Four-pass amplified high-power laser system light beam control monitoring simulation light device

Abstract

An analog light device for light beam monitoring of a four-pass amplification system comprises the four-pass amplification system, a first dichroic mirror and a second dichroic mirror are arranged at the positions of two output reflectors of the four-pass amplification system respectively, and the first dichroic mirror and the second dichroic mirror highly reflect main laser and transmit analog light; the simulation light device of the four-pass amplification system can be continuously stored in a light path under the condition that main laser emission is not affected, and the situation of light beam jitter caused by all optical elements in a laser link in the system can be continuously represented in real time through the simulation light. According to the device, the simulation light has two modes of forward injection and reverse injection, so that the monitoring of the light beam jitter of the whole laser link at different positions can be realized, and the device can adapt to the flexible arrangement of different device characteristics.

Description

Technical Field

[0001] The present invention relates to the technical field of high-power laser systems, and in particular to a four-pass amplified high-power laser system simulation light device, which is used to provide a monitoring light source for beam pointing control, and is kept in the system laser light path before the main laser of the four-pass amplification system is emitted without affecting the main laser emission. Background Art

[0002] In the field of high-power laser systems, various vibration sources, such as earthquakes, industrial noise, wind, temperature changes, etc., cause optical components to vibrate, resulting in laser beam pointing jitter, which will seriously restrict the high-power laser from achieving precision targeting. In order to solve this problem, automatic beam alignment is usually used to improve the accuracy of beam targeting, but this method can only solve the problem of slow drift of the beam within a certain period of time, and cannot solve the problem of high-frequency beam jitter (generally the frequency does not exceed 100Hz) in a short period of time before the high-power laser is launched. One of the foundations and keys to solving high-frequency beam jitter is how to accurately and in real time measure the beam jitter caused by all optical components without affecting the main beam emission. To this end, it is necessary to configure the high-power laser system with an analog optical device that can effectively pass through the laser link of the system before the main laser is launched.

[0003] Existing analog light sources are generally independent of high-power lasers. When in use, they usually move related components into the laser light path through a motion mechanism to couple the analog light into the laser light path, configure the collimated imaging system to a static low-energy debugging state, and then restore to the high-power laser target shooting state after debugging. It takes tens of seconds to switch between debugging and target shooting states, and to solve the problem of high-frequency beam jitter measurement without affecting the main laser emission, the switching time between the two states needs to be less than 10 milliseconds, which cannot be achieved with the existing high-power laser system and the corresponding analog light configuration. Summary of the invention

[0004] In view of the above-mentioned existing high-power laser four-pass amplification system, the present invention provides a four-pass amplified high-power laser system beam control monitoring simulation light device, which can be continuously stored in the laser light path without affecting the main laser emission, and the simulation light is used to real-time characterize the beam jitter caused by all optical components in the laser link in the system. The simulation light device only needs to replace a small number of optical components in the existing four-pass amplification system in situ, and can realize the simulation light that can be stored at any time outside the main laser emission moment of the system. Its principle and structure are simple, the cost is low, and it is easy to implement in engineering.

[0005] To achieve the above objectives, the technical solutions of the present invention are as follows:

[0006] A simulated light device for beam monitoring of a four-pass amplification system, comprising an original four-pass amplification system, characterized in that a first dichroic mirror and a second dichroic mirror are arranged at the positions of two output reflectors of the original four-pass amplification system, wherein the first dichroic mirror and the second dichroic mirror are highly reflective to the main laser and transparent to the simulated light;

[0007] The simulated light injection beam is reversely injected through the first dichroic mirror and then coaxially coupled with the optical axis of the four-pass amplification system. After passing through the four-pass amplification system, it passes through the second dichroic mirror to become a simulated light output beam.

[0008] The simulated light injection beam is forwardly injected through the second dichroic mirror and then coaxially coupled with the optical axis of the four-pass amplification system. After passing through the four-pass amplification system, it passes through the first dichroic mirror and becomes a simulated light output beam.

[0009] The first reflector, the second reflector and the third reflector are highly reflective to the simulated light beam.

[0010] When voltage is applied to the electro-optical switch, the polarization direction of the main laser light changes by 90° when the main laser light passes through the electro-optical switch; when voltage is not applied to the electro-optical switch, the polarization direction of the main laser light or the simulated light does not change.

[0011] The central wavelength of the injected light beam of the reverse simulated light is determined according to the characteristics of the transflective polarizer in the four-pass amplification system, and the transflective polarizer can transmit the injected light beam.

[0012] The outer dimensions of the first dichroic mirror and the second dichroic mirror are consistent with the outer dimensions of the two original reflecting mirrors at the same position in the four-pass amplification system (3).

