Laser beam characteristic measuring device and method

Abstract

The invention discloses a laser beam characteristic measuring device which comprises an adjustable slit, a light splitting device, a near-field beam measuring device and a far-field beam measuring device. The adjustable slit is arranged in a light path of the laser beam to be measured and is attached to the laser light outlet; the light splitting device is arranged in a light path in the light emitting direction of the adjustable slit and is used for splitting the light beam into a first light beam and a second light beam; the near-field light beam measuring device is arranged in a first light beam path, and the adjustable slit is imaged on the near-field light beam characteristic detector through the imaging lens group; the far-field light beam measuring device is arranged in a second light beam path, the focusing lens and the far-field light beam characteristic detector are sequentially arranged in the second light beam propagation direction, and the far-field light beam detector is arranged at the ideal focal plane of the focusing lens. The problems that in the prior art, laser beam near-field and far-field quality characteristic testing is low in integration level, tedious in debugging, low in efficiency and the like are solved.

Description

Technical Field

[0001] The present invention relates to the field of optics, and more particularly to a laser beam characteristic measurement device and method. Background Art

[0002] Excimer laser is a pulsed gas laser with a wavelength in the ultraviolet band, and is an ideal light source for semiconductor lithography. Laser beam quality is the core indicator of laser parameters in lithography light source systems and an important factor affecting lithography imaging quality. It mainly includes spot size, laser divergence angle, beam pointing stability, beam position stability, etc. Among them, the laser divergence angle is an important parameter for marking the effective transmission of the laser system, and beam pointing stability and beam position stability are important indicators of the laser beam timeliness of the laser light source system and the jitter deflection characteristics during long-distance transmission.

[0003] In the test method of the quality characteristics of the excimer laser beam, due to the high energy of the excimer laser, it is difficult for a camera to directly measure the beam at the light outlet of the light source. Usually, an ultraviolet attenuation plate is added before the excimer beam enters the camera to measure the quality characteristics of the attenuated excimer laser output beam. Therefore, the camera can only test the spot size and position stability at a certain position away from the laser light outlet, and then calculate the spot size and position stability at the light outlet through the far-field divergence angle, pointing stability, and distance. In this way, on the one hand, because the excimer laser is a non-ideal fundamental mode Gaussian light source, when the beam quality at the light outlet of the light source is inferred by testing the beam characteristics at a certain position, there is a nonlinear relationship with the position change, which introduces measurement errors. On the other hand, the near-field and far-field test optical paths are separated for independent testing, which has the disadvantages of low integration, cumbersome debugging, and low efficiency. Summary of the invention

[0004] The present application provides a laser beam characteristic measuring device to solve the problems of low integration, complicated debugging, low efficiency, etc. in the prior art for laser beam quality testing.

[0005] The present application provides a laser beam characteristic measuring device, including an adjustable slit, a light splitting device, a near-field beam measuring device, and a far-field beam measuring device;

[0006] The adjustable slit is arranged in the optical path of the laser beam to be measured and fits closely with the laser light outlet;

[0007] The light splitting device is arranged in the light path of the adjustable slit in the light output direction, and is used to split the light beam into a first light beam and a second light beam;

[0008] The near-field beam measuring device comprises an imaging lens group and a near-field beam characteristic detector, and the near-field beam measuring device is arranged in the optical path of the first beam, and an adjustable slit is imaged onto the near-field beam characteristic detector through the imaging lens group;

[0009] The far-field beam measuring device includes a focusing lens and a far-field beam characteristic detector. The far-field beam measuring device is arranged in the optical path of the second beam, and the focusing lens and the far-field beam characteristic detector are arranged in sequence along the propagation direction of the second beam. The far-field beam detector is arranged at the ideal focal plane of the focusing lens.

[0010] Optionally, the near-field beam characteristic detector includes a first beam quality analyzer and a first position sensitive detector.

