Beam shaping system

Abstract

The embodiment of the present application discloses a beam shaping system for shaping a light beam emitted by a light source into a linear light spot with high uniformity and narrow line width at a relatively low cost. The embodiment of the present application comprises: a light source for emitting an initial light beam; a first free-form surface mirror for uniformly distributing the energy in the initial light beam; a second free-form surface mirror for adjusting the size of the initial light beam emitted from the first free-form surface mirror in a first axial direction, and irradiating the adjusted initial light beam to the surface to be measured to form a linear light spot, wherein the first axial direction is perpendicular or parallel to the optical axis of the initial light beam; wherein the size of the initial light beam in the second axial direction is adjusted by the first free-form surface mirror or by the second free-form surface mirror, and the first axial direction is perpendicular to the second axial direction.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of semiconductor detection technology, and in particular to a beam shaping system. Background Art

[0002] Lasers are common optical devices. Due to their advantages such as good monochromaticity and high brightness of emitted light, they have gradually become key optical devices in various fields such as semiconductor testing, national defense, and scientific research. In the field of semiconductor testing, different application scenarios have different requirements for the shape and spatial distribution of the light spot.

[0003] In the field of semiconductor inspection, it is often necessary to shape a Gaussian beam into a flat-top spot with high uniformity and narrow linewidth. To achieve optimal shaping, physical optics shaping is often used. Beam shaping is achieved through the surface microstructure of diffractive optical elements (DOEs).

[0004] However, in order to achieve precise beam shaping, the surface microstructure of DOE is designed to be extremely complex, making it difficult to manufacture and resulting in higher production costs. Summary of the Invention

[0005] The embodiments of the present application provide a beam shaping system for shaping a Gaussian beam into a linear flat-top light with high uniformity and narrow linewidth at a relatively low cost.

[0006] The beam shaping system provided in the first aspect of the embodiment of the present application includes:

[0007] a light source for emitting an initial light beam;

[0008] a first free-form surface mirror, configured to uniformly distribute the energy in the initial light beam;

[0009] a second free-form surface mirror, configured to adjust a size of an initial light beam emitted from the first free-form surface mirror in a first axial direction, and to irradiate the adjusted initial light beam onto the surface to be measured to form a line spot, wherein the first axial direction is perpendicular or parallel to the optical axis of the initial light beam;

[0010] The size of the initial light beam in the second axial direction is adjusted by the first free-form surface mirror or the second free-form surface mirror, and the first axial direction is perpendicular to the second axial direction.

[0011] Optionally, the size of the initial light beam in the second axial direction is adjusted by the first free-form surface mirror, and the surface to be measured is not perpendicular to the optical axis of the adjusted initial light beam;

[0012] The second free-form surface mirror is further used to perform defocus compensation on the initial light beam emitted from the second free-form surface mirror, so that the line light spot formed by irradiating the surface to be measured is in a focused state.

[0013] Optionally, the initial light beam emitted by the light source is incident from the plane of the first free-form surface mirror and is emitted from the free-form surface of the first free-form surface mirror;

[0014] or,

[0015] The initial light beam emitted by the light source is incident from the free-form surface of the first free-form surface mirror and is emitted from the plane of the first free-form surface mirror.

[0016] Optionally, the initial light beam emitted from the first free-form surface mirror is incident from the free-form surface of the second free-form surface mirror, and is emitted from the plane of the second free-form surface mirror;

[0017] or,

[0018] The initial light beam emitted from the first free-form surface mirror is incident from the plane of the second free-form surface mirror and is emitted from the free-form surface of the second free-form surface mirror.

[0019] Optionally, the beam shaping system further includes:

[0020] The beam expansion component located between the light source and the first free-form surface mirror is used to expand the diameter of the initial light beam emitted from the light source and make the initial light beam emitted from the light source reach the first free-form surface mirror.

[0021] Optionally, the beam expanding assembly is a continuously variable magnification beam expanding system, and along the direction in which the initial light beam is incident on the beam expanding assembly, the beam expanding assembly sequentially includes a zoom lens group, a compensation lens group and a fixed lens group.

[0022] Optionally, the zoom lens group is a biconvex lens, the compensation lens group is a biconcave lens, and the fixed lens group is a biconvex lens.

