CN-122000779-A - Adjustable optical compensation method and device for laser resonant cavity

CN122000779ACN 122000779 ACN122000779 ACN 122000779ACN-122000779-A

Abstract

The invention provides an adjustable optical compensation method and a device for a laser resonant cavity, wherein the method comprises the steps of obtaining working condition parameters of the operation of a target laser and current thermal state data of a gain crystal; the method comprises the steps of determining first thermal lens focal power under a current working condition based on working condition parameters and a preset parameter focal power mapping table, determining second thermal lens focal power under the current working condition based on current thermal state data and a preset thermal light conversion mapping table, performing deviation correction based on the first thermal lens focal power and the second thermal lens focal power to obtain corrected target thermal lens focal power, and determining target compensation lenses based on the target thermal lens focal power and fixed focal power of a concave surface end face of a gain crystal in a resonant cavity and a preset stability allowance condition and compensation lens focal power corresponding to a plurality of preset compensation lenses. The invention adapts to the requirement of frequent switching of working condition parameters, and realizes the technical effects of stable laser output power, good beam quality, and high-efficiency and reliable switching.

Inventors

WANG XUN
WANG KECHENG
LI ZHENGZHOU
WANG ZHIHANG

Assignees

广州市普东医疗设备股份有限公司

Dates

Publication Date: 20260508
Application Date: 20260211

Claims (10)

