CN113204126B - Debugging device and method for multi-pass cascade amplification laser driver - Google Patents

Abstract

An optical debugging device and method, in particular a debugging device and method for a multi-pass cascade amplification laser driver, the device includes an optical fiber light source, a wedge mirror, a wavefront sensor, a wave plate, a vacuum unit and a computer. The multi-pass cascaded amplified laser driver consists of a spatial filter, an amplifier, a transflective polarizer, a reflector, an electro-optic switch and an anamorphic mirror. The fiber light source, wave plate and wavefront sensor are used to detect the output beam aberration of the multi-pass cascade amplifier laser driver in real time, and feedback and adjust the cavity space filter and transmission space filter to complete the online fine debugging of the multi-pass cascade amplifier laser driver. The above-mentioned adjusting device and method have the advantages of simple structure, convenient adjustment, and high detection accuracy, which improve the on-line installation, calibration and debugging capability and output beam quality of the multi-pass cascade amplifier laser driver.

Description

Debugging device and method for multi-pass cascade amplification laser driver

technical field

The present invention relates to an optical debugging device and method, in particular to a debugging device and method of a multi-pass cascade amplification laser driver.

Background technique

For decades, the progress of laser technology and its industry has had a profound impact on national economic development, national defense and military construction, and academic scientific and technological research. With the development of laser fusion energy ICF, new requirements and challenges are also proposed for high-power laser drivers. In order to meet the needs of fusion energy and physical exploration, the large-diameter high-power multi-pass cascade laser driver has become an indispensable tool for scientists in the world to carry out laser research, and it is also a laser engineering project that requires precision debugging.

The large-diameter multi-pass cascade laser driver adopts multi-pass laser transmission amplification, which can greatly improve the energy utilization efficiency. Among the multi-pass cascade laser drivers with safe and stable operation in the world, the "four-pass cavity amplifier + two-pass booster" optical path transmission method is one of them, that is, when the beam is transmitted back and forth in the multi-pass cascade laser driver, the two Passing through the booster amplifier once and the cavity amplifier four times, precision debugging and installation and improving the beam quality of the output beam are important research contents in the development of large-aperture multi-pass cascade laser engineering.

In the multi-pass cascaded amplified laser driver, the large-diameter optical components include long-range transmission spatial filters, amplifiers, mirrors, transflective polarizers, electro-optic switches, cavity spatial filters and deformable mirrors. The large-aperture long-range spatial filter is used to suppress nonlinear effects, improve the safe operating flux of the system, filter and cut off high-frequency information, and protect the working medium of the laser. The deformable mirror can be used for real-time wavefront correction to improve the output beam quality and far-field focal spot energy. concentration, so spatial filters and anamorphic mirrors are key optical components. In addition, other optical components have residual aberration due to factors such as processing and alignment, which will also reduce the via efficiency and beam quality of the long-range spatial filter.

In order to meet the spatial arrangement characteristics and technical indicators of the multi-pass cascade amplifier laser driver, it is necessary to build a device and method for on-line precision debugging of all optical components in the whole link. Aiming at the above-mentioned debugging requirements of the multi-pass cascading amplifier laser driver, the present invention provides an online precision debugging device and method in combination with the driver optical path and device arrangement, so as to improve the spatial filtering via efficiency and output beam efficiency of the multi-pass cascading amplifier laser driver. quality and safe operation.

SUMMARY OF THE INVENTION

The invention provides an optical debugging device and method. The device is composed of an optical fiber light source, a sampling mirror, a wavefront sensor, a wave plate, a vacuum unit and a computer. Using fiber light source, wave plate, and wavefront sensor to detect the wavefront of the output beam of the multi-pass cascade amplifier laser driver in real time, feedback the online adjustment of the cavity space filter and transmission space filter, and complete the online fine debugging of the multi-pass cascade amplifier laser driver. The adjusting device and method have the advantages of simple structure, convenient adjustment, and high detection accuracy, which improve the on-line calibrating capability and output beam quality of the multi-pass cascade amplification laser driver.

To achieve the above object, the present invention has adopted the following technical solutions:

A multi-pass cascade amplifier laser driver is characterized in that it includes a transmission space filter, a booster amplifier, a booster mirror, a transflective polarizer, a cavity mirror, an electro-optic switch, a cavity space filter, a cavity amplifier and a deformation mirror.

The multi-pass cascade laser driver adopts the "four-pass cavity amplifier + two-pass booster" optical path transmission method, that is, when the beam is transmitted back and forth in the multi-pass cascade laser driver, it passes through the booster amplifier twice and the cavity amplifier four times.

A debugging device for a multi-pass cascade amplification laser driver includes an optical fiber light source assembly, a wedge-shaped reflector, a wavefront acquisition assembly, a wave plate assembly, a vacuum unit and a computer.

The transmission space filter includes a transmission space vacuum pipe, and a transmission space input lens, a transmission space output lens and a transmission space filter aperture plate fixed on the front and rear ends of the transmission space vacuum pipe, and the transmission space output lens is fixed on the vacuum tube. On the road, the transmission space input lens is provided with a drive motor, which can translate axially along the transmission space vacuum pipeline under vacuum and atmospheric conditions.

The cavity space filter includes a cavity space vacuum pipe, and a cavity space input lens, a cavity space output lens and a cavity space filter aperture plate fixed at the front and rear ends of the cavity space vacuum pipe, and the cavity space input lens and the cavity space The output lenses are all equipped with drive motors, which can translate axially along the vacuum pipeline in the cavity space under vacuum and atmospheric conditions.

The optical fiber light source assembly includes two single-mode optical fiber light sources with adjustable power, and a first optical fiber collimator, a first right-angle total reflection prism, a second optical fiber collimator and a second right-angle total reflection prism located in the transmission space vacuum pipeline. Reflecting prism; the first output end of the single-mode fiber light source enters the transmission space vacuum pipe of the transmission space filter through the first optical fiber and is connected to the first fiber collimator, and the output beam of the first fiber collimator diverges The angle matches the transmission space input lens, and the beam passes through the first right-angle total reflection prism beam splitting mirror to become the outgoing beam of the first small hole of the transmission space filter aperture plate; the second output end of the single-mode fiber light source passes through the second The transmission space vacuum pipe where the optical fiber enters the transmission space filter is connected to the second fiber collimator, the output beam divergence angle of the second fiber collimator matches the transmission space output lens of the transmission space filter, and the beam passes through the second right angle The beam splitting mirror image of the total reflection prism becomes the outgoing beam from the second pinhole of the transmission space filter aperture plate, and the outgoing beam is collimated by the second fiber collimator and the transmission space output lens and then enters the wedge-shaped reflector. The front surface of the wedge-shaped reflector is coated with a reflective coating, and the rear surface is coated with an anti-reflection coating.

The wavefront acquisition assembly includes a wavefront sensor, a small-diameter lens and a reflector located in the transmission space vacuum pipe; the collimated beam output by the second fiber collimator and the transmission space output lens passes through the front surface of the wedge-shaped reflector. After reflection, it is deflected by a small angle and returned to the output lens of the transmission space. After being reflected by the mirror, it enters the small-diameter lens to complete the beam reduction, and then enters the wavefront sensor.

The wave plate assembly includes a first wave plate, a first wave plate drive motor, a second wave plate and a second wave plate drive motor located in the cavity space vacuum pipeline; the first wave plate and the second wave plate are both 1/2 wave plate, the first wave plate is moved to the second small hole of the cavity space filter hole plate by the first wave plate drive motor, and the second wave plate is moved to the second hole by the second wave plate drive motor. At the third small hole of the cavity space filtering hole disk.

The vacuum unit includes a cryogenic pump vacuum combination unit composed of a low vacuum unit and a high vacuum unit, as well as a transmission vacuum gate valve and a cavity vacuum gate valve; the transmission vacuum gate valve and the cavity vacuum gate valve are respectively It communicates with the transmission space filter and the cavity space filter, and maintains the transmission space filter and the cavity space filter in a vacuum or atmospheric state by controlling the opening and closing of the transmission vacuum gate valve and the cavity vacuum gate valve.

The computer is respectively connected with the wavefront sensor and the deformable mirror; the wavefront sensor works in a continuous or pulse single-frame trigger mode, and measures the aberration data of the light beam incident on the wavefront sensor; the computer is based on the The measured wavefront data of the wavefront sensor is fed back to control the deformable mirror to complete aberration correction.

