Laser lens, laser collimator and laser beam quality modulation method thereof

Abstract

The invention discloses a laser lens, a laser collimator and a laser beam quality modulation method thereof, the laser lens is a rectangular cubic laser lens, and the laser lens has gradually-changing refractive indexes from small to large from a light-transmitting plane at one end of an original point to a light-transmitting plane at the other opposite end in the X-axis direction; in the Y-axis direction and the Z-axis direction, the gradient refractive index from the light-transmitting plane at one end of the original point to the light-transmitting plane at the other opposite end is constant; wherein the light-transmitting planes at the two ends in the Y-axis direction are laser incident planes of the laser source, and the light-transmitting plane at the end with the large gradual change refractive index in the X-axis direction is a light-transmitting plane for linearly emitting laser after incident laser is bent in a gradual change manner with the gradual change refractive index in the X-axis direction. The laser incident end surface and the laser emergent end surface are two adjacent surfaces, so that the quality modulation of the output laser beam becomes possible, simple and convenient, and when the device is used for the laser collimator, the performance of the laser collimator can be improved by modulating the quality of the output laser beam.

Description

Technical Field

[0001] The invention relates to a laser lens, a laser collimator and a laser beam quality modulation method thereof. Background Art

[0002] Laser beam quality is defined as the product of the far-field divergence half angle of the beam and the beam waist radius. Leaving aside the cumbersome theory, the beam quality can be vividly understood as "how far the laser can maintain a certain energy density to transmit" or "how small the laser spot can be focused when it is concentrated". Therefore, in the application field of lasers, having better beam quality will mean that the laser can maintain a certain energy density and transmit farther, or the laser spot is smaller when it is focused. It is easy to understand that better beam quality means longer-range destructive capability or longer-range equipment charging effect in the laser military field, and better beam quality means more sophisticated processing and treatment levels in the industrial and medical fields.

[0003] At present, the most widely used product type of gradient refractive index devices (also known as gradient refractive index devices) in the market is self-focusing lens, such as Figure 1 , Figure 2 As shown, the self-focusing lens is a cylindrical optical lens with a refractive index distribution that gradually changes along the radial direction. The refractive index change curve of the self-focusing lens is symmetrical along the radial direction (X axis), and the refractive index of the other axial directions of the self-focusing lens remains unchanged. Laser beam quality modulation technology; Figure 1 In the design of the self-focusing lens, the goal is to make the parallel light beam focus smoothly and continuously inside the self-focusing lens after it is incident. Its working mechanism is: the distribution of the refractive index of the self-focusing lens material gradually decreases from the center to the edge, which can make the light transmitted along the axial direction produce continuous refraction, so that the outgoing light can be smoothly and continuously converged to one point. The laser input end face and the laser output end face are two opposite faces. In other words, when the light is transmitted in a fixed medium, for the direction perpendicular to the propagation direction of the light (such as Figure 1 , 2 The X-axis in the middle), the light will be deflected in the direction of the larger refractive index. If the refractive index in this direction is uniform in all directions, the light will not be deflected. Regarding the modulation methods aimed at improving the quality of laser beams, it is generally believed that the quality of laser beams is determined by the resonant cavity of the laser generator and the excitation method. Once the laser is emitted, it is difficult to change its beam quality. Therefore, this field is blank. It should be noted that some technical means on the market will promote their effects of "optimizing beam quality" and "improving beam quality", such as FAC fast axis collimation technology. This promotional effect should be more rigorously described as "slowing down the degradation of beam quality". For example: using the following in the collimator Figure 3 The single curved surface shown is collimated, or by Figure 4The multiple curved surface collimation shown in the figure means that the laser divergence angle is eliminated through an optical lens (convex or concave mirror) to achieve the effect of the divergence angle approaching zero. The main existing technical means is to use the principle of light refraction of glass lenses to collimate the divergence angle in the form of a single or multiple curved lens combination. Since the quality of the laser beam will gradually degrade with the increase of the propagation distance, the collimation technology mentioned in the propaganda can only "slow down" its degradation rate, rather than "optimize" or "improve" it in the true sense. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide a laser lens, a laser collimator and a method for modulating the laser beam quality thereof. Based on the design process of a self-focusing lens, the cylindrical or arc-shaped convex or concave lens is changed into a rectangular body, the refractive index change curve along the radial center symmetry is changed into a unidirectional change curve, and the coaxial laser input and output are changed into non-coaxial ones, thereby realizing direct modulation of the laser beam quality.