[0011] Optionally, the near-field beam measuring device further comprises: a first refracting mirror, a first ultraviolet attenuation plate, a first beam splitter and a second ultraviolet attenuation plate;

[0012] The first folding mirror, the first ultraviolet attenuation plate, and the first beam splitter are sequentially arranged along the propagation direction of the first light beam;

[0013] The first beam splitter is used to split the first light beam into a third light beam and a fourth light beam;

[0014] The second ultraviolet attenuation sheet and the first position sensitive detector are sequentially arranged along the propagation direction of the third light beam;

[0015] The first beam quality analyzer is arranged along the propagation direction of the fourth light beam. Optionally, the far-field beam characteristic detector includes a second quality analyzer and a second position sensitive detector;

[0016] Optionally, the far-field beam measuring device further comprises: a third ultraviolet attenuation sheet, a fourth ultraviolet attenuation sheet, a focusing lens, a second refracting mirror, a third refracting mirror, a second beam splitter and a fifth ultraviolet attenuation sheet;

[0017] The third ultraviolet attenuation sheet, the fourth ultraviolet attenuation sheet, the focusing lens and the second folding mirror are sequentially arranged along the propagation direction of the second light beam;

[0018] The third folding mirror is connected to the second folding mirror at a preset angle;

[0019] The second beam splitter is connected in sequence with the third folding mirror on the same optical axis, and the second beam splitter is used to split the second light beam into a fifth light beam and a sixth light beam;

[0020] The second beam quality analyzer is arranged along the propagation direction of the sixth light beam;

[0021] The fifth ultraviolet attenuation plate and the second position sensitive detector are arranged in sequence along the propagation direction of the fifth light beam.

[0022] Optionally, a seal is provided between the adjustable slit and the laser beam characteristic measuring device.

[0023] Optionally, the imaging lens group includes a first lens and a second lens:

[0024] The focal lengths of the first lens and the second lens are equal;

[0025] The optical path between the first lens and the second lens on the optical axis is equal to twice the focal length of the first lens;

[0026] The optical path between the first lens and the laser light outlet on the optical axis is equal to the optical path between the second lens and the near-field beam characteristic detector on the optical axis, and both are equal to the focal length of the first lens.

[0027] Optionally, all lenses in the imaging lens group are biconvex lenses.

[0028] Optionally, the near-field beam characteristic detector and the far-field beam characteristic detector are both sealed in the laser beam characteristic measuring device.

[0029] The present application also provides a method for measuring laser beam characteristics, comprising:

[0030] Acquire a laser beam to be measured emitted from an adjustable slit, wherein the adjustable slit is arranged in the optical path of the laser beam to be measured and fits with the laser light outlet;

[0031] Performing a spectroscopic process on the light beam to obtain a first light beam and a second light beam; wherein the spectroscopic process is implemented by a spectroscopic device, and the spectroscopic device is arranged in the light path of the light output direction of the adjustable slit;

[0032] respectively measuring near-field beam characteristics of the first light beam and far-field beam characteristics of the second light beam;

[0033] Among them, the measurement of the near-field beam characteristics of the first light beam is achieved by a near-field beam measuring device, which includes an imaging lens group and a near-field beam characteristics detector, and the near-field beam measuring device is arranged in the optical path of the first light beam, and the adjustable slit is imaged on the near-field beam characteristics detector through the imaging lens group; the measurement of the far-field beam characteristics of the second light beam is achieved by the far-field beam measuring device, which includes a focusing lens and a far-field beam characteristics detector, and the far-field beam measuring device is arranged in the optical path of the second light beam, and the focusing lens and the far-field beam characteristics detector are arranged in sequence along the propagation direction of the second light beam, and the far-field beam detector is arranged at the ideal focal plane of the focusing lens.

