Method and device for setting refraction surface of refraction type rotating mirror lens

Abstract

The invention discloses a method and a device for setting a refraction surface of a refraction type rotating mirror lens. The device comprises a rotating mirror and a projection surface, a reflecting mirror is arranged in the rotating mirror; the reflecting mirror is used for reflecting laser into the rotating mirror refractor so that the laser can be refracted in the rotating mirror refractor, after the laser enters the rotating mirror refractor, under the rotating effect of the rotating mirror, the laser can have different slopes when entering the surface of the lens refractor, and the laser is refracted into laser outgoing lines in different directions. The laser scanning line is obtained by designing the curved surface characteristics of the refracting surface of the lens. The astigmatism phenomenon is reduced through the design of the refracting surface of the lens, the propagation path of light in the rotating mirror can be effectively controlled by optimizing the design of the refracting surface, and the astigmatism problem caused by the prism polyhedron shape is reduced; and due to the design of the refraction type rotating mirror, the loss of laser energy can be reduced to the maximum extent, more laser energy is ensured to be effectively utilized in a processing task, and the processing efficiency and quality are greatly improved.

Description

Technical Field

[0001] The invention relates to a method and a device for setting a refractive surface of a refractive mirror lens, and belongs to the technical field of laser rotating mirror scanning. Background Art

[0002] The application of laser technology is an interdisciplinary and cross-industry high-tech. With the development of laser technology, the application of laser scanning technology in the manufacturing field is also an increasingly widespread application technology. Galvanometer laser scanning technology is often used for high-density and high-power laser sources. The mechanism controls the optical path so that the laser can produce many controllable changes in the travel route, making the processing more diversified. Therefore, due to its simple structure and ability to complete the task, the galvanometer is currently the main laser scanning technology to generate laser scanning lines. Galvanometer laser scanning technology is widely used in laser cleaning, laser welding, laser marking and other fields. The basic principle is to use the reflection of a one-dimensional or two-dimensional galvanometer to use the movement of the galvanometer to make the stationary laser move, and finally realize the laser scanning processing on the workpiece according to the specified rules.

[0003] The method of scanning a laser into a line on a plane is to project light onto a galvanometer to produce a swing of a certain axis (such as the x-axis). The laser scanning line will produce a processing or manufacturing effect on the plane (such as laser welding, laser marking, etc.). When using a galvanometer to generate a scan line, the galvanometer uses swinging to control the optical path to produce a scanning light. Therefore, the motor must have acceleration and deceleration behavior when swinging, and this behavior will cause the controller to heat up and cause problems. In high-speed scanning conditions, the motor control is not feasible due to the high frequency (the controller instruction cycle is not enough, heating, structural fatigue, etc.). Moreover, when the amplitude of the galvanometer is the largest, its speed is 0. In this case, the intensity of the scanning light is very slow when the speed is 0, which causes uneven scanning on the scanned part.

[0004] Therefore, under the requirement of higher scanning speed, another optical machine must be used to improve the shortcomings of traditional galvanometers. The most commonly used mechanism is to use a rotating mirror to solve this problem. For example, laser printers and some projectors use reflective rotating mirror optical machines to generate laser scanning. The reflective rotating mirror uses a motor to rotate the reflector of a prism to reflect light to generate scanning, but because the prism shape is a polyhedron, there is an angle change at the intersection of the two faces. The change in angle causes the laser to hit this place and there will be astigmatism. This astigmatism is an important source of heat generation for the rotating mirror optical machine. This heat is easier to dissipate when the laser energy is very low. In the case of high-energy lasers, this heat is very large and it is not easy to eliminate the heat. This heat is a very difficult problem to deal with in high-energy laser scanners. In addition, this astigmatism will cause the energy of the laser to not be fully utilized. Therefore, it is necessary to propose a method and device for setting the refractive surface of a refractive rotating mirror lens to solve this problem. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the present invention provides a method and device for setting the refractive surface of a refractive mirror lens, thereby solving the above-mentioned technical problems.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a method and device for setting the refractive surface of a refractive mirror lens, the device includes a revolving mirror and a projection surface; a reflector is arranged inside the revolving mirror; the reflector is used to reflect the laser into the refractive mirror of the revolving mirror so that the laser is refracted in the refractive mirror of the revolving mirror, and after the laser enters the refractive mirror of the revolving mirror, the surface of the refractive mirror of the lens will have different slopes under the action of the rotation of the refractive mirror, and the laser is refracted into laser emission lines in different directions, and the laser is formed into a scanning line on the projection surface by designing the curved surface features of the refractive surface of the lens. The present invention can also directly inject the laser into the revolving mirror without using the reflector, and the use of the reflector is only to simplify the design of the refractive mirror. The projection surface can be a certain optical lens or a simple projection surface.

