Free electron laser beam expanding and diagnosing system

Abstract

The invention provides a free electron laser beam expanding and diagnosing system, and relates to the field of free electron laser beam transmission. The free electron laser beam expanding and diagnosing system provided by the invention comprises a vacuum cavity, wherein an incident beam diagnosis device, a first beam expanding lens, a second beam expanding lens, a middle beam diagnosis device and a wavefront beam diagnosis device are sequentially arranged in the vacuum cavity. The incident beam diagnosis device comprises a first importer and a first scintillator, the lifting end of the first importer is connected with the first scintillator, and the first scintillator is provided with a first aim point. The middle beam diagnosis device comprises a second importer and a second scintillator, the lifting end of the second importer is connected with the second scintillator, and the second scintillator is provided with a second aim point. A first observation window and a second observation window are further arranged on the side wall of the vacuum cavity, the first observation window is used for observing the first scintillator, and the second observation window is used for observing the second scintillator. The wavefront beam diagnosis device comprises a Hartmann board and an area array detector, and the area array detector is arranged at the rear end of the Hartmann board. The first beam expander and the second beam expander are arranged in the vacuum cavity, and the modes of incident beam diagnosis, middle beam diagnosis and wavefront beam diagnosis cannot be adopted, so that beam expansion of the free electron laser is realized, the divergence angle of the free electron laser is increased, and the length of a beam line is reduced.

Description

Technical Field

[0001] The present invention relates to the field of free electron laser beam transmission, in particular to a free electron laser beam expansion and diagnosis system. Background Art

[0002] Free electron laser (FEL) has the characteristics of high brightness, high coherence, and ultrashort pulses. It is a powerful tool for basic scientific research. At the same time, in addition to the above characteristics, high repetition rate free electron laser also has the characteristics of high average power of thousands of watts. Taking advantage of the characteristics of high average power, free electron laser is expected to be used as a light source for studying lithography, but there are still many problems in using high repetition rate free electron laser. For example, the problem of high coherence and the problem of high collimation. The present invention is to solve the problem of its high collimation. Due to the high collimation of the free electron laser (that is, the small divergence angle), if you want to naturally transmit the free electron laser and enable it to form a spot size of hundreds of millimeters, you need to extend the length of the beam line to increase the divergence angle of the free electron laser, and this will make the entire beam line need to be thousands of meters long, which will bring great problems in space and cost. For this reason, it is necessary to expand the free electron laser, increase its divergence angle, and reduce the beam line length. There are also a series of problems in the beam expansion and control process:

[0003] In summary, there is an urgent need for a device that can expand the free electron laser beam, increase its divergence angle, but reduce the beam line length. Summary of the Invention

[0004] In order to solve the above problems and related problems, the present invention provides a free electron laser beam expansion and diagnosis system, which is a device that can expand the free electron laser, increase its divergence angle, and reduce the beam line length.

[0005] The present invention provides a free electron laser beam expansion and diagnosis system, comprising a vacuum chamber, in which an incident beam diagnosis, a first beam expander, a second beam expander, an intermediate beam diagnosis, and a wavefront beam diagnosis are sequentially arranged. The first beam expander is used to reflect the incident light and form an intermediate light, and the second beam expander is used to reflect the intermediate light and form an expanded beam. The incident beam diagnosis comprises a first introducer and a first scintillator, wherein the lifting end of the first introducer is connected to the first scintillator, and the first scintillator is provided with a first collimator. The intermediate beam diagnosis comprises a second introducer and a second scintillator, wherein the lifting end of the second introducer is connected to the second scintillator, and the second scintillator is provided with a second collimator. A first observation window and a second observation window are also provided on the top of the vacuum chamber, wherein the first observation window is used to observe the first scintillator, and the second observation window is used to observe the second scintillator. The wavefront beam diagnosis comprises a Hartmann plate and a planar array detector, and the planar array detector is provided at the rear end of the Hartmann plate.

[0006] In one feasible embodiment, a first camera and a second camera are provided outside the vacuum chamber, wherein the first scintillator, the first observation window and the first camera are in a straight line, and the second scintillator, the second observation window and the second camera are in a straight line.

