A low thermal effect ultraviolet laser and calibration method thereof

Abstract

The invention discloses a low thermal effect ultraviolet laser and a calibration method thereof, comprising a first pump light source, a second lens and a first lens arranged in sequence along a first incident direction, a first laser crystal and an acousto-optic Q switch being arranged between the second lens and the first lens; further comprising a second pump light source, a third lens, a second laser crystal and a fourth lens arranged along a second incident direction, the fourth lens being arranged at an acute angle relative to the second incident direction; a frequency doubling component being arranged in the reflection direction of the fourth lens. The first lens, the second lens, the third lens, the fourth lens and the frequency doubling component constitute a circular reflection optical path for light circulation. Light excited by a plurality of laser crystals realizes oscillation circulation in the circular reflection optical path, thereby being converted into pulse light through modulation of the acousto-optic Q switch, and then completing the frequency doubling conversion of the pulse light through the frequency doubling component, and converting it into ultraviolet light with a shorter wavelength, which can promote the diffusion of heat to effectively increase energy and power.

Description

Technical Field

[0001] The invention relates to the technical field of laser structures, and in particular to a low thermal effect ultraviolet laser and a calibration method thereof. Background Art

[0002] Laser structure is a device that amplifies light through stimulated radiation. It can produce light beams with high monochromaticity, high directionality, high brightness and high coherence. It is widely used in communications, medical treatment, industrial processing, optical research and other fields. According to the laser band, it can be divided into ultraviolet lasers, infrared lasers and other types. Among them, ultraviolet lasers are often used in high-precision scenarios such as lithography, biological imaging, and spectral analysis.

[0003] Although ultraviolet lasers have high precision and are of great significance for high-precision scenes, their operating frequency has problems with low pulse energy and low power compared to other types of lasers, and cannot meet the market's demand for higher pulse energy. The conventional improvement plan is to use high-concentration laser crystals to absorb more photons from the pump light, thereby increasing the energy. However, as the ion density in the laser crystal increases, the thermal effect of the laser crystal also increases, which means that more cooling components are needed, limiting the energy increase of the ultraviolet laser.

[0004] Therefore, how to increase the pulse energy and power of the ultraviolet laser and reduce the thermal effect as little as possible is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0005] The object of the present invention is to provide a low thermal effect ultraviolet laser and a calibration method thereof, so as to solve the technical problem that it is difficult to further improve the pulse energy and power of the ultraviolet laser.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A low thermal effect ultraviolet laser comprises a first pump light source, a second lens and a first lens arranged in sequence along a first incident direction, wherein a first laser crystal and an acousto-optic Q switch are arranged between the second lens and the first lens;

[0008] It also includes a second pump light source, a third lens, a second laser crystal and a fourth lens arranged along a second incident direction, wherein the fourth lens is arranged at an acute angle relative to the second incident direction; a frequency doubling component is arranged in the reflection direction of the fourth lens; the frequency doubling component is used to convert the frequency of the light excited by the laser crystal;

[0009] The second lens and the third lens are both transparent to the pump light source, the first lens, the second lens, the third lens and the fourth lens are all reflective to the light excited by the laser crystal, and the first lens, the second lens, the third lens, the fourth lens and the frequency doubling component constitute a circular reflection light path for the light excited by the laser crystal to circulate.

[0010] Optionally, the plane where the first lens is located is arranged perpendicular to the first incident direction;

[0011] The second lens is tilted relative to the first incident direction, the third lens is tilted relative to the second incident direction, and the reflection path of the second lens is respectively set toward the first lens and the third lens, and the reflection path of the third lens is respectively set toward the second lens and the fourth lens.

[0012] Optionally, the frequency doubling component comprises a first frequency doubling crystal, a second frequency doubling crystal and a fifth lens which are sequentially arranged along a reflection path of the fourth lens, and the first lens, the second lens, the third lens, the fourth lens and the fifth lens constitute a circular reflection optical path for the light excited by the laser crystal to circulate;

[0013] The output surface of the first frequency doubling crystal has a reflection path for the light excited by the laser crystal to be reflected to the fourth lens, and has a reflection path for the frequency-doubled light to be emitted from the circular reflection light path.

[0014] Optionally, the output surface of the first frequency doubling crystal is a Brewster angle.

