A laser frequency-doubling walk-off angle compensation method and device

Abstract

The present disclosure relates to the field of optics and laser technology, and particularly relates to a laser frequency doubling walk-off angle compensation method and device, the method is applied to a target optical path comprising a laser source, a frequency doubling crystal and a target optical wedge; the fundamental frequency light emitted by the laser source is controlled to be incident to the frequency doubling crystal; the frequency doubling light emitted by the frequency doubling crystal and the fundamental frequency light are controlled to be incident to the target optical wedge, and the fundamental frequency light and the frequency doubling light exist a target walk-off angle in the frequency doubling crystal; the wedge angle of the target optical wedge is determined according to the target walk-off angle, the refractive index of the target optical wedge to light of different wavelengths and a preset propagation distance, and the fundamental frequency light and the frequency doubling light emitted by the target optical wedge coincide at the preset propagation distance. According to the present disclosure, the fundamental frequency light and the frequency doubling light can coincide at the preset propagation distance only by using the target optical wedge, and the number of components and the space occupation of the target optical path are effectively reduced.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of optics and laser technology, and in particular to a laser frequency doubling walk-off angle compensation method and device. BACKGROUND

[0002] In the field of laser nonlinear frequency conversion, when generating short-wavelength laser light through frequency doubling technology (for example, second-harmonic generation, third-harmonic generation, fourth-harmonic generation, etc.), the nonlinear crystal will generate light walk-off, that is, the second-harmonic light and the fundamental light will generate walk-off effect in the nonlinear crystal, and the shorter the wavelength of the second-harmonic light generated after frequency doubling (for example, ultraviolet light), the greater the walk-off angle of the second-harmonic light and the fundamental light in the nonlinear crystal. SUMMARY

[0003] In view of this, the present disclosure provides a laser frequency doubling walk-off angle compensation method and device.

[0004] According to an aspect of the present disclosure, a laser frequency doubling walk-off angle compensation method is provided, which is applied to a target optical path including a laser source, a frequency doubling crystal, and a target optical wedge. The method controls the fundamental light emitted by the laser source to be incident on the frequency doubling crystal, and controls the second-harmonic light emitted by the frequency doubling crystal and the fundamental light to be incident on the target optical wedge. The fundamental light and the second-harmonic light have a target walk-off angle in the frequency doubling crystal. The wedge angle of the target optical wedge is determined according to the target walk-off angle, the refractive index of the target optical wedge for light of different wavelengths, and a preset propagation distance. The fundamental light and the second-harmonic light emitted by the target optical wedge coincide at the preset propagation distance.

[0005] In a possible implementation, the method further includes controlling the target optical wedge to rotate perpendicular to the optical axis of the target optical path until the area of the light spots of the fundamental light and the second-harmonic light coincide at the preset propagation distance is maximum.

[0006] In a possible implementation, the wedge angle of the target optical wedge is used to indicate the included angle between two optical surfaces of the target optical wedge. The method further includes determining the deviation distance of the fundamental light and the second-harmonic light in the vertical propagation direction after being output from the frequency doubling crystal according to the target walk-off angle and the length of the frequency doubling crystal, and determining the wedge angle θ of the target optical wedge according to the deviation distance, the refractive index of the target optical wedge for light of different wavelengths, and the preset propagation distance, by using the following formula: ; wherein D is the deviation distance, L is the preset propagation distance, n1 is the refractive index of the second-harmonic light in air, n2 is the refractive index of the second-harmonic light in the target optical wedge, n3 is the refractive index of the fundamental light in air, and n4 is the refractive index of the fundamental light in the target optical wedge.

[0007] In a possible implementation, different target walk-off angles correspond to different frequency doubling crystals.

[0008] In a possible implementation, the frequency-doubled light is one of the following: second-harmonic light, third-harmonic light, and fourth-harmonic light.