[0007] In a feasible implementation manner, an incident angle between the first scintillator and the incident light beam is 45° to 90°, and an incident angle between the second scintillator and the intermediate light beam is 45° to 90°.

[0008] In some feasible implementations, the first beam expander is a concave cylindrical mirror with an elliptical cylindrical surface, and the second beam expander is a convex cylindrical mirror with an elliptical cylindrical surface.

[0009] In some feasible implementations, the first beam expander is coated with a damage-resistant high-reflection film, which is an amorphous carbon film. The second beam expander is coated with a damage-resistant high-reflection film, which is an amorphous carbon film.

[0010] In a feasible embodiment, the system further includes a first adjustment mechanism and a second adjustment structure, wherein the first beam expander is disposed on the first adjustment mechanism, and the second beam expander is disposed on the second adjustment structure.

[0011] In one feasible embodiment, the first adjustment mechanism includes a first translation mechanism and a first angle adjustment mechanism, the first angle adjustment mechanism being disposed on the first translation mechanism, and the first beam expander being disposed on the first angle adjustment mechanism. The second adjustment mechanism includes a second translation mechanism and a second angle adjustment mechanism, the second angle adjustment mechanism being disposed on the second translation mechanism, and the second beam expander being disposed on the second angle adjustment mechanism.

[0012] In a feasible embodiment, a third adjustment mechanism is further included, and the wavefront beam diagnosis is provided on the third adjustment mechanism.

[0013] In a feasible implementation manner, the third adjustment mechanism includes a third translation mechanism and a third angle adjustment mechanism, the third angle adjustment mechanism is provided on the third translation mechanism, and the wavefront beam diagnosis is provided on the third angle adjustment mechanism.

[0014] The present invention provides a free electron laser beam expansion and diagnosis system, which has the following beneficial effects: the present invention realizes the beam expansion of the free electron laser by arranging a first beam expander and a second beam expander in a vacuum cavity and adopts incident beam diagnosis, intermediate beam diagnosis and wavefront beam diagnosis, thereby increasing the divergence angle of the free electron laser and reducing the length of the beam line. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a top view of the overall structure of the present invention.

[0016] Figure 2 It is a side view of the overall structure of the present invention.

[0017] Figure 3 It is a structural schematic diagram of the incident light beam diagnosis and intermediate light beam diagnosis in the present invention.

[0018] Figure 4 It is a partial schematic diagram of the present invention.

[0019] Figure 5 Schematic diagram of the structure of the first scintillator and the first aiming point in the present invention.

[0020] Figure 6 Schematic diagram of the structure of the second scintillator and the second aiming point in the present invention.