[0015] Optionally, the first pump light source and the second pump light source are both used to excite 808 nm light; the first laser crystal and the second laser crystal are both used to be excited by 808 nm light to radiate 1064 nm fundamental frequency light;

[0016] The first frequency doubling crystal is a triple frequency doubling crystal, and the second frequency doubling crystal is a double frequency doubling crystal.

[0017] Optionally, the first lens is a convex reflector, and the second lens, the third lens, the fourth lens and the fifth lens are plane reflectors.

[0018] Optionally, the first laser crystal and the acousto-optic Q-switch are arranged in sequence along the first incident direction.

[0019] A power correction method for a low thermal effect ultraviolet laser is applied to the low thermal effect ultraviolet laser as described above, comprising:

[0020] Acquire a first incident surface temperature T11 and a first exit surface temperature T12 of the first laser crystal, and a second incident surface temperature T21 and a second exit surface temperature T22 of the second laser crystal;

[0021] A first average temperature T10 of the first laser crystal is calculated according to the first incident surface temperature T11 and the first exit surface temperature T12, and a second average temperature T20 of the second laser crystal is calculated according to the second incident surface temperature T21 and the second exit surface temperature T22;

[0022] The average temperature of each laser crystal is compared with the preset safety temperature. If the average temperature is higher than the safety temperature, the power of the pump light source corresponding to the laser crystal is reduced until the corresponding average temperature is lower than the safety temperature.

[0023] Optionally, it also includes:

[0024] Obtain a first temperature ratio △T1 according to a quotient of the first exit surface temperature T12 and the first incident surface temperature T11, and obtain a second temperature ratio △T2 according to a quotient of the second exit surface temperature T22 and the second incident surface temperature T21;

[0025] Select a laser crystal with a higher temperature ratio and increase the power adjustment difference of the corresponding laser crystal;

[0026] The method of adjusting the power of the pump light source corresponding to the laser crystal includes:

[0027] Obtaining the power adjustment difference of the laser crystal;

[0028] Subtract the power adjustment difference from the power of the pump light source.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The low thermal effect ultraviolet laser and the calibration method thereof provided by the present invention respectively control the first pump light source to irradiate the first laser crystal and control the second pump light source to irradiate the second laser crystal, so that the first laser crystal and the second laser crystal respectively excite light (fundamental frequency light), and then the light realizes oscillation circulation in the circular reflection light path, thereby being converted into pulse light through modulation of the acousto-optic Q switch, and then completing the frequency doubling conversion of the pulse light through the frequency doubling component, and converting it into ultraviolet light with a shorter wavelength, at which time the ultraviolet light is emitted from the circular reflection light path due to the change in frequency, so as to realize the output of ultraviolet laser. In the above process, at least two pump light sources and two laser crystals are put into use, and the fundamental frequency light is generated by each of the multiple laser crystals, which can reduce the thermal effect of a single laser crystal, promote the diffusion of heat, and then reduce the overall thermal effect, and remove the limitation when increasing the pulse energy and power, so the low thermal effect ultraviolet laser and the calibration method thereof have the advantages of high pulse energy and high power under the same refrigeration environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0032] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical contents disclosed by the present invention.

[0033] Figure 1 A schematic diagram of the optical path structure of a low thermal effect ultraviolet laser provided in an embodiment of the present invention;

[0034] Illustration: 001, first pump light source; 002, second pump light source;

[0035] 101, first lens; 102, second lens; 103, third lens; 104, fourth lens; 105, fifth lens;

[0036] 201, first laser crystal; 202, second laser crystal; 203, first frequency doubling crystal; 204, second frequency doubling crystal; 205, acousto-optic Q switch. DETAILED DESCRIPTION

[0037] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] In the description of the present invention, it should be understood that the terms "upper", "lower", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. It should be noted that when a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally arranged component at the same time.

[0039] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0040] Embodiment 1:

[0041] The low thermal effect ultraviolet laser provided in the embodiment of the present invention is suitable for high-precision scenarios such as lithography, biological imaging, and spectral analysis. This embodiment improves the structure of the low thermal effect ultraviolet laser to make it have the advantages of low thermal effect, high pulse energy, and high power.