[0009] According to another aspect of the present disclosure, a laser frequency-doubled walk-off angle compensation device is provided. The device is applied to a target light path, and the target light path includes a laser source, a frequency doubling crystal, and a target optical wedge. The device includes a first control module configured to control the incidence of fundamental light emitted by the laser source to the frequency doubling crystal, and a second control module configured to control the incidence of frequency-doubled light emitted by the frequency doubling crystal and the fundamental light to the target optical wedge. The fundamental light and the frequency-doubled light have a target walk-off angle in the frequency doubling crystal. A wedge angle of the target optical wedge is determined according to the target walk-off angle, refractive indexes of the target optical wedge for different wavelengths of light, and a preset propagation distance. The fundamental light and the frequency-doubled light emitted by the target optical wedge coincide at the preset propagation distance.

[0010] In a possible implementation, the device further includes a third control module configured to control the rotation of the target optical wedge perpendicular to an optical axis of the target light path until the area of coincidence of light spots of the fundamental light and the frequency-doubled light at the preset propagation distance is maximum.

[0011] In a possible implementation, the wedge angle of the target optical wedge is used to indicate an included angle between two optical surfaces of the target optical wedge. The device further includes a first determination module configured to determine a deviation distance of the fundamental light and the frequency-doubled light in a vertical propagation direction after being output from the frequency doubling crystal according to the target walk-off angle and a length of the frequency doubling crystal, and a second determination module configured to determine the wedge angle θ of the target optical wedge according to the deviation distance, the refractive indexes of the target optical wedge for different wavelengths of light, and the preset propagation distance, by using the following formula: ; wherein D is the deviation distance, L is the preset propagation distance, n1 is a refractive index of the frequency-doubled light in air, n2 is a refractive index of the frequency-doubled light in the target optical wedge, n3 is a refractive index of the fundamental light in air, and n4 is a refractive index of the fundamental light in the target optical wedge.

[0012] In a possible implementation, different target walk-off angles correspond to different frequency doubling crystals.

[0013] In a possible implementation, the frequency-doubled light is one of the following: second-harmonic light, third-harmonic light, and fourth-harmonic light.

[0014] The laser frequency doubling walk-off angle compensation method of the embodiment of the present disclosure controls the fundamental frequency light emitted by the laser source to be incident to the frequency doubling crystal, and the frequency doubling crystal emits the frequency doubling light and the fundamental frequency light, wherein the target walk-off angle exists in the frequency doubling crystal, and then, in order to compensate the walk-off angle, the frequency doubling light and the fundamental frequency light are controlled to be incident to the pre-determined target optical wedge, and since the wedge angle of the target optical wedge is determined according to the target walk-off angle, the refractive index of the target optical wedge to light of different wavelengths, and the preset propagation distance, the fundamental frequency light and the frequency doubling light can be overlapped at the preset propagation distance only by using the target optical wedge, and the number of components and the space occupation of the target optical path are effectively reduced.

[0015] Other features and aspects of the present disclosure will become apparent from the following detailed description of exemplary embodiments with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features, and aspects of the present disclosure and serve to explain the principles of the present disclosure.

[0017] Figure 1 A flowchart of a laser frequency doubling walk-off angle compensation method according to an embodiment of the present disclosure is shown.

[0018] Figure 2 A schematic diagram of determining the wedge angle of a target optical wedge according to an embodiment of the present disclosure is shown.

[0019] Figure 3 A schematic diagram of a target optical path according to an embodiment of the present disclosure is shown.

[0020] Figure 4 A block diagram of a laser frequency doubling walk-off angle compensation device according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0021] Various exemplary embodiments, features, and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. The same reference numbers in the drawings represent functionally the same or similar elements. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

[0022] As used herein, the terms "comprise", "contain", "have", or variants thereof are open, and include one or more stated features, integers, elements, steps, components or functions, but do not exclude the presence or addition of one or more other features, integers, elements, steps, components, functions or groups thereof.

[0023] When an element is referred to as being "connected", "coupled", "responsive", or variants thereof, to another element, it can be directly connected, coupled, or responsive to the other element, or there can be intervening elements.

[0024] Although the terms first, second, third, etc. can be used herein to describe various elements / operations, such elements / operations should not be limited by these terms. These terms are only used to distinguish one element / operation from another. Thus, a first element / operation in some embodiments could be termed a second element / operation in other embodiments without departing from the teachings of the present inventive concepts.

[0025] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations.

[0026] In addition, for the purpose of convenience and brevity, detailed descriptions of well-known devices, methods, procedures, components, and circuits are not described in detail in order to avoid unnecessarily obscuring the present teachings. It is noted that the present teachings can be implemented in various ways, and that the terminology used herein should not be viewed as limiting. For example, the term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations.