[0023] Optionally, the optical center thickness of the biconvex lens and the biconcave lens is greater than or equal to 2 mm, and the edge thickness of the biconvex lens and the biconcave lens is greater than or equal to 1 mm.

[0024] Optionally, the material of the first free-form surface is fused quartz, calcium fluoride or K9, and the material of the second free-form surface is fused quartz, calcium fluoride or K9.

[0025] Optionally, the initial light beam emitted by the light source is ultraviolet light, the material of the first free-form surface is fused quartz, and the material of the second free-form surface is fused quartz.

[0026] As can be seen from the above technical solution, the embodiment of the present application has the following advantages: two free-form surface mirrors are used to achieve beam shaping that was originally performed by a single DOE. The first free-form surface mirror and the second free-form surface mirror are respectively used to perform different functions, and together they achieve the effect of beam shaping. The manufacturing difficulty of the first and second free-form surface mirrors is far lower than that of a DOE that can independently achieve beam shaping. Therefore, the embodiment of the present application achieves a linear spot with uniform energy distribution and narrow linewidth at a lower manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0028] Figure 1 A schematic structural diagram of the beam shaping system disclosed in an embodiment of the present application;

[0029] Figure 2 This is another structural schematic diagram of the beam shaping system disclosed in an embodiment of the present application;

[0030] Figure 3 A schematic diagram of the wavefront difference of the beam expansion assembly disclosed in an embodiment of the present application;

[0031] Figure 4 Refer to the figure for the two-dimensional surface shape of the first free-form surface mirror disclosed in the embodiment of the present application;

[0032] Figure 5 Refer to the figure for the two-dimensional surface shape of the second free-form surface mirror disclosed in the embodiment of the present application;

[0033] Figure 6 A schematic diagram of the shaping effect of the beam shaping system disclosed in an embodiment of the present application;

[0034] Figure 7 A schematic diagram of uniformity analysis of the line spot disclosed in an embodiment of the present application. DETAILED DESCRIPTION

[0035] In order to help those skilled in the art better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0036] In the description of the embodiments of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, they should not be understood as limiting the embodiments of the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0037] In the description of the embodiments of the present application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present application based on the specific circumstances.

[0038] See also Figure 1 , a beam shaping system disclosed in this application includes:

[0039] A light source 101 is configured to emit an initial light beam;

[0040] A first free-form surface mirror 102 is used to uniformly distribute the energy in the initial light beam;

[0041] The second free-form surface mirror 103 is used to adjust the size of the initial light beam emitted from the first free-form surface mirror 102 in the first axial direction, and make the adjusted initial light beam irradiate the surface to be measured to form a line spot, and the first axial direction is perpendicular or parallel to the optical axis of the initial light beam;

[0042] The size of the initial light beam in the second axial direction is adjusted by the first free-form surface mirror 102 or the second free-form surface mirror 103 , and the first axial direction is perpendicular to the second axial direction.

[0043] Specifically, in order to convert the initial light beam into a linear light spot with uniform energy distribution and sufficiently narrow line width (specifically including but not limited to linear flat top light and rectangular linear light spot, etc.), the beam shaping system needs to perform at least the following processing on the initial light beam: 1. Homogenization processing to make the energy distribution uniform everywhere in the light beam; 2. Adjust the shape of the light beam to control the line length of the linear light spot formed when it is irradiated to the surface to be measured; 3. Adjust the shape of the light beam to control the line width of the linear light spot formed when it is irradiated to the surface to be measured. Among them, the first axial direction is parallel to the line length direction or the line width direction of the linear light spot formed when it is irradiated to the surface to be measured, and the second axial direction is parallel to the line length direction or the line width direction of the linear light spot formed when it is irradiated to the surface to be measured. Figure 6 Taking the line spot shown in the lower middle figure as an example, the first axial direction is the direction indicated by the x-axis in the figure and the second axial direction is the direction indicated by the y-axis in the figure, or in other words, the second axial direction is the direction indicated by the x-axis in the figure and the first axial direction is the direction indicated by the y-axis in the figure.

