Transmission grating pair pulse compression device and pulse compression method

Abstract

The invention discloses a transmission grating pulse compression device and a pulse compression method. Comprising a hollow rotating platform which comprises a rotating platform, a supporting frame and a servo motor; the servo motor is installed in the supporting frame and used for driving the rotating platform to rotate around the center shaft. The flat plate is mounted on the supporting frame of the hollow rotating platform; the fixed seat comprises a fixed front seat and a fixed rear seat which are mounted on the rotating platform, and a ball screw motor is mounted in the fixed rear seat; the ball screw nut comprises a ball screw and a nut, one end of the ball screw is driven by a ball screw motor in the fixed rear seat, and the other end of the ball screw extends into the fixed front seat; the sliding platform is fixed on the nut; the two optical gratings are respectively a first optical grating arranged on the fixed front seat and a second optical grating arranged on the sliding platform, and the first optical grating and the second optical grating are both vertical to the ball screw; and the plane mirror is fixed on the flat plate. The device is efficient and easy to adjust, and can meet the pulse compression requirements under different working conditions.

Description

Technical Field

[0001] This invention relates to the field of pulse compression technology, and specifically to a pulse compression device and method using a transmission grating. Background Technology

[0002] Pulsed lasers, due to their high peak power and short pulse width, are widely used in precision machining, lidar, ultrafast laser science, and medical treatment. However, laser pulses are prone to broadening during propagation due to dispersion effects, affecting the pulse's temporal accuracy and energy density. Therefore, pulse compression technology has emerged. The main function of a pulse compressor is to reduce the difference in propagation speed between different wavelengths of light by adjusting the dispersion of light, thereby compressing the pulse and restoring or increasing its peak power.

[0003] Pulse compression techniques typically rely on optical elements such as gratings, optical fibers, or mirrors to precisely control the pulse propagation path and compensate for dispersion caused by materials or other factors. With the development of laser technology, more and more pulse compression methods have emerged, such as grating compression, four-wave mixing, and fiber compression. These technologies continuously improve the efficiency and accuracy of pulse compression, meeting the demands of high peak power pulsed lasers.

[0004] The existing technology still has the following shortcomings: 1. In some high-precision laser pulse compressors, the design of the transmission grating needs to consider the temporal and spatial matching issues in the optical path. The angle and position of the grating, as well as the beam propagation path, all affect the pulse compression effect. If these factors are not precisely matched, it may lead to unsatisfactory pulse compression results or even cause a degradation in system performance.

[0005] 2. Different application scenarios may require adaptability to different wavelength ranges and pulse compression ratios. Existing pulse compression devices are usually unable to flexibly adjust over a wide wavelength range or efficiently meet diverse needs. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a pulse compression device and method using a transmission grating. The pulse compression device of this invention is highly efficient and easy to adjust. After assembly, the device is driven by a ball screw and a motor, enabling it to meet pulse compression requirements under different working conditions.

[0007] The technical solution adopted in this invention is: I. A pulse compression device using a transmission grating The transmission grating pulse compression device includes: A hollow rotating platform includes a rotating platform, a support frame, and a servo motor; the servo motor is installed inside the support frame and is used to drive the rotating platform to rotate around a central axis. The flat plate is installed on the support frame of the hollow rotating platform and does not rotate with the rotating platform; The fixed base, including the fixed front base and the fixed rear base installed on the rotating platform, can rotate synchronously with the rotating platform. A ball screw motor is installed inside the fixed rear base. A ball screw nut includes a ball screw and a nut, wherein one end of the ball screw is driven by a ball screw motor inside a fixed rear seat, and the other end extends into a fixed front seat; The sliding platform is fixed to the nut. Two gratings are provided: a first grating mounted on a fixed front seat and a second grating mounted on a sliding platform. Both the first and second gratings are perpendicular to the ball screw. A plane mirror is fixed on a flat plate.