The transmission space input lens, transmission space output lens, cavity space input lens and cavity space output lens are all thick lenses, and the focal length f satisfies the following formula:

In the formula: n _g is the refractive index of the lens, R ₁ and R ₂ are the curvatures of the spherical surfaces on both sides of the thick lens, D is the thickness between the spherical surfaces on both sides of the center of the lens, and n ₁ and n ₂ are the thickness of the medium on both sides of the thick lens, respectively. refractive index.

The first optical fiber and the second optical fiber are both polarization-maintaining optical fibers, which output a horizontally polarized continuous light source, and are consistent with the operating wavelength of the seed laser light source operated by the multi-pass cascade amplifier laser driver; the first optical fiber collimator and the third optical fiber collimator The right-angle total reflection prism is fixed on the combined adjustment frame in sequence, and the adjustment frame has five-dimensional precision adjustment of overall lift, pitch, yaw, left-right and front-to-back translation; the first fiber collimator, the first right-angle total reflection prism and the transmission space The input lens combination produces a near-diffraction-limited paraxial plane-wave beam incident on a multi-pass cascade-amplified laser driver.

After turning on the wave plate vacuum drive motor and moving the first wave plate and the second wave plate to the second small hole and the third small hole of the cavity space filter hole disk, the near-diffraction limit paraxial plane wave beam After being reflected by the booster reflector, transflective polarizer, cavity reflector and deformable mirror, it is transmitted twice in the cavity space filter, and once in the transmission space filter. The path of the operating seed laser light source is the same, and the aberration data of the output beam after the near-diffraction limit paraxial plane wave beam passes through the multi-pass cascade amplification laser driver is collected by the wavefront acquisition component.

The second optical fiber collimator and the second right-angle total reflection prism are sequentially fixed on the combined adjustment frame, and the adjustment frame has five-dimensional precision adjustment of overall lifting, pitching, yaw, left-right and front-rear translation; the second optical fiber The collimator, the second right-angle total reflection prism and the transmission space output lens combine to generate a near-diffraction-limited coaxial plane wave beam incident on a multi-pass cascaded amplifier laser driver, and the near-diffraction-limited coaxial plane wave beam is reflected by the wedge-shaped mirror and enters the wavefront acquisition component , the aberration data of the near-diffraction-limited coaxial plane wave beam is collected by the wavefront collection component, as the initial data for debugging the multi-pass cascade amplification laser driver.

The transmission space output lens is fixed and takes its optical axis as the reference optical axis, that is, the debugging device of the multi-pass cascade amplifier laser driver and the multi-pass cascade amplifier laser driver all optical components are based on the optical axis and the optical axis of the transmission space output lens. The spatial position is the reference datum to complete the debugging.

The focusing far-field characteristics at the transmission space filtering aperture disk and the cavity space filtering aperture disk are derived from the beam aberration characteristics, which affect the via efficiency of the transmission space filter and the cavity space filter; the laser beam is cascaded in multiple passes. When amplifying the transmission of the laser driver, the divergence angle of the far-field focal spot comes from the defocus aberration, and the remaining aberrations affect the focal spot shape; the axial spatial position of the lens corresponding to the transmission space filter and cavity space filter can be adjusted dynamically. Defocusing aberration of the output beam of the multi-pass cascading amplifying laser driver; adjusting the deformable mirror can dynamically adjust the output beam aberration and far-field focal spot of the multi-pass cascading amplifying laser driver.

A debugging method of a multi-pass cascade amplification laser driver is characterized in that the method comprises the following steps:

①. Install the transmission space vacuum pipe of the transmission space filter on the support frame of the optical table, install the transmission space input lens at the input end, install and fix the transmission space output lens at the output end, and install and fix the transmission space output lens at the output end. The transmission space output lens is coaxial with the optical axis; the focal length of the output lens under the vacuum condition in the transmission space vacuum pipeline is obtained by formula (1), and the center of the second hole of the transmission space filter filter aperture plate coincides with the focal point of the transmission space output lens under vacuum conditions , install the second fiber collimator and the second right-angle total reflection prism combination adjustment frame near the second small hole, the fiber point light source of the second fiber collimator is less than one time of the diffraction limit of the output lens of the transmission space, and with the second The center of the small hole forms a mirror image relationship; the second output end of the single-mode optical fiber light source transmits the light source to the second optical fiber collimator and the second right-angle total reflection prism through the second optical fiber, and passes through the transmission space filter. After the transmission space output lens is collimated, a near-diffraction limit coaxial plane wave beam is generated; a first optical fiber collimator and a first right-angle total reflection prism are installed near the first small hole of the transmission space filter aperture plate of the transmission space filter Combining the adjustment frame, the fiber point light source of the first fiber collimator is smaller than the diffraction limit of one time of the input lens of the transmission space, and forms a mirror image relationship with the center of the first small hole; the first output end of the single-mode fiber light source passes through the first The optical fiber transmits the light source to the first optical fiber collimator and the first right-angle total reflection prism, and is collimated by the transmission space input lens of the transmission space filter to generate a near-diffraction limit paraxial plane wave beam;

②, open the low vacuum unit and high vacuum unit of the cryopump vacuum combination unit of the vacuum unit, and transfer the vacuum gate valve to pump the transmission space filter to a vacuum state; output in the transmission space of the transmission space filter A wedge-shaped mirror is placed behind the lens and its pitch and yaw are adjusted. The near-diffraction-limited coaxial plane wave beam is reflected by the wedge-shaped mirror and enters the wavefront acquisition component. The wavefront sensor measures the output aberration of the reduced beam and finely adjusts the wavefront along the axis. The small-diameter lens in the acquisition component is adjusted to zero, and the aberration data is recorded, denoted as Ф ₀ , as the initial data for debugging the multi-pass cascade amplifier laser driver; the second fiber collimator and the first The combined adjustment frame of the two right-angle total reflection prisms is translated as a whole to the side of the filter aperture plate, that is, it is moved out of the optical path;

3. Through the laser tracker, according to the optical path and spatial arrangement of the multi-pass cascade amplification laser driver, place a booster mirror in the optical path of the near-diffraction-limited paraxial plane wave beam output by the transmission space filter and the transmission space input lens, and adjust the The horizontal deflection and pitch angle of the booster mirror make the incident near-diffraction-limited paraxial plane wave beam reflected by the booster mirror and then re-enter the transmission space filter, and then enter the wedge-shaped mirror and wave beam after passing through the second small hole. The front acquisition component, the wavefront sensor records the aberration data, denoted as Ф ₁ ; the booster amplifier is placed between the booster mirror and the transmission space input lens, and the horizontal deflection and pitch angle of the booster amplifier are adjusted as a whole. The wavefront sensor records the aberration data, denoted as Ф ₂ ; the axial position of the input lens in the transmission space is adjusted by the described drive motor, when the defocus aberration in the aberration data Ф ₂ is divergence, the transmission space input lens along the transmission space The vacuum pipeline moves coaxially in the direction away from the _second small hole, and when the defocus aberration in the aberration data Ф2 is convergence, the transmission space input lens moves along the transmission space vacuum pipeline to approach the second small hole When the defocus aberration is zero in the aberration data Ф ₂ recorded by the wavefront sensor, the input lens stops moving and is fixedly locked;

④. Install the cavity space vacuum pipe of the cavity space filter on the support frame of the optical table, install the cavity space input lens at the input end, install the cavity space output lens at the output end, and install the cavity space space output lens at the output end. The cavity space output lens is the same as the optical axis; the focal length of the cavity space input lens and the cavity space output lens under the vacuum condition in the transmission space vacuum pipeline can be obtained by formula (1). By adjusting the drive motor, the cavity space input lens and the cavity space output lens are adjusted. The focus is coincident, the cavity space filter hole disk of the cavity space filter is placed, and the center of the fifth small hole is located at the common focus with the cavity space input lens and the cavity space output lens; open the low vacuum of the cryopump vacuum combination unit of the vacuum unit The unit, the high vacuum unit, and the cavity vacuum gate valve are used to pump the cavity space filter to a vacuum. Under vacuum conditions, the cavity space input lens and the cavity space output lens are adjusted to Concentric confocal;