[0044] In the prior art, the above-mentioned treatment is usually achieved through a single DOE, which has a high manufacturing cost. In the embodiment of the present application, a free-form surface mirror is creatively used to achieve the above-mentioned treatment. Among them, based on the principle of optical design, it can be known that a free-form surface can be used to achieve at least two of the above-mentioned treatments under the premise of ensuring the treatment effect, and a free-form surface mirror has two surfaces, so a free-form surface mirror can complete the above-mentioned treatment, but the embodiment of the present application uses two free-form surface mirrors. This is because, if the two surfaces of the free-form surface mirror are to be used at the same time to achieve multiple optical treatments, it is necessary to ensure that the optical treatments performed by the two surfaces of the free-form surface mirror respectively do not interfere with each other, which greatly increases the manufacturing cost of the free-form surface mirror, and is contrary to the technical concept of the present application to provide a low-cost beam shaping system. In other words, in order to ensure a lower manufacturing cost, the embodiment of the present application uses the above-mentioned two free-form surface mirrors (i.e., the first free-form surface mirror 102 and the second free-form surface mirror 103) to achieve beam shaping, and only one of the two surfaces of each free-form surface mirror is a free-form surface.

[0045] In the embodiment of the present application, the first free-form surface mirror 102 and the second free-form surface mirror 103 each include a free-form surface and a plane, and the free-form surface included in each free-form surface mirror is used to perform the corresponding portion of the processing required for beam shaping. It should be noted that in order to ensure that after adjusting the beam shape and controlling the line length and line width of the light spot formed by irradiating the surface to be measured, the energy distribution at each location in the linear light spot formed on the surface to be measured is uniform, the step of homogenizing the initial light beam should be placed before all other processing, that is, it should be implemented by the first free-form surface mirror 102.

[0046] In addition, it should be noted that in order to achieve the best shaping effect, the position design of the light source 101, the first free-form surface mirror 102 and the second free-form surface mirror 103 in the embodiment of the present application, the surface design of the free-form surface in the first free-form surface mirror 102 and the surface design of the free-form surface in the second free-form surface mirror 103 can all be obtained by simulation through optical design software. For example, CodeV software and zemax software, etc., are not limited here. Specifically, when designing, the wavelength band of the initial light beam, the value of the energy distribution uniformity (such as greater than 90% or greater than 95%, which can be configured as needed), and the size and position of the light spot formed by the light irradiating the surface to be measured can be set for the optical shaping system. The specific implementation depends on the parameters actually required by each optical design software and is not limited here.

[0047] In the embodiment of the present application, the initial light beam emitted by the light source 101 can be a Gaussian beam or a non-Gaussian beam of any wavelength band, and the materials of the first free-form surface mirror 102 and the second free-form surface mirror 103 can be fused silica, calcium fluoride, or K9, etc., and the actual selection needs to be based on the wavelength band of the light source 101. In some specific implementations, if the initial light beam emitted by the light source 101 is ultraviolet light, fused silica with stronger damage resistance and higher transmittance to ultraviolet light can be selected as the material of the first free-form surface mirror 102 and the material of the second free-form surface mirror 103.

[0048] In this embodiment, two free-form mirrors are used to achieve beam shaping, which would otherwise be accomplished by a single DOE. The first free-form mirror 102 and the second free-form mirror 103 each perform different functions, and together they achieve the beam shaping effect. The manufacturing difficulty of the first and second free-form mirrors 102 and 103 is far lower than that of a DOE that can independently achieve beam shaping. Therefore, this embodiment achieves a linear spot with uniform energy distribution and a narrow linewidth at a lower manufacturing cost.

[0049] Please continue reading Figure 1 In some specific implementations, the size of the initial light beam in the second axial direction is specifically adjusted by the first free-form surface mirror 102. When the surface to be measured is not perpendicular to the optical axis of the adjusted initial light beam, or when the surface to be measured is an inclined surface, the second free-form surface mirror 103 of the beam shaping system is also used to compensate for the defocus of the initial light beam emitted from the second free-form surface mirror 103, so that every point in the line light spot formed by irradiating the surface to be measured is in a focused state.

[0050] Specifically, after introducing defocus compensation, the surface shape design of the free-form surface of the second free-form mirror 103 should also refer to the implementation of the surface shape and position design in the previous embodiment, and be obtained through simulation using optical design software. The specific design can be supplemented with information that the optical shaping system is set to ensure that every point in the linear spot formed by light irradiating the surface to be measured is in a focused state. Other information required for simulating this optical shaping system using optical design software is similar to that in the previous embodiment and is not further described in this embodiment.