[0027] In the field of laser nonlinear frequency conversion, when generating short-wavelength laser light through frequency doubling technology (e.g., second-harmonic generation, third-harmonic generation, fourth-harmonic generation, etc.), the nonlinear crystal generates walk-off of light, that is, the second-harmonic light and the fundamental light generate walk-off effects in the nonlinear crystal, and the shorter the wavelength of the second-harmonic light generated after frequency doubling (e.g., ultraviolet light), the greater the walk-off angle of the second-harmonic light and the fundamental light in the nonlinear crystal.

[0028] The walk-off effect generated by the nonlinear crystal affects applications that require the fundamental light and the second-harmonic light to impinge on the same point in the far field. Therefore, the walk-off effect needs to be compensated.

[0029] In the prior art, the fundamental light and the second-harmonic light are first split, and then combined through the precise adjustment of a mirror to satisfy the condition that the fundamental light and the second-harmonic light impinge on the same point in the far field.

[0030] In the prior art, the laser source emits fundamental light, the fundamental light passes through a frequency doubling crystal to generate second-harmonic light, the fundamental light and the second-harmonic light are separated by a beam splitter, and finally the second-harmonic light is combined with the fundamental light by a beam combiner. By adjusting the pitch and azimuth of the beam combiner, the fundamental light and the second-harmonic light can be made to coincide at a point in the far field.

[0031] In the prior art, the optical path capable of realizing laser frequency doubling walk-off angle compensation has a large number of mirrors and occupies a large space.

[0032] The embodiment of the present disclosure provides a laser frequency multiplication walk-off angle compensation method, which can effectively reduce the number of components and the space occupation of the target optical path while realizing the coincidence of the fundamental frequency light and the frequency multiplication light in the far field. The laser frequency multiplication walk-off angle compensation method provided by the embodiment of the present disclosure is described in detail below.

[0033] Figure 1 A flow chart of a laser frequency multiplication walk-off angle compensation method according to an embodiment of the present disclosure is shown. The method is applied to a target optical path, which includes a laser source, a frequency multiplication crystal, and a target optical wedge. The method includes:

[0034] In step S11, the fundamental frequency light emitted by the laser source is controlled to be incident on the frequency multiplication crystal.

[0035] In step S12, the frequency multiplication light and the fundamental frequency light emitted by the frequency multiplication crystal are controlled to be incident on the target optical wedge, and the fundamental frequency light and the frequency multiplication light have a target walk-off angle in the frequency multiplication crystal. The wedge angle of the target optical wedge is determined according to the target walk-off angle, the refractive index of the target optical wedge to light of different wavelengths, and a preset propagation distance, and the fundamental frequency light and the frequency multiplication light emitted by the target optical wedge coincide at the preset propagation distance.

[0036] The laser frequency multiplication walk-off angle compensation method of the embodiment of the present disclosure controls the fundamental frequency light emitted by the laser source to be incident on the frequency multiplication crystal. Due to the walk-off effect of the frequency multiplication crystal, the frequency multiplication light and the fundamental frequency light have a target walk-off angle in the frequency multiplication crystal. Then, in order to compensate for the walk-off angle, the frequency multiplication light and the fundamental frequency light are controlled to be incident on the target optical wedge. Since the wedge angle of the target optical wedge is determined according to the target walk-off angle, the refractive index of the target optical wedge to light of different wavelengths, and the preset propagation distance, the fundamental frequency light and the frequency multiplication light can coincide at the preset propagation distance only by using the target optical wedge, thereby effectively reducing the number of components and the space occupation of the target optical path.

[0037] Based on the dispersion principle of optical materials, different wavelengths of light will produce dispersion when passing through the same light-transmitting medium due to different refractive indices. Based on this, the size of the wedge angle of the target optical wedge can be designed to control the dispersion angle of the fundamental frequency light and the frequency multiplication light passing through the target optical wedge, thereby compensating for the target walk-off angle between the fundamental frequency light and the frequency multiplication light, and effectively realizing the coincidence of the fundamental frequency light and the frequency multiplication light emitted by the target optical wedge at the preset propagation distance.