⑤. According to the optical path and spatial arrangement of the multi-pass cascaded amplified laser driver, a laser tracker is used to install a deformable mirror at the output end of the cavity space output lens of the cavity space filter; the cavity space input lens of the cavity space filter is used. The transflective polarizer is installed at the place and adjusted to the polarization working angle; the horizontal deflection and pitch angle of the booster mirror are adjusted, and the near-diffraction limit paraxial plane wave beam output from the transmission space input lens of the transmission space filter is passed through the transflective polarizer. After reflection, it enters the cavity space filter; a cavity amplifier is installed between the cavity space output lens of the cavity space filter and the deformable mirror; the near-diffraction limit paraxial plane wave beam is transmitted back and forth in the cavity space filter, the cavity amplifier, and the deformable mirror once, and then returns Transmission spatial filter, wavefront sensor records aberration data, denoted as Ф ₃ ; by driving motor to translate the cavity space output lens along the optical axis, when the defocus aberration in the aberration data Ф ₃ is divergence, the cavity space output lens along the optical axis. The cavity space vacuum pipe is adjusted coaxially to the direction away from the fifth small hole. When the defocus aberration in the aberration data _Ф3 is convergence, the cavity space input lens moves coaxially along the vacuum pipe to the direction close to the fifth small hole. Adjustment, when the defocus aberration in the recorded aberration data Ф ₃ is zero, the cavity space output lens stops moving and completes the fixed locking;

⑥. The electro-optic switch and the cavity mirror are installed behind the transflective polarizer, and the normal direction of the center of the electro-optic switch and the mirror surface of the cavity mirror coincides with the central optical axis of the cavity space filter; the first wave plate of the wave plate assembly passes through the first wave plate. A wave plate driving motor is moved to the second small hole of the cavity space filter orifice plate; the second wave plate of the wave plate assembly is moved to the third small hole of the filter hole plate of the cavity space filter through the second wave plate drive motor ; Fine-tune the attitude of the transflective polarizer to slightly deflect the near-diffraction-limited paraxial plane wave output by the transmission space input lens of the transmission space filter, and then the paraxial pass through the first small hole and then enter the cavity amplifier and the deformable mirror, and fine-tune the attitude of the deformable mirror to reduce the incident beam. After slight deflection, it passes through the second small hole and the first wave plate paraxially. The beam polarization direction is rotated by 90° and then transmitted into the transflective polarizer and the electro-optic switch, and then incident on the cavity mirror. The posture of the cavity mirror is fine-tuned to fold the beam back and transmit After the electro-optic switch and the transflective polarizer enter the third aperture and the second wave plate, the polarization direction of the beam rotates 90° again, and then enters the deforming mirror through the cavity amplifier again. After being reflected by the transflective polarizer, it returns to the booster space filter, and the wavefront sensor is turned on to record the aberration data, denoted as Ф ₄ ; the cavity space input lens is translated along the optical axis by the drive motor, and when the aberration data Ф ₄ is separated from the When the focal aberration is divergent, the input lens in the cavity space moves along the cavity space vacuum pipe to the direction away from the fifth hole for adjustment _. Move and adjust in the direction close to the fifth small hole, when the defocus aberration in the aberration data _Ф4 is zero, the output lens stops moving and completes the fixed locking;

⑦. After completing the above-mentioned debugging process, the recorded aberration data Ф ₀ , Ф ₁ , Ф ₂ , Ф ₃ , Ф ₄ are all adjusted to zero, and the multi-pass cascade amplifier laser driver has Good spatial filtering via efficiency; the difference between the aberration data Ф ₄ and Ф ₀ is the residual aberration after the multi-pass cascade amplifier laser driver is debugged;

⑧. Move the combined adjustment frame of the first fiber collimator and the first right-angle total reflection prism of the fiber light source assembly to the side of the transmission space filter hole disk as a whole, move out of the optical path, and drive the motor through the wave plate vacuum to make the first wave plate and the The second wave plate is moved out of the second hole and the third hole of the cavity space filter hole disk respectively, and the multi-pass cascade amplifier laser driver debugging device completes the debugging work; the operating seed laser light source is injected into the multi-pass cascade amplifier The first small hole of the filter hole disk of the transmission space filter of the laser driver; the aberration output after the seed laser light source is injected into the multi-pass cascade amplification laser driver is corrected through the wavefront sensor, the computer and the deformable mirror.

Principles of the invention

Principle 1 Thick Lens Focal Length

It is well known that the core optical components of a spatial filter are input and output optical lenses with different apertures and focal lengths and filter apertures, and the filter apertures are located at the focal position of the lens. Long-range spatial filters are often used in large-diameter high-power laser driver projects. The performance of the long-range spatial filter and its debugging are crucial for the development and later operation of the device. Due to safety requirements, thick lenses are used in almost all long-range spatial filters in large-diameter high-power laser drivers, and the confocal error of the lens is usually less than 2/10,000. According to the working environment of the large-diameter high-power laser driver, the outer side of the spatial filter is in the atmospheric environment, and the inner side is in a vacuum state, that is, the medium on one side of the lens is the atmosphere, and the other side is vacuum. The refractive index of air is 1.00029, and the refractive index of vacuum is 1. It is not difficult to obtain that the difference between the refractive index of air and the refractive index of vacuum is about 3/10,000, that is, the refractive index difference of the medium on both sides of the thick lens of the long-range spatial filter cannot be ignored. The formula for the focal length when the medium on both sides of the thick lens is different is derived as follows:

In the formula: n _g is the refractive index of the lens, R ₁ and R ₂ are the curvatures of the spherical surfaces on both sides of the lens, respectively, and D is the thickness between the spherical surfaces on both sides of the center of the lens. n ₁ and n ₂ are the refractive indices of the medium on both sides of the lens, respectively.

The values of n ₁ and n ₂ are determined according to the usage environment of the spatial filter in the multi-pass cascade amplifier laser driver. In the early stage of debugging of the spatial filter, when both sides are in the atmosphere, n ₁ =n ₂ =1.00029; after the operation of the spatial filter, the inner side is vacuum, n ₂ =1; the outer side is the atmosphere, n ₁ =1.00029.

Compared with the prior art, the beneficial effects of the present invention:

1) Utilize light source, wave plate and wavefront sensor to detect the wavefront of the output beam of the multi-pass cascade amplifier laser driver in real time, and feedback the online adjustment of the cavity space filter and transmission space filter to complete the online fine debugging of the multi-pass cascade amplifier laser driver. ;

2) It has the characteristics of simple structure, convenient adjustment and high detection accuracy, which improves the online installation, calibration and debugging ability and output beam quality of the multi-pass cascade amplifier laser driver.

Description of drawings

FIG. 1 is a schematic structural diagram of a multi-pass cascade amplification laser driver in the prior art

In the figure, the multi-pass cascade amplification laser driver 7, the transmission spatial filter 71, the booster amplifier 72, the booster mirror 73, the transflective polarizer 74, the cavity mirror 75, the electro-optic switch 76, the cavity spatial filter 77, the cavity Amplifier 78, deformable mirror 79, transmission space input lens 711, transmission space output lens 712, transmission space filter aperture disk 713, cavity space input lens 771, cavity space output lens 772, cavity space filter aperture disk 773

FIG. 2 is a schematic diagram of the optical path transmission of a multi-pass cascade amplification laser driver in the prior art

When the seed light source beam is transmitted in the multi-pass cascaded laser driver, it passes through the booster amplifier twice and the cavity amplifier four times

3 is a schematic structural diagram of a debugging device for a multi-pass cascade amplifier laser driver according to the present invention

In the figure, fiber light source assembly 1, sampling mirror 2, wavefront acquisition assembly 3, wave plate assembly 4, vacuum unit 5, computer 6, multi-pass cascade amplifier laser driver 7

4 is a schematic diagram of the optical fiber light source assembly and the small hole of the transmission space filter according to the present invention

In the figure, the first optical fiber 110, the second optical fiber 120, the first optical fiber collimator 111, the first right angle total reflection prism 112, the second optical fiber collimator 121, the second right angle total reflection prism 122, the transmission space filter hole Disc 713, first small hole 7131, second small hole 7132

5 is a schematic diagram of the wavefront sensor device of the present invention

In the figure, the wavefront acquisition component 3, the wavefront sensor 31, the small-diameter lens 32, and the reflector 33 are shown

FIG. 6 is a schematic diagram of the aperture and the wave plate of the cavity space filter according to the present invention.