[0013] The technical effects of the present invention are as follows:

[0014] For the four-pass amplification high-power laser system, the four-pass amplification system simulation light device of the present invention can be continuously stored in the optical path without affecting the main laser emission. The simulation light can be used to continuously and in real time characterize the beam jitter caused by all optical components in the laser link in the system. The device has two ways of forward and reverse injection of simulation light, which can realize the monitoring of the beam jitter of the entire laser link at different positions, and can be flexibly set to adapt to the characteristics of different devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the light beam monitoring simulation light device (simulated light reverse injection) of the four-pass amplification system of the present invention

[0016] In the figure: 1-simulated light injection beam, 2-first dichroic mirror, 3-four-pass amplification system, 301-electro-optical switch, 302-transmissive polarizer, 303-transmission space filter, 304-cavity space filter, 305-transmission space filter aperture, 306-cavity space filter aperture, 307-first reflector, 308-second reflector, 309-third reflector, 310-boost amplifier, 311-cavity amplifier, 4-second dichroic mirror, 5-simulated light output beam.

[0017] Figure 2 Schematic diagram of the light beam monitoring simulation light device (simulated light forward injection) of the four-pass amplification system of the present invention

[0018] In the figure: 1-simulated light injection beam, 2-first dichroic mirror, 3-four-pass amplification system, 301-electro-optical switch, 302-transmissive polarizer, 303-transmission space filter, 304-cavity space filter, 305-transmission space filter aperture, 306-cavity space filter aperture, 307-first reflector, 308-second reflector, 309-third reflector, 310-boost amplifier, 311-cavity amplifier, 4-second dichroic mirror, 5-simulated light output beam.

[0019] Figure 3 It is a typical transmittance curve of the transflective polarizer 302 of the present invention for different polarization states. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with embodiments and drawings, but the protection scope of the present invention shall not be limited thereto.

[0021] Example

[0022] Figure 1 Schematic diagram of the simulated light device (simulated light reverse injection) for beam monitoring of the four-pass amplification system of the present invention. As can be seen from the figure, the simulated light device for beam monitoring of the four-pass amplification system of the present invention comprises an original four-pass amplification system 3, characterized in that a first dichroic mirror 2 and a second dichroic mirror 4 are arranged at the positions of the two output reflectors of the original four-pass amplification system 3, and the first dichroic mirror 2 and the second dichroic mirror 4 are highly reflective to the main laser and transparent to the simulated light;

[0023] The simulated light injection beam 1 is reversely injected through the first dichroic mirror 2 and then coaxially coupled with the optical axis of the four-pass amplification system 3. After passing through the four-pass amplification system 3, it passes through the second dichroic mirror 4 to become a simulated light output beam 5.

[0024] The simulated light injection beam 1 is forwardly injected through the second dichroic mirror 4 and coaxially coupled with the optical axis of the four-pass amplification system 3 . After passing through the four-pass amplification system 3 , it passes through the first dichroic mirror 2 to become a simulated light output beam 5 .

[0025] The first reflector 307 , the second reflector 308 , and the third reflector 309 are highly reflective to the simulated light beam.

[0026] When voltage is applied to the electro-optical switch 301, the polarization direction of the main laser light changes by 90° when the main laser light passes through the electro-optical switch 301; when no voltage is applied to the electro-optical switch 301, the polarization direction of the main laser light or the simulated light does not change.

[0027] The central wavelength of the injected light beam 1 of the reverse simulated light is determined according to the characteristics of the transflective polarizer 302 in the four-pass amplification system 3 , and the transflective polarizer 302 can transmit the injected light beam 1 .

[0028] The outer dimensions of the first dichroic mirror 2 and the second dichroic mirror 4 are consistent with the outer dimensions of the original two reflecting mirrors at the same position in the four-pass amplification system 3 .

[0029] The four-pass amplification system 3 includes an electro-optical switch 301, a transflective polarizer 302, a transmission space filter 303, a cavity space filter 304, a transmission space filter aperture 305, a cavity space filter aperture 306, a first reflector 307, a second reflector 308, a third reflector 309, a boost amplifier 310, and a cavity amplifier 311.

[0030] The reverse simulated light injection beam 1 passes through the first dichroic mirror 2, is coaxially coupled with the optical axis of the four-pass amplification system 3, and is incident on the second dichroic mirror 4 after passing through the four-pass amplification system 3. The simulated light beam passes through the second dichroic mirror 4 to become a reverse simulated light output beam 5. The optical elements that the simulated light output beam 5 passes through when passing through the four-pass amplification system 3 between the first dichroic mirror 2 and the second dichroic mirror 4 are consistent with those of the main laser, and can accurately characterize the beam pointing characteristics of this section of the optical path.