[0038] In the embodiment of the present disclosure, the fundamental frequency light emitted by the laser source is frequency multiplied by the frequency multiplication crystal. The fundamental frequency light and the frequency multiplication light output by the frequency multiplication crystal have a target walk-off angle in the frequency multiplication crystal due to the walk-off effect of the frequency multiplication crystal, and after being output from the frequency multiplication crystal, they are two parallel lights with a certain deviation distance in the vertical propagation direction. In order to realize walk-off compensation, a target optical wedge corresponding to the frequency multiplication crystal is designed, and then the fundamental frequency light and the frequency multiplication light coincide at a point in the far field after passing through the target optical wedge.

[0039] In one possible implementation, different frequency doubling crystals correspond to different target walk-off angles.

[0040] Frequency doubling crystals can be second-harmonic, third-harmonic, fourth-harmonic, etc., and the target walk-off angles corresponding to different frequency doubling crystals are different. Therefore, it is necessary to design corresponding target optical wedges for different frequency doubling crystals; that is, the wedge angles of the target optical wedges corresponding to different frequency doubling crystals are different.

[0041] In one possible implementation, the wedge angle of the target optical wedge is used to indicate the angle between the two optical surfaces of the target optical wedge; the method further includes: determining the deviation distance between the fundamental frequency light and the frequency-doubled light in the vertical propagation direction after they are output from the frequency-doubled crystal, based on the target walk-off angle and the length of the frequency-doubled crystal; and determining the wedge angle θ of the target optical wedge using the following formula based on the deviation distance, the refractive index of the target optical wedge for different wavelengths of light, and the preset propagation distance: Where D is the deviation distance, L is the preset propagation distance, n1 is the refractive index of the frequency-doubled light in air, n2 is the refractive index of the frequency-doubled light in the target light wedge, n3 is the refractive index of the fundamental frequency light in air, and n4 is the refractive index of the fundamental frequency light in the target light wedge.

[0042] Figure 2 A schematic diagram illustrating the determination of the wedge angle of the target optical wedge according to an embodiment of the present disclosure is shown. Figure 2 As shown, frequency-doubled light L1 and fundamental light L2 are incident parallel and perpendicularly onto the first optical surface of the target wedge. According to geometric relationships, the incident angle of the two beams on the second optical surface of the target wedge is equal to the wedge angle θ. The exit angle of frequency-doubled light L1 is α, and the exit angle of fundamental light L2 is β. After a preset propagation distance L, the two beams coincide, with angles γ and δ between them and the horizontal line. The refractive indices of frequency-doubled light L1 in air and the target wedge are n1 and n2, respectively, and the refractive indices of fundamental light L2 in air and the target wedge are n3 and n4, respectively. The deviation distance of the two beams in the vertical propagation direction after exiting the frequency-doubled crystal is D.

[0043] According to Fresnel's law: , According to geometric relationships, we know that: , , Based on the aforementioned formula, the following can be determined using a small angle approximation: .

[0044] In one example, Figure 2The base frequency light L2 shown is 1064 nm base frequency light, the frequency-doubled light L1 is 266 nm fourth harmonic light, and the target walk-off angle is 85.31 mrad. Assuming that the fourth harmonic crystal length is 7 mm, the deviation distance D between the 1064 nm base frequency light L2 and the 266 nm frequency-doubled light L1 can be calculated as 0.6 mm. For the 266 nm frequency-doubled light L1, the refractive indices in the air and the target optical wedge are n1=1 and n2=1.499, respectively; for the 1064 nm base frequency light L2, the refractive indices in the air and the target optical wedge are n3=1 and n4=1.449, respectively. Assuming that the 1064 nm base frequency light L2 and the 266 nm frequency-doubled light L1 need to coincide at a preset propagation distance L=3.5 m, based on the above formula, it can be determined that the wedge angle of the target optical wedge is θ=0.17°.

[0045] In a possible implementation, the frequency-doubled light is one of the following: second harmonic light, third harmonic light, and fourth harmonic light.

[0046] The laser frequency-doubled walk-off angle compensation method of the embodiments of the present disclosure can compensate for the walk-off angle of the base frequency light and any one of the second harmonic light, the third harmonic light, and the fourth harmonic light according to actual application requirements, and the present disclosure does not make specific limitations thereon.