In the figure, the wave plate assembly 4, the first wave plate 41, the second wave plate 42, the cavity space filter filter hole disk 773, the first small hole 7731, the second small hole 7732, the third small hole 7733, and the fourth small hole 7734, fifth hole 7735

Fig. 7 is the schematic diagram of the vacuum unit of the present invention

In the figure, vacuum unit 5, cryopump vacuum combination unit 51, transmission vacuum gate valve 52, cavity vacuum gate valve 53

Fig. 8 is the result of the debugging experiment of the multi-pass cascade amplified laser driver of the present invention

In the figure, the output beam wavefront before debugging (a), the defocusing aberration of the output beam before debugging (b), the output beam wavefront after debugging (c), and the output beam wavefront after the debugging is corrected by the deformable mirror (d), PV (Peak-to-Valley) and RMS (Root Mean Square) units are operating seed laser light source wavelengths

Detailed ways

Below in conjunction with accompanying drawing and embodiment, the present invention is further described, but should not limit the protection scope of the present invention:

Referring to FIG. 1, as shown in the figure, a multi-pass cascade amplifier laser driver 7 includes a transmission spatial filter 71, a booster amplifier 72, a booster mirror 73, a transflective polarizer 74, a cavity mirror 75, and an electro-optical switch. 76, Cavity Spatial Filter 77, Cavity Amplifier 78 and Deformable Mirror 79

Referring to Figure 2, as shown in the figure, the multi-pass cascade laser driver adopts the "four-pass cavity amplifier + two-way boost" optical path transmission method, that is, when the beam is transmitted back and forth in the multi-pass cascade laser driver, it passes through the booster twice. amplifier, four passes through the cavity amplifier.

Referring to FIG. 3, as shown in the figure, a debugging device for a multi-pass cascade amplification laser driver includes a fiber light source assembly 1, a wedge mirror 2, a wavefront acquisition assembly 3, a wave plate assembly 4, a vacuum unit 5 and a computer 6;

The transmission space filter 71 includes a transmission space vacuum pipe, and a transmission space input lens 712, a transmission space output lens 711 and a transmission space filter aperture 713 fixed at the front and rear ends of the transmission space vacuum pipe. The transmission space output The lens 711 is fixed on the vacuum pipe, and the transmission space input lens 712 is provided with a driving motor, and can translate axially along the transmission space vacuum pipe under vacuum and atmospheric conditions.

The cavity space filter 77 includes a cavity space vacuum pipe, and a cavity space input lens 771, a cavity space output lens 772 and a cavity space filter aperture plate 773 fixed at the front and rear ends of the cavity space vacuum pipe. Both the lens 771 and the cavity space output lens 772 are provided with drive motors, and can translate axially along the cavity space vacuum pipeline under vacuum and atmospheric conditions.

Referring to FIG. 4 , as shown in the figure, the fiber optic light source assembly 1 includes two single-mode fiber optic light sources 113 with adjustable power, and a first fiber collimator 111, a first right-angle total reflection prism 112, a first fiber collimator 111, a first right-angle total reflection prism 112, a first Two fiber collimators 121 and a second right-angle total reflection prism 122; the first output end of the single-mode fiber light source 113 enters the transmission space vacuum pipe of the transmission space filter 71 through the first optical fiber 110, and then communicates with the first optical fiber. The collimator 111 is connected, the divergence angle of the output beam of the first fiber collimator 111 is matched with the transmission space input lens 712, and the beam passes through the first right-angle total reflection prism 112 and the beam splitting mirror becomes the first small size of the transmission space filter aperture disk 713. The output beam of the hole 7131; the second output end of the single-mode fiber light source 113 enters the transmission space vacuum pipe of the transmission space filter 71 through the second fiber 120 and is connected to the second fiber collimator 121, the second fiber The divergence angle of the output beam of the collimator 121 matches the transmission space output lens 711 of the transmission space filter 71 , and the beam is split and mirrored by the second right-angle total reflection prism 122 to become the outgoing beam from the second aperture 7132 of the transmission space filter aperture plate 713 , the outgoing beam is collimated by the second optical fiber collimator 121 and the transmission space output lens 711 and then incident on the wedge-shaped reflector 2, the front surface of the wedge-shaped reflector 2 is coated with a reflective film, and the rear surface is coated with an anti-reflection film .

5 , as shown in the figure, the wavefront acquisition assembly 3 includes a wavefront sensor 31, a small-diameter lens 32 and a mirror 33 located in the transmission space vacuum pipe; the second fiber collimator 121 and the transmission space output lens 711 output the The collimated beam is reflected by the front surface of the wedge-shaped mirror 2 and then deflected by a small angle to return to the transmission space output lens 711. After being reflected by the mirror 33, it enters the small-diameter lens 32 to complete the beam reduction, and then enters the wavefront sensor. 31.

6, as shown in the figure, the wave plate assembly 4 includes a first wave plate 41, a first wave plate driving motor, a second wave plate 42 and a second wave plate driving motor located in the cavity space vacuum pipeline; The wave plate 41 and the second wave plate 42 are both 1/2 wave plates. The first wave plate 41 is moved to the second small hole 7732 of the cavity space filter hole plate 773 by the first wave plate driving motor. The second wave plate 42 is moved to the third small hole 7733 of the cavity space filtering hole disk 773 by the second wave plate driving motor.

7, as shown in the figure, the vacuum unit 5 includes a cryopump vacuum combination unit 51 composed of a low vacuum unit and a high vacuum unit, and a transmission vacuum gate valve 52 and a cavity vacuum gate valve 53; the transmission vacuum The gate valve 52 and the cavity vacuum gate valve 53 are communicated with the transmission space filter 71 and the cavity space filter 77 respectively. By controlling the opening and closing of the transmission vacuum gate valve 52 and the cavity vacuum gate valve 53, the transmission space is maintained. Filter 71 and cavity space filter 77 are in vacuum or atmosphere.

The computer 6 is respectively connected with the wavefront sensor 31 and the deformable mirror 79; the wavefront sensor 31 works in a continuous or pulsed single-frame trigger mode, and measures the aberration data of the light beam incident on the wavefront sensor 31; The computer 6 feeds back and controls the deformable mirror 79 according to the wavefront data measured by the wavefront sensor 31 to complete aberration correction.

The transmission space input lens 712, transmission space output lens 711, cavity space input lens 771 and cavity space output lens 772 are all thick lenses, and the focal length f satisfies the following formula:

In the formula: n _g is the refractive index of the lens, R ₁ and R ₂ are the curvatures of the spherical surfaces on both sides of the thick lens, D is the thickness between the spherical surfaces on both sides of the center of the lens, and n ₁ and n ₂ are the thickness of the medium on both sides of the thick lens, respectively. refractive index.

The first optical fiber 110 and the second optical fiber 120 are both polarization-maintaining optical fibers, which output a horizontally polarized continuous light source, and are consistent with the operating wavelength of the seed laser light source operated by the multi-pass cascade amplifier laser driver 7; the first optical fiber is collimated. The first optical fiber collimator 111 and the first right angle total reflection prism 112 are fixed on the combined adjustment frame in sequence, and the adjustment frame has five-dimensional precision adjustment of overall lifting, pitch, yaw, left and right and front and rear translation; the first optical fiber collimator 111, the first right angle The total reflection prism 112 and the transmission space input lens 712 are combined to generate a near-diffraction-limited paraxial plane wave beam incident on the multi-pass cascade-amplified laser driver 7 .

After the wave plate vacuum drive motor is turned on to move the first wave plate 41 and the second wave plate 42 to the second small hole 7732 and the third small hole 7733 of the cavity space filter hole plate 773, the near diffraction The limit paraxial plane wave beam is reflected by the booster mirror 73, the transflective polarizer 74, the cavity mirror 75 and the deformable mirror 79, and then transmitted twice in the cavity space filter 77 and back and forth in the transmission space filter 71. Once, with the same path as the operating seed laser light source of the multi-pass cascade amplifier laser driver 7, the image of the output beam of the near-diffraction limit paraxial plane wave beam is collected by the wavefront acquisition component 3 after passing through the multi-pass cascade amplifier laser driver 7. poor data.

The second optical fiber collimator 121 and the second right-angle total reflection prism 122 are sequentially fixed on the combined adjustment frame, and the adjustment frame has five-dimensional precision adjustment of overall lift, pitch, yaw, left and right, and front and rear translation; the second The fiber collimator 121, the second right-angle total reflection prism 122 and the transmission space output lens 711 are combined to generate a near-diffraction-limited coaxial plane wave beam incident on the multi-pass cascaded amplifier laser driver 7, and the near-diffraction-limited coaxial plane wave beam passes through the wedge-shaped mirror 2 The aberration data of the near-diffraction-limited coaxial plane wave beam is collected by the wavefront acquisition component 3 as initial data for debugging the multi-pass cascade amplifier laser driver 7 .

The transmission space output lens 711 is fixed and its optical axis is the reference optical axis, that is, the debugging device of the multi-pass cascaded amplification laser driver 7 and all optical elements of the multi-pass cascaded amplification laser driver 7 are based on the transmission space output lens 711. The optical axis and spatial position of the device are used as the reference datum to complete the debugging.

