Illumination lens and optical apparatus

Abstract

The invention provides an illumination lens and optical equipment. The optical device includes a laser source and an illumination lens. The laser source is used for emitting laser, and the illumination lens is used for allowing the laser emitted by the laser source to penetrate and projecting line light spots to a sample surface. The illumination lens comprises an aspheric cylindrical mirror and a cylindrical mirror; the light incident surface of the aspheric cylindrical mirror is an aspheric cylindrical surface, and the generatrix of the aspheric cylindrical surface is along a first direction; the incident surface of the cylindrical mirror is a cylindrical surface, and the generatrix of the cylindrical surface is along a second direction perpendicular to the first direction; the cylindrical mirror has positive focal power. Compared with a traditional micro-lens array and a diffraction optical element, the problems of interference fringes and diffraction spots are avoided, the illumination effect is improved, and the high-power laser array is suitable for being applied to high-power lasers.

Description

Technical Field

[0001] The present application relates to the technical field of optical instruments, and in particular to an illumination lens and an optical device. Background Art

[0002] The illumination system used for semiconductor inspection usually needs to modulate the laser beam to ensure that the spot on the sample surface has a specific shape and uniform distribution. The existing technology usually uses a microlens array or a diffractive optical element to achieve the shaping and homogenization of the laser beam. However, the microlens array is prone to produce interference fringes after modulating the laser beam, and the diffractive optical element will produce randomly distributed diffraction spots around the main spot after modulating the laser beam. The above interference or diffraction phenomena will have a negative impact on the lighting effect. Summary of the invention

[0003] The embodiments of the present application provide an illumination lens and an optical device, which form a uniform line light spot by arranging matching cylindrical mirrors and aspherical cylindrical mirrors in the illumination lens, avoid the generation of interference fringes and diffraction light spots, and ensure good illumination effect of the optical device on the surface of the object to be measured.

[0004] In the first aspect, an embodiment of the present application provides an illumination lens, which is used to be arranged between a sample surface and a laser source, and the illumination lens includes an aspheric cylindrical mirror and a cylindrical mirror; the light incident surface of the aspheric cylindrical mirror is an aspheric cylindrical surface, and the generatrix of the aspheric cylindrical surface is along a first direction; the light incident surface of the cylindrical mirror is a cylindrical surface, and the generatrix of the cylindrical surface is along a second direction perpendicular to the first direction; the cylindrical mirror has a positive optical focal length; the illumination lens is used to allow the laser emitted by the laser source to pass through, and to project a line spot onto the sample surface.

[0005] In the embodiment of the present application, by making the generatrix directions of the cylindrical mirror and the aspheric cylindrical mirror perpendicular to each other, the cylindrical mirror and the aspheric cylindrical mirror can have optical focal length only in two planes perpendicular to each other, for example, the cylindrical mirror has optical focal length only in the first plane perpendicular to the first direction, and the aspheric cylindrical mirror has optical focal length only in the second plane perpendicular to the second direction, so that the incident laser can be modulated by the aspheric cylindrical mirror to form a uniform illumination spot uniformly distributed along the second direction, and after passing through the cylindrical mirror, it is focused into a line spot with a size that meets the requirements along the first direction. Therefore, the embodiment of the present application can avoid the interference fringes and diffraction spots generated by the microlens array or the diffractive optical element, and can form a uniform line spot that meets the length and width requirements through a simple and effective optical path, thereby ensuring a good lighting effect.

[0006] In one embodiment of the first aspect, from the laser source to the sample surface, the aspheric cylindrical mirror and the cylindrical mirror are arranged in sequence, and the aspheric cylindrical mirror has a positive focal power. The vertical distance between the light-emitting surface of the aspheric cylindrical mirror and the sample surface can be called the working distance. By setting the relative position relationship between the aspheric cylindrical mirror and the cylindrical mirror, the size relationship between the working distance and the focal length of the cylindrical mirror can be changed. When the distance between the illumination lens and the sample surface remains unchanged, by arranging the aspheric cylindrical mirror and the cylindrical mirror in sequence from the laser source to the sample surface, the working distance can be made greater than the focal length of the cylindrical mirror, that is, the focal length of the cylindrical mirror is reduced, so that the size of the light spot formed on the sample surface along the first direction is thinner; at the same time, by making the aspheric cylindrical mirror have a positive focal power, the size of the light spot formed on the sample surface after the laser beam passes through the aspheric cylindrical surface is smaller than the size of the laser beam along the second direction. All of the above make the line light spot have a higher energy density, which is conducive to the use of the line light spot for high-precision processing or measurement applications.