[0042] like Figure 1 As shown, the low thermal effect ultraviolet laser in this embodiment includes a first pump light source 001, a second lens 102 and a first lens 101 arranged in sequence along a first incident direction, and a first laser crystal 201 and an acousto-optic Q switch 205 are arranged between the second lens 102 and the first lens 101. The first incident direction is the light emission direction of the first pump light source 001, and the second lens 102 has light transmittance to the first pump light source 001, so the first pump light source 001 can pass through the second lens 102 to excite the first laser crystal 201 to generate fundamental frequency light.

[0043] At the same time, the low thermal effect ultraviolet laser also includes a second pump light source 002, a third lens 103, a second laser crystal 202 and a fourth lens 104 arranged along the second incident direction. The fourth lens 104 is arranged at an acute angle relative to the second incident direction; a frequency doubling component is arranged in the reflection direction of the fourth lens 104; the frequency doubling component is used to convert the frequency of the light excited by the laser crystal. The second incident direction is the light emission direction of the second pump light source 002. The third lens 103 has light transmittance to the second pump light source 002. Therefore, the second pump light source 002 can pass through the third lens 103 to excite the second laser crystal 202 to generate fundamental frequency light. At the same time, the fourth lens 104 is arranged at an acute angle relative to the second incident direction, which means that the fundamental frequency light can be reflected to a direction deviating from the second incident direction.

[0044] At the same time, the second lens 102 can reflect the fundamental frequency light reflected by the first lens 101 to the third lens 103, and after being reflected by the third lens 103, it propagates along the second incident direction, and finally propagates the fundamental frequency light excited by the first laser crystal 201 to the frequency doubling component. However, it should be understood that the frequency doubling component can usually only double the frequency of part of the fundamental frequency light, so the frequency doubling component will emit light of different wavelengths (including fundamental frequency light and ultraviolet light after frequency doubling). At this time, the fundamental frequency light is reflected by the fourth lens 104, and passes through the third lens 103-the second lens 102-the first lens 101-the second lens 102-the third lens 103 in sequence, and finally reflected by the fourth lens 104 to the frequency doubling component, that is, the first lens 101, the second lens 102, the third lens 103, the fourth lens 104 and the frequency doubling component constitute a circulating reflection light path for the light excited by the laser crystal to circulate, and the fundamental frequency light that has not been doubled can oscillate in the above-mentioned circulating reflection light path, while the ultraviolet light after frequency doubling is separated from the circulating reflection light path and emitted from the low thermal effect ultraviolet laser.

[0045] In short, the second lens 102 and the third lens 103 are both transparent to the pump light source, the first lens 101, the second lens 102, the third lens 103 and the fourth lens 104 are all reflective to the light excited by the laser crystal, and the first lens 101, the second lens 102, the third lens 103, the fourth lens 104 and the frequency doubling component constitute a circular reflection light path for the light excited by the laser crystal to circulate.

[0046] In summary, the low thermal effect ultraviolet laser controls the first pump light source 001 to irradiate the first laser crystal 201 and controls the second pump light source 002 to irradiate the second laser crystal 202, so that the first laser crystal 201 and the second laser crystal 202 respectively excite light (fundamental frequency light). Then, the light oscillates and circulates in the circular reflection light path, and is converted into pulse light through the modulation of the acousto-optic Q switch 205. Then, the pulse light is converted into ultraviolet light with a shorter wavelength through the frequency doubling component, that is, ultraviolet light after frequency doubling. At this time, the ultraviolet light is emitted from the circular reflection light path due to the change in frequency, so as to realize the output of ultraviolet laser. In the above process, at least two pump light sources and two laser crystals are invested, and the fundamental frequency light is generated by multiple laser crystals respectively, which can reduce the thermal effect of a single laser crystal, promote the diffusion of heat, and then reduce the overall thermal effect, and remove the limitations when increasing the pulse energy and power. Therefore, the low thermal effect ultraviolet laser and its calibration method have the advantages of high pulse energy and high power under the same refrigeration environment.

