A dynamic thermal focal length controllable module and disk laser

Abstract

The present invention relates to the field of laser technology, and discloses a dynamic thermal focal length controllable module and a disk laser, comprising: a deformable mirror, arranged on the optical path of an outgoing laser after being pumped by a laser crystal, for generating a compensating surface shape conjugate with the aberration of the laser crystal; an imaging component, arranged on the reflected optical path of the deformable mirror, for obtaining the light intensity distribution of the outgoing laser by measuring the outgoing laser reflected by the deformable mirror; and a closed-loop control module, for calculating the variation of the deformable mirror according to the light intensity distribution, adjusting the deformable mirror according to the variation, and compensating for the thermally induced surface shape error of the laser crystal. The present invention uses the deformable mirror as a phase compensation element, and based on the principle of adaptive optics, converts the comprehensive aberration generated by the transmission element into the surface shape error of a single reflecting surface for characterization. By changing the surface shape of the deformable mirror by piezoelectric means, it is ensured that the surface shape of the deformable mirror can accurately correct the wavefront distortion introduced by the surface shape of the disk laser crystal, thereby solving the error accumulation problem in multi-interface interferometry.

Description

Technical Field

[0001] The present invention relates to the field of laser technology, and in particular to a dynamic thermal focus controllable module and a disk laser. Background Art

[0002] Disk laser crystals, typically on the order of hundreds of microns thick, are designed to address the performance degradation of conventional bulk laser crystals during high-power operation caused by thermal effects (such as thermal lensing and thermal stress). Thermal lensing in disk laser crystals can cause cumulative wavefront distortion in multiple incident Gaussian beams, significantly reducing beam quality and impacting output power and stability.

[0003] Currently, interferometers are used to measure the wavefront distribution of Gaussian beams passing through disk laser crystals, calculate the thermal focal length of the disk laser crystal, and compensate for the surface shape of the disk laser crystal based on the thermal focal length to improve the output laser beam quality. However, when traditional interferometers measure multi-interface optical systems, the mutual interference of reflected light from each interface can lead to cumulative measurement errors.

[0004] Therefore, this method has certain limitations and needs to be further optimized or combined with other measurement methods to improve the beam quality. Summary of the Invention

[0005] The purpose of the present invention is to provide a dynamic thermal focus controllable module and a disk laser that can solve at least one of the above-mentioned technical problems. The specific solution is as follows:

[0006] According to the specific embodiments disclosed in the present invention, the first aspect of the present invention discloses a dynamic thermal focus controllable module, comprising:

[0007] A deformable mirror is arranged on the optical path of the laser light emitted after being pumped by the laser crystal, and is used to generate a compensation surface shape that is conjugate with the aberration of the laser crystal;

[0008] an imaging component, disposed on a reflection light path of the deformable mirror, and obtaining a light intensity distribution of the outgoing laser light by measuring the outgoing laser light reflected by the deformable mirror;

[0009] A closed-loop control module calculates a variation of the deformable mirror according to the light intensity distribution, and adjusts the deformable mirror according to the variation to compensate for a thermally induced surface error of the laser crystal.

[0010] Preferably, the imaging assembly comprises: a beam splitter and a camera;

[0011] The beam splitter splits the outgoing laser light reflected by the deformable mirror into a first reflected light and a first transmitted light, and the camera is used to obtain the light intensity distribution of the first reflected light or the first transmitted light.

[0012] Preferably, the closed-loop control module includes:

[0013] a data processing unit, which fits the light intensity distribution using a Zernike polynomial, compares the fitted light intensity distribution with a Gaussian beam, and obtains a voltage amount to be applied to the deformable mirror;

[0014] The piezoelectric control unit drives the deformation of the deformable mirror according to the voltage, so that the light intensity of the outgoing laser reflected by the deformable mirror presents a Gaussian distribution.

[0015] Preferably, the closed-loop control module further includes: an amplification module for enhancing the driving signal of the piezoelectric control unit.

[0016] Preferably, the camera is a CMOS image sensor; and the deformable mirror is a piezoelectric deformable mirror.

[0017] Preferably, it also includes: a wavefront sensing component, which transmits detection light to the deformable mirror, receives the detection light reflected by the deformable mirror, and obtains the wavefront phase distribution of the detection light.

[0018] Preferably, the wavefront sensing assembly comprises: a detection light source, a collimating lens group and a wavefront sensor;

[0019] The detection light emitted by the detection light source is collimated by the collimating lens group and then incident on the deformable mirror as parallel light. After being reflected by the deformable mirror, it is received by the wavefront sensor.

