Annular light spot generating device

Abstract

The application discloses a kind of annular light spot generating devices, it is related to laser optical system field, the device includes: including: collimating laser, expansion device, first conical lens, second conical lens, convex lens, third conical lens and image plane are sequentially arranged in the same optical axis and along the direction of propagation path;The expansion device is arranged in the side of the collimating laser laser emission;The vertex of the first conical lens is towards the expansion device;The base surface of the second conical lens is towards the first conical lens;The base surface of the third conical lens is towards the convex lens.The application improves the stability of the radius of annular light spot.

Description

Technical Field

[0001] This application relates to the field of laser optical system technology, and in particular to a ring-shaped light spot generating device. Background Technology

[0002] Ring-shaped light spot generators are commonly used devices in optical systems. They are essential in fields such as precision laser processing, high-precision optical inspection, and long-term biological microscopy imaging, where stringent requirements are placed on the long-term stability of the ring-shaped light spot. For example, they are used to create ring-shaped light spots on sample surfaces to allow for sample processing according to the shape of these spots.

[0003] Commonly used ring-shaped light spot generating devices include conical lenses, conical mirrors, and diffractive optical elements. For example, see [link to example]. Figure 1 As shown, a commonly used optical path system for a typical adjustable radius laser ring spot is provided. This optical path system includes a conical lens, a convex lens, and an image plane. The conical lens is used to diverge the parallel beam into a ring beam, and the convex lens is used to focus the ring beam on the image plane to form a spot.

[0004] However, the existing optical path for generating a laser ring spot has the following drawbacks: In the traditional optical path, if a small linewidth ring is to be obtained, that is, the image plane is on the focal plane of the convex lens, the image plane sensitivity is high, and the position of the sample surface needs to be strictly controlled. The size of the laser ring radius generated by the traditional optical path is very sensitive to the position error of the sample surface. A small displacement of the sample surface position will cause a large change in the ring radius. Utility Model Content

[0005] The purpose of this application is to provide a ring-shaped light spot generating device to solve the problem described in the background art that the radius of the laser ring generated by the conventional optical path is very sensitive to the positional error of the sample surface.

[0006] To achieve the above objectives, this application provides a ring-shaped light spot generating device, comprising: a collimating laser, a beam expander, a first conical lens, a second conical lens, a convex lens, a third conical lens, and an image plane arranged sequentially along the optical path propagation direction and located on the same optical axis; The beam expander is located on the side of the collimating laser that emits the laser. The apex of the first conical lens faces the beam expander; The base surface of the second conical lens faces the first conical lens; The base surface of the third conical lens faces the convex lens.

[0007] Optionally, the third conical lens and the sample surface are movably disposed along the optical axis.

[0008] Optionally, the beam expander is a negative meniscus lens, with the concave surface of the negative meniscus lens close to the collimating laser and the convex surface close to the first cone lens.

[0009] Optionally, the convex lens is a plano-convex lens, a biconvex lens, or a concave-convex lens.

[0010] Optionally, the beam expander is a Keplerian beam expander, a Galilean beam expander, or a reflective beam expander.

[0011] According to the specific embodiments provided in this application, the following technical effects are disclosed: The annular light spot generating device provided in this application includes: a collimating laser, a beam expander, a first conical lens, a second conical lens, a convex lens, a third conical lens, and an image plane, all arranged sequentially along the same optical axis and the direction of optical propagation. The beam expander is located on the side of the collimating laser emitting laser light. The apex of the first conical lens faces the beam expander; the base surface of the second conical lens faces the first conical lens; and the base surface of the third conical lens faces the convex lens. The positions of the collimating laser, the beam expander, the first conical lens, the second conical lens, the convex lens, the third conical lens, and the image plane can be finely adjusted to present the desired annular light spot on the image plane. The annular light spot generating device provided in this application overcomes the problem of high sensitivity to sample surface position errors in the optical path for generating annular light spots in the prior art. In this device, a combination of three conical lenses and one convex lens can obtain an annular light spot with a stable radius on the sample surface. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 A schematic diagram of a conventional ring-shaped light spot generating device is provided for this application; Figure 2 This is a schematic diagram of the structure of a ring-shaped light spot generating device provided in an embodiment of this application; Figure 3 A schematic diagram of light propagation from a third cone lens to the image plane is provided as an embodiment of this application; Figure 4 A schematic diagram illustrating the propagation of a converged annular beam through a third conical lens, according to an embodiment of this application. Figure 5 A schematic diagram of light propagation from a convex lens to a third conical lens is provided as an embodiment of this application; Figure 6 A schematic diagram comparing the sample surface position sensitivity of a conventional optical path and the optical path of this application, provided as an embodiment of this application; Figure 7 This is a schematic diagram of a ring-shaped light spot with a 2mm positional error on the sample surface in a conventional optical path, provided as an embodiment of this application. Figure 8 This application provides a schematic diagram of an annular light spot with a 2mm positional error on the surface of a sample in an optical path, as provided in one embodiment. Figure 9 A schematic diagram illustrating the relationship between the linewidth of a circular light spot and its defocus position, provided in an embodiment of this application; Figure 10 This is a schematic diagram of the structure of another annular light spot generating device provided in an embodiment of this application.