[0034] Compared with the prior art, this application has the following advantages:

[0035] The embodiment of the present application provides a laser beam characteristic measurement device, which solves the problem of low efficiency of testing near-field and far-field beam quality characteristics (spot size, position stability, divergence angle, pointing stability) separately and independently. The near-field beam measurement device provided by the present application is based on the lens imaging principle. The positions of the light source to be measured, the lens or lens group and the near-field beam characteristic detector are reasonably set by the slit calibration method, and the laser to be measured is imaged 1:1 on the near-field camera, so that the beam characteristics obtained on the near-field beam characteristic detector are the near-field beam characteristics of the light source to be measured. It not only avoids the uncertainty of the test results caused by lens imaging, reduces imaging aberrations, and improves measurement accuracy, but also improves the test efficiency, and solves the problem that the high-energy laser beam characteristics cannot be directly and accurately measured in the prior art. It satisfies the function of measuring the near-field and far-field beam quality characteristics at the same time, eliminates the steps of repeated debugging of the optical path when replacing different beam characteristic detectors, and achieves the advantages of high test integration, simple debugging, high efficiency, and improved accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the overall structure of the laser beam characteristic measurement device provided in an embodiment of the present application.

[0037] Figure 2 It is a first structural schematic diagram of a near-field beam measuring device in a laser beam characteristic measuring device provided in an embodiment of the present application.

[0038] Figure 3 This is a second structural schematic diagram of the near-field beam measuring device in the laser beam characteristic measuring device provided in an embodiment of the present application.

[0039] Figure 4 It is a schematic diagram of the structure of a far-field beam measuring device in a laser beam characteristic measuring device provided in an embodiment of the present application.

[0040] Figure 5 It is a flow chart of a laser beam characteristic measurement method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0041] Many specific details are described in the following description to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present application, so the present application is not limited by the specific implementation disclosed below.

[0042] Since the following devices are used in this application: refracting mirror, UV attenuation sheet, beam splitter, light absorbing sheet, the materials of the above devices are calcium fluoride or fused quartz. In order to facilitate the understanding of this application, the functions of the above devices are uniformly explained as follows:

[0043] Refractometer: Refractometer is actually a reflector. The direction of light reflection is determined by the placement angle. It is used to fold the light path, compress the volume, and improve the portability of the test device.

[0044] Purple attenuation sheet: used to attenuate the beam energy entering the first position sensitive detector and the second position sensitive detector.

[0045] Beam splitter: used to split the received laser into two laser beams, and guide the two separated laser beams to different optical paths according to the position of the beam splitter in this application.

[0046] Light-absorbing sheet: When light shines on the light-absorbing sheet, there is no transmission outside of the illumination, and no mapping or large flare is produced. After absorbing the light, the light-absorbing sheet reflects less light.

[0047] The following is a detailed description of this application:

[0048] Excimer laser is a pulsed gas laser with a wavelength in the ultraviolet band. It has the characteristics of high repetition rate, high energy, short wavelength, and narrow line width. It is an ideal light source for semiconductor lithography. Laser beam quality is the core indicator of laser parameters in lithography light source system and an important factor affecting lithography imaging quality. It mainly includes spot size, laser divergence angle, beam pointing stability, beam position stability, etc. Among them, the laser divergence angle is an important parameter for marking the effective transmission of the laser system, and beam pointing stability and beam position stability are important indicators of the laser beam timeliness of the laser light source system and the jitter deflection characteristics during long-distance transmission.

[0049] In the test method of the quality characteristics of the excimer laser beam, due to the high energy of the excimer laser, it is difficult for a camera to directly measure the beam at the light outlet of the light source. Usually, an ultraviolet attenuation plate is added before the excimer beam enters the camera to measure the quality characteristics of the attenuated excimer laser output beam. Therefore, the camera can only test the spot size and position stability at a certain position away from the laser light outlet, and then calculate the spot size and position stability at the light outlet through the far-field divergence angle, pointing stability, and distance. In this way, on the one hand, because the excimer laser is a non-ideal fundamental mode Gaussian light source, when the beam quality at the light outlet of the light source is inferred by testing the beam characteristics at a certain position, there is a nonlinear relationship with the position change, which introduces measurement errors. On the other hand, the near-field and far-field test optical paths are separated for independent testing, which has the disadvantages of low integration, cumbersome debugging, and low efficiency.

