CN102545031A - High-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser - Google Patents

Abstract

The invention discloses a high-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser, which includes a main oscillator and 2N+1 amplification stages behind the main oscillator, where N is a non-negative integer, and the main oscillator is mainly composed of non-negative The cavity stabilization mirror and the gain module are composed, and at least one beam inverting device is provided on the optical path between the first stage of the amplification stage and the main oscillator and/or on the optical path between any two adjacent amplification stages. The chemical laser of the invention can correct the deflection of the beam transmission direction, has the ability of uniformizing light intensity and suppressing stray light, and can output high-quality laser beams.

Description

High Power Continuous Wave Deuterium Fluoride/Hydrogen Fluoride Chemical Laser

technical field

The invention relates to the field of laser technology, in particular to a deuterium fluoride/hydrogen fluoride chemical laser.

Background technique

Deuterium fluoride/hydrogen fluoride laser is currently the high-energy laser device with the largest continuous wave output power, and has important application value. In order to further expand the application range of deuterium fluoride/hydrogen fluoride lasers, the output power level of deuterium fluoride/hydrogen fluoride lasers needs to be further improved. There are two technical approaches to increase the power level of deuterium fluoride/hydrogen fluoride lasers. One is to use the previous single-cavity solution and only increase the number of gain modules. However, this method makes the power load on the cavity mirror too large and the laser operation The risk of thermal damage to the cavity mirror is very high, so the use of a single resonator solution can only be of practical application value under a certain power level; another method is to use the main oscillation-power amplification (MOPA) technology solution to A deuterium fluoride/hydrogen fluoride laser with high output beam quality and low power level is used as a seed source, and multiple amplification stages are used for power amplification, as shown in Figure 1. This method can maintain a certain output beam quality, while the power load on the cavity mirror is low, and the risk of mirror thermal damage is low. Therefore, the MOPA scheme is the preferred scheme for high-power continuous wave deuterium fluoride/hydrogen fluoride lasers.

However, experiments have found that the existing high-power continuous wave deuterium fluoride/hydrogen fluoride laser using the MOPA scheme has the following three problems, resulting in low quality of the output beam of the laser.

One is that the distribution of the gain medium of the deuterium fluoride/hydrogen fluoride laser along the direction of the flow field is non-uniform, so the output light intensity distribution is not uniform. At high output power levels, the non-uniform light intensity distribution will cause large high-order aberrations on the mirror surface, and these high-order aberrations cannot be effectively compensated by the adaptive optics system, resulting in a decrease in the quality of the output beam.

Second, because the output light intensity distribution has the characteristics of strong upstream and weak downstream, the non-uniform spot irradiation with high power density will produce large oblique aberration on the mirror surface, making the laser beam transmission direction deviate from the design value, due to the length of the amplification stage Longer, weak inclinations will cause the light beam to irradiate the frame of the next reflector when the light beam is transmitted over a long distance, and the thermal deformation of the frame caused by it will also cause the lens to further produce a large-angle misalignment.

The third is that the length of the amplification stage is about several meters, and the beam output by the main oscillation stage is a hollow beam, so the effect of amplified spontaneous emission (ASE) is significant. After multiple amplification stages, strong stray light is generated in the beam. These Strong stray light will cause difficulties in thermal management of the laser. Stray light has a heating effect on the frame, and the thermal deformation of the frame caused by it will also cause a large-angle misalignment of the lens, making the beam transmission direction seriously deviate from the design value, or even exceed the self-adaptive The correction range of the optical system will eventually lead to a decrease in the quality of the output beam.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, and to provide a high-power continuous wave deuterium fluoride with high output beam quality, which can correct the deflection of the beam transmission direction, has the ability of uniformizing light intensity and suppressing stray light / Hydrogen fluoride chemical laser.

In order to solve the above technical problems, the technical solution proposed by the present invention is a high-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser, the laser includes a main oscillator and 2N+1 amplification stages behind the main oscillator, and N is Non-negative integer; the main oscillator is mainly composed of an unstable cavity mirror and a gain module, and the optical path between the first stage of the amplification stage and the main oscillator and/or between any two adjacent amplification stages There is at least one beam turning device on the optical path between them.

