Laser shaping system

Abstract

The utility model relates to the technical field of optics, in particular to a laser shaping system. According to the invention, through the laser shaping system formed by combining a plurality of lenses, the collimated light emitted by the laser can be shaped into uniform flat-top rectangular light spots, and the shaping efficiency of the system is high; and the system can bear higher incident light power, so that higher power density of emergent illumination light spots is ensured.

Description

Technical Field

[0001] The present invention relates to the field of optical technology and relates to a laser shaping system. Background Art

[0002] The shape of the light spot emitted by a common laser is generally circular or elliptical, and the light intensity distribution of the light spot is generally Gaussian distribution, with high power at the center of the light spot and low power around the light spot, that is, the energy distribution of the light spot is uneven. When using a laser as an auxiliary illumination light source for a vision imaging system, in order to ensure uniform illumination within the field of view, beam shaping of the incident laser is required. Generally, industrial camera chips are rectangular, that is, the field of view of imaging is a rectangle. In order to improve the utilization rate of laser energy, the light spot illuminated by the laser needs to be a rectangular light spot or an approximately rectangular light spot. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a laser beam shaping optical path for obtaining a highly uniform rectangular light spot, which can adjust the laser beam into a required rectangular beam.

[0004] In a first aspect, an embodiment of the present invention provides a laser shaping system, including on the propagation path of the incident beam: an energy modulation system, including at least one aspheric cylindrical lens, the incident surface of which is an aspheric structure, for shaping a Gaussian-distributed light spot into a nearly flat-top rectangular light spot; a light spot shape adjustment system, including at least two spherical cylindrical lenses, for adjusting the width of the light spot by adjusting the positional relationship between the cylindrical lens and the energy modulation system or / and the positional relationship between the cylindrical lenses, and for compensating the irradiance distribution to make the rectangular light spot meet a preset aspect ratio.

[0005] In some specific implementation manners, it further includes a beam focusing system, and the beam focusing system is used to focus the waist of the incident beam to be incident on the energy adjustment system, so that the focus of the incident beam is located in front of the energy modulation system.

[0006] In some specific implementation manners, the beam focusing system includes at least two lenses movable along the optical axis, and the relative position between the two lenses is adjusted correspondingly according to the wavelength of the laser beam.

[0007] In some specific implementation manners, the focus of the laser beam passing through the first lens is located in front of the incident surface of the second lens.

[0008] In some specific implementation manners, the energy adjustment system includes two aspheric cylindrical lenses with aspheric incident surfaces.

[0009] In some specific implementation manners, the distance between the two aspheric cylindrical lenses satisfies that the focus is in front of the second aspheric cylindrical lens.

[0010] In some specific implementations, the two lenses are plano-convex spherical cylinders, the convex surface of the first lens is located on the light exit surface, and the convex surface of the second lens is located on the light incident surface.

[0011] In some specific implementations, the light spot shape adjustment system includes two cylindrical lenses, the first cylindrical lens is a negative concave mirror, and the second cylindrical lens is a cylindrical lens.

[0012] In some specific implementations, the concave surface of the negative concave mirror is located at the light incident surface.

[0013] In some specific implementations, the diameter of the incident light beam ranges from 0.9 mm to 1.1 mm.

[0014] The embodiments of the present invention bring the following beneficial effects:

[0015] An embodiment of the present invention provides a laser shaping system. The laser shaping system, composed of a plurality of lens combinations, can shape the collimated light emitted by a laser into a relatively uniform flat-top rectangular light spot. The system has high shaping efficiency. In addition, the system can withstand higher incident light powers, thereby ensuring that the output illumination light spot has a higher power density.

[0016] Other features and advantages of the present disclosure will be set forth in the following description, or some features and advantages may be inferred or unambiguously determined from the description, or may be learned by practicing the above-mentioned technology of the present disclosure.

[0017] In order to make the above-mentioned objectives, features and advantages of the present disclosure more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A schematic diagram of the optical path structure of the laser shaping system provided by an embodiment of the present invention at vertical incidence;

[0020] Figure 2 A schematic diagram of the optical path structure of the laser shaping system provided by an embodiment of the present invention at oblique incidence;

[0021] Figure 3 3a and 3b are schematic diagrams of the irradiance results in the first direction of the laser shaping system at two incident angles respectively;

[0022] Figure 4 Diagrams of the irradiance results in the second direction of the laser shaping system at two incident angles are shown in Figures a and 4b;

[0023] Figure 5 Diagrams of the spot results of the laser shaping system at two incident angles are shown in Figures a and 5b.