[0050] Based on the above problems, Figure 1 As shown, the present application provides a laser beam characteristic measuring device 100, including an adjustable slit 110, a spectrometer 120, a near-field beam measuring device 130 and a far-field beam measuring device 140;

[0051] The adjustable slit 110 is arranged in the optical path of the laser beam to be measured and fits closely with the laser light outlet;

[0052] The light splitting device 120 is disposed in the light path of the adjustable slit light output direction, and is used to split the light beam into a first light beam and a second light beam;

[0053] The near-field beam measuring device 130 includes an imaging lens group 134 and a near-field beam characteristic detector 136. The near-field beam measuring device 136 is disposed in the optical path of the first beam, and the adjustable slit is imaged on the near-field beam characteristic detector 136 through the imaging lens group 134.

[0054] The far-field beam measuring device 140 includes a focusing lens 143 and a far-field beam characteristic detector 146. The far-field beam measuring device 140 is arranged in the second beam optical path, and the focusing lens 143 and the far-field beam characteristic detector 146 are arranged in sequence along the propagation direction of the second beam. The far-field beam detector 146 is arranged at the ideal focal plane of the focusing lens 143.

[0055] The adjustable slit 110 generally refers to one of the main components of the spectrometer. The adjustable slit 110 is a narrow and elongated slit with adjustable width. There are fixed slits, unilaterally adjustable asymmetric slits and bilaterally adjustable symmetrical slits. The adjustable slit 110 in the present application is arranged in the optical path of the laser beam to be measured and fits with the laser light outlet in order to seal the adjustable slit 110 with the laser beam characteristic measuring device 100. It should be noted that: when the sealing is set, the sealed device is filled with nitrogen. The purpose of this setting is to avoid the change of the spot shape caused by the ozone generated by the long-term discharge of ultraviolet light through nitrogen purge, thereby affecting the calibration result and improving the measurement accuracy. The adjustable slit 110 can be used for the calibration of the near-field lens imaging in the near-field beam measuring device 130. The specific calibration process will be described in detail later.

[0056] The spectroscopic device 120 is generally a spectroscope, which is arranged after the adjustable slit 110 in the laser light path, and is used to divide the laser to be measured into a first light beam and a second light beam. Thereby, the first light beam is introduced into the near-field beam measuring device 130 to test the near-field quality characteristics of the light beam, and the second light beam is introduced into the far-field beam measuring device 140 to test the far-field quality characteristics of the light beam. It should be noted that the spectroscopic device 120 in the present application can also be other spectroscopic devices, and no specific restrictions are made here. The imaging lens group 134 includes a first lens 134-1 and a second lens 134-2. The materials of the first lens 134-1 and the second lens 134-2 are selected from calcium fluoride or fused quartz. The focal length of the first lens 134-1 is equal to the focal length of the second lens 134-2, both of which are f1. The specific setting position and function of the imaging lens group will be described in detail later.

[0057] When the near-field beam measuring device 130 tests the near-field quality characteristics of the first beam, it also requires the cooperation of other components. Figure 2 and Figure 3 , the specific structure of the near-field beam measuring device 130 is described:

[0058] The near-field beam characteristic detector 136 includes a first beam quality analyzer 136 - 2 and a first position sensitive detector 136 - 1 .

[0059] like Figure 2 As shown, the near-field beam measuring device 130 also includes: a first refracting mirror 131, a first ultraviolet attenuation plate 132-1, a first beam splitter 135 and a second ultraviolet attenuation plate 132-2, and a first light absorbing plate 133 arranged on the reflection light path of the first ultraviolet attenuation plate 132-1. The first refracting mirror 131, the first ultraviolet attenuation plate 132-1, and the first beam splitter 135 are arranged in sequence along the propagation direction of the first light beam. The first beam splitter 135 is used to split the first light beam into a third light beam and a fourth light beam. The second ultraviolet attenuation plate 132-2 and the first position sensitive detector 136-1 are arranged in sequence along the propagation direction of the third light beam. The first beam quality analyzer 136-2 is arranged along the propagation direction of the fourth light beam. The imaging lens group 134 is arranged between the first ultraviolet attenuation plate 132-1 and the first beam splitter 135. It should be noted that the components such as the refracting mirror, UV attenuation plate, beam splitter, and light absorbing plate in the near-field beam measuring device 130 are not limited to the above components, and all components that can play the same role as the above components are included in the embodiments of the present application.