[0047] In this embodiment, the plane where the first lens 101 is located is arranged perpendicular to the first incident direction; the second lens 102 is arranged obliquely relative to the first incident direction, the third lens 103 is arranged obliquely relative to the second incident direction, and the reflection path of the second lens 102 is arranged toward the first lens 101 and the third lens 103 respectively, and the reflection path of the third lens 103 is arranged toward the second lens 102 and the fourth lens 104 respectively, thereby realizing that the fundamental frequency light excited by the first laser crystal 201 is transmitted from the first laser crystal 201, through the acousto-optic Q switch 205 to the frequency doubling component, and the fundamental frequency light excited by the second laser crystal 202 is transmitted from the second laser crystal 202 to the frequency doubling component. For the convenience of understanding by those skilled in the art, the propagation directions of some fundamental frequency lights are listed as follows: 1. first laser crystal 201, acousto-optic Q switch 205, first lens 101, acousto-optic Q switch 205, second lens 102, third lens 103, fourth lens 104 and frequency doubling component; 2. second laser crystal 202, fourth lens 104, frequency doubling component, fourth lens 104, third lens 103, second lens 102, acousto-optic Q switch 205, first lens 101, acousto-optic Q switch 205, second lens 102, third lens 103, fourth lens 104 and frequency doubling component.

[0048] Further, the frequency doubling component includes a first frequency doubling crystal 203, a second frequency doubling crystal 204 and a fifth lens 105 which are sequentially arranged along the reflection path of the fourth lens 104. The first lens 101, the second lens 102, the third lens 103, the fourth lens 104 and the fifth lens 105 constitute a circular reflection optical path for the light excited by the laser crystal to circulate; the output surface of the first frequency doubling crystal 203 has a reflection path for the light excited by the laser crystal to be reflected to the fourth lens 104, and has a reflection path for the light after frequency doubling to be emitted from the circular reflection optical path. It can be understood that in this embodiment, the fifth lens 105 and the first frequency doubling crystal 203 are used to realize the reflection of the fundamental frequency light from the frequency doubling component to the fourth lens 104, which has the advantage of compact structure; as another optional embodiment, the fundamental frequency light reflected by the fourth lens 104 is directly frequency doubling, and then the frequency doubling ultraviolet light is directly emitted, and the fundamental frequency light that is not frequency doubling is reflected back to the above-mentioned circular reflection optical path through an additional lens.

[0049] As a preferred implementation, the output surface of the first frequency doubling crystal 203 is a Brewster angle, which can reduce the power loss of the laser and obtain a higher power output.

[0050] As an optional implementation, the first pump light source 001 and the second pump light source 002 are both used to excite 808nm light; the first laser crystal 201 and the second laser crystal 202 are both used to be excited by 808nm light to radiate 1064nm fundamental frequency light; wherein the first frequency doubling crystal 203 is a triple frequency crystal, and the second frequency doubling crystal 204 is a double frequency crystal. Specifically, after the 1064nm fundamental frequency light is reflected by the fifth lens 105, it is converted into 532nm light through the double frequency crystal, and then the 532nm light and the 1064nm fundamental frequency light are combined in the triple frequency crystal, and finally output 355nm ultraviolet light.

[0051] As another optional implementation, the laser crystal is a laser crystal that generates 400nm light, the first frequency doubling crystal 203 is a triple frequency doubling crystal, and the second frequency doubling crystal 204 is a double frequency doubling crystal, which corresponds to the output of 267nm ultraviolet light.

[0052] On the basis of the above embodiment, the first lens 101 is a convex reflector, and the second lens 102, the third lens 103, the fourth lens 104 and the fifth lens 105 are plane reflectors. Specifically, the first lens 101 is a high-reflection 1064nm 0° convex reflector, the second lens 102 and the third lens 103 are high-transmittance 808nm, high-reflection 1064nm 45° plane reflectors, the fourth lens 104 is a high-reflection 1064nm sharp-angle plane reflector, and the fifth lens 105 is a high-reflection 532nm, high-reflection 1064nm 0° plane reflector.

[0053] The first laser crystal 201 and the second laser crystal 202 are Nd:YAG laser crystals, the first frequency doubling crystal 203 is an LBO frequency doubling crystal, and the second frequency doubling crystal 204 is an LBO triple frequency doubling crystal.

[0054] On the basis of the above implementation, the first laser crystal 201 and the acousto-optic Q switch 205 are sequentially arranged along the first incident direction.