[0024] Icon: O - incident surface; I - illuminated surface; F1 - first focal plane; F2 - second focal plane;

[0025] G1 - beam convergence system; G2 - energy modulation system; G3 - spot shape adjustment system;

[0026] 1 - first lens; 2 - second lens; 3 - third lens; 4 - fourth lens; 5 - fifth lens; 6 - sixth lens. Detailed implementation manners

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0028] The objective lens provided in the embodiments of the present application is applied to an optical measurement scenario to provide an incident laser beam for the object to be measured. Among them, the optical measurement scenario mainly can be a semiconductor product. Specifically, the laser beam in this embodiment is a flat-top rectangular beam.

[0029] A flat-top beam is a beam with a uniform light intensity distribution within the spot range. Existing methods for shaping a laser beam into a flat-top beam include the aspheric lens method, the diffractive element method, the liquid crystal spatial modulation method, the metasurface and metamaterial method, etc. Among them, compared with other shaping methods, the aspheric lens method has the characteristics of high shaping efficiency, high energy conversion efficiency, and simple structure. In an aspheric lens system, the shaping principle of a Gaussian beam into a flat-top beam is based on the marginal ray theory and the law of conservation of energy, and the coordinate mapping relationship between the incident Gaussian beam and the flat-top beam is realized by designing a free-form aspheric surface.

[0030] Among them, the Powell prism is an aspheric lens often used in the prior art. Its incident surface is an aspheric surface. When a laser passes through this surface, a large spherical aberration will be generated, thereby redistributing the beam energy - reducing the light energy in the central region and increasing the light energy at the edges. In the prior art, an incident laser thin beam is shaped into a relatively uniform linear spot through a Powell prism, and the beam emerging from the Powell prism is a flat-top beam.

[0031] However, when using a Powell prism alone, a linear light spot with a narrow spot width is obtained. Moreover, in the common shaping optical path of a Powell prism, the incident laser is generally focused in the prism. When the laser power is high, the energy density at the focus of the converging light in the prism is very high, and it is easy to damage the lens when exceeding the internal damage threshold of the lens, which limits the increase of the incident laser power. In addition, the divergence angles of current Powell prisms are relatively large, and the corresponding shaped light spots will also be relatively large, and the spot power density is relatively low.

[0032] Therefore, in view of the above technical problems, this embodiment provides a laser shaping system for modulating a laser beam into a rectangular beam with a certain aspect ratio, and then the rectangular beam is adjusted in shape to the required spot shape.

[0033] Specifically, the laser shaping system in this embodiment includes an energy modulation system and a spot shape adjustment system. Among them, the energy modulation system is used to modulate the elliptical spot of the incident beam into a flat-top rectangular spot. And, in order to achieve the use effect of the spot, the size of the rectangular spot is adjusted through the spot shape adjustment system to realize the compensation of the irradiance distribution, and finally a rectangular spot that meets the preset aspect ratio, that is, the preset size, is formed.

[0034] Therefore, the first object of the laser shaping system provided in this embodiment is to provide a flat-top rectangular spot that can meet the preset aspect ratio, that is, the preset size.

[0035] Among them, the implementation effects of the above system are described separately.

[0036] In this embodiment, the energy modulation system is provided with at least one cylindrical lens, and by forming an aspherical structure on the incident surface of the cylindrical lens, the Gaussian-distributed spot is shaped into a flat-top rectangular spot close to it.

[0037] In order to optimize the modulation of the incident beam, in this embodiment, the number of cylindrical lenses in the energy modulation system is two, and the incident surfaces of the two cylindrical lenses are both aspherical structures. Through such a setting, the spot of the incident beam is adjusted to a flat-top rectangular spot.

[0038] In this embodiment, the spot shape adjustment system is used to adjust the width of the above rectangular spot, so that the formed rectangular spot meets the preset aspect ratio and has the preset size of the spot required in the actual scenario.