[0020] According to the specific embodiments disclosed in the present invention, the second aspect of the present invention discloses a disk laser with dynamic thermal focus controllable, comprising: the above-mentioned dynamic thermal focus controllable module, a seed light source module and a multi-pass pump module;

[0021] The outgoing light beam of the seed light source module is M 2 =1 fundamental mode light;

[0022] The laser crystal of the multi-pass pump module is a disk laser crystal;

[0023] The deformable mirror of the dynamic thermal focus controllable module is arranged on the laser light path emitted from the multi-pass pumping module, and the deformable mirror and the laser light path form an included angle.

[0024] Compared with the prior art, the above solution of the embodiment disclosed in the present invention has at least the following beneficial effects:

[0025] This invention incorporates a deformable mirror as a phase compensation element. Based on the principles of adaptive optics, it converts the integrated aberrations generated by the transmission element (disk laser crystal) into a surface error of a single reflective surface for characterization. By varying the deformable mirror's surface shape through piezoelectric means, and through continuous monitoring and adjustment, the deformable mirror's profile accurately corrects the wavefront distortion introduced by the disk laser crystal's surface shape, thus resolving the error accumulation problem in multi-interface interferometry and ensuring the output laser beam quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are incorporated into and constitute a part of the specification, illustrating embodiments consistent with the present disclosure and, together with the specification, explaining the principles of the present disclosure. Obviously, the drawings described below are only some embodiments of the present disclosure, and those skilled in the art can derive other drawings based on these drawings without inventive effort. In the drawings:

[0027] Figure 1 A schematic diagram of an optical path of a dynamic thermal focus controllable module provided by an embodiment of the present invention;

[0028] Figure 2 A schematic diagram of the optical path of a disk laser with dynamic thermal focus controllable according to an embodiment of the present invention;

[0029] Figure 3 A schematic diagram of a closed-loop control module provided in an embodiment of the present invention.

[0030] Reference numerals:

[0031] 1: Dynamic thermal focus controllable module; 2: Multi-pass pump module; 3: Seed light source module; 4. Laser crystal;

[0032] 1-1: Deformable mirror; 1-2 Imaging component; 1-3: Wavefront sensing component;

[0033] 1-2-1: beam splitter; 1-2-2: CMOS image sensor; 1-3-1: wavefront sensor;

[0034] 1-4-1: Data processing unit; 1-4-2: Piezoelectric control unit; 1-4-3: Amplification module. DETAILED DESCRIPTION

[0035] To further clarify the objectives, technical solutions, and advantages of the present invention, a dynamic thermal focus controllable module and disk laser disclosed in the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a portion of the embodiments disclosed in the present invention, and not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments disclosed in the present invention without inventive effort are intended to fall within the scope of protection disclosed in the present invention.

[0036] The terms used in the examples of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms "a," "the," and "the" used in the examples of this application and the appended claims are also intended to include plural forms, and unless the context clearly indicates otherwise, "a plurality" generally includes at least two.

[0037] It should be understood that the term "and / or" as used herein is merely a description of the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0038] It should be understood that although the terms first, second, third, etc. may be used to describe in the embodiments of the present application, these should not be limited to these terms. These terms are only used to distinguish. For example, without departing from the scope of the embodiments of the present application, the first may also be referred to as the second, and similarly, the second may also be referred to as the first.

[0039] It should also be noted that the terms "include," "comprises," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a product or device comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such product or device. In the absence of further limitations, an element defined by the phrase "comprising a" does not exclude the presence of other identical elements in the product or device comprising the element.

[0040] The following is combined with Figure 1-3 Alternative embodiments of the present invention are described in detail.

[0041] Example 1

[0042] like Figure 1 As shown, according to a specific embodiment of the present invention, the present invention provides a dynamic thermal focus controllable module, comprising:

[0043] The deformable mirror 1-1 is arranged on the optical path of the laser light emitted after being pumped by the laser crystal 4, and is used to generate a compensation surface shape that is conjugate with the aberration of the laser crystal 4;

[0044] An imaging component 1-2 is disposed on the reflection light path of the deformable mirror 1-1, and obtains the light intensity distribution of the outgoing laser light by measuring the outgoing laser light reflected by the deformable mirror 1-1;

[0045] The closed-loop control module calculates the variation of the deformable mirror 1 - 1 according to the light intensity distribution, and adjusts the deformable mirror 1 - 1 according to the variation to compensate for the thermally induced surface error of the laser crystal 4 .