[0005] In order to achieve the above object, the scheme of the present invention is: A laser lens, the lens is a rectangular cube laser lens with three groups of relative light-transmitting planes, the rectangular cube laser lenses are arranged parallel to each other relative to the light-transmitting planes, the length of the rectangular cube laser lens is the X axis, the width is the Y axis, the height is the Z axis, the intersection point of the three axes of the X axis, the Y axis and the Z axis is the origin, the laser lens has: in the X-axis direction, from the light-transmitting plane at one end of the origin to the light-transmitting plane at the other end, the gradual refractive index from the light-transmitting plane at one end of the origin to the light-transmitting plane at the other end is constant in the Y-axis direction, and the gradual refractive index from the light-transmitting plane at one end of the origin to the light-transmitting plane at the other end in the Z-axis direction is constant; wherein: the two end light-transmitting planes in the Y-axis direction are the laser incident planes of the laser source, and the end light-transmitting plane with a large gradual refractive index in the X-axis direction is the light-transmitting plane where the incident laser emits the laser in a straight line after being gradually bent with a gradual refractive index in the X-axis direction.

[0006] A further solution is that the gradient refractive index is a straight line change or an arc-shaped change curve from small to large.

[0007] A further solution is that the straight-line laser is perpendicular to the Y-axis direction.

[0008] A further solution is that the length of the laser lens in the X-axis direction is at least the length of the incident laser when the incident laser is emitted in a straight line perpendicular to the Y-axis direction while keeping the incident angle of the main ray of the laser beam unchanged.

[0009] A further solution is that high-transmittance optical film layers are respectively plated on both end faces in the X-axis direction and the Y-axis direction of the laser lens.

[0010] A laser collimator comprises a laser source and a laser lens, wherein the laser lens is the aforementioned rectangular cube laser lens, the laser of the laser source is incident on the laser lens from a light-transmitting plane at one end of the Y-axis at the end side with a small gradient refractive index on the X-axis, and the incident laser is emitted in a straight line from the light-transmitting plane at one end of the laser lens with a large gradient refractive index on the X-axis, and the emitted linear laser is perpendicular to the Y-axis of the laser lens.

[0011] The solution is further that: the straight line emission is a straight line emission from the center point of the light transmission plane at the end of the laser lens with a large gradient refractive index on the X axis A laser beam quality modulation method, wherein the method is a laser beam quality modulation method for emitting laser light using the aforementioned laser lens, wherein two parallel slide rails are arranged beside the rectangular cube laser lens, the two slide rails are parallel to the X-axis direction of the regular rectangular cube laser lens, movable brackets are arranged on the two slide rails respectively, the laser source is arranged on one bracket, and a laser analyzer is arranged on the other bracket, the laser analyzer collects and observes the laser emission spot of the laser emission end face in the X-axis direction of the laser lens, keeps the incident angle of the main light of the laser beam unchanged, and sequentially performs: recording the original coordinate position of the laser emission spot, synchronously translating the laser source and the laser analyzer along the X-axis, and observing the laser emission spot; when the spot is the smallest and the coordinate position of the spot remains unchanged, the emitted laser beam quality is optimal.

[0012] The scheme further includes: adjusting and setting multiple laser beam main ray incident angles, repeatedly performing: recording the original coordinate position of the laser emission spot, synchronously translating the laser source and the laser analyzer along the X-axis, observing the laser emission spot, recording: multiple laser beam main ray incident angles when the spot is smallest and the spot coordinate position remains unchanged, and comparing the minimum spot of multiple laser beam main ray incident angles; wherein: the smallest spot among the minimum spots is the one with the best quality of the emitted laser beam, and the corresponding position of the laser source in the X-axis direction and the incident angle of the laser beam main ray are the laser source position and laser incidence angle that emit the best quality of the laser beam.