[0051] In addition to physical optics shaping, there are also geometric optics shaping methods. A common approach is to use a Powell prism combined with at least two cylindrical lenses to achieve beam shaping. While this approach is low-cost and easy to implement, it cannot achieve linear flat-top beam shaping with high uniformity and narrow linewidth under special application conditions, such as when the surface to be measured is inclined. Therefore, this embodiment can address the problem of the Powell prism combined with cylindrical lenses being unsuitable for such special application scenarios.

[0052] As can be seen from the aforementioned embodiments, each free-form surface mirror of the present application includes a plane and a free-form surface, which allows the initial light beam emitted by the light source 101 to be incident on the free-form surface of the first free-form surface mirror 102 and to be emitted from the plane of the first free-form surface mirror 102. In some embodiments, the initial light beam emitted by the light source 101 can also be incident on the plane of the first free-form surface mirror 102 and to be emitted from the free-form surface of the first free-form surface mirror 102. If the initial light beam is incident on the plane of the first free-form surface mirror 102, the first free-form surface mirror 102 can capture more of the initial light beam, thereby improving the energy utilization efficiency of the entire beam shaping system.

[0053] Similarly, the initial light beam emitted by the light source 101 can be incident from the free-curved surface of the second free-curved surface mirror 103 and emitted from the plane of the second free-curved surface mirror 103; or, the initial light beam emitted by the light source 101 can be incident from the plane of the second free-curved surface mirror 103 and emitted from the free-curved surface of the second free-curved surface mirror 103, which is not limited in this embodiment.

[0054] Furthermore, the present embodiment found that the diameter of the initial light beam incident on the first free plane mirror is slightly larger, and the linear light spot ultimately formed on the surface to be measured has a narrower line width. In addition, since the initial light beam emitted by the light source 101 has a certain error, for example, the default diameter of the output light of the light source 101 is 3mm, but the actual diameter of the light output from the light source 101 may have an error of ±0.5mm, that is, the actual diameter of the light output from the light source 101 falls within the range of 2.5mm-3.5mm. The beam shaping system of this embodiment is designed with the output light having a specific diameter. Therefore, in order to avoid the error between the actual diameter of the initial light beam and the expected diameter, which in turn affects the shaping effect, the present embodiment introduces a beam expansion component 104, which will be described in detail below.

[0055] Please refer to the following Figure 2 Based on the above embodiment, another beam shaping system disclosed in the embodiment of the present application is the same as the above embodiment. Figure 1 The embodiment is similar, except that, in order to obtain a linear light spot with a narrower line width and thus obtain a better detection effect, the beam shaping system of the embodiment of the present application also includes a beam expansion component 104, which is used to expand the diameter of the initial light beam emitted from the light source 101 and make the emitted initial light beam reach the first free-form surface mirror 102.

[0056] Specifically, based on the foregoing, it can be seen that the beam expander 104 should be located between the light source 101 and the first free-form surface mirror 102 to expand the light beam that is not incident on the first free-form surface mirror 102. This ensures that the linear flat top light, which ultimately passes through the first free-form plane mirror and the second free-form surface mirror 103, illuminates the surface to be measured, resulting in a narrower linewidth. The beam expander 104 can be any component that can expand the initial beam diameter, such as a simple beam expander or a continuously variable beam expander system.

[0057] Please continue reading Figure 2 If the beam expansion component 104 is a continuously variable beam expansion system, then along the direction in which the initial light beam is incident on the beam expansion component 104, the beam expansion component 104 includes a zoom lens group 1041, a compensation lens group 1042 and a fixed lens group 1043 in sequence. Among them, the continuously variable beam expansion system is generally composed of three groups of lenses: the zoom lens group 1041, the compensation lens group 1042 and the fixed lens group 1043. Variable magnification beam expansion is achieved by adjusting the spacing between these three groups of lenses. When the zoom lens group 1041 moves, the focal length of the optical system composed of the fixed lens group 1043 and the zoom lens group 1041 will change. At this time, the compensation lens group 1042 is appropriately moved to compensate for the changes caused by the movement of the zoom lens group 1041, thereby keeping the diameter of the output light beam within an acceptable range.

[0058] It should be noted that, based on optical design principles, if the beam expansion assembly 104 is a continuously zooming beam expansion system, the wavefront error (ie, Peak to Valley) of the continuously zooming beam expansion system should generally be less than 1 / 4 of the wavelength.