[0055] In summary, the low thermal effect ultraviolet laser in the embodiment of the present invention excites the laser crystal through two pump lights to effectively reduce the thermal effect. The first lens 101 is a convex reflective lens, which can obtain better mode matching. The laser crystal is a low-concentration doped bonded crystal to reduce the thermal effect. The first frequency doubling crystal 203 and the second frequency doubling crystal 204 are used. The output surface of the first frequency doubling crystal 203 is the Brewster angle, which can reduce power loss and obtain higher power output.

[0056] Embodiment 2:

[0057] This embodiment further provides a power calibration method for a low thermal effect ultraviolet laser, which is applied to the low thermal effect ultraviolet laser in the first embodiment, and includes:

[0058] S110, acquiring a first incident surface temperature T11 and a first exit surface temperature T12 of the first laser crystal 201, and a second incident surface temperature T21 and a second exit surface temperature T22 of the second laser crystal 202;

[0059] S120, calculating a first average temperature T10 of the first laser crystal 201 according to the first incident surface temperature T11 and the first exit surface temperature T12, and calculating a second average temperature T20 of the second laser crystal 202 according to the second incident surface temperature T21 and the second exit surface temperature T22;

[0060] S130, respectively compare the average temperature of each laser crystal with the preset safety temperature. If the average temperature is higher than the safety temperature, reduce the power of the pump light source corresponding to the laser crystal until the corresponding average temperature is lower than the safety temperature. The preset safety temperature is the temperature limit corresponding to the laser crystal, which is determined according to the type of laser crystal, for example, 35°C for Nd:YAG laser crystal.

[0061] Furthermore, the power calibration method of the low thermal effect ultraviolet laser also includes:

[0062] S210, obtaining a first temperature ratio ΔT1 according to a quotient of the first exit surface temperature T12 and the first incident surface temperature T11, and obtaining a second temperature ratio ΔT2 according to a quotient of the second exit surface temperature T22 and the second incident surface temperature T21;

[0063] S220, selecting a laser crystal with a higher temperature ratio, and increasing the power adjustment difference of the corresponding laser crystal; it should be noted that with the long-term use of the laser crystal, the internal structure of the laser crystal may have lattice distortion, microcracks and the like, which will reduce the thermal conductivity of the crystal. Therefore, when the pump light enters the crystal, the heat is difficult to dissipate quickly, resulting in an increase in the temperature inside the crystal, which is ultimately reflected in an increase in the temperature ratio;

[0064] In step S130, the method of adjusting the power of the pump light source corresponding to the laser crystal includes:

[0065] S131, obtaining a power adjustment difference of a laser crystal;

[0066] S132, subtract the power adjustment difference from the power of the pump light source, and after a waiting time T, return to step S110. The waiting time T is related to the detection frequency, and the higher the detection frequency, the shorter the waiting time T.

[0067] Through the above steps S210~S220, during the operation of the low thermal effect ultraviolet laser, the aging degree of each laser crystal can be judged, and the laser crystal with a higher aging degree can be selected, and the power adjustment difference of the corresponding pump light source can be increased, so that the adjustment strategy of the laser crystal with a higher aging degree is more conservative, thereby balancing the heating degree of the two laser crystals so that the two tend to be balanced, thereby effectively reducing the thermal effect and increasing the overall life.

[0068] Furthermore, the power calibration method of the low thermal effect ultraviolet laser also includes:

[0069] S001, when the pump light sources (i.e., the first pump light source 001 and the second pump light source 002) are started with an initial power Pi, a first variation curve of the first exit surface temperature T12 of the first laser crystal 201 and a second variation curve of the second exit surface temperature T22 of the second laser crystal 202 are obtained;

[0070] S002, obtaining a first temperature rise rate R1 of the first laser crystal 201 and a second temperature rise rate R2 of the second laser crystal 202 according to the first change curve and the second change curve;

[0071] S003, select the largest one of the first temperature rise rate R1 and the second temperature rise rate R2 and record it as the comparison temperature rise rate R0, and set the preset temperature rise rate threshold R threshold The quotient of the comparative temperature rise rate R0 is obtained to obtain the adjustment coefficient k, and k≤1; that is, R0≥R threshold When k=R threshold / R0, R0<R threshold When k=1, the temperature rise rate threshold R thresholdIt depends on the type of laser crystal, for example, the temperature of Nd:YAG laser crystal is 3°C / s.