[0013] The beneficial effects of the present invention are: based on the design process of the self-focusing lens, the cylindrical or arc-shaped convex or concave lens is changed into a rectangular body, and the refractive index change curve along the radial center symmetry is changed into a unidirectional change curve. It is easy to see that under the process manufacturing conditions of the existing gradient refractive index device, the difficulty of manufacturing the unidirectional gradient refractive index device of the present invention is relatively low, and the device meets the manufacturability.

[0014] Based on the laser lens of the present invention, by changing the laser input end face and the laser output end face which are two opposite faces into two adjacent faces, it becomes possible, simple and convenient to modulate the output laser beam quality. When it is used in a laser collimator, the performance of the laser collimator can be improved by modulating the output laser beam quality.

[0015] The present invention is described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of a traditional self-focusing lens and laser focusing along the X-axis of the lens; Figure 2 This is a schematic diagram of the refractive index variation curve of the traditional self-focusing lens along the X axis; Figure 3 It is a schematic diagram of traditional single curved surface collimation; Figure 4 It is a schematic diagram of traditional multiple curved surface collimation; Figure 5 It is a schematic diagram of the structure of the laser lens of the present invention; Figure 6 It is a schematic diagram of the refractive index variation curve of the laser lens in the X-axis direction of the present invention; Figure 7 It is a schematic diagram of the refractive index variation curves of the laser lens in the Y-axis direction and the Z-axis direction of the present invention; Figure 8 It is a schematic structural diagram of the relationship between the laser source and the laser lens of the laser collimator of the present invention; Fig. 9 It is a schematic diagram of the structure of the laser beam quality modulation method of the present invention; Fig.10 It is a visual schematic diagram of the laser beam quality modulation of the present invention. DETAILED DESCRIPTION

[0017] The concept of laser beam quality: Laser beam quality is defined as the product of the far-field divergence half angle of the beam and the beam waist radius. Leaving aside the cumbersome theory, the beam quality can be vividly understood as "how far the laser can maintain a certain energy density to transmit" or "how small the laser spot can be focused when it is concentrated". Therefore, in the application field of lasers, having better beam quality will mean that the laser can maintain a certain energy density and transmit farther, or the laser spot is smaller when it is focused. It is easy to understand that better beam quality means longer-range destructive capability or longer-range equipment charging effect in the laser military field, and better beam quality means more sophisticated processing and treatment levels in the industrial and medical fields.

[0018] Embodiment 1: A laser lens is a laser lens that can easily modulate the spot size, such as Figure 5As shown, the lens is a rectangular cube laser lens 1 having three sets of relative light-transmitting planes. The rectangular cube laser lens is arranged parallel to the light-transmitting planes. Definition: The length of the rectangular cube laser lens is the X-axis, the width is the Y-axis, the height is the Z-axis, and the intersection point of the three axes of the X-axis, the Y-axis, and the Z-axis is the origin O. The laser lens is manufactured as follows: in the X-axis direction, from the light-transmitting plane 101 at one end of the origin to the light-transmitting plane 102 at the other end, there is a Figure 6 The gradient refractive index from small to large is shown in FIG. 1 . The gradient refractive index is a linear change or an arc-shaped change curve from small to large. Of course, it can also be other types of curves. The laser lens is made as follows Figure 7 As shown, the gradient refractive index from the light-transmitting plane at one end of the origin to the light-transmitting plane at the other end in the Y-axis direction is constant, and the gradient refractive index from the light-transmitting plane at one end of the origin to the light-transmitting plane at the other end in the Z-axis direction is constant; wherein: the light-transmitting planes 103 and 104 at both ends of the Y-axis direction are the laser incident planes of the laser source, and the light-transmitting plane 102 at one end with a larger gradient refractive index in the X-axis direction is the light-transmitting plane where the incident laser is emitted in a straight line after being gradually bent with a gradient refractive index in the X-axis direction.

[0019] Wherein: the straight line laser is perpendicular to the Y-axis direction. Moreover, to ensure that the laser beam quality can be modulated, the length of the laser lens in the X-axis direction is at least the length of the straight line laser perpendicular to the Y-axis direction when the incident laser keeps the incident angle of the main ray of the laser beam unchanged.