The focused far-field characteristics at the transmission space filter aperture disk 713 and the cavity space filter aperture disk 773 are derived from beam aberration characteristics, which affect the via efficiency of the transmission space filter 71 and the cavity space filter 77 . When the laser beam is transmitted in the multi-pass cascade amplification laser driver 7, the far-field focal spot divergence angle is derived from the defocus aberration, and the remaining aberrations affect the focal spot shape; adjust the transmission space filter 71 and cavity space filter 77. The axial spatial position of the corresponding lens can dynamically adjust the output beam defocus aberration of the multi-pass cascade amplification laser driver 7; adjusting the deformable mirror 79 can dynamically adjust the output beam aberration and far field of the multi-pass cascade amplification laser driver 7 focal spot.

A debugging method for a multi-pass cascade amplification laser driver, comprising the following steps:

①, install the transmission space vacuum pipe of the transmission space filter 71 on the support frame of the optical table, install the transmission space input lens 712 at the input end, install and fix the transmission space output lens 711 at the output end, and transmit the space vacuum pipe machine The central axis is the same as the optical axis of the transmission space output lens 711; the focal length of the output lens 711 under vacuum conditions in the transmission space vacuum pipeline is obtained through the formula described in claim 2, and the center of the second aperture 7132 of the transmission space filter 71 filtering aperture plate 713 Coinciding with the focal point of the transmission space output lens 711 under vacuum conditions, the second fiber collimator 121 and the second right-angle total reflection prism 122 combined adjustment frame are installed near the second small hole 7132, and the fiber point of the second fiber collimator 121 The light source is smaller than the one-time diffraction limit of the transmission space output lens 711, and forms a mirror image relationship with the center of the second aperture 7132; the second output end of the single-mode fiber light source 113 transmits the light source to the second fiber through the second optical fiber 120 The collimator 121 and the second right-angle total reflection prism 122 are collimated by the transmission space output lens 711 of the transmission space filter 71 to generate a near-diffraction-limited coaxial plane wave beam; The first optical fiber collimator 111 and the first right-angle total reflection prism 112 combined adjustment frame is installed near the first small hole 7131 of the transmission space filter aperture plate 713, and the optical fiber point light source of the first optical fiber collimator 111 is smaller than the transmission space input lens 712 1 times the diffraction limit, and form a mirror image relationship with the center of the first small hole 7131; the first output end of the single-mode fiber light source 113 transmits the light source to the first fiber collimator 111 and the first optical fiber 110 through the first fiber 110. The right-angle total reflection prism 112 is collimated by the transmission space input lens 712 of the transmission space filter 71 to generate a near-diffraction limit paraxial plane wave beam;

2. Open the low vacuum unit and high vacuum unit of the cryopump vacuum combination unit 51 of the described vacuum unit 5, and transfer the vacuum gate valve 52 to pump the transmission space filter 71 to a vacuum state; in the described transmission space filter The wedge-shaped mirror 2 is placed behind the output lens 711 of the transmission space of 71 and its pitch and yaw are adjusted. The near-diffraction-limited coaxial plane wave beam is reflected by the wedge-shaped mirror 2 and enters the wavefront acquisition component 3. The wavefront sensor 31 measures the output of the reduced beam Aberration, finely adjust the small-diameter lens 32 in the wavefront acquisition assembly 3 along the axial direction, adjust the defocus aberration to zero, record the aberration data, denoted as Φ ₀ , as the initial step for debugging the multi-pass cascade amplifier laser driver 7 Data; the combined adjustment frame of the second optical fiber collimator 121 and the second right-angle total reflection prism 122 is translated as a whole to the side of the filter aperture plate 713, that is, moved out of the optical path;

3. Through the laser tracker, according to the optical path and spatial arrangement of the multi-pass cascaded amplified laser driver 7, a booster reflection is placed in the optical path of the near-diffraction-limited paraxial plane wave beam output by the transmission space filter 71 and the transmission space input lens 711. Mirror 73, adjust the horizontal deflection and pitch angle of the booster mirror 73, so that the incident near-diffraction limit paraxial plane wave beam is reflected by the booster mirror 73 and then re-incidents the transmission spatial filter 71, and passes through the second small hole. After 7132 incident wedge mirror 2 and wavefront acquisition assembly 3, the wavefront sensor 31 records aberration data, denoted as Φ ₁ ; between the booster mirror 73 and the transmission space input lens 711, a booster amplifier 72 is placed , after the overall adjustment of the horizontal deflection and pitch angle of the booster amplifier 72, the wavefront sensor 31 records the aberration data, denoted as _Ф2 ; the axial position of the transmission space input lens 711 is adjusted by the described drive motor, when the aberration data Ф ₂ When the defocus aberration is divergent, the transmission space input lens 711 moves coaxially along the transmission space vacuum pipeline to the direction away from the second small hole 7132. When the defocus aberration in the aberration data Ф ₂ is convergence , the transmission space input lens 711 moves coaxially along the transmission space vacuum pipeline to the direction close to the _second small hole 7132, when the defocus aberration in the aberration data Φ2 recorded by the wavefront sensor 31 is zero, the input lens 711 stops moving and is fixed and locked;

④. Install the cavity space vacuum pipe of the cavity space filter 77 on the support frame of the optical table, install the cavity space input lens 771 at the input end, install the cavity space output lens 772 at the output end, and install the cavity space vacuum pipe mechanical central axis and the cavity space The input lens 771 and the cavity space output lens 772 have the same optical axis; the focal length of the cavity space input lens 771 and the cavity space output lens 771 under the vacuum condition in the transmission space vacuum pipeline can be obtained by formula (1), and the cavity space input lens 771 can be input by adjusting the drive motor. The focal points of the lens 771 and the cavity space output lens 772 are coincident, the cavity space filter aperture plate 773 of the cavity space filter 77 is placed, and the center of the fifth small hole 7735 is located at the common focus with the cavity space input lens 771 and the cavity space output lens 772; open The low-vacuum unit and high-vacuum unit and the cavity vacuum gate valve 53 of the cryopump-vacuum combination unit 51 of the vacuum unit 5 are used to pump the chamber space filter to a vacuum, and enter the lens 771 and the chamber space through the chamber space under vacuum conditions. The drive motor of the space output lens 772 adjusts the cavity space input lens 771 and the cavity space output lens 772 to be coaxial and confocal;

5. According to the optical path and spatial arrangement of the multi-pass cascade amplification laser driver 7, a laser tracker is used to install a deformable mirror 79 at the exit end of the cavity space output lens 772 of the cavity space filter 77; The transflective polarizer 74 is installed at the cavity space input lens 771, and adjusted to the polarization working angle; the horizontal deflection and pitch angle of the booster mirror 73 are adjusted, and the near-diffraction output of the transmission space input lens 711 of the transmission space filter 71 is adjusted. The limited paraxial plane wave beam is reflected by the transflective polarizer 74 and then enters the cavity space filter 77; a cavity amplifier 78 is installed between the cavity space output lens 772 and the deformable mirror 79 of the cavity space filter 77; The cavity space filter 77, the cavity amplifier 78, and the deformable mirror 79 transmit back and forth once, return to the transmission space filter 71, and the wavefront sensor 31 records the aberration data, denoted as Ф ₃ ; the cavity space output lens is translated along the optical axis by the drive motor 772, when the defocus aberration in the aberration data _Ф3 is divergence, the cavity space output lens 772 is coaxially moved and adjusted along the cavity space vacuum pipeline to the direction away from the fifth small hole 7735, when the aberration data Ф3 is out _of focus When the aberration is convergent, the cavity space input lens 772 is adjusted coaxially along the vacuum pipeline to the direction close to the fifth small hole _7735. When the recorded aberration data Ф3 has zero defocus aberration, the cavity space output lens 772 stops. Move and complete the fixed locking;