In the above-mentioned high-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser, the beam inverting device disposed between any adjacent two amplification stages preferably includes a steering plane reflector, an input plane reflector and an output plane reflector, the The turning plane reflector, the input plane reflector and the output plane reflector are sequentially arranged on the optical path of the output light beam of the previous amplification stage, and enter the next adjacent amplification stage after being output by the output plane reflector. The beam inverting device (that is, the beam inverting device located at the front) on the optical path between the first stage of the amplification stage and the main oscillator preferably includes an input plane reflector and an output plane reflector, and the input plane The reflector and the output plane reflector are sequentially arranged on the optical path of the output beam of the main oscillator; at this time, the turning plane reflector is directly served by the corresponding output coupling mirror in the unstable cavity mirror.

In the above-mentioned high-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser, the center of the input plane reflector is preferably provided with a stray light deriving aperture stop.

In the above-mentioned high-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser, an infrared spot monitoring device is preferably installed in front of the steering plane reflector, and the output plane reflector is installed on a surface that can receive the infrared spot monitoring device. Adjust the signal on the adjustment frame. The infrared spot monitoring device can monitor the offset position of the spot on the steering plane mirror in real time, and calculate the beam deflection angle according to the offset position of the spot, and transmit the angle adjustment signal to the (electrically controlled) adjustment mirror frame to correct the beam Deflection in the direction of transport.

In each of the above-mentioned high-power continuous wave deuterium fluoride/hydrogen fluoride chemical lasers, the unstable cavity mirror preferably includes a concave reflector, an output coupling mirror and a convex reflector, and the gain module is placed on the concave reflector and the convex reflector Between the mirrors, the output coupling mirror is placed between the gain module and the convex mirror and close to the convex mirror; the center of the gain area of the gain module coincides with the optical axis of the unstable cavity mirror.

In each of the above-mentioned high-power continuous wave deuterium fluoride/hydrogen fluoride chemical lasers, as a further improvement and optimization, at least one beam inverting device is provided between any two adjacent amplification stages preferably means that the amplification stage At least one beam reversal device is provided on the optical path between the 2Mth stage of the amplifier stage and the 2M+1st stage of the amplification stage, where M=1, 2, 3, ..., N.

In each of the above-mentioned high-power continuous wave deuterium fluoride/hydrogen fluoride chemical lasers, each of the amplification stages includes a gain module, and the flow field direction of each of the gain modules is the same; the first stage of the amplification stage is the same as the On the optical path between the main oscillators, on the optical path between the 2M stage of the amplification stage and the 2M+1 stage of the amplification stage, a beam inverting device (that is, a total of N+1 light beams is provided) Inverting device); wherein, part of the amplification stage is offset by an appropriate distance relative to the optical axis of the unstable cavity mirror along the direction of the flow field, so that the light beam output by the beam inverting device immediately in front of the optical path can be incident on the shifted mirror parallel to the optical axis In the magnification stage. Each of the amplification stages can also be translated by an appropriate distance along the direction perpendicular to the flow field, so that the beam inverting device can be placed between the corresponding amplification stages.

In the above-mentioned high-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser, the light beam output by the main oscillator is preferably a hollow light beam, and the two edge rays of the hollow light beam pass through the flow field upstream and the flow field of the gain module respectively. Downstream: After the two edge rays are reflected and output by the output coupling mirror, the two edge rays are then adjusted by the beam inverting device so that the two edge rays alternately pass through the downstream of the flow field and the upstream of the flow field of the amplification stage.

In the above-mentioned high-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser, the direction of the optical axis of the steering plane reflector and the unstable cavity mirror is preferably placed at an angle of 45°; the input plane reflector and the unstable cavity The optical axis direction of the mirror is preferably placed at an angle of α, where α is an acute angle, and the straight line formed by the center of the input plane reflector and the center of the steering plane reflector is perpendicular to the optical axis direction of the unstable cavity mirror; the output The plane reflector is preferably placed at an angle β to the direction of the optical axis of the unstable cavity mirror (β=45°+α). The distance between the reflectors can be adjusted so that the transmission direction of the output beam passing through the beam inverting device is consistent with the aforementioned optical axis direction.

Compared with prior art, the beneficial effect of the present invention is:

(1) By using the beam inversion device, the stronger part of the light intensity output by the main oscillation stage or the previous stage passes through the position where the gain coefficient of the latter amplification stage is weaker, and the weaker part of the light intensity passes through the light intensity of the latter amplification stage The stronger part, thereby improving the uniformity of the output light intensity distribution, suppressing the high-order components of the thermal deformation of the cavity mirror, thereby improving the quality of the output beam.

(2) By setting the stray light deriving aperture, the amplified spontaneous emission (ASE) effect and the stray light at the center of the mirror caused by diffraction can be effectively reduced, thereby further improving the quality of the output beam.