[0014] In the figure: 1. Collimating laser; 2. Beam expander; 3. First cone lens; 4. Second cone lens; 5. Convex lens; 6. Third cone lens; 7. Image plane. Detailed Implementation

[0015] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0016] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the contents of this application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] See Figure 2 This application provides a ring-shaped light spot generating device, including: a collimating laser 1, a beam expander 2, a first conical lens 3, a second conical lens 4, a convex lens 5, a third conical lens 6, and an image plane 7, which are located on the same optical axis and arranged sequentially along the optical path propagation direction. The beam expander 2 is disposed on the side of the collimating laser 1 that emits laser light; The apex of the first conical lens 3 faces the beam expander 2; The base surface of the second conical lens 4 faces the first conical lens 3; The base surface of the third conical lens 6 faces the convex lens 5.

[0018] The third conical lens 6 and the sample surface are movable along the optical axis, so that the position of the third conical lens 6 and the sample surface can be adjusted according to the lens principle to adjust the radius and linewidth of the annular light spot.

[0019] Furthermore, the size of the annular light spot radius can be adjusted by fine-tuning the position of the third conical lens 6, and the linewidth of the annular light spot can be adjusted by fine-tuning the position of the sample surface.

[0020] Furthermore, how to achieve movable lens setting is a common technical means in this field, and relevant prior art can be referred to, so this application will not elaborate on it here.

[0021] The relative positions of the collimating laser 1, the beam expander 2, the first conical lens 3, the second conical lens 4, the convex lens 5, the third conical lens 6, and the image plane 7 affect the radius and linewidth of the annular light spot. Therefore, adjusting the distances between the collimating laser 1, the beam expander 2, the first conical lens 3, the second conical lens 4, the convex lens 5, the third conical lens 6, and the image plane 7 can yield the desired annular light spot.

[0022] Among them, collimated laser 1 is used to emit lasers with a radius of 1000 Hz. r A collimated and parallel laser beam of 1.

[0023] Among them, the beam expander 2 is used to expand the laser beam, converting the incident laser beam with a smaller radius into an outgoing laser beam with a larger radius.

[0024] The first conical lens 3 is used to shape the expanded laser beam into a ring beam.

[0025] The second conical lens 4 is used to shape the diverging ring beam into a converging ring beam, and the distance between the second conical lens 4 and the first conical lens 3 affects the size of the ring spot.

[0026] The convex lens 5 is used to focus the annular beam onto the image plane 7 at a specified distance; its focal length... f This is the distance from the image plane 7 to the convex lens 5.

[0027] The third conical lens 6 is used to change the direction of beam propagation and form a nearly parallel annular propagating beam. During use, the third conical lens 6 is adjusted to the right side of the position where the converging annular beam intersects with the optical axis.

[0028] Image plane 7 is used to project the annular light spot. The distance between image plane 7 and convex lens 5 is... f The sample surface is generally placed at the location of image plane 7, so the distance between the sample surface and convex lens 5 is approximately... f That is, the sample surface is basically on the focal plane of convex lens 5, at which point the sample surface will generate a ring-shaped light spot with the minimum linewidth.

[0029] The working principle of the annular light spot generating device provided in this application embodiment is as follows: When a ring-shaped light spot needs to be formed on the sample surface, the sample is placed at the position of the image plane 7; the collimating laser 1 emits collimated parallel light and directs it toward the beam expander 2; the beam expander 2 expands the beam, that is, converts the small-diameter incident laser beam into a large-diameter outgoing laser beam, and projects the expanded beam onto the first conical lens 3; the first conical lens 3 receives the beam and shapes it into a diverging ring beam, and directs the ring beam toward the second conical lens 4; the second conical lens 4 receives the ring beam and shapes the diverging ring beam into a converging ring beam, and sends the converging beam to the convex lens 5; the convex lens 5 receives the converging ring beam, focuses the converging ring beam, and then emits the converging ring beam to the third conical lens 6; the third conical lens 6 receives the converging and focused ring beam and changes the beam propagation direction to form a nearly parallel ring propagating beam, finally forming a ring-shaped light spot on the image plane 7.