1. A method for tunable optical compensation of a laser cavity, comprising: acquiring working condition parameters of the operation of the target laser and current thermal state data of the gain crystal; Determining the first thermal lens focal power under the current working condition based on the working condition parameters and a preset parameter focal power mapping table, and determining the second thermal lens focal power under the current working condition based on the current thermal state data and a preset thermal-optical conversion mapping table; Performing offset correction based on the first thermal lens focal power and the second thermal lens focal power to obtain corrected target thermal lens focal power; Determining a target compensation lens based on the target thermal lens focal power and the fixed focal power of the concave end face of the gain crystal in the resonant cavity by combining a preset stability allowance condition and the compensating lens focal powers corresponding to a plurality of preset compensating lenses; Based on the combination of the target compensation lens and the rotary mirror wheel assembly in the resonant cavity, the target compensation lens is switched to the working position in the optical path of the resonant cavity, and based on the in-place signal of the target compensation lens, the interlocking limit on the running state of the laser is released, so that the laser runs according to the current working condition parameters.
2. The method of claim 1, wherein the operating parameters include repetition rate, average power, duty cycle, and cooling temperature; the determining the first thermal lens focal power under the current working condition based on the working condition parameters and a preset parameter focal power mapping table comprises the following steps: Searching and matching with the parameter power mapping table based on the repetition frequency, the average power, the duty ratio and the cooling temperature as joint indexes to obtain a first matching result; If the first matching result is that the completely consistent calibration records exist, the thermal lens focal power value corresponding to the calibration records is determined to be the first thermal lens focal power, and if the first matching result is that the completely consistent calibration records do not exist, a plurality of calibrated working condition points adjacent to working condition parameters are identified in the parameter focal power mapping table, and an interpolation reference point set is obtained; constructing a plurality of groups of corresponding data pairs of four-dimensional working condition parameters and one-dimensional thermal lens focal power based on the repetition frequency, average power, duty ratio, cooling temperature and thermal lens focal power values stored in association with each calibrated working condition point in the interpolation reference point set; performing multi-linear interpolation processing on the working condition parameters in the corresponding data pair to obtain a continuous optical power estimated value; And determining the first thermal lens focal power under the current working condition based on the focal power estimated value combined with a physical reasonable interval of the preset thermal lens focal power.
3. The method of claim 2, wherein determining the first thermal lens power under the current operating condition based on the power estimate in combination with a physically reasonable interval of a preset thermal lens power comprises: If the optical power estimated value is not located in the physical reasonable interval, all the thermal lens optical power values corresponding to the interpolation reference point set are matched with the physical reasonable interval, and all calibrated working condition points located in the physical reasonable interval are obtained; And selecting a calibrated working condition point corresponding to the thermal lens focal power value closest to the focal power estimated value based on the thermal lens focal power values corresponding to all calibrated working condition points in the physical reasonable interval, and determining the thermal lens focal power value stored in association with the calibrated working condition point as the first thermal lens focal power.
4. The tunable optical compensation method for a laser cavity of claim 1, wherein the performing offset correction based on the first thermal lens power and the second thermal lens power to obtain a corrected target thermal lens power comprises: Calculating an absolute difference value based on the first thermal lens focal power and the second thermal lens focal power to obtain a thermal lens focal power deviation value; Comparing and judging based on the thermal lens focal power deviation amount and a preset deviation tolerance threshold, and determining the second thermal lens focal power as target thermal lens focal power if the thermal lens focal power deviation amount is smaller than or equal to the deviation tolerance threshold; If the thermal lens focal power deviation amount is larger than the deviation tolerance threshold value, determining a deviation direction based on a relative magnitude relation between the first thermal lens focal power and the second thermal lens focal power, wherein the deviation direction comprises positive deviation or negative deviation; And carrying out deviation correction by taking the second thermal lens focal power as a basic reference value and combining the thermal lens focal power deviation amount based on the deviation direction to obtain the corrected target thermal lens focal power.
5. The method of claim 4, wherein the performing offset correction based on the offset direction based on the second thermal lens power reference value in combination with the thermal lens power offset to obtain the corrected target thermal lens power comprises: If the deviation direction is positive deviation, marking the thermal lens focal power deviation amount as upward correction deviation amount, and if the deviation direction is negative deviation, marking the thermal lens focal power deviation amount as downward correction deviation amount; Taking the focal power of the second thermal lens as a basic reference value, and carrying out query matching by combining a preset deviation correction rule table based on the upward correction deviation amount or the downward correction deviation amount to obtain a correction increment value; and correcting the second thermal lens focal power based on the correction increment value to obtain the target thermal lens focal power.
6. The tunable optical compensation method for a laser cavity according to claim 1, wherein determining the target compensation lens based on the target thermal lens power and the fixed power of the concave end face of the gain crystal in the cavity, in combination with a preset stability margin condition and compensation lens powers corresponding to a plurality of preset compensation lenses, comprises: Superposing the focal power of the target thermal lens and the fixed focal power of the concave end face of the gain crystal in the resonant cavity to obtain the current equivalent total focal power of the resonant cavity; Judging whether the current equivalent total optical power is within the allowable range or not based on the allowable range of the total optical power of the resonant cavity in the combination of the current equivalent total optical power and a preset stability allowance condition, and obtaining a judgment result; If the judgment result is not within the allowable range, calculating the excess between the current equivalent total optical power and the upper limit value of the allowable range or the deficiency between the current equivalent total optical power and the lower limit value of the allowable range to respectively obtain negative compensation demand or positive compensation demand; traversing by combining the compensating lens optical power corresponding to a plurality of preset compensating lenses based on the negative compensating demand or the positive compensating demand, screening to obtain candidate compensating lenses with the optical power signs of all the preset compensating lenses consistent with the compensating demand direction and the absolute value smaller than or equal to the compensating demand, and determining the candidate compensating lens with the largest compensating lens optical power absolute value as a preliminary compensating lens; And superposing the compensating lens focal power of the preliminary compensating lens and the current equivalent total focal power to obtain compensated net focal power, and verifying the allowed range of the total focal power of the resonant cavity in the condition of the net focal power and the stable allowance again, and if the allowed range is fallen into the allowed range, determining the preliminary compensating lens as the target compensating lens.
7. The method according to claim 6, wherein if the net optical power does not fall within the allowable range of the total optical power of the resonant cavity in the stable margin condition, the compensating lens optical powers corresponding to the plurality of preset compensating lenses are traversed again, and for each preset compensating lens, the compensating lens optical power is algebraically added to the current equivalent total optical power to obtain a compensated second net optical power; and calculating the absolute distance based on the second net focal power and the nearest boundary of the total focal power allowable range, and determining the preset compensation lens with the minimum calculated absolute distance as the target compensation lens.
8. A tunable optical compensation device for a laser resonator, characterized in that it is applied to a tunable optical compensation method for a laser resonator according to any one of claims 1 to 7, and comprises: The data acquisition module is used for acquiring working condition parameters of the operation of the target laser and current thermal state data of the gain crystal; the thermal lens focal power determining module is used for determining the focal power of the first thermal lens under the current working condition based on the working condition parameters and combining a preset parameter focal power mapping table, and determining the focal power of the second thermal lens under the current working condition based on the current thermal state data and combining a preset thermal optical conversion mapping table; the deviation correction module is used for carrying out deviation correction based on the first thermal lens focal power and the second thermal lens focal power to obtain corrected target thermal lens focal power; The compensation lens screening module is used for determining a target compensation lens based on target thermal lens focal power and fixed focal power of a gain crystal concave surface end face in the resonant cavity and combining preset stability allowance conditions and compensation lens focal power corresponding to a plurality of preset compensation lenses; And the lens switching and interlocking control module is used for switching the target compensation lens to a working position in a resonant cavity light path based on the combination of the target compensation lens and a rotary mirror wheel assembly in the resonant cavity, and releasing the interlocking restriction on the running state of the laser based on an in-place signal of the target compensation lens so that the laser runs according to the current working condition parameters.
9. An electronic device comprising a memory for storing a computer software program, and a processor for reading and executing the computer software program, the processor implementing the tunable optical compensation method for a laser resonator according to any one of claims 1 to 7 when executing the computer software program.
10. A non-transitory computer readable storage medium, characterized in that the storage medium has stored therein a computer software program which, when executed by a processor, implements the tunable optical compensation method for a laser resonator according to any one of claims 1 to 7.