[0059] In some embodiments, the zoom lens group 1041 is a biconvex lens, the compensation lens group 1042 is a biconcave lens, and the fixed lens group 1043 is a biconvex lens. The embodiments of the present application use biconcave and biconvex lenses. Compared to single concave and single convex lenses, the biconcave and biconvex lenses of the embodiments of the present application have better divergence and beam expansion efficiency.

[0060] The foregoing describes various implementations of the optical shaping system of the present application. The following describes a specific implementation of the optical shaping system of the present application and the technical effects that can be achieved by the specific implementation in a specific scenario.

[0061] This embodiment, based on a free-form lens, proposes a novel shaping method. A Gaussian spot with a wavelength of 266 nm and a diameter of 3 mm is shaped into a linear spot with a length of 12 mm ± 1 mm and a width less than 20 μm at a 67° angle to the optical axis of the initial beam (or the optical axis of the beam shaping system). The energy distribution uniformity of the linear spot within the effective 10 mm length of the central line spot is > 90%. It should be noted that the angle between the surface to be measured and the optical axis of the system in this application can range from 0° to 90°. This embodiment simulates the angle at 67°.

[0062] The structure of the beam shaping system is shown in the figure below. Figure 2 As shown, the beam shaping system in this embodiment primarily consists of five lenses: a first free-form surface mirror 102, a second free-form surface mirror 103, a biconvex lens (i.e., zoom lens group 1041), a biconcave lens (i.e., compensation lens group 1042), and a biconvex lens (i.e., fixed lens group 1043). The first free-form surface mirror 102 and the second free-form surface mirror 103 are free-form surface lenses; the biconcave and biconvex lenses are conventional positive and negative lenses. The light source 101 is a laser that emits an initial beam with a diameter of 3 mm.

[0063] A biconvex lens (i.e., zoom lens group 1041), a biconcave lens (i.e., compensating lens group 1042), and a biconvex lens (i.e., fixed lens group 1043) form a continuously variable beam expansion system with a beam expansion range of 1.5x to 2.5x. This continuously variable beam expansion system can compensate for the size of the linear spot on the surface to be measured in real time, reducing the impact of spot size errors on the shaping results, and expanding the beam diameter from 3mm to 6mm. The continuously variable beam expansion system in this embodiment is primarily composed of three parts: the zoom lens group 1041, the compensating lens group 1042, and the fixed lens group 1043, which correspond to the biconvex lens, the biconcave lens, and the biconvex lens, respectively. Among them, the optical center thickness of the biconvex lens and the optical center thickness of the biconcave lens should be greater than or equal to 2 mm, and the edge thickness of the biconvex lens and the edge thickness of the biconcave lens should be greater than or equal to 1 mm; the optical spacing between the first free-form surface mirror 102 and the second free-form surface mirror 103 is 200 mm to 500 mm; the optical spacing between the second free-form surface mirror 103 and the surface to be measured is 50 mm to 400 mm, which can be specifically configured as needed and is not limited here.

[0064] In this embodiment, the biconvex lens (i.e., the zoom lens group 1041) has a center thickness of 5 mm, a diameter of 25.4 mm, a curvature radius of 30 mm to 35 mm, and is made of fused quartz; the biconcave lens (i.e., the compensation lens group 1042) has a thickness of 3 mm, a diameter of 25.4 mm, a curvature radius of 8 mm to 11 mm, and is made of fused quartz; the biconvex lens (i.e., the fixed lens group 1043) has a thickness of 5 mm, a diameter of 25.4 mm, a curvature radius of 75 mm to 85 mm, and is made of fused quartz. The distance between the biconvex lens (i.e., the zoom lens group 1041) and the biconcave lens (i.e., the compensation lens group 1042) varies in the range of 20 mm to 30 mm; the distance between the biconcave lens (i.e., the compensation lens group 1042) and the biconvex lens (i.e., the fixed lens group 1043) varies in the range of 55 mm to 65 mm; the beam expansion system composed of the biconvex lens (i.e., the zoom lens group 1041), the biconcave lens (i.e., the compensation lens group 1042), and the biconvex lens (i.e., the fixed lens group 1043) has a wavefront difference less than 1 / 4 wavelength. Figure 3 In the right middle value range, the maximum wavefront difference is only 8.92×10 -3 , much smaller than 1 / 4 wavelength, Figure 3 The wavefront difference of the light spot after passing through the beam expansion system is significantly less than 1 / 4 wavelength.