[0007] In one embodiment of the first aspect, from the laser source to the sample surface, the cylindrical mirror and the aspherical cylindrical mirror are arranged in sequence, and the aspherical cylindrical mirror has a negative optical focal length. By arranging the cylindrical mirror and the aspherical cylindrical mirror in sequence from the laser source to the sample surface, the working distance can be made smaller than the focal length of the cylindrical mirror, that is, the focal length of the cylindrical mirror is increased, so that the size of the light spot formed on the sample surface along the first direction is coarser; at the same time, by making the aspherical cylindrical mirror have a negative optical focal length, the size of the light spot formed on the sample surface after the laser beam passes through the aspherical cylindrical surface is larger than the size of the laser beam along the second direction. Under the premise of ensuring that the line light spot has sufficient energy density, the above are all conducive to clearly distinguishing the line light spot, and then better detecting the sample surface with the help of the homogenized line light spot. In summary, by changing the relative position relationship between the cylindrical mirror and the aspherical cylindrical mirror, and coordinating the optical focal length of the aspherical cylindrical mirror, line light spots of different sizes can be achieved according to actual needs to meet the illumination requirements of the sample surface under different situations.

[0008] In one implementation of the first aspect, the surface shape of the aspherical cylindrical mirror satisfies the following relationship: Wherein, z represents the sag of the non-spherical cylinder, y represents the coordinate position in the direction perpendicular to the sag direction, c is the radius of curvature of the non-spherical cylinder, k is the cone coefficient of the non-spherical cylinder, α4, α6, α8, α10, α12 and α14 are the coefficients of the 4th, 6th, 8th, 10th, 12th and 14th order non-spherical cylinders respectively. By making the surface shape of the non-spherical cylinder satisfy the above formula, the structure of the non-spherical cylinder can be designed based on the method of geometric ray tracing.

[0009] In one implementation of the first aspect, the working distance d from the light-emitting surface of the aspheric cylindrical mirror to the sample surface is 100 mm-10000 mm. By setting the working distance d of the aspheric cylindrical mirror, different sizes of line spots along the second direction can be achieved on the sample surface.

[0010] In one implementation of the first aspect, the focal length f of the cylindrical mirror and the size d of the line spot along the first direction 1 , the wavelength λ of the laser and the incident size D of the laser satisfy the following relationship: Among them, the size d 1 It can be limited by the size of the Airy spot, and the incident size D can be 3 times the beam waist diameter. Through the above relationship, the focal length f of the cylindrical mirror and the size d of the line spot that meet the product requirements can be obtained: 1 , in order to form a uniform line light spot that meets the length and width requirements, thereby meeting the lighting needs.

[0011] In the second aspect, an embodiment of the present application provides an optical device, including a laser source and the illumination lens described in the first aspect, wherein the laser source is used to emit laser light, and the illumination lens is used to allow the laser light emitted by the laser source to pass through and project a line light spot onto the sample surface. The embodiment of the present application can form a uniform line light spot that meets the length and width requirements through a simple and effective optical path, thereby meeting the lighting requirements. Since the embodiment of the present application does not use a microlens array or a diffractive optical element, the interference fringes and diffraction light spot problems caused by conventional solutions can be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a schematic diagram of an optical device in an embodiment;

[0013] Figure 2 is a schematic diagram of a three-dimensional structure of an illumination lens in an embodiment;

[0014] Figure 3 for Figure 2 A schematic diagram of a three-dimensional structure of the lighting lens from another perspective;

[0015] Figure 4 for Figure 2 Orthographic projection and light path simulation diagram of the illumination lens on the YZ plane;

[0016] Figure 5 for Figure 2 Orthographic projection and light path simulation diagram of the illumination lens on the XZ plane;

[0017] Figure 6 It is a schematic diagram of the Toroidal surface curve;

[0018] Figure 7 is the sagittal height curve of the aspherical cylindrical mirror;

[0019] Figure 8 The Gaussian spot with a beam waist diameter of 3.3 mm is shown;

[0020] Fig. 9 The light intensity distribution at the sample surface after the laser passes through the aspherical cylindrical mirror is shown;

[0021] Fig.10 For Fig. 9 Schematic diagram of the one-dimensional light intensity curve along the Y direction at the center;

[0022] Fig.11 The line spot at the sample surface is shown;

[0023] Fig.12 for Fig.11 Schematic diagram of the one-dimensional light intensity curve of the line spot along the Y direction;

[0024] Fig.13 for Fig.11 Schematic diagram of the one-dimensional light intensity curve of the line spot along the X direction;

[0025] Fig.14 is an orthographic projection and light path simulation diagram of an illumination lens in another embodiment on the YZ plane;

[0026] Fig.15 for Fig.14 Orthographic projection and light path simulation diagram of the illumination lens on the XZ plane.

