Refraction type galvanometer and galvanometer group

Abstract

The invention discloses a refraction type galvanometer and a galvanometer group, the galvanometer comprises a refraction lens and a driving mechanism, and the refraction lens periodically swings under the action of the driving mechanism. The galvanometer group comprises two refraction type galvanometers, and extra space required by light reflection does not need to be reserved, so that the overall structure of the scanning system is simpler and more compact than that of a reflection type galvanometer system. Because the refracting surface of the refracting lens can be changed according to the deflection period and angle and the requirement for generating a scanning curve, the scanning requirement can be met without changing the control of a driving mechanism, the flexibility and adaptability higher than those of a reflective galvanometer system are provided, the speed of scanning laser on a scanning surface can be controlled by utilizing the shape of the refracting surface, and the scanning precision is improved. Therefore, the scorching phenomenon caused by the fact that the scanning speed of the reflection type galvanometer is zero is avoided. In addition, the use of the refraction lens enables the light to directly penetrate through the lens instead of depending on the reflection light, thereby remarkably improving the laser application efficiency, and enhancing the performance and benefits of the whole system.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser scanning, and particularly relates to a refractive galvanometer and a galvanometer group. Background Art

[0002] Laser processing is a technology that uses a laser beam to process an object, which has the advantages of environmental protection, cleanliness, high efficiency, easy operation, etc., and is widely used in the field of production and manufacturing. Laser processing includes laser cutting, laser cleaning, laser welding, etc. Among them, laser cleaning technology, as a new cleaning method, irradiates the surface of the workpiece with a high-energy laser beam, so that the dirt, rust layer or coating on the surface evaporates or peels off instantly, thereby achieving the cleaning purpose. Laser cleaning has the characteristics of non-contact, environmental protection, non-damage and high efficiency, and is particularly suitable for fields with high requirements for cleaning quality such as precision machinery, electronic products and cultural relic protection.

[0003] Handheld laser cleaning equipment has been widely used in recent years and is favored for its flexible, convenient operation and high cleaning efficiency. Handheld laser cleaning systems usually adopt one-dimensional or two-dimensional scanning methods. One-dimensional scanning forms a linear scan by the swing of a galvanometer, while two-dimensional scanning uses two galvanometers that swing in different directions respectively to form a more flexible two-dimensional scan curve. Although galvanometer scanning technology is widely used in laser cleaning, it also has some deficiencies that cannot be ignored, especially in high-power laser applications. Solving these deficiencies, especially heat management, dynamic range and accuracy problems, makes it particularly necessary to promote the research and development of refractive galvanometers.

[0004] The reflective galvanometer scanning system has several disadvantages. First is the heat management problem. When the galvanometer scanning system is moving at high speed, the driving mechanism will generate a large amount of heat. If this heat cannot be effectively dissipated, it may cause the lens to deform or be damaged, thereby affecting the scanning accuracy and stability. In high-power laser applications, heat management is particularly important and an additional cooling system must be relied on to keep the system running normally. Secondly, the dynamic range of the reflective galvanometer is relatively limited. The maximum scanning angle of the scanning system is limited by the physical design of the lens and the ability of the driving system. This becomes an obvious bottleneck in applications that require high-speed and large-range scanning, such as holographic imaging or large-size laser processing.

[0005] In addition, the vibration problem of the galvanometer scanning system is also the key reason for its unstable accuracy. Since the galvanometer is a mechanical moving part, vibration will inevitably occur during high-speed movement. Vibration will affect the accuracy of the scanning line, resulting in an uneven or deviated scanning surface. Although modern galvanometer scanning systems have introduced advanced vibration suppression technologies, the vibration problem still exists and has a certain impact on the system accuracy. In addition, the driving system of the reflective galvanometer is complex and costly, and high-precision driving electronic equipment is required to control its movement, which increases the complexity, cost and maintenance difficulty of the system.

[0006] Between the scanning speed and the range, the reflective galvanometer system needs to make a compromise. High-speed scanning usually results in a reduced scanning range, and vice versa, and it is impossible to meet the requirements of both fast scanning and large-range scanning at the same time. Especially in high-energy laser applications, the uneven speed of the galvanometer will cause uneven laser intensity received on the scanning surface, and even uneven charring, which will seriously affect the cleaning effect.