[0031] Figure 2 Schematic diagram of the light beam monitoring simulation light device (simulated light forward injection) of the four-pass amplification system of the present invention

[0032] The forward simulated light injection beam 1 passes through the second dichroic mirror 4, is coaxially coupled with the optical axis of the four-pass amplification system 3, passes through the first dichroic mirror 2 after passing through the four-pass amplification system 3, and the simulated light beam passes through the first dichroic mirror 2 to become the forward simulated light output beam 5. The optical elements that the forward simulated light output beam 5 passes through when passing through the four-pass amplification system 3 between the second dichroic mirror 4 and the first dichroic mirror 2 are consistent with those of the main laser, and can accurately characterize the beam pointing characteristics of this section of the optical path.

[0033] The first reflector 307 , the second reflector 308 , and the third reflector 309 are highly reflective to the simulated light beam.

[0034] When voltage is applied to the electro-optical switch 301, the polarization direction of the main laser changes by 90° when passing through the electro-optical switch.

[0035] The electro-optical switch 301 does not change the polarization direction of the main laser or the simulated light when no voltage is applied.

[0036] After passing through the second dichroic mirror 4 , the forward injected light beam 6 is coaxial with the injected light beam of the four-pass amplification system 3 and has the same transmission direction.

[0037] The central wavelength of the forward simulated light injection beam 1 is determined according to the characteristics of the transflective polarizer 302 of the four-pass amplification system 3, and the transflective polarizer 302 can transmit part of the wavelength beam.

[0038] Taking Example 1 as an example, the working principle of this device is described as follows:

[0039] The four-pass amplification system based on the large-aperture electro-optic switch of the present invention utilizes the opening and closing of the electro-optic switch 301 to realize the change of the polarization state of the light beam, and combines the transflective polarizer 302 to realize the control of the light beam transmission path, so that the light beam passes through the cavity amplifier 311 four times. Specifically, the small-aperture, low-energy light beam output by the pre-amplifier system is reflected by the second dichroic mirror 308, transmitted to the left through the small hole of the transmission space filter 303, collimated into parallel light after passing through the transmission space filter 303, and amplified once by the boost amplifier 310; then, it is reflected by the first reflector 307 and enters the transflective polarizer 302. At this time, the light beam is S light for the transflective polarizer 302. After being reflected by the transflective polarizer 302, it passes through the electro-optic switch 301 without voltage, and its polarization direction remains unchanged. After passing through the cavity space filter 304 for the first time, it enters the cavity amplifier 311. After the first amplification, it is incident on the second reflector 308 and returns to the cavity amplifier 311. After the second amplification, it is incident on the cavity space filter 304 for the second time. After exiting, it passes through the electro-optic switch 301 with high voltage, and its polarization direction is rotated 90°. At this time, the light beam is not reflected by the transflective polarizer 302 is P light, the light beam will pass through the transflective polarizer 302 and be reflected by the third reflector 309 and return and pass through the transflective polarizer 302; it passes through the electro-optical switch 301 with high voltage for the third time, and its polarization direction rotates 90°, which is consistent with the polarization direction of the first time it passes through the electro-optical switch 301, and enters the cavity amplifier 311 after passing through the cavity space filter 304 for the third time, and is incident on the second reflector 308 after the third amplification and returns to the cavity amplifier 311, and is incident on the cavity space filter 304 for the fourth time after the fourth amplification; after exiting, it passes through the electro-optical switch 301 without high voltage, and at this time the light beam is S light for the transflective polarizer 302, and is completely reflected by the transflective polarizer 302, and is reflected by the first reflector 307 and amplified by the booster amplifier 310 for the second time; then it passes through the transmission space filter 303 for the second time and is reflected by the first dichroic mirror 2 and continues to be transmitted.

[0040] Before emission, the electro-optic switch 301 is kept in an unpressurized state. The incident light beam 1 of the simulated light is transmitted to the left through the first dichroic mirror 2 and is transmitted in the reverse direction along the main laser output direction. When it reaches the transflective polarizer 302 for the first time, the part of the light beam of the simulated light reflected by the transflective polarizer 302 continues to be transmitted in the reverse direction along the main laser transmission direction, and the reflection ratio is R s , represents the reflectivity of the transflective polarizer to S light; when the reflected light beam reaches the transflective polarizer 302 for the second time after being reflected by the second reflector 308, the light beam passing through the transflective polarizer 302 continues to be transmitted in the reverse direction along the main laser transmission direction, and the transmission ratio is T s When the transmitted light beam reaches the transflective polarizer 302 for the second time after being reflected by the third reflector 309, the light beam passing through the transflective polarizer 302 continues to be transmitted in the reverse direction along the main laser transmission direction, and the transmission ratio is T sWhen the transmitted light beam reaches the transflective polarizer 302 for the fourth time after being reflected by the second reflector 308, the light beam reflected by the transflective polarizer 302 continues to be transmitted in the reverse direction along the main laser transmission direction, and its reflection ratio is R s .