[0065] The first free-form surface mirror 102 and the second free-form surface mirror 103 form a shaping system, which shapes the Gaussian spot with a diameter of 6 mm into a line spot.

[0066] Specifically, the dimensions of the first free-form mirror 102 and the second free-form mirror 103 are as follows: diameter 25.4 mm, thickness 3 mm. Furthermore, this embodiment primarily considers light in the 266 nm wavelength band, so fused silica is preferably used for the first free-form mirror 102 and the second free-form mirror 103.

[0067] The incident surface of the first free-curved surface mirror 102 is a plane, and the emitting surface is a free-curved surface; the optical distance between the first free-curved surface mirror 102 and the second free-curved surface mirror 103 is 390 mm; the optical distance between the second free-curved surface mirror 103 and the surface to be measured is 210 mm.

[0068] See also Figure 4 The curvature radius of the exit surface of the first free-form surface mirror 102 is 16.65 mm, the conic coefficient is -0.997, the maximum number of terms is 10, and the normalized radius is 7.5 mm; the two-dimensional surface shape of the exit surface of the first free-form surface mirror 102 on the x-axis (i.e., the first axial direction) and the y-axis (the second axial direction) is referenced Figure 4 As shown in the figure above, Figure 4 The upper middle figure shows that the darker the color, the greater the thickness. The X-direction sag cross-section of the exit surface of the first free-form surface mirror 102 is as follows: Figure 4 As shown in the lower left figure, the vertical axis is the sinking depth of the free-form surface, and the horizontal axis is the different positions of the surface; the Y-direction sag cross-section of the exit surface of the first free-form mirror 102 is shown as follows: Figure 4 As shown in the lower right figure, the vertical axis is the sink depth of the free-form surface, and the horizontal axis is the different positions of the surface; the main function of the first free-form surface mirror 102 is to control the length of the line spot irradiated to the surface to be measured and the uniformity of the energy distribution of the line spot at the surface to be measured.

[0069] See also Figure 5 The incident surface of the second free-form surface mirror 103 is a free-form surface, and the exit surface is a plane; the curvature radius of the incident surface of the second free-form surface mirror 103 is 205.19 mm, the cone coefficient is -0.992, the maximum number of terms is 10, and the normalized radius is 7.5 mm; the two-dimensional surface shape of the incident surface of the second free-form surface mirror 103 is as follows Figure 5 As shown in the figure above; the second free-form mirror 103 incident surface X direction sag cross-section surface diagram is as follows Figure 5 As shown in the lower left figure, the vertical axis is the sinking depth of the free-form surface, and the horizontal axis is the different positions of the surface; the Y-direction sag cross-section of the incident surface 1041 is shown in Figure 5 As shown in the lower right figure, the vertical axis is the sinking depth of the free-form surface, and the horizontal axis is the different positions of the surface; the main function of the second free-form surface mirror 103 is to control the line width of the line light spot irradiated to the surface to be measured; since the surface to be measured is controlled to be an inclined surface, defocus occurs at both ends of the line light spot, and the second free-form surface mirror 103 also needs to provide defocus compensation processing to make the line light spot in a focused state.

[0070] The light source 101 emits a Gaussian beam, such as Figure 2 The diameter of the monitoring spot at position 1 is 3mm, and the results are as follows Figure 6 As shown in the upper left figure, after the 3mm spot is expanded by the beam expander 104, the diameter of the spot detected at position 2 is 6mm. Figure 6 As shown in the upper right figure, a Gaussian beam with a diameter of 6 mm is shaped into a line spot with a length of 12 mm and a line width of less than 20 μm after passing through the above beam shaping system. Figure 6 As shown in the lower middle figure.