[0027] Reference numerals

[0028] 1- Optical equipment;

[0029] 11- Laser source;

[0030] 12-illumination lens; 121-aspherical cylindrical mirror; 122-cylindrical mirror; 121a-light incident surface of the aspherical cylindrical mirror; 121b-light emitting surface of the aspherical cylindrical mirror; 121c-busbar of the aspherical cylindrical mirror; 122a-light incident surface of the cylindrical mirror; 122b-light emitting surface of the cylindrical mirror; 122c-busbar of the cylindrical mirror;

[0031] 13- sample surface;

[0032] 14- Shell. DETAILED DESCRIPTION

[0033] For ease of understanding, the English abbreviations and related technical terms involved in the embodiments of the present application are explained and described below.

[0034] Focal power is equal to the difference between the convergence of the image-side beam and the convergence of the object-side beam. It characterizes the ability of an optical system to deflect light.

[0035] A lens or lens group with positive optical power has a positive focal length and has the effect of converging light.

[0036] A lens or lens group with negative optical power has a negative focal length and has the effect of diverging light.

[0037] Focal length, also known as focal length, is a measure of the convergence or divergence of light in an optical system. It refers to the vertical distance from the optical center of a lens or lens group to the focal plane when an infinitely distant scene forms a clear image on the focal plane through a lens or lens group. From a practical point of view, it can be understood as the distance from the center of the lens to the plane when the object is infinitely far away. For a fixed-focus lens, the position of its optical center is fixed; for an optical lens, the change of the optical center of the lens brings about a change in the focal length of the lens.

[0038] The object side is bounded by the lens. The side where the object is located is called the object side, and the surface of the lens close to the object side is called the object side.

[0039] The image side is bounded by the lens. The side where the image of the object is located is called the image side, and the surface of the lens close to the image side is called the image side.

[0040] The imaging plane is located on the image side of all lenses in the optical lens, and is the plane where the image is formed after the light passes through each lens in the optical lens in sequence. The focus is the point where parallel light rays converge after being refracted by a lens or lens group.

[0041] The image focal plane, also called the back focal plane or the second focal plane, is a plane passing through the image focus (also called the back focus or the second focus) and perpendicular to the optical axis of the system.

[0042] A diffractive optical element (DOE) is a device that modulates the amplitude or phase of incident light using the principle of diffraction optics. It is generally used in the fields of beam convergence, beam shaping, laser beam splitting, and generation of various diffraction patterns.

[0043] A micro lens array (MLA) is an optical element composed of multiple tiny lenses, which are usually arranged in a regular array and can focus, disperse or perform other optical processing on light.

[0044] Gaussian beam, a laser beam with Gaussian distribution, has a light intensity distribution that is strong in the middle and weak at the edges, similar to a normal distribution.

[0045] Cylindrical lens is an optical element whose surface shape is cylindrical, that is, it has curvature in one direction and is flat or nearly flat in another orthogonal direction.

[0046] Aspheric cylindrical mirrors are a special type of optical element that combines a complex surface shape with high-order aspheric coefficients and cylindrical properties. This design enables aspheric cylindrical mirrors to focus and homogenize light in a specific direction, thereby generating a light spot with a specific shape and uniform distribution. In optical systems, aspheric cylindrical mirrors are often used to improve beam quality, improve light spot uniformity, or achieve special optical effects.

[0047] If a moving straight line moves along a known curve C and is always parallel to a certain straight line, the surface formed in this way is called a cylinder. At this time, the curve C is called the directrix and the moving straight line L is called the generatrix.

[0048] The beam waist diameter is the diameter of the beam cross section when the intensity of Gaussian light drops to 13.6% of the peak value.

[0049] Airy disk, the diffraction pattern produced by a point light source passing through a circular aperture (such as a lens or diaphragm), the center of the diffraction pattern is a bright circular spot, surrounded by a group of weaker concentric ring-shaped stripes of light and dark. The central bright spot bounded by the first dark ring is called the Airy disk. The diameter of the Airy disk is related to the wavelength λ of the incident light, the focal length f of the lens, and the entrance pupil diameter D.