(3) The position of the spot on the mirror surface is monitored by the infrared spot monitoring device, and the tilt adjustment of the mirror frame is driven to control the deviation of the transmission direction of the high-energy laser beam, so as to avoid the large-angle misadjustment of the mirror surface caused by the laser irradiation of the mirror frame.

Description of drawings

Fig. 1 is a schematic diagram of a high-power continuous-wave deuterium fluoride/hydrogen fluoride laser in the existing MOPA scheme.

Fig. 2 is a distribution diagram of the small-signal gain coefficient of the laser along the direction of the flow field in Embodiment 1 of the present invention.

FIG. 3 is a small-signal gain distribution and superposition diagram of the laser before and after beam inversion in Embodiment 1 of the present invention.

Fig. 4 is a schematic diagram of the MOPA scheme laser in Embodiment 1 of the present invention.

FIG. 5 is a schematic diagram of the correction signal given by the infrared spot monitoring device in Embodiment 1 of the present invention.

Fig. 6 is a schematic diagram of the MOPA scheme laser in Embodiment 2 of the present invention.

Fig. 7 is a distribution diagram of the output light intensity of the laser of the MOPA scheme in Embodiment 2 of the present invention.

FIG. 8 is a graph showing the distribution of output light intensity of a conventional MOPA scheme laser.

illustration:

1. Gain module; 2. Concave mirror; 3. Output coupling mirror; 4. Convex mirror; 5. Steering plane mirror; 6. Output plane mirror; 7. Input plane mirror; 8. Electric control adjustment mirror 9. Infrared spot monitoring device; 10. Stray light export aperture; 11. Second edge light; 12. Optical axis; 13. First edge light.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Example 1:

A high-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser of the present invention as shown in Figure 4, comprises main oscillator and 2N+1 amplification stages (N non-negative integer) behind the main oscillator, the main oscillator It is mainly composed of an unstable cavity mirror (a positive confocal unstable cavity with an output coupling mirror) and a gain module 1 . Gain module 1 is a device that generates excited deuterium fluoride/hydrogen fluoride molecules and accelerates them to supersonic flow. The gas flow direction is perpendicular to the optical axis 12 of the unstable cavity. Due to the flow characteristics of the gas, the gain medium is distributed along the direction of the flow field. It is non-uniform, and the distribution of its small-signal gain coefficient along the direction of the flow field is shown in Figure 2. The unstable cavity mirror includes a concave mirror 2, an output coupling mirror 3 and a convex mirror 4, the gain module 1 is placed between the concave mirror 2 and the convex mirror 4, and the output coupling mirror 3 is placed between the gain module 1 and the convex mirror Between 4 and close to the convex mirror 4, the output coupling mirror 3 is a plane mirror with an elliptical hole (or rectangular hole) in the center, and the center of the output coupling mirror 3 coincides with the optical axis 12 of the unstable cavity; the gain module 1 The center of the gain region coincides with the optical axis 12 of the unstable cavity mirror. The light beam output by the main oscillator is a hollow light beam, and the hollow light beam includes two edge rays, which are respectively a first edge ray 13 and a second edge ray 11, and the first edge ray 13 and the second edge ray 11 pass through the gain module 1 respectively. Upstream of the flow field and downstream of the flow field (see the arrow in FIG. 4 for the direction of the flow field), and then reflect the output through the output coupling mirror 3 .

In this embodiment, a light beam inverting device (wherein M=1, 2, 3, . Specifically, the beam output from the first stage of the amplification stage directly enters the second stage of the amplification stage, and a beam reversal device is placed between the second stage and the third stage. Repeat the above steps, placing the beam flipping device between the even-numbered amplification stage and the immediately following odd-numbered amplification stage, but not between the odd-numbered amplification stage and the immediately following even-numbered amplification stage The beam flipping device finally makes the beam emitted by the main oscillator pass through 2N+1 amplification stages. The beam inverting device located between two adjacent amplification stages comprises a steering plane mirror 5, an input plane mirror 7 and an output plane mirror 6, and the steering plane mirror 5, the input plane mirror 7 and the output plane mirror 6 are sequentially It is arranged on the optical path of the output beam of the previous amplification stage (that is, the 2M stage).

In addition, a beam inversion device is also provided on the optical path between the first stage of the amplification stage of the present embodiment and the main oscillator, and the beam inversion device includes an input plane reflector 7 and an output plane reflector 6, and the main oscillator The output coupling mirror 3 in the system directly acts as a turning plane mirror 5, and at this time, the output coupling mirror 3, the input plane mirror 7 and the output plane mirror 6 are sequentially arranged on the optical path of the output beam of the main oscillator.