[0008] Specifically, the angle between the ball screw and the normal of the plane mirror is configured to be the same as the incident angle. The first grating receives the incident light from the external laser emitting device. After the incident light is diffracted by the first grating and the second grating, it is reflected back to the second grating by the plane mirror. After being diffracted by the second grating and the first grating, a pulse-compressed beam is generated. An external autocorrelator receives the pulse-compressed beam and measures the pulse width after compression.

[0009] Furthermore, the transmission grating pulse compression device also includes two grating adjustment mechanisms: a first grating adjustment mechanism mounted on a fixed front seat and a second grating adjustment mechanism mounted on a sliding platform.

[0010] Specifically, the grating adjustment mechanism mainly consists of a grating frame, a pressure plate, a gear, and a rack. The grating frame is arranged above its own platform. The grating frame adopts an L-shaped bracket. A pressure plate is arranged on the vertical part of the L-shaped bracket to fix the grating. A through groove is opened on the horizontal part of the L-shaped bracket. A gear is arranged in the through groove, and the gear meshes with a rack set on one side wall of the through groove. The length direction of the L-shaped bracket, the through groove, and the rack are all arranged perpendicular to the ball screw.

[0011] Furthermore, the transmission grating pulse compression device also includes two grating adjustment motors, namely a first grating adjustment motor built into the fixed front seat and a second grating adjustment motor built into the sliding platform; the grating adjustment motor is dynamically connected to the gear of the grating adjustment mechanism installed on its own platform, and the grating adjustment motor can drive the gear to rotate, thereby driving the grating on the grating frame to move in a direction perpendicular to the ball screw through the meshing of the gear and rack.

[0012] Furthermore, the servo motor includes a closed-loop feedback module for adjusting the rotation angle in real time.

[0013] Furthermore, the transmission grating pulse compression device also includes an anti-drop pad, the front end of the ball screw is supported on a fixed front seat, and the end is axially positioned by the anti-drop pad.

[0014] Furthermore, the transmission grating pulse compression device also includes at least one guide rod parallel to the ball screw for constraining the rotation of the nut.

[0015] II. A pulse compression method using the above-mentioned transmission grating for a pulse compression device. The pulse compression method includes the following steps: calculating the target rotation angle of the rotating platform and the target moving distance of the sliding platform based on the wavelength and incident angle of the incident light, the target compensation dispersion amount, and the grating parameters of the first grating and the second grating; and driving the rotating platform to rotate and the sliding platform to move along the ball screw based on the target rotation angle of the rotating platform and the target moving distance of the sliding platform, respectively.

[0016] The target grating spacing is obtained using the following formula, based on the wavelength of the incident light, the period of the grating, the incident angle, and the target compensation dispersion: In the formula, GDD is the target compensation dispersion, λ is the wavelength of the incident light, L is the target grating spacing, c is the speed of light, d is the period of the grating, and α is the incident angle.

[0017] Specifically, the incident angle is set as the Littrow angle, which is obtained by the following formula: In the formula, α Littrow Let λ be the Littrow angle, m be the diffraction order, λ be the wavelength of the incident light, and d be the period of the grating.

[0018] The beneficial effects of this invention are: 1. This invention adopts an integrated structure, eliminating the need for cumbersome debugging in different application scenarios. After the grating is installed, it can maintain strict parallelism, and the adjustment accuracy of the sliding platform and the rotating platform is high, with a sensitive response.

[0019] 2. The present invention uses the movement of the sliding platform on the ball screw and the movement of the second grating on the sliding platform to ensure that all the light diffracted by the first grating falls on the second grating. It is convenient and simple to operate and applicable to a variety of application scenarios. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the optical path of the pulse compression device of the transmission grating of the present invention; Figure 2 This is a schematic diagram of the structure of the transmission grating pulse compression device of the present invention; Figure 3 This is a schematic diagram of the grating adjustment mechanism in the pulse compression device of the transmission grating of the present invention.