[0050] Geometric ray tracing is an important method in the design and analysis of optical systems. It is based on the principles of geometric optics and calculates and predicts the performance of optical systems by tracing the propagation path of light in the optical system. In this method, light is regarded as a geometric line with a certain direction and position. When the light encounters an optical element (such as a lens, a reflector, etc.), the new direction and position of the light are calculated according to the laws of reflection and refraction of light. By continuously tracing and calculating the propagation path of light, the complete trajectory of the light in the system can be obtained, thereby analyzing the performance parameters of the optical system such as imaging quality, beam shape, and spot size.

[0051] An embodiment of the present application provides an optical device, which includes but is not limited to a semiconductor detection device and a three-dimensional scanning device.

[0052] Figure 1 FIG. 1 is a schematic diagram of an optical device 1 in an embodiment. Figure 1As shown, the optical device 1 may include a housing 14 and a laser source 11, an illumination lens 12, and a sample surface 13 located in the housing 14. The laser source, the illumination lens, and the sample surface may be arranged in sequence, or the illumination lens may be located between the laser source and the sample surface. The laser source is used to emit laser light, and the light intensity distribution of the laser light presents the characteristics of being strong in the middle and weak at the edge, which is similar to a normal distribution and may be referred to as Gaussian incident light. In order to form a line light spot with uniform light intensity, an illumination lens is required to adjust the laser beam. The illumination lens is used to adjust the shape of the laser and make the intensity distribution of the laser uniform, which may be referred to as beam shaping and homogenization. The sample surface is used to receive the laser light shaped and homogenized by the illumination lens, so as to realize applications such as semiconductor detection and three-dimensional scanning.

[0053] Understandably, Figure 1 The structure of the optical device shown is only a schematic diagram and is not limited in this embodiment.

[0054] Figure 2 is a schematic diagram of the three-dimensional structure of the lighting lens 12 in an embodiment, Figure 3 for Figure 2 Schematic diagram of the three-dimensional structure of the illumination lens 12 from another perspective. For ease of description, the following can be constructed Figure 2 and Figure 3 The XYZ three-dimensional space coordinate system shown in . It can be understood that the XYZ three-dimensional space coordinate system contains three coordinate axis directions, namely the X-axis direction, the Y-axis direction and the Z-axis direction, and any two of these three coordinate axis directions are perpendicular to each other. Among them, the Z-axis direction can be along the laser incident direction, or in other words, the Z-axis direction can be parallel to the central axis of each lens of the illumination lens 12. hereinafter, the X-axis direction is referred to as the X-direction, the Y-axis direction is referred to as the Y-direction, and the Z-axis direction is referred to as the Z-direction. The planes formed by the intersection of any two of the X-axis, Y-axis, and Z-axis directions are respectively referred to as the XY plane, the XZ plane, and the YZ plane, and any two of these three planes are perpendicular to each other.

[0055] like Figure 2 and Figure 3 As shown, the illumination lens 12 may include an aspherical cylindrical mirror 121 and a cylindrical mirror 122. Exemplarily, the aspherical cylindrical mirror 121 and the cylindrical mirror 122 are arranged in sequence along the incident direction of the laser.

[0056] Combination Figure 2 and Figure 3 As shown, the incident surface 121a of the aspheric cylindrical mirror 121 may be an aspheric cylindrical surface, and the generatrix 121c of the aspheric cylindrical surface may be along a first direction, and the first direction may be perpendicular to the central axis direction of the aspheric cylindrical mirror 121 (for example Figure 2 or Figure 3 The first direction may be, for example, the X direction. The light emitting surface 121b of the aspherical cylindrical mirror 121 may be a plane.

[0057] Combination Figure 2 and Figure 3 As shown, the light incident surface 122a of the cylindrical mirror 122 may be a cylinder, and the generatrix 122c of the cylinder may be along a second direction, the second direction being perpendicular to the first direction, and the second direction may be, for example, the Y direction. The light emitting surface 122b of the cylindrical mirror 122 may be a plane.

[0058] Figure 4 for Figure 2 Orthographic projection and light path simulation diagram of the illumination lens 12 on the YZ plane, Figure 5 for Figure 2 Orthographic projection and light path simulation diagram of the illumination lens 12 on the XZ plane.

[0059] like Figure 2-Figure 5 As shown, illustratively, the focal length of the aspheric cylindrical mirror 121 can be positive, and has positive focal length only in the YZ plane. Thus, when light passes through the aspheric cylindrical mirror 121, only the light in the YZ plane will be significantly refracted or focused, while the light outside the YZ plane (such as the light in the XZ plane) will not be significantly affected by the aspheric cylindrical mirror 121, which can make the incident laser converge and homogenize along the second direction, as will be explained below.