[0030] Furthermore, during the formation of the annular light spot, the positions of the collimating laser 1, the beam expander 2, the first conical lens 3, the second conical lens 4, the convex lens 5, the third conical lens 6, and the image plane 7 can be finely adjusted to change the position, radius, and linewidth of the annular light spot.

[0031] Furthermore, according to the lens principle, without the third conical lens 6, the ring beam converged by the second conical lens 4 will first intersect the optical axis after passing through the convex lens 5, and then hit the image plane 7. Thus, the beam hitting the image plane 7 is a non-parallel ring beam with a large exit angle. If the third conical lens 6 is placed to the right of the position where the converged ring beam intersects the optical axis, the propagation direction of the ring beam will change.

[0032] Further, see Figure 3 The propagation direction of the ring beam can be changed to obtain an approximately parallel beam by the following method: Based on geometric relationships, the radius of the ring hitting image plane 7... r The formula is: in, h The exit height of the annular beam at the third conical lens 6. L The distance from the third cone lens 6 to the image plane 7 is... θ The exit angle of the ring beam at the third conical lens 6 is... θ The angle of incidence (ADI) and refractive index of the third cone lens (6) are related, and these are inherent properties of a lens and generally do not change. If the exit angle can be... This allows the light beam emitted through the third conical lens 6 to be essentially parallel to the optical axis, thus obtaining the radius of the annulus. r ≈ h That is, whenh When the radius remains constant, the radius of the ring remains essentially unchanged. Since the light that finally hits image plane 7 is approximately parallel, a ring-shaped spot with a highly stable radius can be obtained, and the minute axial displacement of the sample surface will have virtually no effect on the radius of the ring-shaped spot. r The size of the sample is such that even if the sample surface is not ideally placed on image plane 7, a ring-shaped light spot with a stable radius can still be formed on the sample surface.

[0033] In addition, for ease of description, in this application, the radius of the annular spot and the radius of the circle have the same meaning.

[0034] Furthermore, the launch angle can be adjusted using the following methods. θ =0, see Figure 4 The figure shows a schematic diagram of the converged annular beam propagating through the third conical lens 6. Assuming the refractive index in air is 0, the angle of incidence can be derived from the law of refraction. θ The formula: in, The refractive index of the third conical lens 6 is... The bottom angle of the third cone lens 6, The refraction angle of the third cone lens is 6. The calculation formula is: in, θ 2 Let be the incident angle of the third conical lens 6. From the formula for the exit angle, it can be seen that if... θ 2 The launch angle has been determined. θ Only the cone angle of the third cone lens 6 and Regarding, order: The value used to determine the refractive index can be calculated. The bottom angle of the third cone lens 6 The formula is: The refractive index at this time is n The bottom angle of the third cone lens 6 of 3 Enabling That is, the light emitted through the third conical lens 6 is approximately parallel light.

[0035] Furthermore, if you want to change the radius of the ring... r It can be changed h The size is determined by the radius of the annulus. r The change will not affect θ angle of departure θ The value is always 0, meaning that the annular beam emitted from the third conical lens 6 is always parallel to the optical axis, and the radius of the annular spot on the sample surface always remains highly stable.

[0036] Further, see Figure 5 , h The size can be changed by the following method: the height of the incident light at the third cone lens 6 h 2 is: Due to the launch height h The calculation formula is: in, Let be the axial distance of the light beam propagating in the third conical lens 6. Therefore, according to geometric relationships, such as... Figure 3 As shown, the final radius of image plane 7 is hit. r The expression is: Under the condition of a thin conical lens Basically constant, as can be seen from the formula, changing (Moving the third conical lens 6 along the optical axis) can change the radius of the ring. r Size, as stated in the preceding text θ The formula states that changing the position of the third cone lens 6 does not affect... θ The value is always 0, meaning that the annular beam emitted from the third conical lens 6 is always parallel to the optical axis, and the radius of the annular spot on the sample surface always remains highly stable.

[0037] The annular light spot generating device provided in this application overcomes the problem of high sensitivity to positional errors on the sample surface in the optical path for generating annular light spots in the prior art. In this device, a combination of three conical lenses and one convex lens 5 can be used to obtain an annular light spot with a stable radius on the sample surface.

[0038] like Figure 6 The diagram shows the sample surface position sensitivity of the optical path in the prior art and the optical path of this application. As can be seen from the left figure, using the optical path of the prior art, when the sample surface moves axially, the radius of the generated annular spot... r The variation is significant. Using the optical path of this application (right side of the figure), when the sample surface moves axially, the radius of the annular spot generated on the sample surface is... r The basic structure remains unchanged. Therefore, using the optical path system of this application, the position of the sample surface is easier to control, and the radius... r It will not change due to minute movements of the sample surface.

