Optical path collimation adjustment method for rod amplifier

Abstract

The application discloses a light path collimation adjustment method for a rod-shaped amplifier. The direction of an outgoing laser diffraction stripe is tested by using a CCD, so as to determine the transmission direction of the light beam in the rod-shaped amplifier and the degree of light cutting. The direction of the incident light is adjusted, so that the incident laser can pass through the long-size rod-shaped amplifier without cutting and the integrity of the outgoing laser spatial spot is maintained. The application is simple in operation, scientific and effective, high in precision and strong in practicability, and can be applied to the adjustment of various rod-shaped amplifiers, so as to improve the quality of the amplified light beam.

Description

Technical Field

[0001] This invention relates to the field of laser amplification and adjustment, and in particular to a method for adjusting the collimation of incident and outgoing light in a rod amplifier. Background Technology

[0002] High-power laser systems have important applications in laser processing, light-matter interaction, and other fields. Rod amplifiers are a commonly used type of amplifier in high-power laser systems. In actual laser system setups, the beam spot size is sometimes slightly smaller than the aperture of the rod amplifier's gain medium. This can easily cause the beam to be cut off at the rod's edge after passing through the amplifier, resulting in diffraction. Furthermore, larger beam spots also readily induce diffraction. Diffraction fringes can affect the quality of the amplified beam and even damage the gain medium. Therefore, it is necessary to find a method to minimize the appearance of diffraction fringes after the beam passes through the rod amplifier.

[0003] Currently, the main method for adjusting the collimation of the incident and outgoing light of a rod amplifier is to first build a collimated optical path using a pinhole. After the pinhole is calibrated, the amplifier is placed in front of the pinhole in the optical path, and the amplifier's orientation is adjusted to ensure that the beam passes through the center of the pinhole. However, this method also has problems, namely, the various components in the optical path have a slow drift problem after being built, and sometimes the optical path needs to be modified. After a long time, the pinhole calibration position will also be deviated. Summary of the Invention

[0004] The purpose of this invention is to provide a method for adjusting the optical path collimation of a rod amplifier, overcoming the shortcomings of existing methods. This method can be applied to the adjustment of various rod amplifiers, thereby improving the quality of the amplified beam.

[0005] To achieve the objectives of the invention described above, the technical solution of the present invention is as follows:

[0006] A method for collimating and adjusting the optical path of a rod amplifier is characterized by setting two reflectors in the incident optical path of the rod amplifier and setting a CCD in the output optical path of the rod amplifier; using the CCD to observe the direction of the diffraction fringes of the output beam, the transmission direction and the degree of light interception in the rod amplifier are determined, and by adjusting the attitude of the reflectors, the incident light can pass through the rod amplifier without light interception, thus ensuring the integrity of the spatial spot of the output laser.

[0007] The method of the present invention specifically includes the following steps:

[0008] ①: Setting up the optical path: The first reflector, the second reflector (3) and the rod amplifier are set up in sequence along the direction of the incident laser, so that the incident laser with a diameter equivalent to that of the rod amplifier passes through the first reflector and the second reflector and enters the rod amplifier in sequence.

[0009] ②: Place the CCD at the output end of the rod amplifier and use the CCD to observe the normal direction of the outgoing light diffraction fringes to determine the initial position. If there are no obvious diffraction fringes, or the fringes are chaotic but uniform, select either the first or the second mirror and continuously adjust the attitude in the same direction to make the diffraction fringes more obvious and obvious diffraction fringes appear in the adjustment direction. After determining the center point 1 of the fringes according to the normal direction of the diffraction fringes, return to the initial position.

[0010] ③: Adjust the same mirror to the same orientation in the opposite direction to the adjustment direction in step ②. The rest of the process is the same as in step ②. Determine the center point 2 of the diffraction fringe according to the normal direction of the diffraction fringe.

[0011] ④: Adjust the same orientation of the mirror as in step ②, and follow the same procedure as steps ② and ③. Confirm again the positions of the two center points to which the stripes point.

[0012] ⑤: With the two center points 1 and 2 in the same horizontal position, adjust any one of the second mirrors to make the diffraction fringes significantly deviate from the center position; adjust the first mirror, adjusting its position to be the same as the second mirror's position, but in the opposite direction, to restore the diffraction fringes to their original state until the two center points on the CCD are aligned in one direction.

[0013] ⑥: Adjust the next orientation of the reflector; the rest of the process is the same as step ⑤.