[0060] like Figure 2-Figure 5 As shown, for example, the focal length of the cylindrical mirror 122 can be positive, and has focal length only in the XZ plane. Therefore, when light passes through the cylindrical mirror 122, only the light in the XZ plane will be significantly refracted or focused, while the light outside the XZ plane (such as the light in the YZ plane) will not be significantly affected by the cylindrical mirror 122, which can make the laser passing through the aspherical cylindrical mirror 121 focus on the sample surface 13 along the first direction to form a line spot, which will be explained below.

[0061] like Figure 2-Figure 5 As shown, the vertical distance between the light-emitting surface 121b of the aspheric cylindrical mirror 121 and the sample surface 13 can be called the working distance d. By adjusting the relative position relationship between the aspheric cylindrical mirror 121 and the cylindrical mirror 122, the size relationship between the working distance d and the focal length f of the cylindrical mirror 122 can be changed. When the distance between the illumination lens 12 and the sample surface 13 remains unchanged, the above adjustment can change the size of the focal length f, thereby modulating the thickness of the formed line spot, so as to achieve a finer spot while ensuring that the lines are distinguishable. The specific formula will be used for explanation below.

[0062] In this embodiment, the generatrix directions of the aspherical cylindrical mirror 121 and the cylindrical mirror 122 are perpendicular to each other (eg Figure 1 X and Y directions in the figure), and only in two mutually perpendicular planes (such as Figure 4The YZ plane and Figure 5 The optical power in the two planes does not interfere with each other. This lens combination method can be called two-dimensional orthogonal. Due to the use of a two-dimensional orthogonal lens combination method, the lens parameters of the aspherical cylindrical lens 121 and the cylindrical lens 122 can be designed independently. The following is an explanation.

[0063] The parameters of the aspheric cylindrical mirror 121 can be designed as needed. For example, the surface shape of the aspheric cylindrical mirror 121 can be toroidal, which can be defined by the following aspheric cylindrical formula:

[0064]

[0065] Wherein, z represents the vector height of the non-spherical cylinder, y represents the coordinate position in the direction perpendicular to the vector height direction, c is the radius of curvature of the non-spherical cylinder, k is the cone coefficient of the non-spherical cylinder, α4, α6, α8, α10, α12 and α14 are the coefficients of the 4th, 6th, 8th, 10th, 12th and 14th order non-spherical cylinders respectively. When the non-spherical cylindrical mirror 121 has positive optical power, the radius of curvature c is a positive value; when the non-spherical cylindrical mirror 121 has negative optical power, the radius of curvature c is a negative value.

[0066] Figure 6 It is a schematic diagram of the Toroidal surface curve. Figure 6 As shown, the surface shape of the non-spherical cylinder is designed in the YZ plane, and the coordinate in the X-axis direction is 0. In the direction of the sagittal height, the height difference between the highest point of the curve and the lowest point of the curve is R. When the Y-axis coordinate is y, the sagittal height is z y , the height difference from the lowest point of the curve is Rz y .

[0067] The aspheric cylindrical mirror 121 in this embodiment can generate a Toroidal cylindrical surface with high-order aspheric coefficients based on the method of geometric ray tracing, which is conducive to forming uniform illumination in the second direction (Y direction).

[0068] Exemplarily, the beam waist diameter of the incident laser can be 3.3 mm, the working distance d of the aspheric cylindrical mirror 121 is 470 mm, and the thickness of the aspheric cylindrical mirror 121 can be 2 mm. In one embodiment, the lens parameters of the aspheric cylindrical mirror 121 can be as shown in Table 1, including the surface shape, radius of curvature, thickness, material and aspheric cylindrical coefficient (A4, A6, A8, A10, A12 and A14 are 4th, 6th, 8th, 10th, 12th and 14th order aspheric cylindrical coefficients respectively). Among them, serial number 2 represents the medium between the aspheric cylindrical mirror 121 and the sample surface 13, which can be air, for example. The thickness of serial number 2 refers to the working distance d of the aspheric cylindrical mirror 121.

[0069]

[0070] Figure 7 is the sagittal height curve of the aspherical cylindrical mirror 121. Figure 7 As shown, the horizontal axis is the Y-axis coordinate of the surface curve, and the vertical axis is the sagittal height, both in mm. Figure 7 It can be seen that the distance from the highest point to the lowest point in the direction of the sagittal height is about 40 μm.