[0039] Further, see Figure 7 and Figure 8, Figure 7 and Figure 8 This is a schematic diagram showing the annular light spot with an axial error of 2 mm on the sample surface when comparing the optical path of the prior art with that of this application under specific conditions. Figure 7 and Figure 8 As can be seen from the image, when using the optical path of this application, the radius of the annular light spot is... r Basically unchanged, only the line width remains the same. d The radius of the annular spot changes and becomes insensitive to positional errors on the sample surface.

[0040] Furthermore, this application overcomes the limitation of existing optical paths in conveniently controlling the radius when generating annular light spots. r and line width d The problem.

[0041] Among them, the control linewidth: In this application, if the sample surface is located on the focal plane of the convex lens 5, the radius of the annular spot is... r Minimum, such as Figure 9 As shown, the rightmost plane is image plane 7, and the sample surface moves a distance relative to image plane 7. x According to geometric relationships, the width of the annulus is... d The calculation formula is: in, r 2 The radius of the expanded beam is given by the formula, which shows the axial movement distance of the sample surface. x With the width of the circular line d The relationship is linear; the farther the sample surface is from the image plane 7, the wider the linewidth. d The larger the radius. r The calculation formula is: Furthermore, due to the fact that in this device Therefore, radius It remains basically constant.

[0042] Control radius: due to the radius of the annulus r Approximately equal to the speed of light at the exit height of the third conical lens 6 h Therefore, if you want to change the radius r The size needs to be changed by altering the launch height h; due to the launch height h The calculation formula is: because x 2. Basically constant, Once the optical path parameters of the third conical lens 6 and the preceding lenses are determined, they are also constants; therefore, the exit height needs to be changed. h At this time, it is necessary to change the height of the incident beam to the third conical lens 6. h2, and that height h The formula for calculating 2 is: Therefore, the distance between the third conical lens 6 and the convex lens 5 can be changed. Change h 2; As can be seen from the formula, The smaller the value, the higher the incident height at the third cone lens 6. h The smaller the value of 2, the higher the launch altitude. h The smaller the radius of the ring r The smaller the value, the better. Furthermore, the annular linewidth remains essentially unchanged if the sample surface does not move.

[0043] Therefore, it can be seen that the radius of the annulus can be controlled by moving the sample surface position and the position of the third conical lens 6. r With line width d The size, and the radius of the ring r With line width d The controls do not affect each other.

[0044] Therefore, using the annular light spot generating device provided in this application, the final annular emission angle is obtained. θ The calculation formula is: exist In this case, the bottom angle of the third cone lens 6 can be obtained. The calculation formula is as follows: By selecting a lens according to this base angle, the emitted light can be made to be always parallel, and different circular radii can be generated. r The ring-shaped light spot, and h The change does not affect θ The ring beam is always parallel to the optical axis, and within the controllable ring radius, the radius of the ring spot on the sample surface remains highly stable.

[0045] Optionally, see Figure 10 In another exemplary embodiment of this application, the beam expander 2 is a negative meniscus lens, with the concave surface of the negative meniscus lens close to the collimating laser 1 and the convex surface close to the first conical lens 3.

[0046] Optionally, in another exemplary embodiment of this application, the convex lens 5 is a plano-convex lens.

[0047] Optionally, in another exemplary embodiment of this application, the convex lens 5 is a biconvex lens.

[0048] Optionally, in another exemplary embodiment of this application, the convex lens 5 is a concave-convex lens.

[0049] Alternatively, in another exemplary embodiment of this application, the beam expander 2 is a Keplerian beam expander, a Galilean beam expander, or a reflective beam expander.

[0050] Of course, the beam expander can also be other types of beam expanders, and this application does not limit this.

[0051] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0052] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A ring-shaped light spot generating device, characterized in that, include: A collimating laser, a beam expander, a first cone lens, a second cone lens, a convex lens, a third cone lens, and an image plane are arranged sequentially along the same optical axis and along the direction of optical propagation. The beam expander is located on the side of the collimating laser that emits the laser. The apex of the first conical lens faces the beam expander; The base surface of the second conical lens faces the first conical lens; The base surface of the third conical lens faces the convex lens.

2. The annular light spot generating device according to claim 1, characterized in that, The third conical lens and the sample surface are movable along the optical axis.

3. The annular light spot generating device according to claim 1, characterized in that, The beam expander is a negative meniscus lens, with its concave surface close to the collimating laser and its convex surface close to the first cone lens.

4. The annular light spot generating device according to claim 1, characterized in that, The convex lens is a plano-convex lens, a biconvex lens, or a concave-convex lens.

5. The annular light spot generating device according to any one of claims 1-4, characterized in that, The beam expander is a Keplerian beam expander, a Galilean beam expander, or a reflective beam expander.

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