[0007] To overcome the disadvantages of the reflective galvanometer scanning system, the refractive galvanometer has become an important research and development direction. The refractive galvanometer uses the principle of a lens and can effectively avoid the light deviation problem caused by the reflective galvanometer. Since the lens can directly transmit light without being blocked, it can significantly reduce the volume of the scanning system and avoid the space occupation caused by the lens deviation in the reflective galvanometer. Existing transmissive galvanometer devices, such as the flat transmissive galvanometer mentioned in Patent CN102922130A, although they can avoid light being blocked, their scanning effect is relatively limited and cannot meet the application requirements of high precision and high performance. Therefore, there is an urgent need for a new refractive galvanometer design to improve the deficiencies of existing transmissive galvanometers in scanning accuracy and functionality. Summary of the Invention

[0008] To solve one or more of the above technical problems, the present invention provides a refractive galvanometer and a galvanometer group, which can improve the performance of the laser processing system by avoiding the light blocking and space occupation of the reflective galvanometer, especially in high-precision and high-power laser applications.

[0009] The technical solutions provided by the present invention are as follows:

[0010] A refractive galvanometer includes a refractive lens. At least one of the opposite upper surface and lower surface of the refractive lens is a curved surface, and the refractive lens is provided with a rotation axis connected to a driving mechanism. The driving mechanism is used to make the rotation axis perform periodic forward / backward rotation, and then make the refractive lens swing periodically around the rotation axis; it also includes a laser light source and a control module connected to the driving mechanism. The control module is used to adjust the swing period and swing amplitude of the refractive lens by controlling the driving mechanism;

[0011] The laser enters the refractive lens from the upper surface of the refractive lens, and after being refracted by the light, it exits from the lower surface of the refractive lens. The outgoing light forms a projection point at the projection position on the projection surface at a projection angle that meets the scanning requirements; during the periodic swing of the refractive lens, the incident angle of the laser is continuously changed, so that a series of continuous projection points of the outgoing light on the projection surface form a one-dimensional scanning straight line.

[0012] Furthermore, the upper and lower surfaces of the refractive lens that face each other are both curved surfaces, and the upper and lower surfaces are centrosymmetric and / or axially symmetric.

[0013] Furthermore, when the incident laser spot is not a point, the curved surface shape of the refractive lens is obtained by making corrections according to the actual situation using optical software.

[0014] Preferably, the rotation axis is located at the center of symmetry or on the axis of symmetry; the curved surface is a hyperboloid.

[0015] A refractive galvanometer group includes two refractive galvanometers as described above, which are respectively called the first galvanometer and the second galvanometer; the refractive lens and the rotation axis included in the first galvanometer are respectively called the first lens and the first rotation axis, and the refractive lens and the rotation axis included in the second galvanometer are respectively called the second lens and the second rotation axis;

[0016] Laser enters from the upper surface of the first lens and exits from the lower surface of the first lens as the first outgoing light after refraction of the light. The first outgoing light enters from the upper surface or the lower surface of the second lens and exits from the lower surface or the upper surface of the second lens as the second outgoing light. The second outgoing light forms a projection point on the projection surface; the first lens continuously changes the incident angle of the laser incident thereon during the periodic swinging process, and / or the second lens continuously changes the incident angle of the first outgoing light incident thereon during the periodic swinging process, so that a series of continuous projection points of the second outgoing light on the projection surface form a two-dimensional scanning curve.

[0017] Preferably, the first rotation axis and the second rotation axis are perpendicular or parallel to each other.

[0018] Compared with the prior art, the present invention exhibits many remarkable advantages. First of all, the present invention can accurately control the speed of the scanning laser on the scanning surface, thus effectively avoiding the charring phenomenon caused by the uneven scanning speed of the traditional reflective galvanometer. Secondly, when using the refractive galvanometer design, the combination of the two galvanometers does not need to leave extra space for the light to pass through like the traditional reflective galvanometer, which makes the volume of the scanning system more compact and the overall structure more streamlined than the existing reflective galvanometer. Further, since the deflection period and angle of the galvanometer can be controlled, the two-dimensional scanning curve generated by the present invention is more diverse, providing higher flexibility and adaptability than the traditional reflective galvanometer system. Finally, the use of the refractive lens allows the light to directly pass through the lens instead of relying on the reflected light. Since the material and manufacturing method of ordinary lenses can achieve a light transmittance higher than the reflectivity, this design significantly improves the efficiency of laser applications and enhances the performance and benefits of the overall system. Therefore, the present invention shows great optimization in terms of laser scanning accuracy, efficiency and volume through the advantages of the refractive galvanometer. Description of the Drawings

[0019] The accompanying drawings are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation to the present invention.