[0071] Figure 8 The figure shows a Gaussian spot with a beam waist diameter of 3.3 mm. Fig. 9 The light intensity distribution at the sample surface 13 after the laser passes through the aspherical cylindrical mirror 121 is shown.

[0072] See also Figure 8 , the incident laser directly irradiates the sample surface 13 to form an approximately elliptical non-uniform Gaussian spot. It can be understood that Figure 8 The shape of the incident laser beam shown is only a schematic representation. In another embodiment, the incident laser beam may also be a circular laser beam, which is not limited in this embodiment.

[0073] See also Fig. 9 The laser passes through the aspherical cylindrical mirror 121 and reaches the sample surface 13 at 470 mm, forming a light spot that is evenly distributed along the second direction (Y direction).

[0074] Fig.10 For Fig. 9 Schematic diagram of the one-dimensional light intensity curve along the Y direction at the center. Fig.10 As shown, Fig.10 The horizontal axis is Fig. 9 The Y-axis coordinate in ( Fig. 9 The Y-axis coordinate of the center of the light spot is 0), the unit is mm, and the 0 scale on the horizontal axis corresponds to Fig. 9 The center of the light spot on the Y axis; Fig.10 The vertical axis is the irradiance, in watts per square millimeter. Fig.10 It can be seen that when the Y-axis coordinate is less than -0.55mm, the irradiance is 0. When the Y-axis position continues to move to the right, the irradiance rises rapidly and steeply, and is maintained at 1.68W / mm2 to 1.89W / mm2 at -0.55mm to 0.55mm, and then rapidly drops to 0 near the position of 0.55mm. The shape of this distribution is similar to the flat top of a rectangle, so it can be called a flat-top uniform distribution. The Y-axis coordinate range of the "flat top" can be approximated to the size of the spot along the second direction, which is approximately 1mm. The aspherical cylindrical mirror 121 has a positive optical focal length, so after the laser passes through the mirror, the spot size formed in the second direction is smaller than the size of the incident laser.

[0075] It can be understood that the parameters of the aspheric cylindrical mirror 121 described above and shown in Table 1 are only illustrative examples. In fact, the working distance d, curvature radius c and aspheric coefficient α of the aspheric cylindrical mirror 121 can be adjusted according to product requirements to achieve the desired size of the light spot in the second direction.

[0076] like Figure 4 , Figure 5 and Fig. 9 As shown, after the aspherical cylindrical mirror 121 homogenizes the incident laser along the second direction, the cylindrical mirror 122 is needed to focus the light beam along the first direction to form a line light spot of the required thickness (size in the first direction).

[0077] For example, according to the thickness of the line spot, the focal length f of the cylindrical mirror 122 can be adjusted according to the following relationship:

[0078]

[0079] Among them, d 1 is the size of the line spot in the first direction (i.e., the Airy spot size), λ is the laser wavelength, and D is the incident size of the laser. 1 =30μm, D=9.9mm (3 times of the beam waist diameter), λ=0.3μm, according to the above formula, the focal length of the cylindrical mirror 122 can be calculated to be f=405mm.

[0080] like Figure 2-Figure 5 As shown, in a possible implementation, the aspherical cylindrical mirror 121 and the cylindrical mirror 122 are arranged in sequence along the incident direction of the laser, so that the working distance d and the focal length f satisfy the relationship: d>f. At this time, the focal length f of the cylindrical mirror 122 is small, so that the first direction size d of the line spot 1 The smaller the laser beam, the thinner the line spot. The line spot can have a higher energy density, which is beneficial for the line spot to be used in high-precision processing or measurement applications.

[0081] In another possible implementation, the cylindrical mirror 122 and the aspherical cylindrical mirror 121 are arranged in sequence along the incident direction of the laser, which can be regarded as Figure 2 The positions of the aspherical cylindrical mirror 121 and the cylindrical mirror 122 are swapped. At this time, the working distance d and the focal length f satisfy the relationship: d<f. 1 Larger, the line spot formed is larger than Figure 5 The line light spot in the image is relatively thick, which is conducive to clearly distinguishing the line light spot, and then better detecting the sample surface 13 with the help of the homogenized line light spot, under the premise of ensuring that the line light spot has sufficient energy density.

[0082] Fig.11 The line spot at the sample surface 13 is shown. Fig.12 for Fig.11 Schematic diagram of the one-dimensional light intensity curve of the line spot along the Y direction, Fig.13 for Fig.11 Schematic diagram of the one-dimensional light intensity curve of the line spot along the X direction.