In this embodiment, the steering plane reflector 5 of the beam reversal device is placed at an angle of 45° to the direction of the optical axis 12, and the input plane reflector 7 is placed at an angle of α° to the direction of the optical axis 12 (α is an acute angle), and the input plane reflection The straight line formed by the center of the mirror 7 and the center of the steering plane reflector 5 is perpendicular to the optical axis 12 direction, and the output plane reflector 6 is placed at an angle of β=α+45° with the optical axis 12 direction; the distance between each mirror surface can be Adjust, so that the transmission direction of the beam emitted by the beam inverting device is the same as the direction of the optical axis 12.

The cross-section of the beam emitted by the main oscillator is a circular or rectangular hollow spot. After transmission through the amplification stage, due to the diffraction effect and the ASE effect, there will be strong stray light in the center of the spot, which will affect the beam quality and Thermal management has a serious impact. Therefore, the light beam inversion device of this embodiment introduces a stray light deriving aperture 10 , that is, a stray light deriving aperture 10 is opened in the center of the input plane reflector 7 . The stray light deriving aperture 10 is a small hole of suitable shape processed on the input plane reflector 7, the shape of the small hole is projected on the plane perpendicular to the beam transmission direction and the output coupling mirror 3 is perpendicular to the optical axis 12 direction The projection is the same and slightly smaller on the face of . In this way, the ASE effect can be effectively suppressed, thereby improving the output beam quality of the laser.

In this embodiment, an infrared spot monitoring device 9 is correspondingly installed in front of the steering plane reflector 5. The infrared spot monitoring device 9 is composed of an infrared thermal imager and a data acquisition and processing system. The thermal imager of the infrared spot monitoring device 9 The direction of the optical axis of the optical lens is perpendicular to the steering plane reflector 5 of the beam inverting device. The output plane reflector 6 is mounted on a two-dimensionally inclined electrically controlled adjustable mirror frame 8 to adjust the tilting direction of the mirror in real time. When the infrared spot monitoring device 9 detects that the spot position on the steering plane reflector 5 deviates from the design range, it will provide a correction signal to drive the electronically controlled adjustment mirror frame 8, and the electronically controlled adjustable mirror frame 8 can be adjusted according to the infrared spot monitoring device 9. The given correction signal is used to adjust the pitch angle and the left and right angles, so that the light spot on the steering plane mirror 5 returns to the design position. By this method, the deviation of the laser beam transmission direction can be corrected in real time, and the high-energy laser beam can be avoided from irradiating the mirror frame. The heat caused by the frame and the misalignment of the mirror at a large angle. There is no need to use the infrared spot monitoring device 9 in the beam reversal device before the first stage of the amplification stage.

In this embodiment, the principle of the correction signal given by the infrared spot monitoring device 9 is shown in FIG. 5 . The center of the light beam reflected by the steering plane mirror 5 is set as the origin, the beam transmission direction is the z-axis, and the x-axis direction is perpendicular to the inside of the paper to establish a rectangular coordinate system. When the high-energy laser beam is irradiated on the steering plane mirror 5, due to the weak scattering effect of the mirror surface, the infrared thermal imager can detect the spot distribution on the mirror surface; the actual spot and the designed ideal spot position can be found through the data acquisition and processing device Compared with Δx and Δy in the x and y directions, respectively (the software for calculating these offsets is commercial mature software). Suppose that the distance between the center of the turning plane reflector 5 and the center of the output plane reflector 6 of the upper-level beam inverting device along the optical axis is L, then the distance from the output plane reflector 6 of the upper level to the beam inverting device of the current stage is When turning to the plane reflector 5 for transmission, the pitch angle of the laser beam and the deviation angle of the left and right angles are respectively: After the infrared spot monitoring device 9 obtains the deviation angle signal, it sends a corresponding drive signal to the upper-level electronic control adjustment mirror frame 8, so that the output plane reflector 6 of the upper-level beam flipping device can be adjusted to the corresponding inclination angle, so that this The light spot on the plane reflector 5 returned to the design position by the first-stage beam turning device.

The above-mentioned beam inverting device in this embodiment can invert the cross-section of the beam from left to right, and has the functions of beam translation, beam deflection, stray light suppression and the like.