Description

Adjustable optical compensation method and device for laser resonant cavity Technical Field The invention relates to the technical field of lasers, in particular to an adjustable optical compensation method and device for a laser resonant cavity. Background In solid laser devices such as a xenon lamp side-pumped solid laser, the stability of the resonant cavity directly determines the stability of laser output power and the quality of a light beam. Because the gain medium can form a heat source effect in the pumping process, the temperature gradient can cause the effects of refractive index gradient, stress birefringence and the like, the dominant effects are generally equivalent to a thermal lens with positive focal power in engineering, and the equivalent focal length can be obviously changed along with the change of the pumping heat load. For widely used planar-planar resonators, the resonator itself has no stability in the geometrical optics layer, and the resonator needs to be made to traverse the ABCD matrix to satisfy the stability condition by relying on the positive focusing effect provided by the thermal lens, so as to form an oscillatable fundamental mode. Aiming at the characteristic that a plane-plane resonant cavity depends on a gain medium thermal lens effect to realize stable oscillation, the prior art generally adopts an optical compensation method for processing a concave structure on the end face of a gain crystal, namely, fixed negative focal power is provided through a concave surface to offset the positive focal power of a thermal lens which is too strong under a high-power/high-frequency working condition, so that the resonant cavity meets a stable condition and the volume utilization rate of a mode is optimized. However, in the existing optical compensation method, the adjustment or replacement of the compensation lens depends on manual operation, so that the switching efficiency is low, the repeatability is poor, the method cannot adapt to the use scene of frequent switching of working condition parameters, in addition, the negative focal power of the concave crystal is a fixed value, only a single thermal lens intensity interval can be adapted, wide range change of the focal power of the thermal lens is difficult to cover, when the laser is switched to a low-power/low-frequency working condition, the net focal power of the resonant cavity is insufficient easily caused by excessive compensation, the plane-plane resonant cavity falls into an unstable region, the problems of fluctuation of output power, light spot distortion and the like are caused, and under the working condition of the high-frequency/high-power strong thermal lens, the mode volume utilization rate is reduced possibly caused by insufficient compensation, and the high-precision requirement of laser output cannot be met. Disclosure of Invention The invention provides an adjustable optical compensation method and device for a laser resonant cavity, which are used for solving the problem of instability of the resonant cavity caused by excessive compensation under the working condition of low power/low frequency, optimizing the mode volume utilization rate under the working condition of high power/high frequency, simultaneously adapting to the requirement of frequent switching of working condition parameters, realizing the technical effects of stable laser output power, good beam quality and high-efficiency and reliable switching, and meeting the high-precision requirement of laser output. In a first aspect, the invention provides a tunable optical compensation method for a laser cavity, comprising: acquiring working condition parameters of the operation of the target laser and current thermal state data of the gain crystal; Determining the first thermal lens focal power under the current working condition based on the working condition parameters and a preset parameter focal power mapping table, and determining the second thermal lens focal power under the current working condition based on the current thermal state data and a preset thermal-optical conversion mapping table; Performing offset correction based on the first thermal lens focal power and the second thermal lens focal power to obtain corrected target thermal lens focal power; Determining a target compensation lens based on the target thermal lens focal power and the fixed focal power of the concave end face of the gain crystal in the resonant cavity by combining a preset stability allowance condition and the compensating lens focal powers corresponding to a plurality of preset compensating lenses; Based on the combination of the target compensation lens and the rotary mirror wheel assembly in the resonant cavity, the target compensation lens is switched to the working position in the optical path of the resonant cavity, and based on the in-place signal of the target compensation lens, the interlocking limit on the running state of the laser is released, so th