[0021] Reference numerals

[0022] Vacuum chamber 1

[0023] First observation window 11

[0024] Second observation window 12

[0025] First Camera 13

[0026] Second camera 14

[0027] Incident beam diagnosis 2

[0028] First importer 21

[0029] First scintillator 22

[0030] First crosshair 22.1

[0031] First beam expander 3

[0032] Intermediate beam diagnostics 4

[0033] Second introducer 41

[0034] Second scintillator 42

[0035] Second crosshair 42.1

[0036] Second beam expander 5

[0037] Wavefront Beam Diagnostics6

[0038] Hartmann Plate 61

[0039] Area array detector 62

[0040] First adjustment mechanism 7

[0041] First translation mechanism 71

[0042] First angle adjustment mechanism 72

[0043] Second adjustment mechanism 8

[0044] Second translation mechanism 81

[0045] Second angle adjustment mechanism 82

[0046] The third adjustment mechanism 9

[0047] The third translation mechanism 91

[0048] Third angle adjustment mechanism 92 DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "rear end", "front end", "left side", "right side", "upper side", "lower side", "above", "below", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0050] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0051] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0052] The present invention provides a free electron laser beam expansion and diagnosis system, see Figure 1 and Figure 2The free electron laser beam expansion and diagnosis system includes a vacuum chamber 1, in which an incident beam diagnosis system 2, a first beam expander 3, an intermediate beam diagnosis system 4, a second beam expander 5, and a wavefront beam diagnosis system 6 are sequentially arranged. The first beam expander 3 is used to reflect the incident light and form an intermediate beam, and the second beam expander 5 is used to reflect the intermediate light and form an expanded beam. The incident beam diagnosis system 2 includes a first introducer 21 and a first scintillator 22. The first scintillator 22 is provided with a first collimator 22.1. The lifting end of the first introducer 21 is connected to the first scintillator 22. The intermediate beam diagnosis system 4 includes a second introducer 41 and a second scintillator 42. The second scintillator 42 is provided with a second collimator 42.1. The lifting end of the second introducer 41 is connected to the second scintillator 42. The top of the vacuum chamber 1 is also provided with a first observation window 11 and a second observation window 12. The first observation window 11 is used to observe the first scintillator 22, and the second observation window 12 is used to observe the second scintillator 42. For illustration, the vacuum chamber 1 is further provided with a light hole for allowing the free-point laser to pass through. The first introducer 21 and the second introducer 41 are both motors, and the drive motors can be any one of a stepper motor, a servo motor, or a DC reduction motor, preferably a stepper motor. The first introducer 21 and the second introducer 41 can be fixed to the top of the inner cavity of the vacuum chamber 1. The first scintillator 22 and the second scintillator 42 are respectively connected to the drive rods of the first introducer 21 and the second introducer 41. The wavefront beam diagnosis 6 includes a Hartmann plate 61 and a planar array detector 62. The planar array detector 62 is disposed at the rear end of the Hartmann plate 61 and is used to receive the expanded beam. As a supplementary explanation, the first beam expander 3 focuses the free electron laser to the middle position between the first beam expander 3 and the second beam expander 5, that is, the position of the middle beam diagnosis 4, and the virtual focus of the second beam expander 5 is also set at the middle position between the first beam expander 3 and the second beam expander 5, so that the horizontal and vertical directions of the free electron laser (the horizontal and vertical here are based on the cross-section of the free electron laser, similar to the horizontal and vertical directions of XFEL) are both based on the middle position of the first beam expander 3 and the second beam expander 5 as the focus or virtual focus. Since the distance between the light source point and the first beam expander 3 and the second beam expander 5 is much greater than the focal length of the first beam expander 3 and the second beam expander 5, it can be ensured that the divergence angles of the free electron laser in the vertical and horizontal directions are basically consistent.

[0053] In the free electron laser beam expansion and diagnostic system provided by the present invention, the incident angle between the first scintillator 22 and the incident light is 45° to 90°, preferably 45°; the incident angle between the second scintillator 42 and the intermediate light beam is 45° to 90°, preferably 90°.

[0054] In the free electron laser beam expansion and diagnostic system provided by the present invention, the first beam expander 3 is a concave cylindrical mirror with an elliptical cylindrical surface; the second beam expander 4 is a convex cylindrical mirror with an elliptical cylindrical surface. The first beam expander 3 is coated with a damage-resistant, highly reflective film, which is an amorphous carbon film; the second beam expander 5 is coated with a damage-resistant, highly reflective film, which is an amorphous carbon film.

[0055] In the free electron laser beam expansion and diagnostic system provided by the present invention, refer to Figure 1 and Figure 2 , also includes a first adjustment mechanism 7 and a second adjustment structure 8. The first collimator 3 is arranged on the first adjustment mechanism 7, and the second collimator 5 is arranged on the second adjustment structure 8. The first adjustment mechanism 7 and the second adjustment mechanism 8 are used to adjust the positions and angles of the first collimator 3 and the second collimator 5 respectively. Further, the first adjustment mechanism 7 includes a first translation mechanism 71 and a first angle adjustment mechanism 72. The first angle adjustment mechanism 72 is arranged on the first translation mechanism 71, and the first collimator 3 is arranged on the first angle adjustment mechanism 72. The second adjustment mechanism 8 includes a second translation mechanism 81 and a second angle adjustment mechanism 82. The second angle adjustment mechanism 82 is arranged on the second translation mechanism 81, and the second collimator 5 is arranged on the second angle adjustment mechanism 82. As an illustration, taking the first translation mechanism 71 and the first angle adjustment mechanism 72 as an example, the first translation mechanism 71 can realize translation in two directions, namely direction one and direction two. 1) Direction one: as Figure 2 The direction shown by L1 is the height of the first beam expander 3; 2) Direction 2: Figure 1 The direction indicated by L2 in the figure moves the first beam expander 3 left and right. The first angle adjustment mechanism 72 can adjust three rotation angles: pitch angle, roll angle, and swing angle. 1) Pitch angle: Rotation around direction 1 adjusts the incident angle of the first beam expander 3; 2) Roll angle: Rotation around the propagation direction of the incident light beam; 3) Swing angle: Rotation around direction 2.