The 2N+1 amplification stages in this embodiment are respectively composed of 2N+1 gain modules 1, each gain module 1 constituting the amplification stage is the same as the gain module 1 used by the main oscillator, and the flow field directions of all the gain modules 1 are the same , and the lengths of each gain module 1 along the direction of the optical axis 12 are the same. Each amplification stage can be translated a proper distance along the direction of the flow field or perpendicular to the direction of the flow field so that the beam inverting device is placed between the gain modules 1 . In this embodiment, every two adjacent amplification stages form a group (for example, the first stage and the second stage form a group, the third stage and the fourth stage form a group, ...), each group of amplification stages along the The direction of the flow field is offset by an appropriate distance relative to the optical axis 12 of the unstable cavity mirror, so that the light beams output by the beam flipping device immediately in front of the group of amplification stages can be parallel to the optical axis 12 and enter the shifted group of amplification stages; In the direction of the optical path, the distance of the offset of the group of amplification stages at the rear is larger, thus forming a similar ladder-like distribution; each amplification stage can also be translated by an appropriate distance along the direction perpendicular to the flow field, so that between the corresponding amplification stages (for example, the first Between the second level and the third level, between the fourth level and the fifth level, ...) Place the beam flipping device.

The above-mentioned high-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser with high output beam quality in this embodiment has the following working principle: since the light intensity output by the main oscillator is non-uniform along the direction of the flow field, and this non-uniformity It is corresponding to the distribution of the small signal gain coefficient, the light intensity corresponding to the position with a large gain coefficient is stronger (that is, the first marginal ray 13), and the light intensity corresponding to a position with a smaller gain coefficient is weaker (that is, the second marginal ray 11 ); after the light beam output by the main oscillator passes through the beam flipping device, the cross section of the beam is flipped up and down, and the light intensity corresponding to the upstream position of the flow field (i.e. the first edge light 13) is the same as the light intensity corresponding to the downstream position of the flow field (i.e. the second After the edge light 11) exchanges positions, it enters the first stage of the amplification stage; since the direction of the flow field in the amplification stage is the same as the direction of the flow field of the main oscillator, this makes the light intensity corresponding to the position with stronger gain in the first stage. Weak (that is, the second marginal ray 11), and the light intensity corresponding to the position with weaker gain (that is, the first marginal ray 13), so the non-uniformity of the light intensity has been improved after this level of amplification, and the cavity mirror The high-order components in the thermal deformation are suppressed, and the quality of the output beam is improved; the beam output from the first stage of the amplification stage directly enters the second stage of the amplification stage. At this time, the beam has not been flipped, and the light intensity distribution is the same as that of the first stage. In the second stage of amplification, the distribution of light intensity along the direction of the flow field shows non-uniformity. Therefore, a beam flipping device is installed again between the second stage and the third stage of the amplification stage, so that the output beam of the second stage passes through The flipping of the beam turning device in the amplification stage enters the third stage of the amplification stage. After the third stage of amplification, the non-uniformity of the light intensity is improved again, the outgoing light intensity becomes uniform again, and the quality of the output beam is improved again. By analogy, after a total of N cycles, the final beam is output from the 2N+1 amplifier stage, and the beam emitted from the 2N+1 amplifier stage has a uniform light intensity distribution, which can make the high-energy deuterium fluoride The laser irradiation received by many laser relay mirrors in the subsequent inner channel of the hydrogen fluoride laser is relatively uniform, which can suppress the difficult-to-correct high-order aberrations produced by the many laser relay mirrors in the inner channel, so that the output laser has Very high beam quality.

We can also understand the principle that beam inversion can make the output light intensity uniform from another perspective. Beam inversion can also be equivalent to the inversion of the small-signal gain coefficient distribution of the gain module 1 along the flow field direction in the first stage of the amplification stage, and the inverted small-signal gain coefficient distribution is the same as the small-signal Gain distributions are superimposed and divided by 2 to obtain a comprehensive small-signal gain distribution, as shown in Figure 3. The uniformity of the integrated small-signal gain distribution is significantly improved compared with the small-signal gain distribution before flipping, so the uniformity of the output light intensity can be improved accordingly.