[0072] S004. Multiply the initial power Pi by the adjustment coefficient k to obtain the working power.

[0073] At this time, before step S110, obtaining the first incident surface temperature T11 and the first exit surface temperature T12 of the first laser crystal 201, and the second incident surface temperature T21 and the second exit surface temperature T22 of the second laser crystal 202, it includes S005, making the pump light source work at the working power, and executing step S110.

[0074] It should be noted that during the process of starting the pump light source with an initial power Pi, the heat inside the laser crystal gradually accumulates with the transmission of light, so the output surface often reflects the cumulative thermal effect. After the pump light is transmitted through the entire crystal, the heat load on the output surface is the cumulative effect of the entire crystal. Since the output surface is the end point of the energy scattering and transmission of the entire crystal, it will be affected by more accumulated heat and can accurately reflect the overall thermal effect, thereby maintaining the operating power in an appropriate range and preventing any laser crystal from overheating during operation.

[0075] As a preferred implementation in this embodiment, the power calibration method of the low thermal effect ultraviolet laser specifically includes:

[0076] S301, when the pump light sources (i.e., the first pump light source 001 and the second pump light source 002) are started with an initial power Pi, a first change curve of the first exit surface temperature T12 of the first laser crystal 201 and a second change curve of the second exit surface temperature T22 of the second laser crystal 202 are obtained;

[0077] S302, obtaining a first temperature rise rate R1 of the first laser crystal 201 and a second temperature rise rate R2 of the second laser crystal 202 according to the first change curve and the second change curve;

[0078] S303, select the largest one of the first temperature rise rate R1 and the second temperature rise rate R2 and record it as the comparison temperature rise rate R0, and set the preset temperature rise rate threshold R threshold The quotient of the comparative temperature rise rate R0 is obtained to obtain the adjustment coefficient k, and k≤1; that is, R0≥R threshold When k=R threshold / R0, R0<R threshold When , let k = 1;

[0079] S304, multiplying the initial power Pi by the adjustment coefficient k to obtain the working power;

[0080] S305, making the first pump light source 001 and the second pump light source 002 work at working powers respectively, and obtaining the first incident surface temperature T11 and the first exit surface temperature T12 of the first laser crystal 201, and the second incident surface temperature T21 and the second exit surface temperature T22 of the second laser crystal 202;

[0081] S306, calculating the first average temperature T10 of the first laser crystal 201 according to the first incident surface temperature T11 and the first exit surface temperature T12, and calculating the second average temperature T20 of the second laser crystal 202 according to the second incident surface temperature T21 and the second exit surface temperature T22;

[0082] S307, obtaining a first temperature ratio △T1 according to a quotient of the first exit surface temperature T12 and the first incident surface temperature T11, and obtaining a second temperature ratio △T2 according to a quotient of the second exit surface temperature T22 and the second incident surface temperature T21;

[0083] S308, selecting a laser crystal with a higher temperature ratio, and increasing the power adjustment difference of the corresponding laser crystal;

[0084] After step S306, it also includes: S309, comparing the average temperature of each laser crystal with the preset safety temperature respectively. If the average temperature is higher than the safety temperature, reducing the power of the corresponding pump light source according to the power adjustment difference corresponding to the laser crystal, using the reduced power as the new working power, and returning to execute step S305.

[0085] As described above, the above embodiments are only used to illustrate the technical solutions of 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 the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. 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 embodiments of the present invention.

Claims

1. A low thermal effect ultraviolet laser, characterized in that: It comprises a first pump light source (001), a second lens (102) and a first lens (101) which are arranged in sequence along a first incident direction, wherein a first laser crystal (201) and an acousto-optic Q switch (205) are arranged between the second lens (102) and the first lens (101); It also comprises a second pump light source (002), a third lens (103), a second laser crystal (202) and a fourth lens (104) arranged along a second incident direction, wherein the fourth lens (104) is arranged at an acute angle relative to the second incident direction; a frequency doubling component is arranged in the reflection direction of the fourth lens (104); the frequency doubling component is used to convert the frequency of light excited by the laser crystal; The second lens (102) and the third lens (103) are both transparent to the pump light source, the first lens (101), the second lens (102), the third lens (103) and the fourth lens (104) are all reflective to the light excited by the laser crystal, and the first lens (101), the second lens (102), the third lens (103), the fourth lens (104) and the frequency doubling component form a circular reflection light path for the light excited by the laser crystal to circulate; The plane where the first lens (101) is located is arranged perpendicular to the first incident direction, the second lens (102) is arranged obliquely relative to the first incident direction, the third lens (103) is arranged obliquely relative to the second incident direction, and the reflection path of the second lens (102) is arranged towards the first lens (101) and the third lens (103), respectively, and the reflection path of the third lens (103) is arranged towards the second lens (102) and the fourth lens (104), respectively; The first laser crystal (201) and the acousto-optic Q switch (205) are arranged in sequence along the first incident direction, and the first lens (101) is a convex reflector.