[0046] In this embodiment, the deformable mirror 1 - 1 is used to reflect the light beam emitted by the laser crystal, and then the imaging component is used to introduce the light beam carrying the surface information of the laser crystal into different measurement optical paths.

[0047] Specifically, the light intensity distribution of the beam of light is measured using an imaging component. The imaging component 1-2 includes a beam splitter 1-2-1 and a camera.

[0048] In this embodiment, the beam splitter 1-2-1 is placed on the optical path of the outgoing laser to split the light beam with aberration introduced by the surface shape of the disk laser crystal into transmitted light and reflected light. A camera is placed on any beam path to measure the light intensity distribution of the light spot.

[0049] As an optional implementation, the camera uses a CMOS image sensor 1-2-2 to acquire a light intensity distribution image.

[0050] As an optional implementation, the deformable mirror uses a piezoelectric deformable mirror. When different voltages are applied to the piezoelectric material, the local deformation of the mirror surface can be controlled, thereby correcting the wavefront distortion.

[0051] In this embodiment, the light intensity distribution information is obtained by measuring the light beam reflected by the deformable mirror, and the beam quality information of the laser beam is fitted based on the light intensity distribution. This information is compared with the ideal Gaussian beam, and the amount of voltage that needs to be applied to the deformable mirror is calculated. By adjusting the surface shape of the deformable mirror, the light intensity of the light beam is Gaussian distributed, thereby forming a closed-loop control.

[0052] like Figure 3 As shown, the closed-loop control module includes:

[0053] The data processing unit 1-4-1 fits the light intensity distribution using a Zernike polynomial, compares the fitted light intensity distribution with a Gaussian beam, and calculates the voltage required to be applied to the deformable mirror;

[0054] The piezoelectric control unit 1-4-2 drives the deformation of the deformable mirror according to the voltage amount, so that the light intensity of the outgoing laser reflected by the deformable mirror presents a Gaussian distribution.

[0055] The amplification module 1-4-3 is used to enhance the driving signal of the piezoelectric control unit to ensure that the deformable mirror can obtain sufficient driving force to achieve the required deformation.

[0056] The entire process forms a closed-loop control system that, through continuous monitoring and adjustment, ensures that the deformable mirror's surface shape can accurately correct the aberrations introduced by the disk laser crystal, thereby ensuring the beam quality of the output laser.

[0057] Example 2

[0058] Based on the introduction of the deformable mirror in Example 1, since the wavefront phase distribution of the light wave passing through the deformable mirror 1-1 is conjugate with the wavefront phase distribution passing through the disc crystal 4, the wavefront curvature radius of the laser crystal can be obtained by adding a wavefront sensing component, and the thermal focal length of the laser crystal can be further obtained.

[0059] like Figure 2 As shown, the wavefront sensing component 1-3 includes: a detection light source, a collimating lens group and a wavefront sensor 1-3-1. The detection light emitted by the detection light source is collimated by the collimating lens group and then incident on the deformable mirror 1-1 as parallel light. After being reflected by the deformable mirror 1-1, it is received by the wavefront sensor 1-3-1.

[0060] Specifically, wavefront sensor 1-3-1 is used to characterize the surface shape of the laser crystal in real time. When a light beam is incident on wavefront sensor 1-3-1, the microlens array on wavefront sensor 1-3-1 splits the beam into numerous tiny sub-apertures. Each portion of the light wave converges at the sub-aperture focal point after passing through the microlenses, forming a sub-aperture spot array image. When the incident light wave is an ideal plane wave, a set of uniform, regularly distributed focal points is obtained at the microlens array focal point. When the incident light wave exhibits wavefront distortion, the array image obtained at the focal plane of the microlens array is no longer uniformly distributed, but is offset from the focal point of the ideal wavefront. This offset is the wavefront slope. Based on this wavefront slope, a wavefront restoration algorithm can be used to reconstruct the wavefront phase distribution of the light wave passing through deformable mirror 1-1. Since the wavefront phase distribution of the light wave passing through deformable mirror 1-1 is conjugate with the wavefront phase distribution of disk crystal 4, the wavefront radius of curvature of laser crystal 4 can be calculated, and thus the thermal focal length of disk crystal 4 can be calculated.

[0061] Therefore, this embodiment measures the surface shape of the deformable mirror and converts the comprehensive aberration produced by the transmission element (disk laser crystal) into the surface shape error of a single reflecting surface for characterization, thereby avoiding the problem of multi-interface errors introduced by traditional wavefront sensors or interferometers when measuring the surface shape of the disk laser crystal.