[0039] Specifically, the spot shape adjustment system in this embodiment includes at least two cylindrical lenses. The adjustment of the spot size is achieved by adjusting the relative positions between the above-mentioned at least two cylindrical lenses, or by adjusting the relative positional relationship between the above two cylindrical lenses and the energy modulation system. Moreover, it can also be achieved by simultaneously adjusting the relative positions between the above-mentioned at least two cylindrical lenses and the relative positional relationship between the two cylindrical lenses and the energy modulation system.

[0040] Among them, adjusting the relative position refers to adjusting the front-back positional relationship between the above-mentioned lenses and systems along the optical axis as the adjustment path, including adjusting forward and backward.

[0041] Furthermore, the principle of adjusting the spot size by the above-mentioned positional relationship is a basic optical principle and will not be elaborated in this embodiment.

[0042] This embodiment can adjust the laser beam from an elliptical spot to a flat-top rectangular spot through the above two systems, and can adjust the size of the rectangular spot to the target size according to actual needs. Compared with the prior art, this solution can not only change the spot shape, but also adjust the spot size, greatly improving the richness of shaping compared with the prior art.

[0043] As described in the background art, in the prior art, when the laser power is high, the energy density at the focus of the converging light is high, which causes damage to the lens. Therefore, for the laser shaping system in the above embodiment, it not only needs to be able to achieve the shaping of the flat-top beam, but also needs to solve the problem of lens damage caused by high energy density in the prior art.

[0044] For the solution to the above problem in this embodiment, the focus of the incident beam is adjusted to avoid the focus being on the incident surface of the lens on the optical path, thereby solving the problem of lens damage. Generally, the adjustment of the focus can be achieved by adjusting the position of the lens. However, in the actual scenario, because the positions of the foci generated by incident beams of different wavelengths are different, when the wavelength of the incident beam needs to be adjusted in the actual scenario, the lens after the position adjustment will be inapplicable.

[0045] Therefore, in this embodiment, to solve this technical problem, a beam convergence system is also provided on the optical path before the incident beam enters the energy modulation system. In this embodiment, the beam convergence system is used to converge the beam waist of the incident beam to be incident on the energy adjustment system to generate a focus, so that the focus of the incident beam is located before the energy modulation system.

[0046] Among them, the beam convergence system in this embodiment includes at least two lenses. The purpose of setting at least two lenses is to make corresponding adjustments according to the wavelengths of different laser beams, thereby solving the beam waist adjustment of laser beams with different wavelengths.

[0047] Preferably, in order to reduce the complexity of the system, the number of beam convergence systems in this embodiment is two.

[0048] The above-mentioned laser shaping system is described again according to the light propagation route. Refer to Figure 1 and Figure 2 , which are the optical path structures of the laser shaping system at different incident angles. Among them, Figure 1 is the optical path structure of the laser shaping system when the light is vertically incident, Figure 2 is the optical path structure of the laser shaping system when the light is obliquely incident. Specifically, when the light is obliquely incident, the incident angle is 70°.

[0049] Specifically, the laser shaping system in this embodiment is arranged between the incident surface O and the illuminated surface I. The incident surface O can be understood as a light source or other optical systems, including but not limited to a collimation system, etc. Among them, the diameter range of the incident light beam is 0.9 mm - 1.1 mm. For the laser shaping system in this embodiment, a beam convergence system G1, an energy modulation system G2, and a spot shape adjustment system G3 are sequentially arranged along the light propagation path.

[0050] Among them, the beam convergence system G1 includes a first lens 1 and a second lens 2 along the light propagation path. In this embodiment, the first lens 1 and the second lens 2 are plano-convex spherical mirrors. The convex surface of the first lens 1 is located on the light-emitting surface, and the convex surface of the second lens 2 is located on the light-incident surface.

[0051] In this embodiment, the first lens 1 and the second lens 2 can be applied to laser beam scenarios with different wavelengths by adjusting their relative positions. Moreover, through the beam convergence system G1, the focus of the incident light beam can be controlled in front of the energy modulation system G2, avoiding damage to the lens due to the high focus energy. Refer to Figure 1 and Figure 2 , the focus in the beam convergence system G1 is the first focal plane F1, which is between the first lens 1 and the second lens 2.

[0052] The energy modulation system G2 includes a third lens 3 and a fourth lens 4. In order to form a flat-top spot, the incident surfaces of the third lens 3 and the fourth lens 4 in this embodiment are aspherical cylindrical lenses with aspherical structures.