[0007] The lens refractive surface includes an inner contour surface and an outer contour surface, and the contours can be described by polar coordinate functions (r, θ) respectively; wherein r is the distance from the center to the contour, θ is the angle between a certain point of the contour and the reference line, θ=ωt;

[0008] The contour equation of the inner contour surface is:

[0009] r=r 1 (θ) -π / N≤θ<π / N

[0010] The contour equation of the outer contour surface is:

[0011] r=r 2 (θ) -π / N≤θ<π / N

[0012] Where N is the number of times the scanning line goes back and forth when the mirror rotates one circle.

[0013] Furthermore, assuming that the laser spot is a point (in reality, if the laser spot is not a point, the spot can be divided into many points for analysis, and the surface shape of each point can be calculated. These shapes can be used as references to find the best refraction mirror surface). When t = 0 (t is the time axis), the rotating mirror is in the instantaneous state when it starts to rotate. Let r 1 (0), r 2 The slope of (0) is 0 as the starting point (this is mainly to simplify the description of the coordinates, and the slope can also be non-zero). In the initial state, the laser refracted by the refractor will not be affected by the refraction, and the light directly hits the point on the projection surface (A) from point o. 5), when t = T, the mirror rotates counterclockwise by ωT (T is the time for the mirror to start rotating from zero, ω is the rotation speed of the mirror), at this time, the distance between the inner refractive surface where the laser reflected by the reflector enters and point o is r 1 (-ωT), the surface tangent angle is α 1 After the mirror rotates ωT, the laser path first goes from o to point A. 2 , then from point A 2 To point A 4 , then from point A 4 To point A 6 ; Point A 1 The intersection point between the laser and the inner contour of the refraction mirror when the mirror is not rotating; the point A 2 It is the intersection point of the inner contour after the laser and the rotating mirror rotate by ωT; the point A 4 It is the intersection point of the outer contour of the laser and the rotating mirror after rotating by ωT; the point A 6 It is the point where the light hits the projection surface after the mirror has rotated by ωT.

[0014] The slope of the coordinates is the relationship between polar coordinates and rectangular coordinates. 2 The point can get the surface tangent angle α 1 :

[0015]

[0016] The light hits the refraction point A 2 , if the material refractive index is n i , surface tangent angle α 1 , angle of incidence With refraction angle α 2 The refraction formula between:

[0017]

[0018] From the above formula, we can get α 2 , the refracted light goes along α 2 Keep going forward until you meet A 4 , at point A 4 The tangent angle can be obtained as α 5 :

[0019]

[0020] In the above formula, β 1 -ωT ​​is the intersection point between the laser and the outer contour after the mirror rotates ωT (A 4 ) is the angle of the unrotated coordinate, and β 1 = ∠A 1 oA 4 , the last term ωT in equation (3) is the angle correction after the mirror rotates ωT; β 1It is a clockwise rotation angle, so its value is negative in terms of coordinates. Its value is determined by the light and r = r 2 (θ) is determined by the intersection point. From the above, the following relationship can be obtained:

[0021]

[0022]

[0023] Then, from the geometric relationship, we can get the following formula:

[0024]

[0025] where α 3 It is laser and A 4 The angle between the normal lines of the curve at point ; after rearranging the above formula, we can get

[0026] α 3 =α 1 +α 2 -α 5 (6);

[0027] A 4 Point laser incident angle α 3 With refraction angle α 4 The refraction formula between:

[0028]

[0029] From the above formula, we can get the refraction angle α 4

[0030] sinα 4 =n i sinα 3 (7);

[0031] where α 6 is the angle between the laser and the projection surface.

[0032] Furthermore, the distance d(ωT) traveled by light in the y direction is

[0033] d(ωT)=r 2 (β 1 -ωT)sin beta 1 +(Br 2 (β 1 -ωT)cosθ 1 )sinα 6 (8)

[0034] Assuming that T is reduced to a very small value, only the differential ΔT is left, then

[0035]

[0036] The polar coordinate differential at any time T can be obtained by the formula (9-10) 1 ′(θ), r 2 The differential of ′(θ).

