate measuring instrument probe, select at least three measuring points on the back surface of the pinhole stop to form a circle, and find the coordinates of the center point of the pinhole stop. S220: Repeat the step of S210 to measure the second pinhole stop and find the coordinates of the center point of the second pinhole stop; S230: Fitting a line connecting the center of the first pinhole stop and the center of the second pinhole stop as the propagation path of the light, and obtaining the spatial normal vector (X1, Y1, Z1) of the optical axis.

2. The method for measuring and eliminating the deviation angle between the optical axis and the mechanical axis of the laser alignment system according to claim 1, characterized in that: In S210, a three-dimensional coordinate measuring instrument probe is used to measure a point at every 30° on the back surface of the aperture stop, and a total of 7 measuring points are set within a range of 180°.

3. The method for measuring and eliminating the deviation angle between the optical axis and the mechanical axis of the laser alignment system according to claim 1, characterized in that: S300 specifically includes the following steps: S310: Use the three-dimensional coordinate measuring machine probe to measure five points on the reference plane of the laser collimator assembly to form a plane, which is the normal plane of the mechanical axis of the laser collimator assembly; S320: Find the intersection of the normal plane of the mechanical axis in step S310 and the straight line of the optical axis in step S230. A straight line passing through this point and perpendicular to the normal plane of the mechanical axis in step S310 is the mechanical axis of the laser collimation assembly, and obtain the spatial normal vector (X2, Y2, Z2) of the mechanical axis.

4. The method for measuring and eliminating the deviation angle between the optical axis and the mechanical axis of a laser alignment system according to claim 1, characterized in that: S400 specifically includes the following steps: S410: Calculate the angle between the optical axis and the mechanical axis along the X direction ; （1） S420: Calculate the angle between the optical axis and the mechanical axis along the Z direction ; （2）。 5. The method for measuring and eliminating the deviation angle between the optical axis and the mechanical axis of the laser alignment system according to claim 4, characterized in that: In step S400, A1 and A2 are the angles between the optical axis space normal vector, the mechanical axis space normal vector and the YZ plane, and X1 and X2 are the distances between the optical axis space normal vector, the mechanical axis space normal vector and the YZ plane; B1 and B2 are the angles between the optical axis space normal vector, the mechanical axis space normal vector and the XY plane, and Z1 and Z2 are the distances between the optical axis space normal vector, the mechanical axis space normal vector and the XY plane.

6. The method for measuring and eliminating the deviation angle between the optical axis and the mechanical axis of the laser alignment system according to claim 1, characterized in that: S500 specifically includes the following steps: S510: Design a cross section with reference to the reference plane of the laser collimator assembly, and stretch the cross section to obtain an initial wedge; S520: Use the wedge to compensate the X direction, and deflect the initial normal line 22 of the wedge reference surface along the X direction. Obtaining the X-direction deflection normal 23 of the compensation surface along the X direction; S530: Use the wedge to compensate the Z direction, and deflect the X-direction deflection normal 23 obtained in step S520 along the Z direction. Obtain the Z-direction deflection normal 24 of the wedge compensation surface; S540: Use the Z-direction deflection normal 24 to draw a compensation surface, and use the compensation surface to cut the wedge to form a wedge compensation surface. The wedge compensation surface is aligned with the reference surface, and the other surface of the wedge is aligned with the mating surface.

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