[0056] The free electron laser beam expansion and diagnosis system provided by the present invention further includes a third adjustment mechanism 9, and the wavefront beam diagnosis 6 is arranged on the third adjustment mechanism 9. Further, the third adjustment mechanism 9 includes a third translation mechanism 91 and a third angle adjustment mechanism 92, and the third angle adjustment mechanism 92 is arranged on the third translation mechanism 91, and the wavefront beam diagnosis 6 is arranged on the third angle adjustment mechanism 92. As an illustration, the third translation mechanism 91 can drive the wavefront beam diagnosis 6 to move in the following manner: Figure 1 The L2 direction shown, Figure 2 The third angle adjustment mechanism 92 can drive the wavefront beam diagnosis 6 to move in the L1 direction as shown. Figure 1 He Ru Figure 2Rotation is performed on the plane shown.

[0057] The free electron laser beam expansion and diagnosis system provided by the present invention needs to be calibrated before use, so a calibration method of the present invention is provided herein, and the specific calibration method is as follows: 1) emit a free electron laser for calibration, and then adjust the relative positions of the first beam expander 3 and the second beam expander 5 respectively through the first adjustment mechanism 7 and the second adjustment mechanism 8, so that the wavefront beam diagnosis 6 can receive the expanded free electron laser. Usually, whether the beam expansion is successful is judged based on the spot size of the free electron laser received by the wavefront beam diagnosis 6; 2) after the beam expansion is completed, the first scintillator 22 and the second scintillator 42 are moved respectively by the first introducer 21 and the second introducer 41, and it is ensured that the first first center 22.1 of the first scintillator 22 and the second second center 42.1 of the second scintillator 42 can be respectively located in the optical path of the free electron laser. Generally speaking, the first first center 22.1 is a smaller circular area, which can be referred to. Figure 5 , the second crosshair 42.1 is approximately a vertical straight line, refer to Figure 6 . In addition, a first camera 13 and a second camera 14 are provided outside the vacuum chamber 1. The first camera 13 is used to photograph the light spot on the first scintillator 22, and the second camera 14 is used to photograph the light spot on the second scintillator 42. The first camera 13 and the second camera 14 enable the operator to better observe the light spots on the first scintillator 22 and the second scintillator 42. Compared with naked eye observation, the camera can better observe the light spots to improve the accuracy of the calibration process. In addition, the first scintillator 22 and the second scintillator 42 should be made of a material with a high absorption rate for the incident light beam and the intermediate light beam, such as Jager scintillator, to increase the observation effect. After completing the above-mentioned calibration process, the free electron laser beam expansion and diagnosis system provided by the present invention can be used directly. When in use, the free electron laser used for calibration is replaced with the free electron laser used for testing and its light spot is detected in the wavefront beam diagnosis 6. The position of the wavefront beam diagnosis 6 can be adjusted by the third adjustment mechanism 9.