[0021] In the diagram, 1. Hollow rotating platform, 2. Ball screw, 3. Nut, 4. Anti-drop pad, 5. Fixed front seat, 6. Grating frame, 7. Pressure plate, 8. Grating, 9. Plane mirror, 10. Fixed rear seat, 11. Servo motor, 12. Sliding platform, 13. Flat plate, 14. Guide rod, 15. Gear, 16. Rack; 001. First grating, 002. Second grating, 003. Incident light. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] This invention provides a pulse compression device for a transmission grating.

[0025] like Figure 2 As shown, the pulse compression device of the transmission grating of the present invention includes: The hollow rotating platform 1 includes a rotating platform, a fixed support frame, and a servo motor 11; the servo motor 11 is installed inside the support frame and is used to drive the rotating platform to rotate around its own central axis. Flat plate 13 is fixedly installed on the support frame of hollow rotating platform 1 and does not rotate with the rotating platform; The fixed base includes a fixed front base 5 and a fixed rear base 10 mounted on the rotating platform. They are arranged in a straight line along the same radial direction of the rotating platform and can rotate synchronously with the rotating platform. A ball screw motor is installed in the fixed rear base 10, which is used to drive the ball screw 2 to rotate. The ball screw nut includes a ball screw 2 and a nut 3. The inner circumferential surface of the nut 3 is provided with a precision thread groove, which engages with the helical track on the outer circumferential surface of the ball screw 2 through ball meshing to form a closed loop, thereby achieving efficient and low-resistance rolling transmission. One end of the ball screw 2 is driven by a ball screw motor in the fixed rear seat 10, and the other end extends into the fixed front seat 5. After the ball screw motor is started, the ball screw 2 begins to rotate, thereby driving the nut 3 to move linearly along the ball screw 2. The sliding platform 12 is fixed to the nut 3; Two gratings 8 are a first grating 001 installed on the fixed front seat 5 and a second grating 002 installed on the sliding platform 12. Both the first grating 001 and the second grating 002 are perpendicular to the ball screw 2. Plane mirror 9 is fixed on plate 13.

[0026] like Figure 1 As shown, the optical path in the pulse compression device of the transmission grating of the present invention is as follows: the angle between the ball screw 2 and the normal of the plane mirror 9 is configured to be the same as the incident angle of the incident light 003. The first grating receives the incident light 003 from the external laser emitting device. The incident light 003 is diffracted sequentially by the first grating and the second grating, and then reflected back to the second grating by the plane mirror 9. It is then diffracted sequentially by the second grating and the first grating to generate a pulse-compressed beam. The pulse-compressed beam is received by an external autocorrelator, and the pulse width after compression is measured.

[0027] Specifically, the laser emitting device transmits incident light 003 through a PBS and a quarter glass slide to the first grating. After pulse compression, the beam passes through the quarter glass slide and is reflected by the PBS to the autocorrelator.

[0028] Furthermore, such as Figure 3 As shown, the transmission grating pulse compression device also includes two grating adjustment mechanisms: a first grating adjustment mechanism mounted on the fixed front seat 5 and a second grating adjustment mechanism mounted on the sliding platform 12. The grating adjustment mechanism mainly consists of a grating frame 6, a pressure plate 7, a gear 15, and a rack 16. The grating frame 6 is arranged above its own platform. The grating frame 6 adopts an L-shaped bracket. The vertical part of the L-shaped bracket adopts a frame structure. The pressure plate 7 is arranged on the frame structure and is used to fix the grating 8. The horizontal part of the L-shaped bracket has a through groove. The gear 15 is arranged in the through groove and meshes with the rack 16 set on one side of the groove wall. The length direction of the L-shaped bracket, the through groove, and the rack 16 are all arranged in a direction perpendicular to the ball screw 2.