[0020] Figure 1 is a schematic diagram of the principle of a refractive galvanometer provided by an embodiment of the present invention;

[0021] Figure 2 is a top view of a refractive lens provided by an embodiment of the present invention;

[0022] Figure 3 is a schematic diagram of the light refraction after the galvanometer rotates by a certain angle provided by an embodiment of the present invention;

[0023] Figure 4 is a schematic diagram of the principle of a refractive galvanometer group provided by an embodiment of the present invention;

[0024] Figure 5 is a schematic diagram of the light refraction of the second lens in the galvanometer group provided by an embodiment of the present invention;

[0025] Figure 6 is a schematic diagram of the refraction of the second lens in the galvanometer group in the direction parallel to the rotation axis. Detailed Embodiments

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] Embodiment 1

[0028] This embodiment provides a refractive galvanometer. As Figure 1 shown, the refractive galvanometer includes a refractive lens 1. The upper surface and / or the lower surface of the refractive lens 1 is a curved surface, and a rotation axis 2 connected to a driving mechanism is fixedly arranged at the center of the refractive lens 1. By driving the rotation axis 2 to rotate forward / backward, the refractive lens 1 swings periodically around the rotation axis 2. The laser 3 enters the lens from the upper surface of the refractive lens 1, and after refraction, exits from the lower surface of the refractive lens 1. The outgoing light 8 forms a projection point 81 on the projection surface 9. Since the refractive lens 1 continuously changes the incident angle of the laser 3 during the periodic swinging process, the outgoing angle of the outgoing light 8 and its projection position on the projection surface 9 are changed. A series of continuous projection points 81 finally form a one-dimensional scan line 91 on the projection surface 9.

[0029] Figure 2Upper view of a refractive galvanometer. The upper surface 11 and the lower surface 12 of the lens 1 are represented by polar curves r 11 (α1) and r 12 (α2) respectively. r 11 On Figure 2 the label is 6, r 12 On Figure 2 the label is 7, α1 on Figure 2 the label is 13, α2 on Figure 2 the label is 14. The label 22 is the optical axis in the direction of the vertical rotation axis 2 of the lens 1. In this figure, it shows the position of the optical axis after the galvanometer rotates clockwise by an angle α1. In polar coordinates, α1 and α2 are positive in the counterclockwise direction (starting from the optical axis 22 of the lens 1). α1 and α2 are functions of time t, and r 11 and r 12 are positive in the outward direction. It should be noted here that the galvanometer rotates clockwise, but the angle α1 is counterclockwise in polar coordinates. The intersection point 64 of the incident laser 3 and the curve r 11 (α1), the laser 3 is refracted into the outgoing light 8 after passing through the lens, and the intersection point 74 of the outgoing light 8 and the curve r 12 (α2).

[0030] Figure 3 In order to make the drawing clear, the lens contour is omitted, and only the normal and tangent diagrams of the intersection points of the light rays at α1 = 0 and α1 = α1 are left. The solid line 4 is the tangent of the intersection point of the laser 3 and the surface 11 (r 11 (0)) of the lens 1 when the swing angle is zero, and the solid line 5 is the tangent of the intersection point of the laser and the surface 12 (r 12 (0)) of the lens 1 when the swing angle is zero. In this embodiment, the lens is symmetric left and right to find the curve, so the tangents 4 and 5 are parallel and the slope is zero. The lens thickness h(45) is defined as the sum of the lengths of r 11 and r 12 when the swing angle is zero. That is

[0031] r 11 (0) + r 12 (0) = h

[0032] As for what r 11 and r 12 are respectively, it is up to the designer to control. If the shapes of r 11 (α1) and r 12 (α2) are not very different, the center of the rotation axis 2 can be set at r 11 (0) = r 12 (0) = h / 2, otherwise r 11 (0) and r 12(0) Place the rotation axis 2 at the center of the lens cross-section. The galvanometer swing angle is α1 in the clockwise direction (here, the rotation angle of the galvanometer is in the opposite direction of the polar angle of r 11 ), and let α1 be a simple harmonic motion:

[0033]

[0034] α is the amplitude of the galvanometer swing angle, and T is the swing period.