[0047] In a possible implementation, the method further includes: rotating the target optical wedge perpendicular to the optical axis of the target optical path until the overlapping area of the light spots of the base frequency light and the frequency-doubled light at the preset propagation distance is maximum.

[0048] In order to compensate optimally, the target optical wedge can also be rotated perpendicular to the optical axis of the target optical path until the overlapping area of the light spots of the base frequency light and the frequency-doubled light at the preset propagation distance is maximum.

[0049] Figure 3 A schematic diagram of a target optical path according to an embodiment of the present disclosure is shown. As shown, the 1064 nm base frequency light emitted by the laser source, after passing through the second harmonic crystal, outputs 1064 nm base frequency light and 532 nm second harmonic light, wherein the 1064 nm base frequency light and the 532 nm second harmonic light produce a 4.22 mrad walk-off angle on the xoz plane in the second harmonic crystal; after passing through the third harmonic crystal, 1064 nm base frequency light, 532 nm second harmonic light, and 355 nm third harmonic light are output, wherein the 1064 nm base frequency light and the 355 nm third harmonic light propagate in the same direction in the third harmonic crystal, and the 532 nm second harmonic light produces a 9.42 mrad walk-off angle on the yoz plane in the third harmonic crystal; after passing through the fourth harmonic crystal, 1064 nm base frequency light, 532 nm second harmonic light, 355 nm third harmonic light, and 266 nm fourth harmonic light are output, wherein the 532 nm second harmonic light and the 266 nm fourth harmonic light produce an 85.31 mrad walk-off angle on the xoz plane in the fourth harmonic crystal. Figure 3 The 1064 nm base frequency light emitted by the laser source, after passing through the second harmonic crystal, outputs 1064 nm base frequency light and 532 nm second harmonic light, wherein the 1064 nm base frequency light and the 532 nm second harmonic light produce a 4.22 mrad walk-off angle on the xoz plane in the second harmonic crystal; after passing through the third harmonic crystal, 1064 nm base frequency light, 532 nm second harmonic light, and 355 nm third harmonic light are output, wherein the 1064 nm base frequency light and the 355 nm third harmonic light propagate in the same direction in the third harmonic crystal, and the 532 nm second harmonic light produces a 9.42 mrad walk-off angle on the yoz plane in the third harmonic crystal; after passing through the fourth harmonic crystal, 1064 nm base frequency light, 532 nm second harmonic light, 355 nm third harmonic light, and 266 nm fourth harmonic light are output, wherein the 532 nm second harmonic light and the 266 nm fourth harmonic light produce an 85.31 mrad walk-off angle on the xoz plane in the fourth harmonic crystal.

[0050] In practice, 355nm third harmonic light and 532nm second harmonic light are almost coincident with 1064nm because of large spot and small walk-off angle. 266nm fourth harmonic light has large walk-off, so the calibration of 266nm fourth harmonic light and 1064nm fundamental light is mainly used.

[0051] Therefore, Figure 3 The wedge angle of the target optical wedge in the target optical path is designed based on the fourth harmonic crystal to compensate the walk-off angle of the fourth harmonic light generated by the target optical wedge. After passing through the target optical wedge, the 1064nm fundamental light, the 532nm second harmonic light, the 355nm third harmonic light, and the 266nm fourth harmonic light can be incident on the same point in the far field.

[0052] The laser frequency doubling walk-off angle compensation method of the embodiment of the present disclosure controls the fundamental light emitted by the laser source to be incident on the frequency doubling crystal, and the frequency doubling crystal emits the frequency doubling light and the fundamental light. The target walk-off angle exists in the frequency doubling crystal, and then, in order to compensate the walk-off angle, the frequency doubling light and the fundamental light are controlled to be incident on the target optical wedge determined in advance. Since the wedge angle of the target optical wedge is determined according to the target walk-off angle, the refractive index of the target optical wedge to light of different wavelengths, and the preset propagation distance, the fundamental light and the frequency doubling light can be coincident at the preset propagation distance only by using the target optical wedge, effectively reducing the number of components and the space occupation of the target optical path.