[0041] From the above analysis, it can be seen that after the simulated light passes through the transflective polarizer 302 multiple times along the reverse path of the main laser, the remaining ratio is: T 4path =T s ·R s ·T s ·R s , ignoring factors such as the absorption of the transflective polarizer, T s +R s =1, then when T s =R s =0.5, T 4path There is a maximum value.

[0042] Furthermore, ignoring the difference in the overall static transmittance of the main laser and the simulated light after the four-pass amplification system, according to about T static =50% calculation; the first dichroic mirror and the second dichroic mirror adopt the same film system, and the reflectivity of the main laser is generally greater than 99.5%. In this case, the transmittance of the simulated light wavelength T dichroic >90% is achievable. Therefore, for the simulated beam, the total system transmittance of the simulated light is The maximum value is about 2.5%. For the main laser, consider the transflective polarizer T s :T p =1:200, without considering the dichroic mirror, the total transmittance of the system is: T all =1.25×10 -5 Therefore, the transmittance of the simulated light is about 2000 times that of the main laser when the electro-optical switch 301 is not working.

[0043] According to the above analysis, the selection of the center wavelength λ of the simulated light needs to be determined according to the characteristics of the transflective polarizer 302. The transmittance curve of the transflective polarizer 302 for S light is as follows: Figure 3 The spectral width of the simulated light is as small as possible to ensure good overall transmittance in the entire spectral range.

Claims

1. A simulated optical device for monitoring a beam of a four-pass amplification system, comprising a four-pass amplification system (3), Its characteristic is that A first dichroic mirror (2) and a second dichroic mirror (4) are respectively arranged at the positions of the two output reflective mirrors of the four-pass amplification system (3); the first dichroic mirror (2) and the second dichroic mirror (4) have high reflectivity for the main laser and high transmittance for the simulated light; The simulated light injection beam (1) can be reversely injected through the first dichroic mirror (2) and then coaxially coupled with the optical axis of the four-pass amplification system (3). After passing through the four-pass amplification system (3), it passes through the second dichroic mirror (4) to become a reverse simulated light output beam (5). The simulated light injection beam (1) can also be injected forward through the second dichroic mirror (4) and then coaxially coupled with the optical axis of the four-pass amplification system (3). After passing through the four-pass amplification system (3), it passes through the first dichroic mirror (2) to become a forward simulated light output beam (5).

2. The simulated optical device for beam monitoring of a four-pass amplification system according to claim 1, It is characterized in that The four-pass amplification system comprises an electro-optic switch, a transflective polarizer, a transmission space filter, a cavity space filter, a plurality of reflectors, a booster amplifier and a cavity amplifier, wherein when a voltage is applied to the electro-optic switch (301), the polarization direction of the main laser light changes by 90° when the main laser light passes through the electro-optic switch (301); and when no voltage is applied to the electro-optic switch (301), the polarization direction of the main laser light or the simulated light is not changed.

3. The simulated optical device for beam monitoring of a four-pass amplification system according to claim 1, It is characterized in that The plurality of reflectors have high reflectivity to the simulated light.

4. The simulated optical device for beam monitoring of a four-pass amplification system according to claim 1 or 2, Features The central wavelength of the simulated light injection beam (1) is determined according to the characteristics of the transflective polarizer (302) in the four-pass amplification system (3) to ensure the transmission efficiency of the simulated light injection beam (1) on the transflective polarizer (302).

5. The simulated optical device for beam monitoring of a four-pass amplification system according to any one of claims 1 to 4, Features The outer dimensions of the first dichroic mirror (2) and the second dichroic mirror (4) are consistent with the outer dimensions of the two original reflecting mirrors at corresponding positions in the four-pass amplification system (3).

6. The simulated optical device for beam monitoring of a four-pass amplification system according to any one of claims 1 to 4, It is characterized in that The spectral width of the simulated light injection beam (1) is controlled within a relatively small range to ensure a good overall transmittance in the entire spectral range.

7. The simulated optical device for beam monitoring of a four-pass amplification system according to any one of claims 1 to 4, It is characterized in that By adjusting the power of the simulated light injection beam (1) and the characteristics of the transflective polarizer, the transmittance of the simulated light when no voltage is applied to the electro-optical switch is much higher than the transmittance of the main laser, thereby achieving efficient beam monitoring.

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