[0035] Swing speed

[0036]

[0037] Let it be that after the galvanometer rotates by an angle α1, the intersection point of the curve r 11 (α1) and the incident laser 3 is 64. At this time, the tangent 61 and the normal 62 of r 11 (α1) ( Figure 3 shown as a dotted line in the figure, and the slope can be found using the differential of r 11 ). The relationship between the incident angle θ1 (labeled 63) and the refraction angle θ2 (labeled 68) is given by the refractive index formula. The angle between the refraction optical path 65 and the laser incident ray 3 is θ3 (labeled 66), and the intersection point of the optical path 65 and r 12 (α2) is labeled as 74 (the angle α2 labeled as 14 represents the polar coordinate angle between r 12 at the intersection point 74 and the central axis of the lens after the lens rotates by an angle α1). The normal 72 and the tangent 71 at 74 can be found using the differential of r 12 respectively. The angle θ4 (labeled 21) between r 12 (the straight line 7) and the incident laser 3 can be seen from Figure 3 to contain two angles α1 and α2. The angle θ5 (labeled 67) between the optical path 65 and the lower surface normal 72 at the intersection point 74; the refraction angle θ6 (labeled 73) of the optical path 8 after the intersection point 74, the angle θ7 (labeled 82) between the optical path 8 and the projection plane, the vertical line 75 passing through the point 74 and the incident laser 3, and the angle θ8 (labeled 76) between the vertical line 75 and the tangent 71 can be found using the differential of r 12 respectively. x (labeled 91) is the distance between the intersection point 81 of the optical path 8 and the projection plane 9 and the intersection point 31 of the incident ray 3 and the projection plane after the galvanometer rotates by α1. From Figure 3 the following relationships between the parameters can be obtained:

[0038]

[0039] can be rewritten as

[0040]

[0041] From the refractive index formula:

[0042]

[0043] n J is the refractive index of the lens, which can be obtained from Figure 3 the geometric relationship:

[0044] θ3 = θ1 - θ2 (3)

[0045] θ4 = α1 + α2 (4)

[0046] And the relationship between θ8 and r 12 (the slope of α2) and α2 is as follows:

[0047]

[0048] can be rewritten as

[0049]

[0050] And then from Figure 3 the geometric relationship, we can get

[0051] θ5 = θ3 + θ8 (6)

[0052] And

[0053]

[0054] from the refractive index, we can get

[0055]

[0056] Let the distance between point 64 and point 74 be l, then

[0057]

[0058] Adding the triangle formed by point 64, point 74 and point 2, then

[0059]

[0060] we can get

[0061]

[0062] In addition, let the distance between the center of the galvanometer rotation axis and the projection plane be m, then the length x of 91 is:

[0063] x = (m - r 12 (α2)cosθ4)cotθ7 + r 12 (α2)sinθ4 (10)

[0064] In the above formula, x is the projection point of the scan line corresponding to α1, which is a function of α1 and also a design parameter. Its function can be determined according to the scan requirements. For example, if the scan speed is to be a constant, x can be defined as x = vt, where v is the designed scan speed, and θ7 is the projection angle of the laser on the projection plane desired by the designer.

[0065] It is very difficult to obtain solutions for equations (1) to (10) because they contain differential terms. Therefore, the differential equations are written as geometric equations using the finite difference method. The amplitude α(t) of the galvanometer is a function of time t. Since the lens is assumed to be symmetric in this example, only the lens shape for a quarter period T of the galvanometer swing needs to be calculated. Therefore, the time T is divided into n time intervals, that is, in the i + 1 interval:

[0066]

[0067] In the above formula

[0068]

[0069] And α1 i+1 At t i+1 = t i + Δt, the angle is

[0070] α1 i+1 = α(t i+1 )

[0071] Here, i = 0………n. In this example, the swing is set as

[0072]

[0073] When i = 0, α1 0 = 0, and r 11 0 Is a known value of the design and can be set as Or the distance between the center of the lens shape and the upper mirror curve. Similarly, α2 0 = 0, and r 12 0 Is a known value of the design and can be set as Or the distance between the center of the lens shape and the upper mirror curve. And And Can be rewritten as finite difference formulas respectively:

[0074]

[0075] Using the above two formulas, equations (1) to (10) can be rewritten as

[0076]

[0077] θ4 i+1 = α1i+1 +α2 i+1 (4’)

[0078]

[0079]

[0080] x i+1 =(m - r 12 i+1 (α2 i+1 )cosθ4 i+1 )cotθ7 i+1 +r 12 i+1 (α2 i+1 )sinθ4 i+1 (10’)