[0053] It can be understood that the above-mentioned various method embodiments of the present disclosure can be combined with each other to form combined embodiments without deviating from the principle logic. Limited by the length, the present disclosure will not be repeated. Those skilled in the art can understand that the specific execution order of each step in the above-mentioned method should be determined according to its function and possible internal logic.

[0054] In addition, the present disclosure also provides a laser frequency doubling walk-off angle compensation device, which can be used to realize any one of the laser frequency doubling walk-off angle compensation methods provided by the present disclosure. The corresponding technical solutions and descriptions are referred to the corresponding description in the method part, and will not be repeated.

[0055] Figure 4 A block diagram of a laser frequency doubling walk-off angle compensation device according to an embodiment of the present disclosure is shown. The device is applied to a target optical path, which includes a laser source, a frequency doubling crystal, and a target optical wedge. As shown in Figure 4 The device 40 includes:

[0056] A first control module 41 is configured to control the fundamental light emitted by the laser source to be incident on the frequency doubling crystal.

[0057] The second control module 42 is configured to control the frequency-doubled light and the fundamental light emitted by the frequency-doubling crystal to be incident on the target optical wedge, and the fundamental light and the frequency-doubled light have a target walk-off angle in the frequency-doubling crystal.

[0058] The wedge angle of the target optical wedge is determined according to the target walk-off angle, the refractive index of the target optical wedge to light of different wavelengths, and the preset propagation distance, and the fundamental light and the frequency-doubled light emitted by the target optical wedge coincide at the preset propagation distance.

[0059] In a possible implementation, the apparatus 40 further includes:

[0060] The third control module is configured to control the target optical wedge to rotate perpendicularly to the optical axis of the target optical path until the area of the light spots of the fundamental light and the frequency-doubled light at the preset propagation distance is maximum.

[0061] In a possible implementation, the wedge angle of the target optical wedge is used to indicate an included angle between two optical surfaces of the target optical wedge.

[0062] The apparatus 40 further includes:

[0063] The first determination module is configured to determine, according to the target walk-off angle and the length of the frequency-doubling crystal, a deviation distance of the fundamental light and the frequency-doubled light in a vertical propagation direction after being output from the frequency-doubling crystal.

[0064] The second determination module is configured to determine, according to the deviation distance, the refractive index of the target optical wedge to light of different wavelengths, and the preset propagation distance, the wedge angle θ of the target optical wedge by using the following formula:

[0065] ;

[0066] In the formula, D is the deviation distance, L is the preset propagation distance, n1 is the refractive index of the fundamental light in air, n2 is the refractive index of the fundamental light in the target optical wedge, n3 is the refractive index of the frequency-doubled light in air, and n4 is the refractive index of the frequency-doubled light in the target optical wedge.

[0067] In a possible implementation, different frequency-doubling crystals correspond to different target walk-off angles.

[0068] In a possible implementation, the frequency-doubled light is one of the following: second-harmonic light, third-harmonic light, and fourth-harmonic light.

[0069] In some embodiments, the apparatus provided by the embodiments of the present disclosure has functions or includes modules that can be used to perform the methods described in the above method embodiments, and the specific implementation can refer to the description of the above method embodiments. For brevity, it will not be repeated here.

[0070] The above description of the various embodiments is intended to be illustrative and not exclusive. Many modifications and changes can be made by those skilled in the art to the particular embodiment disclosed without departing from the scope and spirit of the disclosed embodiments. The scope of the various embodiments disclosed herein is not to be limited by the description of the various embodiments contained herein, but instead is to be defined by the appended claims and their equivalents.

[0071] Those skilled in the art will appreciate that the order of steps in the above-described methods of the specific embodiments is not meant to imply a strict order of execution but that the specific order of execution of the steps should be determined by the function and the possible inherent logic of the steps.

[0072] The above description of the various embodiments is intended to be illustrative and not exclusive. Many modifications and changes can be made by those skilled in the art to the particular embodiment disclosed without departing from the scope and spirit of the disclosed embodiments. The scope of the various embodiments disclosed herein is not to be limited by the description of the various embodiments contained herein, but instead is to be defined by the appended claims and their equivalents.