[0029] Furthermore, the transmission grating pulse compression device also includes two grating adjustment motors, namely a first grating adjustment motor built into the fixed front seat 5 and a second grating adjustment motor built into the sliding platform 12; the grating adjustment motor is dynamically connected to the gear 15 of the grating adjustment mechanism installed on its own platform, and the grating adjustment motor can drive the gear 15 to rotate, and through the meshing of the gear 15 and the rack 16, drive the grating 8 on the grating frame 6 to move in a direction perpendicular to the ball screw 2.

[0030] Furthermore, the servo motor 11 includes a closed-loop feedback module for adjusting the rotation angle in real time.

[0031] Furthermore, the transmission grating pulse compression device also includes an anti-drop pad 4. The front end of the ball screw 2 is supported on the fixed front seat 5 by a bearing, and the end is axially positioned by the anti-drop pad 4.

[0032] Furthermore, the transmission grating pulse compression device also includes at least one guide rod 14 parallel to the ball screw 2, used to constrain the rotation of the nut 3.

[0033] Optionally, the guide rod 14 passes through the corresponding guide hole on the sliding platform 12, and its two ends are fixed to the fixed front seat 5 and the fixed rear seat 10, respectively.

[0034] Furthermore, the pulse compression device of the present invention also includes a control unit, which is electrically connected to a servo motor 11, a ball screw motor and two grating adjustment motors, so that the device can automatically complete pulse compression adjustment or manually adjust it.

[0035] By inputting parameters such as laser wavelength, dispersion to be compensated, grating parameters, and initial incident angle into the control unit, the actual incident angle and grating spacing can be calculated. This is automatically converted into the angle the gears should rotate, and after confirmation, the rotation and translation can be completed automatically. After compression, the gear rotation angle can still be finely adjusted on the control panel to achieve the best compression effect.

[0036] The present invention also provides a pulse compression method using the above-described transmission grating for a pulse compression device.

[0037] The method of the present invention includes the following steps: calculating the target rotation angle of the rotating platform and the target movement distance of the sliding platform 12 on the ball screw 2 based on the wavelength and incident angle of the incident light 003, the target compensation dispersion amount, and the grating parameters of the first grating 001 and the second grating 002; and driving the rotating platform to rotate and the sliding platform 12 to move along the ball screw 2 respectively using the ball screw motor and the servo motor 11 based on the target rotation angle of the rotating platform and the target movement distance of the sliding platform 12.

[0038] Optionally, based on the wavelength of the incident light 003, the period of the grating 8, the incident angle, and the target compensation dispersion, the target grating spacing can be obtained using the following formula: In the formula, GDD is the target compensation dispersion, λ is the wavelength of the incident light 003, L is the target grating spacing, c is the speed of light in vacuum, d is the period of grating 8, and α is the incident angle (relative to the grating normal).

[0039] Optionally, the incident angle is set as the Littrow angle, which is obtained by the following formula: In the formula, α Littrow Let θ be the Littrow angle, m be the diffraction order, λ be the wavelength of the incident light θ, and d be the period of the grating θ.

[0040] The above specific embodiments are used to explain and illustrate the present invention, but not to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A pulse compression device using a transmission grating, characterized in that, include: The hollow rotating platform (1) includes a rotating platform, a support frame, and a servo motor (11); the servo motor (11) is installed inside the support frame and is used to drive the rotating platform to rotate around the central axis. The flat plate (13) is installed on the support frame of the hollow rotating platform (1) and does not rotate with the rotating platform; The fixed seat, including the fixed front seat (5) and the fixed rear seat (10) installed on the rotating platform, can rotate synchronously with the rotating platform. The fixed rear seat (10) is equipped with a ball screw motor. The ball screw nut includes a ball screw (2) and a nut (3), one end of which is driven by a ball screw motor in a fixed rear seat (10), and the other end extends into a fixed front seat (5). The sliding platform (12) is fixed on the nut (3); Two gratings (8) are a first grating (001) installed on the fixed front seat (5) and a second grating (002) installed on the sliding platform (12). Both the first grating (001) and the second grating (002) are perpendicular to the ball screw (2). A plane mirror (9) is fixed on a flat plate (13).