[0081] There are a total of 10 unknowns, namely r 11 i+1 , r 12 i+1 , α2 i+1 , θ1 i+1 , θ2 i+1 , θ3 o+1 , θ4 i+1 , θ5 i+1 , θ6 i+1 and θ8 i+1 , and the known design parameters are α1 i+1 , θ7 i+1 and x i+1 . α1 i+1 is the rotation angle of the galvanometer mirror changing with time t i+1 , θ7 i+1 and x i+1 are the position and projection angle of the laser on the projection plane at time t i+1 . However, observing equations (1’) to (10’), if only r 11 i+1 , r 12 i+1 and α2 i+1 are to be found, then only equations (3’), (4’), (8’), (9’) and (10’) need to be used to obtain them. These 5 equations are basically non - linear algebraic equations. The methods for solving general numerical non - linear algebraic equations can be used to find r 11 i +1 , r 12 i+1 and α2 i+1 .

[0082] If the design requirement here is and xi+1 = v(i + 1)Δt, where v is the laser scanning speed on the projection plane and is a constant. At this time Swing speed The lens projects α1 i+1 onto the projection plane at a constant speed v and When i + 1 = n, (This point is the position where it is most likely to burn the projection plane when using a conventional reflective galvanometer) is at zero swing speed but becomes a constant speed v after passing through the lens. Physically, the lens cannot reach this point, which is a geometric singularity. Therefore, in this situation, this part of the energy must be discarded, that is, the lens refracts this part of the energy to other places on the projection plane near i = n to avoid this singularity. Here, it is assumed that the laser is a point light source. If the light spot is not a single point, the optimal curve can be obtained by using the curve obtained by the above method as the basic curve and making corrections according to the actual situation using optical software.

[0083] Embodiment 2

[0084] This embodiment provides a refractive galvanometer group. Two of the above-mentioned refractive galvanometers are combined into a galvanometer group to form a two-dimensional scanning system. Since the scanning light is generated by refraction, there is no need to leave a space for the light to be reflected through when two galvanometers are combined, which can greatly reduce the overall volume of the scanning system. Of course, replacing one of the refractive galvanometers in the galvanometer group with a reflective galvanometer can also generate two-dimensional scanning light on the projection plane.

[0085] As Figure 4 shown, the rotation axes of the two refractive lenses (1 and 1') are perpendicular to each other in space, and the perpendicular distance between the rotation axes is mm. The swing angle α1 of the first lens 1 is expressed as:

[0086]

[0087] The swing angle α of the second lens 1' 1′ with an amplitude α' and a period T 1′ is expressed as:

[0088]

[0089] The above-mentioned swing is determined by the control of the driving motor of the galvanometer. The scanning line on the projection plane is designed for the first lens 1 as The scanning line on the projection plane is designed for the second lens 1' as Here, x1 and x 1′For the x in formula (10), the difference lies in different m values for different lenses. The first lens 1 is replaced by mm, and the second lens 1' is replaced by m'. The cross-sections of these two lenses can be found using similar formulas (1) to (10) (the formulas are the same but the labels are changed to 1 and 1' according to the lens), and the lenses are extended along the axis direction with the designed curved surface to form a 2.5D lens structure. That is, the corresponding upper and lower surfaces in the lens cross-section profile are hyperbolas.

[0090] As Figure 5 shown, the second lens 1' is scanned by the laser beam emitted from the first lens 1 and projected onto the projection plane 9' through the second lens 1', and a two-dimensional curve is obtained on the projection plane 9'. The incident angle of the light scanned by the first lens 1 on the second lens, in addition to the scanning angle of the scanning line of the first lens, also adds the swing angle α 1′ (labeled as 81') of the second lens 1'. Assume that the upper surface shape parameter r 11 ' of the second lens 1', the lower surface shape parameter r 12 ', the polar coordinate angle α 1′ of the upper surface shape parameter, and the polar coordinate angle α 21′ of the lower surface shape parameter. The included angle 82 between the light ray 8 at the scanning time t of the first lens 1 and the curved surface of the second lens 1' is θ7, and x1 is the scanning distance 91 of the first lens from the laser origin (t = 0) to t (which can be obtained from formula 10). Figure 6 is the cross-sectional view of the light ray 8 passing through the axis of the second lens 1'. The projection direction of the scanning line of the first lens 1 is set at the intersection point 16' of the axis of the second lens 1' and the upper curved surface at t = 0, and the light ray 8 is incident on the mirror surface 11' at t. The refraction angle 82' of the projection point is θ7 (because 11' and 12' are parallel in the axial direction, so the incident angle and the exit angle are equal). Although the projection direction of the scanning line of the first lens 1 is fixed, due to the swing of the second lens 1' over time, the intersection point 16' will move left and right on the second lens due to the swing of the second lens, and the lens thickness 15' will change with the swing of the second lens 1'. From Figure 5 it can be seen that the lens thickness 15' at t is r 11 '(α 1′ ) + r 12 '(α 1′ ). There will be a height change of r 11 '(α 1′ ) - r 11 '(0) on the upper curved surface of the second lens, and x1 of the first lens 1 will also change accordingly