[0083] like Figure 4 , Figure 5 and Fig.11 As shown, the laser reaches the sample surface 13 after passing through the aspherical cylindrical mirror 121 and the cylindrical mirror 122 in sequence, forming a line light spot on the sample surface 13 with a uniform light intensity distribution and a length along the second direction (Y direction) and a width along the first direction (X direction).

[0084] like Fig.12 As shown, the horizontal axis is Fig.11 The Y-axis coordinate in ( Fig.11 The Y-axis coordinate of the center of the light spot is 0), the unit is mm, and the X-axis position is always located at the center of the light spot; the vertical coordinate is the irradiance, the unit is watt / square millimeter. Fig.12 It can be seen that the light spot forms a flat-top uniform distribution in the Y-axis direction, with a maximum irradiance of about 480 W / mm2 and a length of about 1 mm.

[0085] like Fig.13 As shown, the horizontal axis is Fig.11 The X-axis coordinate in ( Fig.11 The X-axis coordinate of the center of the light spot is 0), the unit is mm, and the Y-axis position is always located at the center of the light spot; the vertical coordinate is the irradiance, the unit is watt / square millimeter. Fig.13 It can be seen that the focusing effect of the light spot in the X-axis direction is very significant, the maximum irradiance is about 480 W / mm2, and the width of the light spot is about 30 μm.

[0086] like Figure 8-Figure 13 As shown, the solution of this embodiment adopts an aspheric cylindrical mirror 121 based on ray tracing optimization to form a one-dimensional uniform illumination in the second direction, and combines with a cylindrical mirror 122 designed to be orthogonal to the aspheric cylindrical mirror 121 in two dimensions to focus in the first direction to form a line spot, the length direction of the line spot is along the second direction, and the width direction is along the first direction. By designing the working distance d, the radius of curvature c and the aspheric coefficient α of the aspheric cylindrical mirror 121, the size of the spot in the second direction can be adjusted; by designing the focal length f of the cylindrical mirror 122, the size of the spot in the first direction can be adjusted. The line spot formed by the laser beam passing through the illumination lens 12 of this embodiment has a higher energy density and a smaller size, and is suitable for high-precision processing or measurement applications (such as semiconductor detection and three-dimensional scanning, etc.).

[0087] The solution of this embodiment uses a non-spherical cylindrical surface to form a one-dimensional uniform illumination spot. Compared with a traditional microlens array, it does not produce interference fringes and intensity modulation; compared with a diffractive optical element, there is no interference from high-order diffraction orders, so there is no randomly distributed speckle, thereby improving the lighting quality.

[0088] The aspherical cylindrical mirror 121 and the cylindrical mirror of this embodiment are arranged in a simple two-dimensional orthogonal manner, which is simple to manufacture and has a simple and effective optical path, thereby facilitating high-power laser applications.

[0089] Based on the above embodiments, the relationship between the working distance d of the aspherical cylindrical mirror 121 and the focal length f of the cylindrical mirror 122, as well as the optical power of the aspherical cylindrical mirror 121 can be adjusted to obtain other embodiments.

[0090] Fig.14 is an orthographic projection and light path simulation diagram of the illumination lens 12 on the YZ plane in another embodiment, Fig.15 for Fig.14 Orthographic projection and light path simulation diagram of the illumination lens 12 on the XZ plane.

[0091] like Fig.14 and Fig.15 As shown, in a possible implementation, the aspheric cylindrical mirror 121 may have a negative optical power, and the cylindrical mirror 122 may have a positive optical power, and the two are arranged in a two-dimensional orthogonal manner. In this lens combination, the incident laser first passes through the cylindrical mirror 122, is focused along the first direction, and forms a line beam. Subsequently, the laser passes through the aspheric cylindrical mirror 121, diverges and is homogenized along the second direction, and finally forms a uniform line spot on the sample surface 13, the size of which is larger than the size of the incident laser in the second direction. Under the premise of ensuring that the line spot has sufficient energy density, this is conducive to clearly distinguishing the line spot, and then better detecting the sample surface with the help of the homogenized line spot.

[0092] like Fig.14 and Fig.15 As shown, in a possible implementation, the cylindrical mirror 122 and the aspherical cylindrical mirror 121 can be arranged in sequence along the direction of laser incidence. It can also be understood that the working distance d of the aspherical cylindrical mirror 121 and the focal length f of the cylindrical mirror 122 satisfy the relationship: d<f. When the distance between the illumination lens and the sample surface remains unchanged, Fig.15 The focal length f shown is greater than Figure 5 The focal length f shown is the focal length of the cylindrical mirror 122. According to the formula:

[0093]

[0094] When other parameters remain unchanged, increasing the focal length f can make the size d of the line spot along the first direction1 Increased, so that the line spot can be clearly distinguished.