[0060] Combination Figure 2 and Figure 3 , the structural setting of the near-field beam measuring device 130 in this application is briefly described:

[0061] Since the energy of the laser to be measured is relatively strong, in order to prevent the laser to be measured from damaging the near-field beam characteristic detector 136, a first ultraviolet attenuation plate 132-1 is provided in the near-field beam measuring device 130. In the near-field beam measuring device 130, the imaging lens group 134 is provided between the laser light outlet and the near-field beam characteristic detector 136. The damage threshold of the first position sensitive detector 136-1 is much lower than that of the first beam quality analyzer 136-2, so a second ultraviolet attenuation plate 132-2 is provided between the first beam splitter 135 and the first position sensitive detector 136-1 to ensure the safety of the first position sensitive detector 136-1.

[0062] Since the measurement of the near-field beam characteristics in this application is based on the lens imaging method, the near-field beam measuring device 130 needs to be calibrated before the measurement. The specific calibration process is: set the calibration device: determine the propagation direction of the laser light source light path, and place the spectroscopic device 120, the refracting mirror 131, the ultraviolet attenuation plate 132-1, the first lens 134-1 in the above-mentioned imaging lens group 134, and the first spectroscope 135 and the near-field beam characteristic detector 136 in sequence along the light path direction of the laser light source transmission. It should be noted that when placing, the following conditions need to be met: the optical path of the first lens 134-1 and the second lens 134-2 on the optical axis is equal to twice the focal length of the first lens 134-1, that is, 2f1. The optical path of the first lens 134-1 and the laser light outlet on the optical axis is equal to the optical path of the second lens 134-2 and the near-field beam characteristic detector 136 on the optical axis, both of which are f1. After arranging the devices on the optical path according to the above requirements, the setting of the calibration device is completed. Then adjust the size of the adjustable slit 110 so that part of the laser beam to be measured enters the calibration device, and at the same time fine-tune the distance between the first position sensitive detector 136-1 in the near-field beam characteristic detector 136 and the first beam quality analyzer 136-2. During the fine-tuning process, always observe the spot size measured by the near-field beam characteristic detector 136 and the size of the adjustable slit 110. When it is observed that the spot size measured by the near-field beam characteristic detector 136 is consistent with the size of the adjustable slit 110, stop fine-tuning at this time and complete the calibration. After the calibration is completed, adjust the size of the adjustable slit 110 so that the laser beam to be measured can pass through the adjustable slit 110 without obstruction. At this time, the spot size measured by the first beam quality analyzer 136-2 and the position stability measured by the first position sensitive detector 136-1 are the near-field beam quality characteristics of the laser beam to be measured.

[0063] In addition, Figure 3 As shown, the lens imaging group 134 in the near-field beam measurement device 130 in the present application can also be replaced by a single imaging lens 137. At this time, if the focal length of the imaging lens 137 is f2, it is necessary to ensure that the optical path between the imaging lens 137 and the laser light outlet on the optical axis is equal to the optical path between the imaging lens 137 and the near-field beam characteristic detector 136 on the optical axis, both of which are equal to twice the focal length of the imaging lens 137 (2f2). In order to reduce aberrations and improve measurement accuracy, the imaging lens in the near-field beam measurement device in the present application selects a biconvex lens, and the material of the imaging lens is calcium fluoride and fused quartz.

[0064] When the far-field beam measuring device 140 tests the far-field quality characteristics of the second beam, it also requires the cooperation of other components. Figure 4 , the specific structure of the far-field beam measuring device 140 is described:

[0065] The far-field beam characteristic detector 146 includes a second beam quality analyzer 146 - 2 and a second position sensitive detector 146 - 1 .