[0091] x1(t) = x 1m (t) - (r 11 '(α 1′ ) - r 11 '(0)) tanθ7

[0092] In the above formula, x 1m (t) is the result obtained by substituting m in formula (10) into mm. 91’ is the scanning distance x1′ from the laser origin (t = 0) to t, and the refraction angle 77’ is θ 10 . The distance 29’ from the center of the rotation axis to the projection plane 9’ is m′. Therefore

[0093] x1′ = x 1m (t) - (r 11 ′(α 1′ ) - r 11 ′(0))tanθ7 + (r 11 ′(α1′) + r 12 ′(α 1′ ))sinθ 10 + (m′ - r 12 ′(α 1′ ))cotθ7

[0094] In the above formula

[0095]

[0096] The scanning curve projected onto the projection plane 9’ can be obtained with the coordinates of x1 varying with time as the x-axis and x1′ as the y-axis

[0097] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting it; under the idea of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above. For the sake of brevity, they are not provided in detail; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application

Claims

1. A refractive galvanometer, characterized in that, It includes a refractive lens, at least one of the opposite upper and lower surfaces of the refractive lens is a curved surface, and the refractive lens is provided with a rotation axis connected to a driving mechanism, and the driving mechanism is used to make the rotation axis perform periodic forward / backward rotation, so that the refractive lens swings periodically around the rotation axis; it also includes a laser light source and a control module connected to the driving mechanism, and the control module is used to adjust the swing period and swing amplitude of the refractive lens by controlling the driving mechanism; The laser enters the refractive lens from the upper surface of the refractive lens, and after being refracted by the light, it exits from the lower surface of the refractive lens. The outgoing light forms a projection point at the projection position on the projection surface at a projection angle that meets the scanning requirements; during the periodic swing of the refractive lens, the incident angle of the laser is continuously changed, so that a series of continuous projection points of the outgoing light on the projection surface form a one-dimensional scanning straight line; the curved surface shape of the refractive lens is deduced from the positions of the continuous projection points and the projection angle of the laser.

2. The refractive galvanometer according to claim 1, wherein Both the opposite upper and lower surfaces of the refractive lens are curved surfaces, and the upper and lower surfaces are centrosymmetric and / or axially symmetric.

3. A refractive galvanometer as claimed in claim 1, wherein, When the incident laser spot is not a single point, the curved surface shape of the refractive lens is corrected according to the actual situation using optical software.

4. The refractive galvanometer according to claim 2, wherein, The rotation axis is located at the center of symmetry or the axis of symmetry.

5. The refractive galvanometer according to claim 2, wherein, The curved surface is a hyperboloid.

6. A refractive galvanometer group, characterized in that, It includes two refractive galvanometers as described in any one of claims 1 to 5, which are respectively called the first galvanometer and the second galvanometer; the refractive lens and the rotation axis included in the first galvanometer are respectively called the first lens and the first rotation axis, and the refractive lens and the rotation axis included in the second galvanometer are respectively called the second lens and the second rotation axis; The laser enters from the upper surface of the first lens and after being refracted by the light, exits from the lower surface of the first lens as the first outgoing light. The first outgoing light enters from the upper surface or the lower surface of the second lens and after being refracted by the light, exits from the lower surface or the upper surface of the second lens as the second outgoing light. The second outgoing light forms a projection point on the projection surface; during the periodic swing of the first lens, the incident angle of the laser incident thereon is continuously changed, and / or during the periodic swing of the second lens, the incident angle of the first outgoing light incident thereon is continuously changed, so that a series of continuous projection points of the second outgoing light on the projection surface form a two-dimensional scanning curve.

7. The refractive galvanometer group according to claim 6, characterized in that, The first rotation axis and the second rotation axis are perpendicular or parallel to each other.

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