[0037] When d(ωT) and α 4 is a known design parameter. From equations (7) and (8), we can solve r for different T. 1 (ωT), r 2 (ωT) value, and the obtained r 1 (ωT), r 2 (ωT) is the inner and outer contours of the rotating mirror lens r 1 (θ), r 2 (θ);

[0038] When d(ωT) and α 4 As an uncertain design parameter, r 1 (ωT) or r 2 (ωT) One of the functions is known, if r 1 (θ) is known and can be obtained by using formula (8) and related formulas 2 (ωT), which is the outer contour of the rotating mirror lens; r 2 (θ) If r 2 (θ) is known and can be obtained by using formula (1-8) and related formulas 1 (ωT) is the inner and outer contours of the rotating mirror lens r 1 (θ);

[0039] When α 4 For the case where d(ωT) is unknown, r 1 (ωT) or r 2 (ωT) One of the functions is known, if r 1 ((θ) is known and can be obtained by using formula (8) and related formulas 2 (ωT), which is the outer contour of the rotating mirror lens; if r 2 (θ) is known and can be obtained by using formula (1-7) and related formulas 1 (ωT) is the inner and outer contours of the rotating mirror lens r1 ( θ).

[0040] The beneficial effects of the present invention are:

[0041] 1) Reduce astigmatism: By optimizing the refractive surface design, the propagation path of light in the rotating mirror can be effectively controlled, reducing the astigmatism problem caused by the polyhedral shape of the prism. This not only improves the focusing effect of the laser, but also ensures that the laser beam maintains a more consistent energy distribution during the processing;

[0042] 2) Improve energy utilization: The design of the refractive mirror can minimize the loss of laser energy and ensure that more laser energy is effectively used in the processing task. This is especially important for high-energy laser applications and can improve processing efficiency and quality;

[0043] 3) Reduce heat accumulation: By optimizing the refraction angle and material selection, the refractive mirror can better dissipate heat and reduce the heat accumulation caused by astigmatism and multiple reflections. This allows the laser scanner to maintain stable performance when working at high power and high frequency, extending the service life of the equipment;

[0044] 4) Improve scanning speed and processing uniformity: The optimized design of the refractive mirror allows the laser beam to maintain a stable focus state at a higher scanning speed, thereby avoiding uneven processing caused by speed changes. This is especially important for applications that require high precision and high speed (such as laser welding, marking, etc.);

[0045] 5) Simplify the control system: By improving the optical properties of the rotating mirror, the requirements for the control system can be reduced, the heat burden of the controller under high-frequency operation can be reduced, and the risk of controller failure can be reduced. This makes the entire laser scanning system more reliable and easier to maintain;

[0046] 6) Expand the application areas: The improved refractive mirror design is not only suitable for traditional laser welding, marking and other fields, but can also be expanded to higher-demand applications such as laser cleaning and precision machining, thereby promoting the application of laser technology in a wider range of fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The present invention provides curved surface features on the upper or (and) lower surface of the lens refractive surface on the rotating mirror;

[0048] Figure 2 It is a schematic diagram of the change of the upper and lower surfaces of the lens refractive surface on the rotating mirror of the present invention when the rotating mirror rotates;

[0049] Figure 3 The present invention is a method for detecting the light passing through the refractive surface r. 1 (ωT), r 2 (ωT) after which the light path with oscillating behavior is formed. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below through the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0052] The embodiment of the present invention provides a lens refractive surface design on a rotating mirror to add curved surface features on the upper surface or (and) the lower surface of the rotating mirror, so that the incident laser is refracted and the rotating mirror is rotated to generate scanning light. Its structure is as follows Figure 1 .exist Figure 1 The laser enters from the side of the rotating mirror, and then is reflected by a reflector and rotated 90 degrees to enter the rotating mirror refractor. The laser is refracted in the rotating mirror refractor. After the refractor rotates, the laser does not move but the refractor rotates, so the surface of the laser entering the refractor will have different slopes, refracting the laser into laser emission lines in different directions. If the surface of the lens is properly designed, a laser scanning line can be obtained. Figure 2 is the relationship between the rotating mirror and the projection surface. B is the distance between the center of the rotating mirror and the projection surface. The inner and outer contours of the refractive lens can be described by polar coordinate functions (r, θ) respectively. r is the distance from the center to the contour. θ is the angle between a certain point of the contour and the reference line. The two functions can be expressed by the following formula:

[0053] The contour equation of a certain inner surface is r = r 1 (θ) 0≤θ<2π / N

[0054] The contour equation of a certain section is r = r 2 (θ) 0≤θ<2π / N

[0055] The equation N in the above is the number of times the mirror rotates a circle to scan the line back and forth. It can be a continuous function or a continuous function that is differentiated continuously more than once. θ = 0 refers to the origin of the polar coordinates, which is the point where the direction of the laser reflection entering the refractive lens coincides. The calculation method of the inner and outer contours has been explained in the above equations (1-10) and related explanations.