[0066] like Figure 4 As shown, the far-field beam measuring device 140 includes, in addition to the focusing lens 143, a third ultraviolet attenuation plate 141-1, a fourth ultraviolet attenuation plate 141-2, a second folding mirror 144-1, a third folding mirror 144-2, a second beam splitter 145 and a fifth ultraviolet attenuation plate 141-3. The third ultraviolet attenuation plate 141-1, the fourth ultraviolet attenuation plate 141-2, the focusing lens 143 and the second folding mirror 144-2 are sequentially arranged along the propagation direction of the second light beam, and the third light absorbing plate 142-2 is arranged on the reflection light path of the fourth ultraviolet attenuation plate 141-2. The third refraction mirror is connected to the second refraction mirror at a preset angle; the second beam splitter 145 is connected to the third refraction mirror 144-2 in sequence on the same optical axis, and the second beam splitter 145 is used to split the second light beam into a fifth light beam and a sixth light beam; the second beam quality analyzer 146-2 is arranged along the propagation direction of the sixth light beam; the fifth ultraviolet attenuation plate 141-3 and the second position sensitive detector 146-1 are arranged in sequence along the propagation direction of the fifth light beam.

[0067] Combination Figure 4 , the structural setting of the far-field beam measuring device 140 in the present application is briefly described: when the far-field beam measuring device 140 of the present application is used to measure the far-field divergence angle and pointing stability near the laser light outlet, since the energy of the laser to be measured is relatively strong, in order to avoid the laser to be measured from damaging the remote beam characteristic detector 146, a third attenuation plate 141-1 and a fourth ultraviolet attenuation plate 141-2 are set before the focusing lens 143. A focusing lens 143 with a long focal length is selected to reduce the measurement error. In order to improve the portability of the test device, a second fold mirror 144-1 and a third fold mirror 144-2 are used to fold the light path. The far-field beam characteristic detector 146 is set at the ideal focal plane of the focusing lens 143, and the second beam splitter 145 divides the second beam into two, namely, a fifth beam and a sixth beam. The sixth beam is used for the second beam quality analyzer 146-1 to test the far-field divergence angle, and the fifth beam is used for the second position sensitive detector 146-2 to test the pointing stability. Furthermore, the damage threshold of the second position sensitive detector 146-2 is much lower than that of the second beam quality analyzer 18, so a fifth ultraviolet attenuation plate 141-3 is provided between the second beam splitter 145 and the second position sensitive detector 146-2 to ensure the safety of the second position sensitive detector 146-2. It should be noted that the material of the focusing lens is calcium fluoride or fused quartz.

[0068] In addition, in order to improve the accuracy of the test results, the near-field beam characteristic detector 136 and the far-field beam characteristic detector 146 are both sealed in the laser beam characteristic measuring device 100 .

[0069] The present application provides a laser beam characteristic measurement device, which solves the problem of low efficiency of testing near-field and far-field beam quality characteristics (spot size, position stability, divergence angle, pointing stability) separately and independently. The near-field beam measurement device provided by the present application is based on the lens imaging principle. The positions of the light source to be measured, the lens or lens group and the near-field beam characteristic detector are reasonably set by the adjustable slit calibration method. The laser to be measured is imaged 1:1 on the near-field beam characteristic detector, so that the beam characteristics obtained on the camera are the beam characteristics of the light source to be measured. It not only avoids the uncertainty of the test results caused by lens imaging, but also reduces the imaging aberration and improves the measurement accuracy by reasonably selecting the focal length and placement position of the lens or lens group. At the same time, it improves the test efficiency of the original method (inferring the beam quality characteristics at the light source according to the far-field divergence angle and pointing stability), and solves the problem that the high-energy laser beam characteristics cannot be directly and accurately measured in the prior art. It satisfies the function of measuring the near-field and far-field beam quality characteristics at the same time, saves the steps of repeated debugging of the optical path when changing different cameras, and achieves the advantages of high test integration, simple debugging, high efficiency, and improved accuracy.