[0020] In order to ensure the light transmission performance, the two end surfaces 101 and 102 in the X-axis direction and the two end surfaces 103 and 104 in the Y-axis direction of the laser lens are respectively coated with optical film layers with high transmittance.

[0021] Regarding the manufacturing process of the gradient refractive index device, the manufacturing process is a mature existing technology: 1) The device material is optical glass material, commonly used materials in the industry, such as SiO2, Ti2O5, TiO2, Si3N The gradient refractive index device (also called gradient refractive index device) currently available in the market is a widely used product, for example: self-focusing lens, which is a cylindrical optical lens with a refractive index distribution that gradually changes radially toward the center.

[0022] 2) High-transmittance coating is not an absolute necessity. The function of the four sides of the device is transmission. It can transmit light whether it is coated or not, but coating with high-transmittance coating can improve the transmittance. In actual design and use, it is necessary to increase the optical power and reduce the loss in principle. Therefore, it is necessary to coat with high-transmittance coating (also known as "anti-reflection coating", "AR coating") to make the transmittance of the four sides greater than 99.5%. In addition, the coating can be carried out according to the needs as to which side to coat and how many sides to coat.

[0023] 3) Regarding coating materials, it is a common technology in the optoelectronics industry. Common anti-reflection film materials include Al2O3, SiO, SiO2, TiO2, Ti2O3, ZrO2, MgF2, BaF2, YF3, Na3AlF6, etc. In order to improve the transmittance of the film layer, it is generally a multi-layer film structure.

[0024] 4) Regarding the coating method, it is a conventional technology in the optoelectronics industry. Common coating methods include vacuum evaporation, which uses vacuum coating machines and other equipment. Its mechanism is to heat the coating material at high temperature in a vacuum environment, so that the material components are evaporated in the form of atomic groups or ions, so that they adhere to the optical surface to form a thin film. Other coating methods include vacuum sputtering, which uses electrons or high-energy lasers to bombard the coating material in a vacuum environment, so that the material components are sputtered in the form of atomic groups or ions, so that they are precipitated and attached to the optical surface to form a thin film.

[0025] Regarding the device size, the size ratio is length × width × height, which can be 10 × 5 × 1, in mm. In actual design and use, the device size does not limit the ratio. For the length and width, the principle of limiting the length and width is "sufficient for the light path to be deflected from the incident surface to the exit surface (optical path)". For the height (thickness) size, the restriction condition only needs to meet the spot size. The height (thickness) can be designed according to different spot sizes.

[0026] Embodiment 2: A laser collimator, such as Figure 8 As shown, the laser collimator includes a laser source 2 and a laser lens, wherein the laser lens is the rectangular cube laser lens 1 described in Example 1, and the laser 201 of the laser source 2 is incident on the laser lens from a light-transmitting plane 104 at one end of the Y-axis on the side of an end 101 with a small gradient refractive index on the X-axis, and the incident laser is emitted in a straight line from a light-transmitting plane 102 at one end of the laser lens with a large gradient refractive index on the X-axis, and the emitted linear laser is perpendicular to the Y-axis of the laser lens.

[0027] In addition, by adjusting the incident angle of the main light beam of the incident laser and the position of the laser source in the X-axis direction, the incident laser is emitted in a straight line at the center point of the light-transmitting plane at the end of the laser lens with a large gradient refractive index in the X-axis, which is shown as an emission spot 8 in the figure.

[0028] Embodiment 3: A method for modulating the quality of a laser beam, wherein the method is a method for modulating the quality of a laser beam emitted by a laser lens in a laser lens according to claim 1 and a laser collimator according to claim 2, such as Fig. 9 and Fig.10As shown, two parallel slide rails are arranged beside the rectangular cube laser lens 1, namely, the first slide rail 3 and the second slide rail 4. The two slide rails are parallel to the X-axis direction of the regular rectangular cube laser lens. Movable brackets 5 and 6 are arranged on the two slide rails respectively. The laser source 2 is arranged on one bracket 5, and the laser analyzer 7 is arranged on the other bracket 6. The laser analyzer 7 collects and observes the laser emission spot 8 of the laser emission end face 102 in the X-axis direction of the laser lens. Of course, two brackets can also be placed on one slide rail; the incident angle of the main light of the laser beam is kept unchanged, and the following are performed in sequence: recording the original coordinate position of the laser emission spot, synchronously translating the laser source and the laser analyzer along the X-axis, and observing the laser emission spot; when the spot is the smallest and the coordinate position of the spot is unchanged, the quality of the emitted laser beam is optimal.