[0053] Moreover, regarding the relative positions of the third lens 3 and the fourth lens 4, the position of the second focal plane F2 of the incident light beam after passing through the third lens 3 needs to be considered. Specifically, in this embodiment, the second focal plane F2 of the incident light beam passing through the third lens 3 is located at the front end of the fourth lens 4. That is, the second focal plane F2 should be between the third lens 3 and the fourth lens 4 and cannot be on the light incident surface of the fourth lens 4, so as to avoid damage to the lens due to the relatively high energy density.

[0054] For the spot shape adjustment system G3, in this embodiment, it includes a fifth lens 5 and a sixth lens 6. Among them, the fifth lens 5 and the sixth lens 6 are cylindrical lenses. Among them, the fifth lens 5 is a negative concave mirror, and the second cylindrical lens is a cylindrical lens. Specifically, the concave surface of the fifth lens 5 is located at the light incident surface.

[0055] Moreover, the relative positions between the fifth lens 5 and the sixth lens 6 in this embodiment can be adjusted to realize the adjustment of the spot width, so as to compensate the irradiance distribution and make the rectangular spot meet the preset aspect ratio.

[0056] The laser shaping system composed of the above lens combinations in this embodiment can shape the collimated light beam emitted by the laser into a relatively uniform flat-top rectangular spot, and the shaping efficiency of the system is relatively high; moreover, this system can withstand a relatively high incident light power, so as to ensure a relatively high power density of the emitted illumination spot.

[0057] Refer to Figure 3 、 Figure 4 and Figure 5 are respectively schematic diagrams of the irradiance results on two different direction objects of the laser shaping system at two incident angles, and schematic diagrams of the spot results at two incident angles. Among them, the two incident angles are perpendicular incidence and oblique incidence at 70°. The three different direction objects are the X direction and the Y direction respectively.

[0058] As can be seen from the above figures, for the shaping optical path, it can still ensure good spot uniformity when irradiating at a relatively large oblique angle, and the stretched spot width in the oblique direction can be narrowed by adjusting the lenses of the shaping system, so as to improve the power density of the illuminated area.

[0059] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. 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 described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A laser shaping system, characterized in that, Including on the propagation path of the incident light beam: An energy modulation system, including at least one aspheric cylindrical lens, whose incident light surface is an aspheric structure, for shaping the spot with Gaussian distribution into a flat-top rectangular spot; A spot shape adjustment system, including at least two spherical cylindrical lenses, the positional relationship between the cylindrical lenses and the energy modulation system or / and the positional relationship between the cylindrical lenses can be adjusted to achieve a change in the spot width, for compensating the irradiance distribution to make the rectangular spot meet the preset aspect ratio.

2. The laser shaping system according to claim 1, wherein It also includes a beam convergence system, and the beam convergence system is used to converge the beam waist of the incident light beam to be incident on the energy adjustment system, so that the focus of the incident light beam is located in front of the energy modulation system.

3. The laser shaping system according to claim 2, wherein, The beam convergence system includes at least two lenses movable along the optical axis, and the relative position between the two lenses is correspondingly adjusted according to the wavelength of the laser beam.

4. The laser shaping system according to claim 3, characterized in that, The focus of the laser beam passing through the first lens is located at the front end of the incident light surface of the second lens.

5. The laser shaping system according to claim 2, wherein The energy adjustment system includes two aspheric cylindrical lenses with aspheric incident light surfaces.

6. The laser shaping system according to claim 4, wherein The distance between the two aspheric cylindrical lenses satisfies that the focus is in front of the second aspheric cylindrical lens.

7. The laser shaping system according to claim 4, wherein The two lenses are plano-convex spherical cylindrical lenses, the convex surface of the first lens is located on the light-emitting surface, and the convex surface of the second lens is located on the incident light surface.

8. The laser shaping system according to claim 1, characterized in that The spot shape adjustment system includes two cylindrical lenses, the first cylindrical lens is a negative concave mirror, and the second cylindrical lens is a cylindrical lens.

9. The laser shaping system according to claim 8, wherein The concave surface of the negative concave mirror is located at the incident light surface.

10. The laser shaping system according to claim 1, wherein The diameter range of the incident light beam is 0.9 mm - 1.1 mm.

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