[0014] ⑦: If center point 1 and center point 2 are not perfectly aligned, return to step ⑤; if a standard pinhole diffraction pattern appears on the CCD, that is, the diffraction pattern has only one center point and the beam is perfectly aligned, then the adjustment is complete; if not perfectly aligned, repeat steps ⑤ and ⑥, reducing the adjustment range until a standard pinhole diffraction pattern appears on the CCD.

[0015] This invention treats the process of laser light passing through a rod-shaped amplifier as two circular aperture diffractions, one on the front and one on the back surface of the amplifier. If the light beam does not pass through the center of the front and back surfaces of the amplifier's dielectric rod, but the lateral positions when passing through the front and back surfaces are the same, an asymmetrical diffraction ring will appear. However, the diffraction ring has only one center point. If the light beam does not pass through the center of the front and back surfaces of the amplifier's dielectric rod and the lateral positions when passing through the front and back surfaces are not the same, a more chaotic diffraction fringe will appear. This is caused by the superposition of the two diffractions, and the diffraction fringes of the two diffractions have different center points. Therefore, two center points can be observed by the CCD at the end.

[0016] Compared with existing technologies, the advantages of this invention are: simple operation, scientific effectiveness, high precision and strong practicality. It can be applied to the adjustment of various rod amplifiers to improve the quality of the amplified beam. Attached Figure Description

[0017] Figure 1 This is a flowchart of the optical path collimation adjustment method for the rod amplifier of the present invention;

[0018] Figure 2 This is a schematic diagram of the optical path in this invention;

[0019] Figure 3 The images show the diffraction patterns acquired by the CCD before and after adjustment, where 1 represents the diffraction pattern before adjustment and 2 represents the diffraction pattern after adjustment. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the scope of protection of the present invention.

[0021] A method for adjusting the collimation of incident and outgoing light in a rod amplifier, the adjustment process is as follows: Figure 1 As shown

[0022] Step ①: An incident laser 1 with a diameter equivalent to that of the rod passes through the first reflecting mirror 2 and the second reflecting mirror 3 in sequence, and then enters the rod-shaped amplifier 4.

[0023] Step 2:

[0024] Place the CCD5 at the output end of the rod amplifier 4, observe the normal direction of the outgoing light diffraction fringes using the CCD5, and determine the initial position. If there are no obvious diffraction fringes, or the fringes are chaotic but uniform, select any orientation adjustment of the first mirror 2 and the second mirror 3 (two orientations of the mirrors: pitch forward and backward or rotation left and right), and continuously adjust this orientation of the mirrors in the same direction (forward, backward, left and right) to make the diffraction fringes more obvious and only obvious diffraction fringes appear in the adjustment direction. Determine the center point 1 of the fringes by the normal direction of the diffraction fringes, and then return to the initial position.

[0025] The CCD5 is placed at the output of the rod amplifier, and the normal direction of the outgoing light diffraction fringes is observed using the CCD5. If there are no obvious diffraction fringes, or the fringes are disordered but uniform, any adjustment direction of any reflector is selected, and this direction is continuously adjusted until the diffraction fringes become obvious and only appear in the adjusted direction. The center point 1 of the fringes is determined by the normal direction of the diffraction fringes, and then the mirror is returned to the initial position.

[0026] Step ③: Adjust the mirror to the same position as in Step ②, and adjust it in the opposite direction to Step ②. The rest of the process is the same as in Step ②. Determine the center point 2 of the diffraction fringes by the direction of the normal to the diffraction fringes.

[0027] Step 4: Adjust the mirror to the same orientation as in Step 2, but follow the same procedures as in Steps 2 and 3. Reconfirm the center points 1 and 2 of the diffraction pattern (see attached diagram). Figure 2 Adjust the position of the arrow tail to ensure that the center points 1 and 2 are correctly positioned; readjust the mirror as in step ②, and adjust the direction perpendicular to step ②. Repeat steps ② and ③, and reconfirm the center points 1 and 2 of the diffraction pattern (see attached image). Figure 2 The position of the arrow tail is checked to ensure that the positions of center points 1 and 2 are correct.

[0028] Step 5:

[0029] First, level the center points 1 and 2 in the same orientation. Then, adjust any orientation of the mirror 2 so that the diffraction fringes are significantly deviated from the center position. Adjust the first mirror 1 in the same orientation as the second mirror 2, but in the opposite direction (front, back, left, right) to restore the diffraction fringes to their original state. Repeat the above process until the two center points on the CCD are aligned in one direction.