⑥, the electro-optic switch 76 and the cavity reflector 75 are installed behind the described transflective polarizer 74, the electro-optic switch 76 and the cavity reflector 75 mirror center normal direction coincides with the center optical axis of the cavity space filter 77; the wave plate assembly 4 The first wave plate 41 is moved to the second small hole 7732 of the cavity space filter hole plate 773 by the first wave plate driving motor; the second wave plate 42 of the wave plate assembly 4 is moved to the cavity space by the second wave plate driving motor At the third small hole 7733 of the filter aperture plate 773 of the filter 77; the attitude of the fine-tuning transflective polarizer 74 slightly deflects the near-diffraction-limited paraxial plane wave output by the transmission space input lens 711 of the transmission space filter 71 and then passes through the first After the small hole 7731 enters the cavity amplifier 78 and the deformable mirror 79, the posture of the deformable mirror 79 is fine-tuned to slightly deflect the incident beam and then pass through the second small hole 7732 and the first wave plate 41 paraxially, and the beam polarization direction is rotated by 90° and then transmitted into The transflective polarizer 74 and the electro-optical switch 76 are incident on the cavity mirror 75, and the posture of the cavity mirror 75 is fine-tuned to bend the beam back and transmit it through the electro-optic switch 76 and the transflective polarizer 74 to enter the third aperture 7733 and the second wave plate 42. The polarization direction of the beam is rotated by 90° again, and is incident on the deforming mirror 79 through the cavity amplifier 78 again. The beam is reflected and folded by the deforming mirror 79, passes through the fourth small hole 7734, and is reflected by the transflective polarizer 74 and returns to the booster space. Filter 71, open the wavefront sensor 31 to record the aberration data, denoted as Ф4 _; the cavity space input lens 771 is translated along the optical axis by the drive motor, when the defocus aberration in the aberration data _Ф4 is divergence, the cavity space input The lens 771 is moved and adjusted along the cavity space vacuum pipeline to the direction away from the fifth small hole 7735. When the defocus aberration in the aberration data _Φ4 is convergence, the input lens 771 is moved along the cavity space vacuum pipeline to the direction close to the fifth small hole 7735. Direction movement adjustment, when the defocus aberration in the aberration data _Ф4 is zero, the output lens 771 stops moving and completes the fixed locking;

⑦. After completing the above-mentioned debugging process, the recorded aberration data Ф ₀ , Ф ₁ , Ф ₂ , Ф ₃ , Ф ₄ are all adjusted to zero, and the multi-pass cascade amplification laser driver 7 It has good spatial filtering via hole efficiency; the difference between the aberration data Ф ₄ and Ф ₀ is the residual aberration after the multi-pass cascade amplification laser driver 7 is debugged;

8. Translate the combined adjustment frame of the first fiber collimator 111 and the first right-angle total reflection prism 112 of the fiber light source assembly 1 to the side of the filter aperture plate 713 as a whole, move out of the optical path, and drive the motor through the wave plate vacuum to make the first wave The plate 41 and the second wave plate 42 are respectively moved out of the second small hole 7732 and the third small hole 7733 of the cavity space filtering hole plate 773, and the multi-pass cascade amplifier laser driver 7 debugging device completes the debugging work; The first small hole 7131 of the filter hole disk 713 of the booster spatial filter 71 of the multi-pass cascade amplification laser driver 7; The aberration output after cascading amplifying the laser driver 7 is corrected.

In the embodiment, the above-mentioned multi-pass cascade amplification laser driver adjustment device and method are applied to the Shenguang laser device. The transmission space filter 71 and the cavity space filter 77 are both long-range space filters, the transmission space filter 71 is about 32m in length, and the transmission space input lens 712 and the transmission space output lens 711 have focal lengths of 16056mm and 15973mm under vacuum conditions, respectively. The length of the spatial filter 77 is about 22 m, and the focal lengths of the cavity space input lens 771 and the cavity space output lens 772 under vacuum conditions are 11886 mm and 11117 mm, respectively. The near-diffraction-limited coaxial plane-wave beam, the near-diffraction-limited paraxial plane-wave beam and the beam diameter of the operating seed laser light source are all 300mm×300mm (square); the working angle of the transflective polarizer 74 is 53°; the wavelength of the operating seed laser light source is 1.053μm ; The output power of the first optical fiber 110 of the optical fiber light source assembly 1 is about 450 mW, and the output power of the second optical fiber 120 is about 50 mW; the measurement accuracy of the wavefront sensor 31 is 0.01 μm, and the measurement range is 30 μm; The wave plates 42 are all 1/2 wave plates; the front surface of the wedge mirror is coated with a 0.5% reflectivity reflective film, and the rear surface is coated with a 0.05% reflectivity anti-reflection coating; the measurement accuracy of the laser tracker (API company) is 15μm±5ppm ; The pumping speed of the medium Edward low vacuum unit of the cryogenic pump vacuum unit 51 of the vacuum unit 5 is 100 liters/second, and the pumping speed of the CTI high vacuum unit is 5000 liters/second.

Referring to Figure 8, as shown in the figure, the aberration acquisition data shows that the defocus aberration (PV=9.504, RMS = 2.003), then the deformed mirror corrects the residual output aberration of the seed laser light source, and the beam quality is greatly improved (PV=0.825, RMS=0.151) (the above experimental data are compared with the second fiber collimator 121, the second right-angle total reflection The prism 122 and the output lens 711 of the transmission spatial filter 71 are combined to generate the coaxial near-diffraction limit high-quality plane wave constructed by the debug reference light source wavefront data), thus enabling safe operation and improving the online installation and calibration of large-scale laser drivers The debugging ability and output beam quality have the ability to reliably carry out physical experiment operation tasks.

Claims (8)

1. A debugging device of a multi-pass cascade amplification laser driver, wherein the multi-pass cascade amplification laser driver (7) comprises a transmission spatial filter (71), a boosting amplifier (72), a boosting reflector (73), a transflective polarizer (74), a cavity reflector (75), an electro-optical switch (76), a cavity spatial filter (77), a cavity amplifier (78) and a deformable mirror (79), and is characterized in that: the debugging device comprises an optical fiber light source component (1), a wedge-shaped reflector (2), a wavefront acquisition component (3), a wave plate component (4), a vacuum unit (5) and a computer (6);

the transmission space filter (71) comprises a transmission space vacuum pipeline, and a transmission space input lens (712), a transmission space output lens (711) and a transmission space filter hole disc (713) which are fixed at the front end and the rear end of the transmission space vacuum pipeline, wherein the transmission space output lens (711) is fixed on the vacuum pipeline, and the transmission space input lens (712) is provided with a driving motor and can axially translate along the transmission space vacuum pipeline in vacuum and atmospheric states;

the cavity space filter (77) comprises a cavity space vacuum pipeline, and a cavity space input lens (771), a cavity space output lens (772) and a cavity space filtering hole disc (773) which are fixed at the front end and the rear end of the cavity space vacuum pipeline, wherein the cavity space input lens (771) and the cavity space output lens (772) are both provided with driving motors and can axially translate along the cavity space vacuum pipeline in vacuum and atmospheric states;

the fiber light source assembly (1) comprises two paths of power-adjustable single-mode fiber light sources (113), a first fiber collimator (111), a first right-angle total reflection prism (112), a second fiber collimator (121) and a second right-angle total reflection prism (122) which are positioned in a vacuum pipeline of a transmission space; a first output end of the single-mode fiber light source (113) enters a transmission space vacuum pipeline of the transmission space filter (71) through a first path of optical fiber (110) and then is connected with a first fiber collimator (111), an output light beam divergence angle of the first fiber collimator (111) is matched with that of a transmission space input lens (712), and light beams are split and mirrored through a first right-angle total reflection prism (112) to form emergent light beams of a first small hole (7131) of a transmission space filter hole disc (713); a second output end of the single-mode fiber light source (113) enters a transmission space vacuum pipeline of a transmission space filter (71) through a second path of fiber (120) and is connected with a second fiber collimator (121), the divergence angle of an output light beam of the second fiber collimator (121) is matched with that of a transmission space output lens (711) of the transmission space filter (71), the light beam is subjected to beam splitting and mirror image by a second right-angle total reflection prism (122) to form an outgoing light beam of a second small hole (7132) of a transmission space filter hole disc (713), the outgoing light beam is collimated by the second fiber collimator (121) and the transmission space output lens (711) and then enters the wedge-shaped reflector (2), the front surface of the wedge-shaped reflector (2) is plated with a reflecting film, and the rear surface of the wedge-shaped reflector is plated with an anti-reflection film;

the wave front acquisition assembly (3) comprises a wave front sensor (31), a small-caliber lens (32) and a reflector (33) which are positioned in a transmission space vacuum pipeline; collimated light beams output by the second optical fiber collimator (121) and the transmission space output lens (711) are reflected by the front surface of the wedge-shaped reflector (2), then deflected by a tiny angle and returned to the transmission space output lens (711), and enter the small-aperture lens (32) after being reflected by the reflector (33) to finish beam contraction, and then enter the wavefront sensor (31);

the wave plate assembly (4) comprises a first wave plate (41), a first wave plate driving motor, a second wave plate (42) and a second wave plate driving motor which are positioned in the cavity space vacuum pipeline; the first wave plate (41) and the second wave plate (42) are both 1/2 wave plates, the first wave plate (41) is moved to a second small hole (7732) of the cavity space filtering aperture plate (773) through a first wave plate driving motor, and the second wave plate (42) is moved to a third small hole (7733) of the cavity space filtering aperture plate (773) through a second wave plate driving motor;