[0070] like Figure 5 As shown, the present application also provides a method for measuring laser beam characteristics, comprising:

[0071] Step S501: obtaining a laser beam to be measured emitted from an adjustable slit, wherein the adjustable slit is arranged in the optical path of the laser beam to be measured and fits with the laser light outlet;

[0072] Step S502: performing a splitting process on the light beam to obtain a first light beam and a second light beam; wherein the splitting process is implemented by a splitting device, and the splitting device is arranged in the light path of the light output direction of the adjustable slit;

[0073] Step S503: respectively measuring the near-field beam characteristics of the first light beam and the far-field beam characteristics of the second light beam; wherein, measuring the near-field beam characteristics of the first light beam is achieved by a near-field beam measuring device, the near-field beam measuring device at least includes an imaging lens group and a near-field beam characteristics detector, the near-field beam measuring device is arranged in the optical path of the first light beam, and the adjustable slit is imaged on the near-field beam characteristics detector through the imaging lens group; measuring the far-field beam characteristics of the second light beam is achieved by a far-field beam measuring device, the far-field beam measuring device at least includes a focusing lens and a far-field beam characteristics detector, the far-field beam measuring device is arranged in the optical path of the second light beam, and the focusing lens and the far-field beam characteristics detector are arranged in sequence along the propagation direction of the second light beam, and the far-field beam detector is arranged at the ideal focal plane of the focusing lens.

[0074] The adjustable slit is fitted with the laser light outlet so that the laser to be tested does not diffuse outward when emitting the laser into the spectroscopic device, thereby affecting the accuracy of the test result.

[0075] The imaging lens group includes a first lens and a second lens, and the focal lengths of the first lens and the second lens are equal. In order to ensure the accuracy of the near-field beam measurement device in measuring the first beam, the first lens and the second lens need to be set at specific positions in the near-field beam measurement device, and specifically need to meet the following requirements: the optical path of the first lens and the second lens on the optical axis is equal to twice the focal length of the first lens, and the optical path of the first lens and the laser light outlet on the optical axis is equal to the optical path of the second lens and the near-field beam characteristic detector on the optical axis, and both are equal to the focal length of the first lens.

[0076] The imaging lens group can also be a single imaging lens, in which case the requirements that need to be met in the optical path are:

[0077] The optical path between the laser light outlet and the imaging lens on the optical axis is equal to the optical path between the imaging lens and the near-field beam characteristic detector on the optical axis, and both are equal to twice the focal length of the imaging lens.

[0078] The materials of the imaging lens in the near-field beam measuring device and the focusing lens in the far-field beam measuring device are both calcium fluoride or fused quartz.

[0079] In order to reduce measurement errors, the focusing lens in the far-field beam measurement device of the present application uses a lens with a larger focal length. Generally speaking, a lens with a focal length greater than 800 mm is selected, and the measurement error of the far-field beam quality characteristics meets actual needs.

[0080] Although the present application is disclosed as above in the form of a preferred embodiment, it is not intended to limit the present application. Any technical personnel in this field may make possible changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined by the claims of the present application.

Claims

1. A laser beam characteristic measuring device, characterized in that: It includes an adjustable slit, a light splitting device, a near-field beam measuring device and a far-field beam measuring device; The adjustable slit is arranged in the optical path of the laser beam to be measured and fits closely with the laser light outlet; The light splitting device is arranged in the light path of the adjustable slit in the light output direction, and is used to split the light beam into a first light beam and a second light beam; The near-field beam measuring device comprises an imaging lens group and a near-field beam characteristic detector, and the near-field beam measuring device is arranged in the optical path of the first beam, and an adjustable slit is imaged onto the near-field beam characteristic detector through the imaging lens group; The far-field beam measuring device includes a focusing lens and a far-field beam characteristic detector. The far-field beam measuring device is arranged in the optical path of the second beam, and the focusing lens and the far-field beam characteristic detector are arranged in sequence along the propagation direction of the second beam. The far-field beam detector is arranged at the ideal focal plane of the focusing lens.