[0030] First, align center points 1 and 2 horizontally in one direction. Then, adjust mirror 2 in one direction until the diffraction fringes are noticeably off-center. Next, adjust mirror 1 in the same but opposite direction as mirror 2, restoring the diffraction fringes to their original state. Repeat this process until the two center points on the CCD are aligned in one direction.

[0031] Step 6: Adjust to a different posture than in Step 5; the rest of the process is the same as in Step 5.

[0032] Adjust the direction perpendicular to step ⑤, and repeat the rest of the process as in step ⑤.

[0033] Step 7: If the beam is perfectly aligned, a standard pinhole diffraction pattern will appear on the CCD, and the diffraction pattern will have only one center point. If it is not perfectly aligned, repeat steps 5 and 6 but reduce the adjustment range until a standard pinhole diffraction pattern appears on the CCD.

[0034] This invention treats the process of laser light passing through a rod-shaped amplifier as two circular aperture diffractions, one on the front surface and one on the back surface of the amplifier. If the beam does not pass through the center of the front and back surfaces of the amplifier's dielectric rod, but the lateral positions when passing through the front and back surfaces are the same, an asymmetrical diffraction ring will appear. However, the diffraction ring has only one center point. If the beam does not pass through the center of the front and back surfaces of the amplifier's dielectric rod and the lateral positions when passing through the front and back surfaces are not the same, more chaotic diffraction fringes will appear. This is caused by the superposition of the two diffractions, and the diffraction fringes of the two diffractions have different center points. Therefore, two center points can be observed by the CCD at the end. Figure 3 As shown in Figure 1. Then, through continuous adjustment... Figure 2 The attitude of the mirror in the middle was obtained Figure 3The standard pinhole diffraction pattern in section 2 is now in the adjusted state.

[0035] The invention ultimately yielded a standard pinhole diffraction pattern, such as... Figure 3 As shown in Figure 2, this indicates that the beam passes through the center of the front and rear surfaces of the amplifier dielectric rod, which helps to improve the quality of the amplified beam.

Claims

1. A method for adjusting the optical path collimation of a rod amplifier, characterized in that, Two reflectors are set in the incident light path of the rod amplifier, and a CCD is set in the outgoing light path of the rod amplifier. The direction of the diffraction fringes of the outgoing beam is observed by the CCD to determine the transmission direction and the degree of light interception in the rod amplifier. By adjusting the attitude of the reflectors, the incident light can pass through the rod amplifier without light interception, ensuring the integrity of the outgoing laser spatial spot. The method specifically includes the following steps: : Setting up the optical path: The first reflector (2), the second reflector (3) and the rod amplifier (4) are set up in sequence along the direction of the incident laser (1), so that the incident laser (1) with a rod diameter equivalent to that of the rod amplifier (4) passes through the first reflector (2) and the second reflector (3) and is incident into the rod amplifier (4) in sequence; Place the CCD (5) at the output end of the rod amplifier (4), observe the normal direction of the outgoing light diffraction stripes using the CCD (5), and determine the initial position. If there are no obvious diffraction stripes, or the stripes are chaotic but uniform, select either the first mirror (2) or the second mirror (3) and continuously adjust the attitude in the same direction to make the diffraction stripes more obvious and obvious diffraction stripes appear in the adjustment direction. After determining the center point 1 of the stripe direction according to the normal direction of the diffraction stripes, return to the initial position. : Towards and Steps Adjust the mirror in the opposite direction to achieve the same orientation; other processes and steps. Similarly, based on the normal direction of the diffraction fringes, determine the center point 2 to which the fringes point; Adjustment and Steps Different orientations of the same mirror, other processes and steps Similarly, confirm again the positions of the two center points to which the stripes point; : With the two center points 1 and 2 in the same horizontal position, adjust the position of any one of the second mirrors so that the diffraction fringes are significantly deviated from the center position; adjust the first mirror so that the position is the same as that of the second mirror, but the direction of adjustment is opposite, so that the diffraction fringes return to their original state until the two center points on the CCD are aligned in one direction. Adjusting the reflector to its next orientation, other processes and steps. same; If center point 1 and center point 2 are not perfectly aligned, return to step 2. ; If a standard pinhole diffraction pattern is displayed on the CCD (5), that is, the diffraction pattern has only one center point and the beam is perfectly aligned, then the adjustment is complete; if it is not perfectly aligned, repeat the steps. Reduce the adjustment range until a standard pinhole diffraction pattern appears on the CCD.

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