Example 2:

A high power continuous wave deuterium fluoride/hydrogen fluoride chemical laser for the present invention with 3 amplification stages as shown in FIG. 6 . The laser includes a main oscillator and three amplification stages (i.e. N=1) behind the main oscillator. The main oscillator is mainly composed of an unstable cavity mirror (a positive branch confocal unstable cavity with an output coupling mirror) and a gain Module 1 constitutes. Gain module 1 is a device that generates excited deuterium fluoride/hydrogen fluoride molecules and accelerates them to supersonic flow. The gas flow direction is perpendicular to the optical axis 12 of the unstable cavity. Due to the flow characteristics of the gas, the gain medium is distributed along the direction of the flow field. is non-uniform. The unstable cavity mirror includes a concave mirror 2, an output coupling mirror 3 and a convex mirror 4, the gain module 1 is placed between the concave mirror 2 and the convex mirror 4, and the output coupling mirror 3 is placed between the gain module 1 and the convex mirror 4 and close to the convex mirror 4, the output coupling mirror 3 is a plane mirror with a rectangular hole in the center, and the projection size of the rectangular hole on a plane perpendicular to the optical axis 12 is 15mm×45mm, and the center of the output coupling mirror 3 It coincides with the optical axis 12 of the unstable cavity; the center of the gain area of the gain module 1 coincides with the optical axis 12 of the unstable cavity mirror. The beam output by the main oscillator is a hollow beam, the hollow beam cross section is a hollow rectangular spot, the outer size is 45mm×135mm, and the inner hole size is 15mm×45mm. The hollow light beam includes two edge rays, respectively a first edge ray 13 and a second edge ray 11, and the first edge ray 13 and the second edge ray 11 respectively pass through the flow field upstream and the flow field downstream of the gain module 1 (flow field See the arrow in Figure 6 for the direction), and then reflect the output through the output coupling mirror 3.

The laser of this embodiment includes two beam inversion devices, specifically, a beam inversion device is provided on the optical path between the first stage of the amplification stage and the main oscillator, and in addition, the second stage of the amplification stage and the first stage of the amplification stage A beam flipping device is also placed between the three stages. The latter beam inverting device located between adjacent two amplification stages includes a turning plane mirror 5, an input plane mirror 7 and an output plane mirror 6, and a steering plane mirror 5, an input plane mirror 7 and an output plane mirror 6 are sequentially arranged on the optical path of the second-stage output beam. And be located at the first light beam inverting device behind the master oscillator and comprise input planar reflector 7 and output planar reflector 6, the output coupler mirror 3 in the master oscillator then directly acts as turning plane reflector 5, output coupler mirror 3 and output planar reflector 6 The direction of the optical axis 12 is placed at an angle of 45°, the input plane reflector 7 is placed at an angle of 15° to the direction of the optical axis 12, the center of the input plane reflector 7 is 450 mm away from the center of the output coupling mirror 3, and the connecting line between the two centers Q1 is perpendicular to the direction of the optical axis 12, the center of the output plane reflector 6 coincides with the center line of the first stage of the amplification stage, and the distance from the straight line Q1 is 86mm. At this time, the output coupling mirror 3 , the input plane mirror 7 and the output plane mirror 6 are sequentially arranged on the optical path of the output beam of the main oscillator.

In this embodiment, the light beam output from the first stage of the amplification stage directly enters the second stage of the amplification stage, and after the light beam exits from the second stage, it enters the third amplification stage through the beam inverting device. At this moment, the center of the steering plane reflector 5 of the beam turning device coincides with the second-level centerline, and is placed at an angle of 45° with the direction of the optical axis 12; the input plane reflector 7 is at an angle of α=15° with the direction of the optical axis 12 Place; the center of the input plane reflector 7 is 450mm apart from the center of the steering plane reflector 5, and the straight line Q2 formed by connecting the two centers is perpendicular to the optical axis 12 direction; the center of the output plane reflector 6 and the third stage of the amplification stage The center lines of the output plane reflector 6 and the direction of the optical axis 12 are placed at an angle of β=60°, and the distance between the center of the output plane reflector 6 and the straight line Q2 is 86 mm; the distance between each mirror surface is adjustable, so that the light beam The transmission direction of the light beam emitted by the turning device is the same as the direction of the optical axis 12 .

The cross-section of the beam emitted by the main oscillator is a rectangular hollow spot. After transmission through the amplification stage, due to the diffraction effect and the ASE effect, there will be strong stray light in the center of the spot. These stray lights will affect the beam quality and thermal management. Therefore, a stray light deriving aperture 10 is introduced into the beam inverting device of this embodiment, that is, a stray light deriving aperture 10 (with a size of 14mm×44mm) is opened in the center of the input plane mirror 7 . The stray light deriving aperture 10 is a small hole of suitable shape processed on the input plane reflector 7, the shape of the small hole is projected on the plane perpendicular to the beam transmission direction and the output coupling mirror 3 is perpendicular to the optical axis 12 direction The projection is the same and slightly smaller on the face of . In this way, the ASE effect can be effectively suppressed, thereby improving the output beam quality of the laser.