[0095] In another possible implementation, the aspherical cylindrical mirror 121 and the cylindrical mirror 122 are arranged in sequence along the incident direction of the laser, so that the working distance d and the focal length f satisfy the relationship: d>f. In this case, the focal length f of the cylindrical mirror 122 is small, so that the size d of the line spot along the first direction is 1 The formed line light spot is thinner in the first direction, and the line light spot can have a higher energy density, which is conducive to the use of the line light spot in high-precision processing or measurement applications.

[0096] The solution of this embodiment forms a uniform line light spot through a simple and effective optical path by setting a two-dimensional orthogonal aspheric cylindrical mirror and a cylindrical mirror in the lighting lens, and avoids interference fringes caused by intensity modulation and interference of high-order diffraction orders. The lighting quality is high and can meet the lighting needs of optical equipment for semiconductor detection and three-dimensional scanning.

[0097] In the description of the embodiments of the present application, unless otherwise specified, "plurality" means two or more.

[0098] The terms "first", "second", etc. are used for descriptive purposes only and should not be understood to imply or suggest relative importance or implicitly indicate the number of technical features indicated. Features qualified as "first" or "second" may explicitly or implicitly include one or more of the features.

[0099] "Connect" should be understood in a broad sense, for example, "connect" can be detachably connected or non-detachably connected; it can be directly connected or indirectly connected through an intermediate medium. "Fix" should also be understood in a broad sense, for example, "fix" can be directly fixed or indirectly fixed through an intermediate medium.

[0100] The directional terms mentioned in the embodiments of the present application, such as "upper", "lower", "front", "back", "left", "right", "inner", "outer", "side", "top", "bottom", etc., are only reference directions of the drawings. The directional terms are for better and clearer explanation and understanding of the embodiments of the present application, and do not explicitly or implicitly indicate that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, etc., and therefore cannot be understood as limiting the embodiments of the present application.

[0101] In the description of the embodiments of the present application, unless otherwise specified, "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone.

[0102] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A lighting lens, characterized in that: Used to be placed between the sample surface and the laser source. The illumination lens includes an aspherical cylindrical lens and a cylindrical lens; The light incident surface of the aspherical cylindrical mirror is an aspherical cylindrical surface, and the generatrix of the aspherical cylindrical surface is along the first direction; The light incident surface of the cylindrical mirror is a cylinder, and the generatrix of the cylinder is along a second direction perpendicular to the first direction; the cylindrical mirror has positive optical power; The aspherical cylindrical mirror and the cylindrical mirror are both used to transmit the laser light emitted by the laser source, so that the illumination lens projects a line light spot onto the sample surface.

2. The lighting lens according to claim 1, characterized in that: In the direction from the laser source to the sample surface, the aspheric cylindrical mirror and the cylindrical mirror are arranged in sequence, and the aspheric cylindrical mirror has positive optical power.

3. The lighting lens according to claim 1, characterized in that: In the direction from the laser source to the sample surface, the cylindrical mirror and the aspherical cylindrical mirror are arranged in sequence, and the aspherical cylindrical mirror has negative optical power.

4. The lighting lens according to any one of claims 1 to 3, characterized in that: The surface shape of the aspherical cylindrical mirror satisfies the following relationship: Among them, z represents the vector height of the aspherical cylinder, y represents the coordinate position in the direction perpendicular to the vector height direction, c is the radius of curvature of the aspherical cylinder, k is the cone coefficient of the aspherical cylinder, α4, α6, α8, α10, α12 and α14 are the 4th, 6th, 8th, 10th, 12th and 14th order aspherical cylinder coefficients respectively.

5. The lighting lens according to any one of claims 1 to 3, characterized in that: The working distance d from the light-emitting surface of the aspherical cylindrical mirror to the sample surface is 100 mm-10000 mm.

6. The lighting lens according to any one of claims 1 to 3, characterized in that: The focal length f of the cylindrical mirror, the size d1 of the line spot along the first direction, the wavelength λ of the laser and the incident size D of the laser satisfy the following relationship: The incident size D of the laser is 3 times the beam waist diameter of the laser.

7. An optical device, characterized in that: It comprises a laser source and the illumination lens according to any one of claims 1 to 6, wherein the laser source is used to emit laser light, and the illumination lens is used to allow the laser light emitted by the laser source to pass through and project a line light spot onto a sample surface.

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