[0029] This only determines the position of the laser source 2 when the best laser beam quality is output. Taking into account the influence of the incident angle on the beam quality, as a determination of the incident angle, the method further includes: adjusting and setting multiple laser beam main ray incident angles, repeatedly performing: recording the original coordinate position of the laser emission spot, synchronously translating the laser source and the laser analyzer along the X-axis, observing the laser emission spot, recording: multiple laser beam main ray incident angles when the spot is smallest and the spot coordinate position remains unchanged, and comparing the minimum spot of multiple laser beam main ray incident angles; wherein: the smallest spot among the minimum spots is the one with the best laser beam quality, and the corresponding position of the laser source in the X-axis direction and the incident angle of the laser beam main ray are the laser source position and laser incidence angle that emit the best laser beam quality.

[0030] For the implementation principle of the beam quality modulation and collimation technology of this embodiment, combined with Figure 5 , Figure 6 and Figure 7 , in the context of geometric optics, we discuss the scenario where a single light ray enters the laser lens from the light-transmitting plane 104 at one end of the Y axis. It is easy to see that no matter at what incident angle the light ray enters the gradient device from the light-transmitting plane 104 (total reflection is not considered here), the light ray will be continuously refracted inside the device ( Figure 7), thereby gradually deflecting the laser emission end face 102 in the X-axis direction of the laser lens, and finally propagating in a straight line in a propagation direction parallel to the X-axis (the direction of refractive index change). When discussing a large number of light rays, each light ray will eventually propagate in a straight line along the X-axis. In actual operation, the laser will follow the laws of physical optics. According to theoretical calculations, all light rays are not absolutely parallel to each other. Limited by the diffraction limit, the light beam will have a residual divergence angle of about 0.1°, and the residual divergence angle has nothing to do with the beam quality of the original laser beam. This means that no matter what the beam quality of the original laser beam is, the residual divergence angle remains at a value of about 0.1°. According to the above discussion, even if there is a residual divergence angle of about 0.1°, it can already meet the needs of the collimation technology very well. For the collimation technology adjustment method, the key is that the size of the gradient device meets the size of the light deflected to the straight line propagation along the X-axis. In the actual adjustment process, the adjustment can be achieved with the help of a laser analyzer (CCD), a multi-axis adjustment frame, a guide rail slider and other combined fixtures.

[0031] Depend on Fig. 9 Figure 10 shows that ( Fig.10 The image shows the laser divergence state). The translation of the light source will make the light beam have different starting refractive index and starting refractive index change rate (slope) when it is incident at different incident points. It is easy to know that the higher the refractive index, the greater the light deflection angle, and the higher the refractive index change rate, the faster the light deflection speed (or the larger the deflection arc). Therefore, in Figure 6 Based on the limited refractive index change curve, the following operations are performed: keep the incident angle of the laser beam principal ray unchanged, and translate the light source to the left along the X-axis. At this time, a beam with a smaller spot width will be obtained, which means that the light source can be changed by adjusting the translation along the X-axis. Fig.10 The laser beam waist size shown in the figure is that since the far-field divergence angle is almost unchanged, and the beam quality is defined as the product of the beam waist radius and the far-field divergence angle, the translation adjustment can change the beam quality of the laser output. This is the principle of beam quality modulation achieved by the gradient device.

[0032] The above-mentioned laser lens, laser collimator and laser beam quality modulation method embodiment, based on a rectangular cubic laser lens, changes the laser input end face and the laser output end face which are two opposite faces into two adjacent faces, so that it becomes possible, simple and convenient to modulate the output laser beam quality. When it is used in a laser collimator, the performance of the laser collimator can be improved by modulating the output laser beam quality.