Claims

1. A laser frequency doubling walk-off angle compensation method, characterized in that, The method is applied to a target optical path, which includes: a laser source, a frequency doubling crystal, and a target optical wedge; the method includes: The fundamental frequency light emitted from the laser source is controlled to be incident on the frequency doubling crystal; The frequency-doubled light emitted from the frequency-doubled crystal and the fundamental light are controlled to be incident on the target optical wedge, and the fundamental light and the frequency-doubled light have a target walk-off angle within the frequency-doubled crystal; The wedge angle of the target optical wedge is determined based on the target walk-off angle, the refractive index of the target optical wedge for different wavelengths of light, and the preset propagation distance. The fundamental frequency light and the frequency-doubled light emitted from the target optical wedge coincide at the preset propagation distance in the far field. The method further includes: The target optical wedge is controlled to rotate perpendicular to the optical axis of the target optical path until the area of ​​the light spot overlap between the fundamental frequency light and the frequency-doubled light at the preset propagation distance is maximized.

2. The method according to claim 1, characterized in that, The wedge angle of the target optical wedge is used to indicate the included angle between the two optical surfaces of the target optical wedge; The method further includes: Based on the target walk-off angle and the length of the frequency doubling crystal, determine the deviation distance between the fundamental frequency light and the frequency-doubled light in the vertical propagation direction after they are output from the frequency doubling crystal; Based on the deviation distance, the refractive index of the target optical wedge for different wavelengths of light, and the preset propagation distance, the wedge angle θ of the target optical wedge is determined using the following formula: ； Wherein, D is the deviation distance, L is the preset propagation distance, n1 is the refractive index of the frequency-doubled light in air, n2 is the refractive index of the frequency-doubled light in the target light wedge, n3 is the refractive index of the fundamental frequency light in air, and n4 is the refractive index of the fundamental frequency light in the target light wedge.

3. The method according to claim 1, characterized in that, Different frequency doubling crystals correspond to different target walk-off angles.

4. The method according to claim 1, characterized in that, The frequency-doubled light is one of the following: second-harmonic light, third-harmonic light, or fourth-harmonic light.

5. A laser frequency doubling walk-off angle compensation device, characterized in that, The device is applied to a target optical path, which includes: a laser source, a frequency doubling crystal, and a target optical wedge; the device includes: The first control module is used to control the fundamental frequency light emitted from the laser source to be incident on the frequency doubling crystal; The second control module is used to control the frequency-doubled light and the fundamental light emitted from the frequency-doubled crystal to be incident on the target light wedge, wherein the fundamental light and the frequency-doubled light have a target walk-off angle within the frequency-doubled crystal; The wedge angle of the target optical wedge is determined based on the target walk-off angle, the refractive index of the target optical wedge for different wavelengths of light, and the preset propagation distance. The fundamental frequency light and the frequency-doubled light emitted from the target optical wedge coincide at the preset propagation distance in the far field. The device further includes: The third control module is used to control the rotation of the target optical wedge perpendicular to the optical axis of the target optical path until the overlap area of ​​the light spots of the fundamental frequency light and the frequency-doubled light at the preset propagation distance is the largest.

6. The apparatus according to claim 5, characterized in that, The wedge angle of the target optical wedge is used to indicate the included angle between the two optical surfaces of the target optical wedge; The device further includes: The first determining module is used to determine the deviation distance between the fundamental frequency light and the frequency-doubled light in the vertical propagation direction after they are output from the frequency-doubled crystal, based on the target walk-off angle and the length of the frequency-doubled crystal. The second determining module is used to determine the wedge angle θ of the target optical wedge using the following formula, based on the deviation distance, the refractive index of the target optical wedge for different wavelengths of light, and the preset propagation distance: ； Wherein, D is the deviation distance, L is the preset propagation distance, n1 is the refractive index of the frequency-doubled light in air, n2 is the refractive index of the frequency-doubled light in the target light wedge, n3 is the refractive index of the fundamental frequency light in air, and n4 is the refractive index of the fundamental frequency light in the target light wedge.

7. The apparatus according to claim 5, characterized in that, Different frequency doubling crystals correspond to different target walk-off angles.

8. The apparatus according to claim 5, characterized in that, The frequency-doubled light is one of the following: second-harmonic light, third-harmonic light, or fourth-harmonic light.

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