[0058] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A free electron laser beam expansion and diagnostic system, characterized by: The invention comprises a vacuum cavity (1), wherein an incident light beam diagnosis (2), a first beam expander (3), a second beam expander (5), an intermediate light beam diagnosis (4), and a wavefront light beam diagnosis (6) are sequentially arranged in the vacuum cavity (1); the first beam expander (3) is used to reflect the incident light and form intermediate light, and the second beam expander (5) is used to reflect the intermediate light and form expanded light; The incident light beam diagnosis (2) comprises a first introducer (21) and a first scintillator (22), wherein the lifting end of the first introducer (21) is connected to the first scintillator (22), and the first scintillator (22) is provided with a first collimator (22.1); the intermediate light beam diagnosis (4) comprises a second introducer (41) and a second scintillator (42), wherein the lifting end of the second introducer (41) is connected to the second scintillator (42), and the second scintillator (42) is provided with a second collimator (42.1); A first observation window (11) and a second observation window (12) are further provided on the top of the vacuum chamber (1), wherein the first observation window (11) is used for observing the first scintillator (22), and the second observation window (12) is used for observing the second scintillator (42); The wavefront beam diagnosis (6) comprises a Hartmann plate (61) and a planar array detector (62), wherein the planar array detector (62) is arranged at the rear end of the Hartmann plate (61).

2. The free electron laser beam expansion and diagnostic system according to claim 1, wherein: A first camera (13) and a second camera (14) are provided outside the vacuum chamber (1); the first scintillator (22), the first observation window (11) and the first camera (13) are located on the same straight line, and the second scintillator (42), the second observation window (12) and the second camera (14) are located on the same straight line.

3. The free electron laser beam expansion and diagnostic system according to claim 1, wherein: The incident angle between the first scintillator (22) and the incident light beam is 45° to 90°, and the incident angle between the second scintillator (42) and the intermediate light beam is 45° to 90°.

4. The free electron laser beam expansion and diagnostic system according to claim 1, wherein: The first beam expander (3) is a concave cylindrical mirror, and its surface shape is an elliptical cylindrical surface; the second beam expander (5) is a convex cylindrical mirror, and its surface shape is an elliptical cylindrical surface.

5. The free electron laser beam expansion and diagnostic system according to claim 1, wherein: The first beam expander (3) is coated with a damage-resistant high-reflection film, which is an amorphous carbon film; the second beam expander (5) is coated with a damage-resistant high-reflection film, which is an amorphous carbon film.

6. The free electron laser beam expansion and diagnostic system according to claim 1, wherein: It also includes a first adjustment mechanism (7) and a second adjustment structure (8); the first beam expander (3) is arranged on the first adjustment mechanism (7), and the second beam expander (5) is arranged on the second adjustment structure (8).

7. The free electron laser beam expansion and diagnostic system according to claim 6, characterized in that: The first adjustment mechanism (7) comprises a first translation mechanism (71) and a first angle adjustment mechanism (72), the first angle adjustment mechanism (72) being arranged on the first translation mechanism (71), and the first beam expander (3) being arranged on the first angle adjustment mechanism (72); The second adjustment mechanism (8) comprises a second translation mechanism (81) and a second angle adjustment mechanism (82); the second angle adjustment mechanism (82) is arranged on the second translation mechanism (81); and the second beam expander (5) is arranged on the second angle adjustment mechanism (82).

8. The free electron laser beam expansion and diagnostic system according to claim 1, wherein: It also includes a third adjustment mechanism (9), and the wavefront beam diagnosis (6) is arranged on the third adjustment mechanism (9).

9. The free electron laser beam expansion and diagnostic system according to claim 8, characterized in that: The third adjustment mechanism (9) comprises a third translation mechanism (91) and a third angle adjustment mechanism (92); the third angle adjustment mechanism (92) is arranged on the third translation mechanism (91); and the wavefront beam diagnosis (6) is arranged on the third angle adjustment mechanism (92).

10. The calibration method of the free electron laser beam expansion and diagnosis system according to any one of claims 1 to 9, wherein the specific steps are as follows: 1) emitting a free electron laser for calibration, and adjusting the relative positions of the first beam expander (3) and the second beam expander (5) respectively, so that the wavefront beam diagnosis (6) can receive the expanded free electron laser; 2) After beam expansion is completed, the first scintillator (22) and the second scintillator (42) are moved, and it is ensured that the first collimator (22.1) of the first scintillator (22) and the second collimator (42) (42) can be respectively located in the optical path of the free electron laser.

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