Claims

1. A laser lens, characterized in that: The lens is a rectangular cube laser lens with three groups of relative light-transmitting planes. The rectangular cube laser lenses are arranged parallel to each other relative to the light-transmitting planes. The length of the rectangular cube laser lens is the X axis, the width is the Y axis, and the height is the Z axis. The intersection point of the three axes of the X axis, the Y axis, and the Z axis is the origin. The laser lens has: in the X-axis direction, the light-transmitting plane at one end of the origin to the light-transmitting plane at the other end has a gradual refractive index from small to large, in the Y-axis direction, the gradual refractive index from the light-transmitting plane at one end of the origin to the light-transmitting plane at the other end is constant, and in the Z-axis direction, the gradual refractive index from the light-transmitting plane at one end of the origin to the light-transmitting plane at the other end is constant; wherein: the two end light-transmitting planes in the Y-axis direction are the laser incident planes of the laser source, and the end light-transmitting plane with a large gradual refractive index in the X-axis direction is the light-transmitting plane where the incident laser emits the laser in a straight line after being gradually bent with a gradual refractive index in the X-axis direction.

2. A laser lens according to claim 1, characterized in that: The gradient refractive index is a linear change or an arc-shaped change curve from small to large.

3. The laser lens according to claim 1, characterized in that: The straight-line laser is perpendicular to the Y-axis direction.

4. The laser lens according to claim 1, characterized in that: The length of the laser lens in the X-axis direction is at least the length of the incident laser beam in the Y-axis direction when the incident laser beam is emitted in a straight line while keeping the incident angle of the main ray of the laser beam unchanged.

5. The laser lens according to claim 1, characterized in that: Optical film layers with high transmittance are respectively plated on both end surfaces in the X-axis direction and the Y-axis direction of the laser lens.

6. A laser collimator, comprising a laser source and a laser lens, characterized in that: The laser lens is a rectangular cube laser lens as described in claim 1, and the laser of the laser source enters the laser lens from a light-transmitting plane at one end of the Y-axis at the end side with a small gradient refractive index on the X-axis, and the incident laser is emitted in a straight line from a light-transmitting plane at one end of the laser lens with a large gradient refractive index on the X-axis, and the emitted linear laser is perpendicular to the Y-axis of the laser lens.

7. A laser collimator according to claim 6, characterized in that: The linear emission is emitted from the center point of the light-transmitting plane at one end of the laser lens with a large gradient refractive index on the X-axis.

8. A laser beam quality modulation method, characterized in that: The method is a laser beam quality modulation method for emitting laser light using the laser lens in claim 1 or claim 6. Two parallel slide rails are arranged beside the rectangular cube laser lens. The two slide rails are parallel to the X-axis direction of the regular rectangular cube laser lens. Movable brackets are respectively arranged on the two slide rails. The laser source is arranged on one bracket, and a laser analyzer is arranged on the other bracket. The laser analyzer collects and observes the laser emission spot of the laser emission end face in the X-axis direction of the laser lens, keeps the incident angle of the main light of the laser beam unchanged, and sequentially performs the following steps: recording the original coordinate position of the laser emission spot, synchronously translating the laser source and the laser analyzer along the X-axis, and observing the laser emission spot. When the spot is the smallest and the coordinate position of the spot remains unchanged, the quality of the emitted laser beam is optimal.

9. The method according to claim 8, characterized in that The method further includes: adjusting and setting multiple laser beam main ray incident angles, repeatedly performing: recording the original coordinate position of the laser emission spot, synchronously translating the laser source and the laser analyzer along the X-axis, observing the laser emission spot, recording: multiple laser beam main ray incident angles when the spot is minimum and the spot coordinate position remains unchanged, and comparing the minimum spot of the multiple laser beam main ray incident angles; wherein: the smallest spot among the minimum spots is the one with the best quality of the emitted laser beam, and the corresponding position of the laser source in the X-axis direction and the laser beam main ray incident angle are the laser source position and laser incidence angle of the laser beam with the best quality of the emitted laser beam.

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