2. The pulse compression device with a transmission grating according to claim 1, characterized in that: The angle between the ball screw (2) and the normal of the plane mirror (9) is configured to be the same as the incident angle. The first grating (001) receives the incident light (003) from the external laser emitting device. After the incident light (003) is diffracted by the first grating (001) and the second grating (002), it is reflected back to the second grating (002) by the plane mirror (9). After being diffracted by the second grating (002) and the first grating (001), a pulse-compressed beam is generated. The external autocorrelator receives the pulse-compressed beam and measures the pulse width after compression.

3. The pulse compression device with a transmission grating according to claim 1, characterized in that: The transmission grating pulse compression device also includes two grating adjustment mechanisms, namely a first grating adjustment mechanism installed on the fixed front seat (5) and a second grating adjustment mechanism installed on the sliding platform (12); The grating adjustment mechanism is mainly composed of a grating frame (6), a pressure plate (7), a gear (15), and a rack (16); the grating frame (6) is arranged above its own platform, the grating frame (6) adopts an L-shaped bracket, the vertical part of the L-shaped bracket is provided with a pressure plate (7), the pressure plate (7) is used to fix the grating (8), the horizontal part of the L-shaped bracket is provided with a through groove, the through groove is provided with a gear (15), the gear (15) meshes with the rack (16) set on one side of the through groove wall; The length direction of the L-shaped bracket, through groove and rack (16) is arranged perpendicular to the ball screw (2).

4. The pulse compression device with a transmission grating according to claim 3, characterized in that: The transmission grating pulse compression device also includes two grating adjustment motors, namely a first grating adjustment motor built into the fixed front seat (5) and a second grating adjustment motor built into the sliding platform (12); The grating adjustment motor is dynamically connected to the gear (15) of the grating adjustment mechanism installed on its own platform. The grating adjustment motor can drive the gear (15) to rotate, and through the meshing of the gear (15) and the rack (16), it drives the grating (8) on the grating frame (6) to move in a direction perpendicular to the ball screw (2).

5. The pulse compression device with a transmission grating according to claim 1, characterized in that: The servo motor (11) includes a closed-loop feedback module for adjusting the rotation angle in real time.

6. The pulse compression device with a transmission grating according to claim 1, characterized in that: The transmission grating pulse compression device also includes an anti-drop pad (4), the front end of the ball screw (2) is supported on the fixed front seat (5), and the end is axially positioned by the anti-drop pad (4).

7. The pulse compression device for a transmission grating according to claim 1, characterized in that: The transmission grating pulse compression device also includes at least one guide rod (14) parallel to the ball screw (2) for constraining the rotation of the nut (3).

8. A pulse compression method using a pulse compression device with a transmission grating as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Based on the wavelength and incident angle of the incident light (003), the target compensation dispersion, and the grating parameters of the first grating (001) and the second grating (002), the target rotation angle of the rotating platform and the target movement distance of the sliding platform (12) are calculated. Based on the target rotation angle of the rotating platform and the target movement distance of the sliding platform (12), the rotating platform is driven to rotate and the sliding platform (12) is driven to move along the ball screw (2).

9. The pulse compression method according to claim 8, characterized in that: Based on the wavelength of the incident light (003), the period of the grating (8), the incident angle, and the target compensation dispersion, the target grating spacing is obtained using the following formula: In the formula, GDD is the target compensation dispersion, λ is the wavelength of the incident light (003), L is the target grating spacing, c is the speed of light, d is the period of the grating (8), and α is the incident angle.

10. The pulse compression method according to claim 9, characterized in that: The incident angle is set as the Littrow angle, which is obtained by the following formula: In the formula, α Littrow Let λ be the Littrow angle, m be the diffraction order, λ be the wavelength of the incident light (003), and d be the period of the grating (8).

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