In this embodiment, an infrared spot monitoring device 9 is correspondingly installed in front of the steering plane reflector 5. The infrared spot monitoring device 9 is composed of an infrared thermal imager and a data acquisition and processing system. The thermal imager of the infrared spot monitoring device 9 The direction of the optical axis of the optical lens is perpendicular to the steering plane reflector 5 of the beam inverting device. The output plane reflector 6 is mounted on a two-dimensionally tilted electronically controlled adjustable mirror frame 8 (placed at an angle of 60° to the optical axis direction) to adjust the tilt direction of the mirror in real time. When the infrared spot monitoring device 9 detects that the spot position on the steering plane reflector 5 deviates from the design range, it will provide a correction signal to drive the electronically controlled adjustment mirror frame 8, and the electronically controlled adjustable mirror frame 8 can be adjusted according to the infrared spot monitoring device 9. The given correction signal is used to adjust the pitch angle and the left and right angles, so that the light spot on the steering plane mirror 5 returns to the design position. By this method, the deviation of the laser beam transmission direction can be corrected in real time, and the high-energy laser beam can be avoided from irradiating the mirror frame. The heat on the frame and the large-angle mirror misalignment caused by the above (the working principle of the infrared spot monitoring device 9 is the same as that of embodiment 1). There is no need to use the infrared spot monitoring device 9 in the beam reversal device before the first stage of the amplification stage.

The above-mentioned beam inverting device in this embodiment can invert the cross-section of the beam from left to right, and has the functions of beam translation, beam deflection, stray light suppression and the like.

The three amplification stages of this embodiment are respectively composed of three gain modules 1, each gain module 1 constituting the amplification stage is the same as the gain module 1 used by the main oscillator, and the flow field directions of all the gain modules 1 are the same, and each The lengths of the gain modules 1 along the direction of the optical axis 12 are all the same. Each amplification stage can be translated a proper distance along the direction of the flow field or perpendicular to the direction of the flow field so that the beam inverting device is placed between the gain modules 1 . In this embodiment, the first stage and the second stage of the amplification stage form a group, and the center line of the group of amplification stages is offset by 300mm along the direction of the flow field relative to the optical axis 12 of the unstable cavity mirror, so that the first The light beam output by the beam inverting device before the stage can be parallel to the optical axis 12 and enter the shifted set of amplification stages; the further the rearward amplification stage in the direction of the optical path, the greater the offset distance, for example, the center line of the third stage is offset The distance of shifting the center line of the second stage is also 300mm, and the distance of shifting the optical axis 12 is 600mm, thus forming a similar stepped distribution (not necessarily stepped, if the beam turning device is placed symmetrically, then the third stage can also be return to the position coincident with the optical axis); each amplification stage can also be translated by an appropriate distance along the direction perpendicular to the flow field, so that a beam flipping device can be placed between the corresponding amplification stages (such as between the second stage and the third stage) .

The above-mentioned high-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser with high output beam quality in this embodiment has the following working principle: since the light intensity output by the main oscillator is non-uniform along the direction of the flow field, and this non-uniformity It is corresponding to the distribution of the small signal gain coefficient, the light intensity corresponding to the position with a large gain coefficient is stronger (that is, the first marginal ray 13), and the light intensity corresponding to a position with a smaller gain coefficient is weaker (that is, the second marginal ray 11 ); after the light beam output by the main oscillator passes through the beam flipping device, the cross section of the beam is flipped up and down, and the light intensity corresponding to the upstream position of the flow field (i.e. the first edge light 13) is the same as the light intensity corresponding to the downstream position of the flow field (i.e. the second After the edge light 11) exchanges positions, it enters the first stage of the amplification stage; since the direction of the flow field in the amplification stage is the same as the direction of the flow field of the main oscillator, this makes the light intensity corresponding to the position with stronger gain in the first stage. Weak (that is, the second marginal ray 11), and the light intensity corresponding to the position with weaker gain (that is, the first marginal ray 13), so the non-uniformity of the light intensity has been improved after this level of amplification, and the cavity mirror The high-order components in the thermal deformation are suppressed, and the quality of the output beam is improved; the beam output from the first stage of the amplification stage directly enters the second stage of the amplification stage. At this time, the beam has not been flipped, and the light intensity distribution is the same as that of the first stage. In the second stage of amplification, the distribution of light intensity along the direction of the flow field shows non-uniformity. Therefore, a beam flipping device is installed again between the second stage and the third stage of the amplification stage, so that the output beam of the second stage passes through The flipping of the beam turning device in the amplification stage enters the third stage of the amplification stage. After the third stage of amplification, the non-uniformity of the light intensity is improved again, the outgoing light intensity becomes uniform again, and the quality of the output beam is improved again. In this embodiment, the beam output by the main oscillator is output after passing through the first beam inverting device, the first stage of the amplification stage, the second stage of the amplification stage, the second beam inverting device, and the third stage of the amplifier stage, and the obtained output The light intensity distribution on the beam cross section is shown in FIG. 7 , and the light intensity distribution obtained by directly following the prior art shown in FIG. 1 is shown in FIG. 8 . After comparison, it can be seen that the uniformity of output light intensity can be significantly improved and stray light can be effectively suppressed by using the method of the present invention, so that laser output with high output beam quality can be obtained.