[0056] Example 1: First, the shape of the inner circle is set to a circle, that is,

[0057] r=r 1 (θ) = R

[0058] Therefore, from formula (1-2), we can get α 1 =0, And α 3 =α 2 -α 5 , β 1 =0.

[0059]

[0060] α 4 is the angle of refraction of the refractive surface, and (3) can be rewritten according to this case as

[0061]

[0062] If you want to r 1 (θ) calculates the formation function at multiple points, and divides θ into many small segments, for example, 120 segments between 0 and 2π / N, then

[0063]

[0064] Any time can be expressed as:

[0065] t i =iΔt i=0-119;

[0066] but

[0067] θ i =iωΔt i=0-119;

[0068] Here α 4 (-θ i ) is the known design parameter required for scanning, i = 0 when α 4 (0) = 0, r 2 (0) = H, r 2 '(0) = 0. If the coordinates of each point are required, equations (10) and (11) can be rewritten as:

[0069]

[0070] Set α with i=0 4 and r 2 Substitute the values ​​into (10')(11') in order to solve for r 2 (-ωt i ) can find the coordinates of each point from i = 0 to 119. The polar coordinates of the outer contour r 2 (-ωt i ) Using the coordinates of each point we can get the equation.

[0071] Embodiment 2:

[0072] The shape of the outer ring is set as a circle, that is,

[0073] r=r 2 (θ) = H;

[0074] If you want to r 1(θ) calculates the formation function at multiple points, and divides θ into many small segments, for example, 120 segments between 0 and 2π / N, then

[0075]

[0076] Then any time can be expressed as:

[0077] t i =iΔt i=0-119;

[0078] but

[0079] θ i =iωΔt i=0-119;

[0080] Formula (1) can be rewritten using the above formula as

[0081]

[0082] And (9) can be rewritten as

[0083]

[0084] Substituting (9′) into (1′), we can obtain:

[0085]

[0086] From formula (5′), we can get i hour:

[0087]

[0088] Depend on Figure 3 , if r 2 When it is a circle, we know:

[0089]

[0090] The previous formula already has

[0091] α 3 =α 1 +α 2 -α 5 (6);

[0092] Substituting (14) into (6) we can obtain:

[0093]

[0094] sinα 4 =n i sinα 3 (7)

[0095] And the five parameters to be solved are α1 , α 2 , α 3 , β 1 and r 1 (-ωt i ; Formulas (2), (7), (12), (13) and (15) can be used to solve these five parameters; so from formula (7), we can get the known α 4 (ωt i ) to get the α at that time 3 ; Here α 4 (-ωt i ) is the design parameter required for scanning, when i = 0, r 1 (0) = R, r 1 Substituting the value of ′(0)=0 into (2), (12), (13) and (15) to obtain α at each time point 1 , α 2 , β 1 and r 1 (-ωt i ), and get r 1 (-ωt i ) After finding all the points, the polar coordinate equation of the inner contour can be obtained.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

[0097] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method and device for setting the refractive surface of a refractive mirror lens, It is characterized in that The device includes a laser emitter, a rotating mirror with a refraction mirror, and a projection surface; The laser enters the rotating mirror refraction mirror, causing the laser to be refracted in the rotating mirror refraction mirror. After the laser enters the rotating mirror refraction mirror, the rotating mirror rotates, causing the surface of the laser entering the lens refraction mirror to have different slopes at different times, refracting the laser into laser emission lines in different directions. By designing the curved surface features of the lens refraction surface, the laser forms a scanning line on the projection surface.

2. A method and device for setting the refractive surface of a refractive mirror lens according to claim 1, It is characterized in that The lens refractive surface includes an inner contour surface and an outer contour surface, and the contours can be described by polar coordinate functions (r, θ) respectively; wherein r is the distance from the center to the contour, θ is the angle between a certain point of the contour and the reference line, θ=ωt, ω is the rotation speed of the rotating mirror; The contour equation of the inner contour surface is: r=r 1 (θ) -π / N≤θ<π / N The contour equation of the outer contour surface is: r=r 2 (θ) -π / N≤θ<π / N Where N is the number of times the scanning line goes back and forth when the mirror rotates one circle.