finely adjusting the posture of a transmission and reflection polarizing plate (74), slightly deflecting paraxial waves output by a transmission space input lens (711) of a transmission space filter (71) after paraxial waves near diffraction limit paraxial planes pass through a first small hole (7731), and then entering a cavity amplifier (78) and a deformable mirror (79); the light beam is reflected and folded by the deforming mirror (79), passes through a fourth aperture (7734), is reflected by the transflective polarizer (74), returns to the center of a fifth aperture (7735) of the boosting spatial filter (71) again and is positioned at the common focus of the cavity space input lens (771) and the cavity space output lens (772);

the vacuum unit (5) comprises a low-temperature pump vacuum combination unit (51) consisting of a low vacuum unit and a high vacuum unit, a transmission vacuum gate valve (52) and a cavity vacuum gate valve (53); the transmission vacuum gate valve (52) and the cavity vacuum gate valve (53) are respectively communicated with the transmission space filter (71) and the cavity space filter (77), and the transmission space filter (71) and the cavity space filter (77) are maintained in a vacuum or atmospheric state by controlling the opening and closing of the transmission vacuum gate valve (52) and the cavity vacuum gate valve (53);

the computer (6) is respectively connected with the wavefront sensor (31) and the deformable mirror (79); the wave-front sensor (31) works in a continuous or pulse single-frame trigger mode, and aberration data of a light beam incident to the wave-front sensor (31) is measured; the computer (6) controls the deformable mirror (79) to complete aberration correction according to the measured wavefront data of the wavefront sensor (31).

2. The debugging device of the multi-pass cascade amplification laser driver according to claim 1, wherein: the transmission space input lens (712), the transmission space output lens (711), the cavity space input lens (771) and the cavity space output lens (772) are all thick lenses, and the focal length f meets the following formula:

in the formula: n is _g Is the refractive index of the lens, R ₁ And R ₂ Respectively the curvature of the two side spherical surfaces of the thick lens, D is the thickness between the two side spherical surfaces at the center of the lens, n ₁ And n ₂ Respectively the refractive index of the medium on both sides of the thick lens.

3. The debugging device of the multi-pass cascade amplification laser driver according to claim 1, wherein: the first path of optical fiber (110) and the second path of optical fiber (120) are both polarization-maintaining optical fibers, output horizontal polarization continuous light sources and are consistent with the working wavelength of a seed laser light source operated by a multi-path cascade amplification laser driver (7); the first optical fiber collimator (111) and the first right-angle total reflection prism (112) are sequentially fixed on the combined adjusting frame from front to back, and the adjusting frame has five-dimensional precision adjustment of integral lifting, pitching, deflection, left-right translation and front-back translation; the first optical fiber collimator (111), the first right-angle total reflection prism (112) and the transmission space input lens (712) are combined to generate a paraxial plane wave beam incidence multi-pass cascade amplification laser driver (7) with a diffraction limit.

4. The debugging device of the multi-pass cascade amplification laser driver according to claim 1, wherein: and starting a wave plate vacuum driving motor, enabling a first wave plate (41) and a second wave plate (42) to move to a second small hole (7732) and a third small hole (7733) of a cavity space filter hole disc (773) respectively, enabling the paraxial plane wave beams close to the diffraction limit to be reflected by the boosting reflector (73), the transmission reflection polarizer (74), the cavity reflector (75) and the deformation mirror (79) and then transmitted to and fro twice in the cavity space filter (77), enabling the paraxial plane wave beams close to the diffraction limit to be transmitted to and fro once in the transmission space filter (71), enabling the paraxial plane wave beams close to the diffraction limit to be the same as the path of the operation seed laser light source of the multi-pass cascade amplification laser driver (7), and acquiring aberration data of the paraxial plane wave beams close to output the beam after passing through the multi-pass cascade amplification laser driver (7) through the wavefront acquisition component (3).

5. The debugging device of the multi-pass cascade amplification laser driver according to claim 1, wherein: the second optical fiber collimator (121) and the second right-angle total reflection prism (122) are sequentially fixed on the combined adjusting frame from front to back, and the adjusting frame has five-dimensional precision adjustment of integral lifting, pitching, deflection, left-right translation and front-back translation; the second optical fiber collimator (121), the second right-angle total reflection prism (122) and the transmission space output lens (711) are combined to generate a near-diffraction limit coaxial plane wave beam to enter the multi-pass cascade amplification laser driver (7), the near-diffraction limit coaxial plane wave beam is reflected by the wedge-shaped reflector (2) to enter the wavefront acquisition component (3), and aberration data of the near-diffraction limit coaxial plane wave beam is acquired by the wavefront acquisition component (3) and is used as initial data for debugging the multi-pass cascade amplification laser driver (7).

6. The debugging device of the multi-pass cascade amplification laser driver according to claim 1, wherein: the transmission space output lens (711) is fixed and takes the optical axis thereof as a reference optical axis, namely, the debugging device of the multi-pass cascade amplification laser driver (7) and all optical elements of the multi-pass cascade amplification laser driver (7) finish debugging by taking the optical axis and the spatial position of the transmission space output lens (711) as reference standards.

7. The debugging device of the multi-pass cascade amplification laser driver according to claim 1, wherein: the focusing far field characteristics at the transmission space filtering hole disc (713) and the cavity space filtering hole disc (773) are derived from beam aberration characteristics, and the via hole efficiency of the transmission space filter (71) and the cavity space filter (77) is influenced; when the laser beam is transmitted by the multi-pass cascade amplification laser driver (7), the far-field focal spot divergence angle comes from defocusing aberration, and the rest aberration influences the focal spot form; the defocusing aberration of the output beam of the multi-pass cascade amplification laser driver (7) can be dynamically adjusted by adjusting the axial spatial positions of the corresponding lenses of the transmission spatial filter (71) and the cavity spatial filter (77); the distortion mirror (79) can be adjusted to dynamically adjust the multi-pass cascade amplification laser driver (7) to output beam aberration and far-field focal spots.

8. A method for debugging a multi-pass cascade amplification laser driver according to any of claims 1-7, comprising the steps of:

firstly, a transmission space vacuum pipeline of a transmission space filter (71) is arranged on a support frame of an optical table, a transmission space input lens (712) is arranged at the input end, a transmission space output lens (711) is arranged and fixed at the output end, and the mechanical central axis of the transmission space vacuum pipeline and the transmission space output lens (711) have the same optical axis; the focal length of an output lens (711) in a vacuum transmission space pipeline under a vacuum condition is obtained through the formula (1), the center of a second small hole (7132) of a filter hole disc (713) of a transmission space filter (71) is superposed with the focal point of the transmission space output lens (711) under the vacuum condition, a second optical fiber collimator (121) and a second right-angle total reflection prism (122) combined adjusting frame are arranged near the second small hole (7132), and an optical fiber point light source of the second optical fiber collimator (121) is smaller than the one-time diffraction limit of the transmission space output lens (711) and forms a mirror image relation with the center of the second small hole (7132); the second output end of the single-mode optical fiber light source (113) transmits the light source to a second optical fiber collimator (121) and a second right-angle total reflection prism (122) through a second optical fiber (120), and the light source is collimated by a transmission space output lens (711) of the transmission space filter (71) to generate a near-diffraction limit coaxial plane wave light beam; a first optical fiber collimator (111) and a first right-angle total reflection prism (112) combined adjusting frame are arranged near a first small hole (7131) of a transmission space filtering hole disc (713) of the transmission space filter (71), and an optical fiber point light source of the first optical fiber collimator (111) is smaller than one-time diffraction limit of a transmission space input lens (712) and forms a mirror image relation with the center of the first small hole (7131); the first output end of the single-mode fiber light source (113) transmits the light source to a first fiber collimator (111) and a first right-angle total reflection prism (112) through a first path of fiber (110), and the light source is collimated by a transmission space input lens (712) of the transmission space filter (71) to generate paraxial plane wave light beams close to the diffraction limit;

secondly, starting a low vacuum unit and a high vacuum unit of a low-temperature pump vacuum combined unit (51) of the vacuum unit (5), and pumping a transmission space filter (71) to a vacuum state by a transmission vacuum gate valve (52); a wedge-shaped reflector (2) is arranged behind a transmission space output lens (711) of the transmission space filter (71) and the pitching and the deflection of the wedge-shaped reflector are adjusted, a coaxial plane wave beam close to the diffraction limit is reflected by the wedge-shaped reflector (2) to enter a wave front acquisition component (3), a wave front sensor (31) measures the output aberration of a beam shrinking beam, a small-aperture lens (32) in the wave front acquisition component (3) is finely adjusted along the axial direction, the defocusing aberration is adjusted to be zero, aberration data is recorded and recorded as phi ₀ As initial data for debugging the multi-pass cascade amplification laser driver (7); the second optical fiber collimator (121) and the second right angleThe combined adjusting frame of the reflecting prism (122) integrally translates to the side edge of the transmission space filtering hole disc (713), namely moves out of the optical path;