[0062] Example 3

[0063] The present invention also provides device embodiments that are consistent with the above embodiments. The interpretations based on the same name meanings are the same as those of the above embodiments, and have the same technical effects as the above embodiments, which will not be repeated here.

[0064] Combine Figure 2 As shown, the present invention discloses a dynamic thermal focus controllable disk laser, comprising: a dynamic thermal focus controllable module 1, a seed light source module 3 and a multi-pass pumping module 2.

[0065] Among them, the outgoing beam of the seed light source module is M 2 = 1. The multi-pass pump module 2, which generates pump light, uses a disk laser crystal 4 as the laser crystal. This, combined with the seed light, produces laser output. The dynamic thermal focus controllable module 1 is positioned in the laser light path emitted by the multi-pass pump module 2. To measure the emitted laser light, the deformable mirror 1-1 is angled with the laser light path. The positions and functions of the other optical components required for laser output are not detailed in the figure.

[0066] In this embodiment, the conjugate compensation properties of a deformable mirror are utilized to transform complex transmitted wavefront measurements into relatively simple reflected surface profile measurements. By measuring the deformable mirror, the thermal focal length of the disk crystal can be inverted to correct for systematic errors in the interferometer, thus avoiding the multi-interface errors introduced by traditional wavefront sensors or interferometers when measuring the surface profile of a disk laser crystal. Furthermore, the intensity distribution of the emitted laser light can be calculated, and the deformable mirror can be adjusted accordingly to compensate for thermally induced surface errors in the laser crystal, thereby improving beam quality.

[0067] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. References to the common and similar parts between the various embodiments will be sufficient. For the systems or devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, their descriptions are relatively simple; for relevant details, refer to the descriptions of the methods.

[0068] The above embodiments are only used to illustrate the technical solutions disclosed in the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments disclosed in the present invention.

Claims

1. A dynamic thermal focus controllable module, characterized in that: include: A deformable mirror is arranged on the optical path of the laser light emitted after being pumped by the laser crystal, and is used to generate a compensation surface shape that is conjugate with the aberration of the laser crystal; an imaging component, disposed on a reflection light path of the deformable mirror, and obtaining a light intensity distribution of the outgoing laser light by measuring the outgoing laser light reflected by the deformable mirror; a closed-loop control module, which calculates a variation of the deformable mirror according to the light intensity distribution, and adjusts the deformable mirror according to the variation to compensate for a thermally induced surface error of the laser crystal; The wavefront sensing component transmits a probe light to the deformable mirror, receives the probe light reflected by the deformable mirror, obtains the wavefront phase distribution of the probe light, and calculates the thermal focal length of the laser crystal using the wavefront phase distribution of the probe light.

2. The dynamic thermal focus controllable module according to claim 1, characterized in that: The imaging assembly includes: a beam splitter and a camera; The beam splitter splits the outgoing laser light reflected by the deformable mirror into a first reflected light and a first transmitted light, and the camera is used to obtain the light intensity distribution of the first reflected light or the first transmitted light.

3. The dynamic thermal focus controllable module according to claim 1, characterized in that: Closed-loop control module, including: a data processing unit, which fits the light intensity distribution using a Zernike polynomial, compares the fitted light intensity distribution with a Gaussian beam, and obtains a voltage amount to be applied to the deformable mirror; The piezoelectric control unit drives the deformation of the deformable mirror according to the voltage, so that the light intensity of the outgoing laser reflected by the deformable mirror presents a Gaussian distribution.

4. The dynamic thermal focus controllable module according to claim 3, characterized in that: The closed-loop control module further includes: an amplification module for enhancing the driving signal of the piezoelectric control unit.

5. The dynamic thermal focus controllable module according to claim 2, characterized in that: The camera is a CMOS image sensor; the deformable mirror is a piezoelectric deformable mirror.

6. The dynamic thermal focus controllable module according to claim 1, characterized in that: The wavefront sensing assembly includes: a detection light source, a collimating lens group and a wavefront sensor; The detection light emitted by the detection light source is collimated by the collimating lens group and then incident on the deformable mirror as parallel light. After being reflected by the deformable mirror, it is received by the wavefront sensor.

7. A disk laser with dynamic thermal focus controllable, characterized in that: Comprising the dynamic thermal focus controllable module, the seed light source module and the multi-pass pump module according to any one of claims 1 to 6; The outgoing light beam of the seed light source module is M 2 =1 fundamental mode light; The laser crystal of the multi-pass pump module is a disk laser crystal; The deformable mirror of the dynamic thermal focus controllable module is arranged on the laser light path emitted from the multi-pass pumping module, and the deformable mirror and the laser light path form an included angle.

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