3. A method and device for setting the refractive surface of a refractive mirror lens according to claim 2, It is characterized in that Assuming that the laser spot is a point, when t = 0, the rotating mirror is in the instantaneous state when it just starts to rotate. In the initial state, the laser refracted by the refracting mirror will not be affected by refraction, and the light directly hits the point on the projection surface (A) from point o. 5 ), when t = T, the mirror rotates counterclockwise by ωT, T is the time it takes for the mirror to start rotating from zero. At this time, the distance between the inner refractive surface where the laser reflected by the mirror enters and point o is r 1 (-ωT), the surface tangent angle is α 1 After the mirror rotates ωT, the laser path first goes from o to point A. 2 , and then from point A 2 To point A 4 , and then from point A 4 To point A 6 ; Point A 1 The intersection point between the laser and the inner contour of the refraction mirror when the mirror is not rotating; the point A 2 It is the intersection point of the inner contour after the laser and the rotating mirror rotate by ωT; Point A 4 It is the intersection point of the outer contour of the laser and the rotating mirror after rotating by ωT; Point A 6 It is the point where the light hits the projection surface after the mirror has rotated by ωT.

4. A method and device for setting the refractive surface of a refractive mirror lens according to claim 3, It is characterized in that The slope of the coordinates is the relationship between polar coordinates and rectangular coordinates. 2 The point can get the surface tangent angle α 1 : The light hits the refraction point A 2 , if the material refractive index is n i , surface tangent angle α 1 , angle of incidence With refraction angle α 2 The refraction formula between: From the above formula, we can get α 2 , the refracted light goes along α 2 Keep going forward until you meet A 4 , at point A 4 The tangent angle can be obtained as α 5 : In the above formula, β 1 -ωT ​​is the intersection point between the laser and the outer contour after the mirror rotates ωT (A 4 ) is the angle of the unrotated coordinate, and β 1 ∠A 1 oA 4 , the last term ωT in equation (3) is the angle correction after the mirror rotates ωT; β 1 It is a clockwise rotation angle, so its value is negative in terms of coordinates. Its value is determined by the light and r = r 2 (θ) is determined by the intersection point. From the above, the following relationship can be obtained: Then, from the geometric relationship, we can get the following formula: where α 3 It is laser and A 4 The angle between the normal lines of the curve at point ; after rearranging the above formula, we can get α 3 ＝α 1 +α 2 -α 5 (6)； A 4 Point laser incident angle α 3 With refraction angle α 4 The refraction formula between: From the above formula, we can get the refraction angle α 4 sinα 4 =n i sinα 3 (7); where α 6 is the angle between the laser and the projection surface.

5. A method and device for setting the refractive surface of a refractive mirror lens according to claim 4, It is characterized in that The distance traveled by light in the y direction is d(ωT) d(ωT)=r 2 (b 1 -ωT)sin beta 1 +(Br 2 (b 1 -ωT)cosθ 1 )sina 6 (8) Assuming that T is reduced to a very small value, only the differential ΔT is left. The polar coordinate differential at any time T can be obtained by the formula (9-10) i ′(θ), r 2 The differential of ′(θ).

6. A method and device for setting the refractive surface of a refractive mirror lens according to claim 5, It is characterized in that When d(ωT) and α 4 is a known design parameter. From equations (7) and (8), we can solve r for different T. 1 (ωT), r 2 (ωT) value, and the obtained r 1 (ωT), r 2 (ωT) is the inner and outer contours of the rotating mirror lens r 1 (θ), r 2 (θ); When d(ωT) and α 4 As an uncertain design parameter, r 1 (ωT) or r 2 (ωT) One of the functions is known, if r 1 (θ) is known and can be obtained by using formula (8) and related formulas 2 (ωT), which is the outer contour of the rotating mirror lens; r 2 (θ) If r 2 (θ) is known and can be obtained by using formula (1-8) and related formulas 1 (ωT) is the inner and outer contours of the rotating mirror lens r 1 (θ); When α 4 As we know, when d(ωT) is uncertain, we can use r 1 (ωT) or r 2 (ωT) One of the functions is known, if r 1 (θ) is known and can be obtained by using formula (8) and related formulas 2 (ωT), which is the outer contour of the rotating mirror lens; if r 2 (θ) is known and can be obtained by using formula (1-7) and related formulas 1 (ωT) is the inner and outer contours of the rotating mirror lens r 1 (θ).

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