2. A low thermal effect ultraviolet laser according to claim 1, characterized in that: The frequency doubling component comprises a first frequency doubling crystal (203), a second frequency doubling crystal (204) and a fifth lens (105) which are arranged in sequence along a reflection path of the fourth lens (104); the first lens (101), the second lens (102), the third lens (103), the fourth lens (104) and the fifth lens (105) constitute a cyclic reflection light path for the light excited by the laser crystal to circulate; The output surface of the first frequency doubling crystal (203) has a reflection path for the light excited by the laser crystal to be reflected to the fourth lens (104), and has a reflection path for the frequency-doubled light to be emitted from the circular reflection light path.

3. A low thermal effect ultraviolet laser according to claim 2, characterized in that: The output surface of the first frequency doubling crystal (203) is a Brewster angle.

4. A low thermal effect ultraviolet laser according to claim 2, characterized in that: The first pump light source (001) and the second pump light source (002) are both used to excite 808 nm light; the first laser crystal (201) and the second laser crystal (202) are both used to be excited by 808 nm light to radiate 1064 nm fundamental frequency light; The first frequency doubling crystal (203) is a triple frequency doubling crystal, and the second frequency doubling crystal (204) is a double frequency doubling crystal.

5. The low thermal effect ultraviolet laser according to claim 2, characterized in that: The second lens (102), the third lens (103), the fourth lens (104) and the fifth lens (105) are plane reflectors.

6. A power calibration method for a low thermal effect ultraviolet laser, characterized in that: Applied to the low thermal effect ultraviolet laser as claimed in any one of claims 1 to 5, comprising: S301, when the pump light source is started with an initial power Pi, obtaining a first change curve of a first exit surface temperature T12 of a first laser crystal, and obtaining a second change curve of a second exit surface temperature T22 of a second laser crystal; S302, obtaining a first temperature rise rate R1 of the first laser crystal and a second temperature rise rate R2 of the second laser crystal according to the first change curve and the second change curve; S303, select the largest one of the first temperature rise rate R1 and the second temperature rise rate R2 and record it as the comparison temperature rise rate R0, and set the preset temperature rise rate threshold R threshold The quotient of the temperature rise rate R0 is obtained to obtain the adjustment coefficient k, and k≤1; when R0≥R threshold When k=R threshold / R0, R0<R threshold When , let k = 1; S304, multiplying the initial power Pi by the adjustment coefficient k to obtain the working power; S305, operating the first pump light source and the second pump light source at operating powers respectively, and obtaining a first incident surface temperature T11 and a first exit surface temperature T12 of the first laser crystal, and a second incident surface temperature T21 and a second exit surface temperature T22 of the second laser crystal; S306, calculating a first average temperature T10 of the first laser crystal according to the first incident surface temperature T11 and the first exit surface temperature T12, and calculating a second average temperature T20 of the second laser crystal according to the second incident surface temperature T21 and the second exit surface temperature T22; S307, obtaining a first temperature ratio △T1 according to a quotient of the first exit surface temperature T12 and the first incident surface temperature T11, and obtaining a second temperature ratio △T2 according to a quotient of the second exit surface temperature T22 and the second incident surface temperature T21; S308, selecting a laser crystal with a higher temperature ratio, and increasing the power adjustment difference of the corresponding laser crystal; Among them, after step 306, it also includes: S309, comparing the average temperature of each laser crystal with the preset safety temperature respectively. If the average temperature is higher than the safety temperature, reducing the power of the corresponding pump light source according to the power adjustment difference corresponding to the laser crystal, using the reduced power as the new working power, and returning to execute step S305.

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