[0071] exist Figure 6 Based on the figure in the middle and lower part, the energy distribution cross section of the line spot in the x direction is taken to analyze the uniformity of the spot and the energy distribution cross section in the x direction as shown in the figure below. Figure 7 As shown in the middle left picture; intercept Figure 7 In the left-center image, the 11mm line spot in the middle is used as the effective length for energy distribution uniformity analysis, and it can be seen that the uniformity is greater than 90%. Figure 6 Based on the figure in the middle and lower part, the energy distribution cross section of the line spot in the y direction is taken to analyze the uniformity of the spot and the energy distribution cross section in the y direction. Figure 7 As shown in the middle right picture; select Figure 7 In the middle right figure, where the energy is 1 / e^2 (approximately 0.135), the corresponding effective width is the line width of the light spot, which is less than 20μm. This extremely fine line width of less than 20μm cannot be achieved by existing physical optical shaping methods and geometric optical shaping methods.

[0072] It should be noted that the uniformity of the line spot can be calculated by the following formula:

[0073]

[0074] Among them, if we want to calculate the energy uniformity of the line spot along the line length, I MAX is the maximum energy of the line spot within its effective length, I MIN is the minimum energy value of the line spot within its effective length; if we want to calculate the energy uniformity of the line spot along the line length, I MAX is the maximum energy of the line spot within its effective width, I MIN It is the minimum energy value of the line spot within its effective width.

[0075] The above content is an explanation of the present application in conjunction with specific embodiments, and it cannot be considered that the specific implementation of the present application is limited to these embodiments. For ordinary technicians in the technical field to which the present application belongs, a number of changes and substitutions can be made without departing from the concept of the present application, and in this case, they should be considered to fall within the scope of protection of the present application.

Claims

1. A beam shaping system, characterized in that: include: a light source for emitting an initial light beam; a first free-form surface mirror, configured to uniformly distribute the energy in the initial light beam; a second free-form surface mirror, configured to adjust a size of an initial light beam emitted from the first free-form surface mirror in a first axial direction, and to irradiate the adjusted initial light beam onto the surface to be measured to form a line spot, wherein the first axial direction is perpendicular or parallel to the optical axis of the initial light beam; The size of the initial light beam in the second axial direction is adjusted by the first free-form surface mirror or the second free-form surface mirror, and the first axial direction is perpendicular to the second axial direction; The size of the initial light beam in the second axial direction is adjusted by the first free-form surface mirror, and the surface to be measured is not perpendicular to the optical axis of the adjusted initial light beam; The second free-form surface mirror is further used to perform defocus compensation on the initial light beam emitted from the second free-form surface mirror, so that the line light spot formed by irradiating the surface to be measured is in a focused state.

2. The beam shaping system according to claim 1, wherein: The initial light beam emitted by the light source is incident from the plane of the first free-form surface mirror and is emitted from the free-form surface of the first free-form surface mirror; or, The initial light beam emitted by the light source is incident from the free-form surface of the first free-form surface mirror and is emitted from the plane of the first free-form surface mirror.

3. The beam shaping system according to claim 1, wherein: The initial light beam emitted from the first free-form surface mirror is incident from the free-form surface of the second free-form surface mirror and is emitted from the plane of the second free-form surface mirror; or, The initial light beam emitted from the first free-form surface mirror is incident from the plane of the second free-form surface mirror and is emitted from the free-form surface of the second free-form surface mirror.

4. The beam shaping system according to claim 1, wherein: The beam shaping system further comprises: The beam expansion component located between the light source and the first free-form surface mirror is used to expand the diameter of the initial light beam emitted from the light source and make the emitted initial light beam reach the first free-form surface mirror.

5. The beam shaping system according to claim 4, characterized in that The beam expansion assembly is a continuously variable magnification beam expansion system. Along the direction in which the initial light beam is incident on the beam expansion assembly, the beam expansion assembly sequentially includes a zoom lens group, a compensation lens group and a fixed lens group.

6. The beam shaping system according to claim 5, characterized in that The zoom lens group is a biconvex lens, the compensation lens group is a biconcave lens, and the fixed lens group is a biconvex lens.

7. The beam shaping system according to claim 6, wherein: The optical center thickness of the biconvex lens and the biconcave lens is greater than or equal to 2 mm, and the edge thickness of the biconvex lens and the biconcave lens is greater than or equal to 1 mm.

8. The beam shaping system according to claim 1, wherein: The material of the first free-form surface is fused silica, calcium fluoride or K9, and the material of the second free-form surface is fused silica, calcium fluoride or K9.

9. The beam shaping system according to claim 5, wherein: The initial light beam emitted by the light source is ultraviolet light, the material of the first free-form surface is fused silica, and the material of the second free-form surface is fused silica.

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