2. The device according to claim 1, characterized in that The near-field beam characteristic detector includes a first beam quality analyzer and a first position sensitive detector.

3. The device according to claim 2, characterized in that The near-field beam measuring device further comprises: a first refracting mirror, a first ultraviolet attenuation plate, a first beam splitter and a second ultraviolet attenuation plate; The first folding mirror, the first ultraviolet attenuation plate, and the first beam splitter are sequentially arranged along the propagation direction of the first light beam; The first beam splitter is used to split the first light beam into a third light beam and a fourth light beam; The second ultraviolet attenuation sheet and the first position sensitive detector are sequentially arranged along the propagation direction of the third light beam; The first beam quality analyzer is arranged along the propagation direction of the fourth light beam.

4. The device according to claim 1, characterized in that The far-field beam characteristic detector includes a second mass analyzer and a second position sensitive detector.

5. The device according to claim 4, characterized in that The far-field beam measuring device further comprises: a third ultraviolet attenuation plate, a fourth ultraviolet attenuation plate, a second refracting mirror, a third refracting mirror, a second beam splitter and a fifth ultraviolet attenuation plate; The third ultraviolet attenuation sheet, the fourth ultraviolet attenuation sheet, the focusing lens and the second folding mirror are sequentially arranged along the propagation direction of the second light beam; The third folding mirror is connected to the second folding mirror at a preset angle; The second beam splitter is connected in sequence with the third folding mirror on the same optical axis, and the second beam splitter is used to split the second light beam into a fifth light beam and a sixth light beam; The second beam quality analyzer is arranged along the propagation direction of the sixth light beam; The fifth ultraviolet attenuation plate and the second position sensitive detector are arranged in sequence along the propagation direction of the fifth light beam.

6. The device according to claim 1, characterized in that include: The adjustable slit is sealed with the laser beam characteristic measuring device.

7. The system according to claim 2, characterized in that The imaging lens group includes a first lens and a second lens: The focal lengths of the first lens and the second lens are equal; The optical path between the first lens and the second lens on the optical axis is equal to twice the focal length of the first lens; The optical path between the first lens and the laser light outlet on the optical axis is equal to the optical path between the second lens and the near-field beam characteristic detector on the optical axis, and both are equal to the focal length of the first lens.

8. The device according to claim 2, characterized in that The lenses in the imaging lens group are all biconvex lenses.

9. The device according to claim 1, characterized in that include: The near-field beam characteristic detector and the far-field beam characteristic detector are both sealed in the laser beam characteristic measuring device.

10. A method for measuring laser beam characteristics, characterized in that: include: Acquire a laser beam to be measured emitted from an adjustable slit, wherein the adjustable slit is arranged in the optical path of the laser beam to be measured and fits with the laser light outlet; Performing a spectroscopic process on the light beam to obtain a first light beam and a second light beam; wherein the spectroscopic process is implemented by a spectroscopic device, and the spectroscopic device is arranged in the light path of the light output direction of the adjustable slit; respectively measuring near-field beam characteristics of the first light beam and far-field beam characteristics of the second light beam; Among them, the measurement of the near-field beam characteristics of the first light beam is achieved by a near-field beam measuring device, which includes an imaging lens group and a near-field beam characteristics detector, and the near-field beam measuring device is arranged in the optical path of the first light beam, and the adjustable slit is imaged on the near-field beam characteristics detector through the imaging lens group; the measurement of the far-field beam characteristics of the second light beam is achieved by the far-field beam measuring device, which includes a focusing lens and a far-field beam characteristics detector, and the far-field beam measuring device is arranged in the optical path of the second light beam, and the focusing lens and the far-field beam characteristics detector are arranged in sequence along the propagation direction of the second light beam, and the far-field beam detector is arranged at the ideal focal plane of the focusing lens.

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