Claims (9)

1. A high-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser, the laser includes a main oscillator and 2N+1 amplification stages positioned behind the main oscillator, N is a non-negative integer, and the main oscillator is mainly composed of An unstable cavity mirror and a gain module are formed, and it is characterized in that: the optical path between the first stage of the amplification stage and the main oscillator and/or the optical path between any adjacent two amplification stages is at least provided with A beam flipping device. 2. The high-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser according to claim 1, characterized in that: the beam inversion device on the optical path between the first stage of the amplification stage and the main oscillator comprises The input plane reflector and the output plane reflector, the input plane reflector and the output plane reflector are sequentially arranged on the optical path of the output beam of the main oscillator; the beam flipping between any adjacent two amplification stages The device comprises a diverting plane reflector, an input plane reflector and an output plane reflector, and the diverting plane reflector, the input plane reflector and the output plane reflector are sequentially arranged on the optical path of the output light beam of the previous amplification stage. 3. The high-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser according to claim 2, characterized in that: the center of the input plane reflector is provided with a stray light deriving aperture stop. 4. The high-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser according to claim 2, characterized in that: an infrared spot monitoring device is correspondingly installed in front of the steering plane reflector, and the output plane reflector is installed on It is on the adjustment mirror frame that can receive the adjustment signal sent by the infrared spot monitoring device. 5. The high-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser according to any one of claims 1 to 4, wherein the unstable cavity mirror includes a concave mirror, an output coupling mirror and a convex mirror, The gain module is placed between the concave reflector and the convex reflector, and the output coupling mirror is placed between the gain module and the convex reflector and is close to the convex reflector; the center of the gain region of the gain module and The optical axes of the unstable cavity mirrors coincide. 6. The high-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser according to claim 5, characterized in that: at least one beam reversal device is provided between any adjacent two amplification stages, specifically referring to the At least one beam reversal device is provided on the optical path between the 2Mth stage of the amplification stage and the 2M+1st stage of the amplification stage, where M=1, 2, 3, ..., N. 7. The high-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser according to claim 6, characterized in that: gain modules are included in each of the amplification stages, and the flow field direction of each of the gain modules is the same; A beam reversal device is provided on the optical path between the first stage of the amplification stage and the main oscillator, and on the optical path between the 2M stage of the amplification stage and the 2M+1 stage of the amplification stage; Part of the amplification stage is shifted by an appropriate distance relative to the optical axis of the unstable cavity mirror along the direction of the flow field, so that the light beam output by the beam reversal device immediately in front of the optical path can enter the shifted amplification stage. 8. The high-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser according to claim 7, characterized in that: the beam output by the main oscillator is a hollow beam, and two edge rays of the hollow beam pass through the The upstream of the flow field and the downstream of the flow field of the gain module; after the two edge rays are reflected and output by the output coupling mirror, and then adjusted by the beam flipping device, the two edge rays respectively pass through the flow field of the amplification stage alternately Downstream and upstream of the flow field. 9. The high-power continuous wave deuterium fluoride/hydrogen fluoride chemical laser according to claim 8, characterized in that: the steering plane reflector is placed at an angle of 45° to the optical axis direction of the unstable cavity mirror; the input The plane reflector and the optical axis of the unstable cavity mirror are placed at an angle α, where α is an acute angle, and the straight line passing through the center of the input plane reflector and the center of the steering plane reflector is perpendicular to the unstable cavity mirror Optical axis direction: the output plane reflector is placed at an angle of 45°+α to the optical axis direction of the unstable cavity mirror.

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