thirdly, amplifying the light path and the space arrangement of a laser driver (7) through a laser tracker according to the multi-pass cascade, placing a boosting reflector (73) in the light path of a paraxial plane wave beam output by a transmission space input lens (711) of a transmission space filter (71), adjusting the horizontal deflection and the pitch angle of the boosting reflector (73), enabling the incident paraxial plane wave beam with the diffraction limit to re-enter the transmission space filter (71) after being reflected by the boosting reflector (73), entering a wedge-shaped reflector (2) and a wavefront collection component (3) after passing through a second small hole (7132), and recording aberration data by a wavefront sensor (31) and recording the aberration data as phi ₁ (ii) a A booster amplifier (72) is arranged between the booster reflector (73) and the transmission space input lens (711), after the horizontal deflection and the pitch angle of the booster amplifier (72) are integrally adjusted, the wave front sensor (31) records aberration data which are recorded as phi ₂ (ii) a Adjusting the axial position of the transmission space input lens (711) by the driving motor when the aberration data phi ₂ When the middle defocusing aberration is divergent, the transmission space input lens (711) moves coaxially along the transmission space vacuum pipeline to the direction far away from the second small hole (7132), and when the aberration data phi is in a diverging state ₂ When the middle defocusing aberration is convergent, the transmission space input lens (711) moves coaxially along the transmission space vacuum pipeline to the direction close to the second small hole (7132), and when the aberration data phi recorded by the wavefront sensor (31) ₂ When the middle defocusing aberration is zero, the transmission space input lens (711) stops moving and is fixedly locked;

installing a cavity space vacuum pipeline of the cavity space filter (77) on a support frame of the optical table board, installing a cavity space input lens (771) at an input end, installing a cavity space output lens (772) at an output end, and enabling a mechanical central axis of the cavity space vacuum pipeline to be coaxial with the cavity space input lens (771) and the cavity space output lens (772); obtaining the focal lengths of a cavity space input lens (771) and a cavity space output lens (771) under the vacuum condition in a transmission space vacuum pipeline by the formula (1), enabling the focal points of the cavity space input lens (771) and the cavity space output lens (772) to be coincided by adjusting a driving motor, placing a cavity space filtering hole disc (773) of a cavity space filter (77), and enabling the center of a fifth small hole (7735) to be located at the common focal point of the cavity space input lens (771) and the cavity space output lens (772); starting a low vacuum unit, a high vacuum unit and a cavity vacuum gate valve (53) of a cryopump vacuum combination unit (51) of the vacuum unit (5), vacuumizing a cavity space filter, and adjusting a cavity space input lens (771) and a cavity space output lens (772) to be coaxial and confocal through driving motors of the cavity space input lens (771) and the cavity space output lens (772) under a vacuum condition;

fifthly, according to the optical path and the spatial arrangement of the multi-pass cascade amplification laser driver (7), a deformable mirror (79) is arranged at the outlet end of a cavity space output lens (772) of the cavity space filter (77) by using a laser tracker; installing a transflective polarizer (74) at the cavity space input lens (771) of the cavity space filter (77) and adjusting to a polarization working angle; adjusting the horizontal deflection and the pitch angle of a boosting reflector (73), and reflecting paraxial plane wave beams which are output by a transmission space input lens (711) of a transmission space filter (71) and are close to a diffraction limit by a transmission and reflection polarizing plate (74) and then entering a cavity space filter (77); a cavity amplifier (78) is arranged between a cavity space output lens (772) of the cavity space filter (77) and the deformable mirror (79); the paraxial plane wave light beam with the diffraction limit is transmitted back and forth once in the cavity space filter (77), the cavity amplifier (78) and the deformable mirror (79) and returns to the transmission space filter (71), and the wave front sensor (31) records aberration data which is recorded as phi ₃ (ii) a Translating the cavity space output lens (772) along the optical axis by a drive motor when the aberration data phi ₃ When the middle defocusing aberration is divergent, the cavity space output lens (772) moves and adjusts along the cavity space vacuum pipeline in the direction away from the fifth small hole (7735) coaxially, and when the aberration data phi is ₃ When the medium defocusing aberration is convergent, the cavity space input lens (772) moves coaxially along the vacuum pipeline to be adjusted towards the direction close to the fifth small hole (7735), and recorded aberration data phi ₃ When the middle defocusing aberration is zero, the cavity space output lens (772) stops moving and completes fixing and locking;

sixthly, an electro-optical switch (76) and a cavity reflector (75) are arranged behind the transflective polarizer (74), and the electro-optical switch (76) and the cavity reflector (75) are arrangedThe surface center normal direction coincides with the central optical axis of the cavity space filter (77); the first wave plate (41) of the wave plate assembly (4) is moved to the second small hole (7732) of the cavity space filtering hole disc (773) through the first wave plate driving motor; the second wave plate (42) of the wave plate component (4) is moved to a third small hole (7733) of a filter hole disc (773) of the cavity space filter (77) through a second wave plate driving motor; the attitude of a transmission and reflection polarizing plate (74) is finely adjusted, a paraxial wave output by a paraxial plane wave close to a diffraction limit input lens (711) of a transmission space filter (71) is subjected to tiny deflection, the paraxial wave passes through a first small hole (7731) and then enters a cavity amplifier (78) and a deformable mirror (79), the attitude of the deformable mirror (79) is finely adjusted, an incident beam passes through a paraxial hole (7732) and a first wave plate (41) after being subjected to tiny deflection, the polarization direction of the beam is rotated by 90 degrees and then is transmitted into the transmission and reflection polarizing plate (74) and an electro-optical switch (76) and then enters a cavity reflector (75), the attitude of the cavity reflector (75) is finely adjusted, the beam is turned back and then is transmitted through the electro-optical switch (76) and the transmission and reflection polarizing plate (74) and then enters a third small hole (7733) and a second wave plate (42), the polarization direction of the beam is rotated by 90 degrees again and then is again passed through the cavity amplifier (78) and then enters the deformable mirror (79), the beam after being reflected by the deformable mirror (79), the deformable mirror (79) and then passes through a fourth small hole (7734) After reflection, the wave is returned to the boosting spatial filter (71), the wave front sensor (31) is started to record aberration data which is recorded as phi ₄ (ii) a Translating the cavity space input lens (771) along the optical axis by a drive motor when the aberration data phi ₄ When the middle defocusing aberration is divergent, the cavity space input lens (771) moves and adjusts along the cavity space vacuum pipeline to the direction far away from the fifth small hole (7735), and when the aberration data phi is obtained ₄ When the middle defocusing aberration is convergent, the cavity space input lens (771) moves and is adjusted towards the direction close to the fifth small hole (7735) along the cavity space vacuum pipeline, and when the aberration data phi is obtained ₄ When the middle defocusing aberration is zero, the cavity space output lens (771) stops moving and completes fixing and locking;

seventhly, after the debugging process is completed, the recorded aberration data phi ₀ ，Ф ₁ ，Ф ₂ ，Ф ₃ ，Ф ₄ The intermediate defocusing aberration is adjusted to be zero, and the multi-pass cascade amplification laser driver (7) has good spatial filtering via hole efficiency; aberration data phi ₄ Phi of ₀ The difference between the two is the residual aberration after the multi-pass cascade amplification laser driver (7) finishes debugging;

integrally translating a combined adjusting frame of a first optical fiber collimator (111) and a first right-angle total reflection prism (112) of an optical fiber light source component (1) to the side edge of a transmission space filtering hole disc (713), moving out a light path, respectively moving a first wave plate (41) and a second wave plate (42) out of a second small hole (7732) and a third small hole (7733) of a cavity space filtering hole disc (773) through a wave plate vacuum driving motor, and completing debugging work by a debugging device of a multi-pass cascade amplification laser driver (7); injecting a seed laser light source into a first small hole (7131) of a filter hole disc (713) of a transmission spatial filter (71) of the multi-pass cascade amplification laser driver (7); the aberration output after the seed laser light source is injected into the multi-pass cascade amplification laser driver (7) is corrected through the wavefront sensor (31), the computer (6) and the deformable mirror (79).

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