High-spectral-resolution echelle grating spectrometer

Abstract

The invention relates to the field of optics, in particular to a high-spectral-resolution echelle grating spectrometer, which is characterized in that a front pre-light-splitting module is used for compressing the spectral range of incident light and emitting a light beam in a set wavelength range; the echelle grating dispersion module is located on an emergent light path of the front pre-light-splitting module. The echelle grating dispersion module comprises an entrance slit, an optical transmission assembly, an echelle grating and a turning plane mirror group. The optical path transmission direction is on a meridian plane, and the dispersion direction of the echelle grating is on a sagittal plane. Light beams pass through the entrance slit and are incident to the echelle grating through the optical transmission assembly for dispersion, the dispersed light beams are incident to the echelle grating through the turning plane mirror group for multiple times for dispersion, the light beams subjected to multiple times of dispersion are incident to the spectrum detection module, and spectrum information is obtained through the spectrum detection module. Therefore, spectrum misreading can be avoided while the femtometer-level spectral resolution is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the field of optics, and particularly relates to an echelle grating spectrometer with high spectral resolution. Background Art

[0002] A spectrometer is a scientific instrument that can detect the wavelength and intensity distribution of each monochromatic light in a composite light. It has had a huge impact on modern scientific research and industrial production, showing extremely important value in many fields such as scientific research exploration, production practice, and quality control, and has been widely concerned by instrument science researchers since its birth. In recent years, with the rapid development of a series of cutting-edge scientific research fields such as plasma spectral analysis and excimer laser lithography, the requirement for the spectral resolution of spectrometer products has been greatly improved, and the spectral resolution needs to reach the femtometer level standard. At present, the echelle grating spectrometer, relying on the advantage of its large grating blaze angle, can provide higher spectral resolution compared with the ordinary blazed grating spectrometer. With the optical path structure of multiple diffractions, it is expected that the spectrometer can reach the femtometer-level spectral resolution.

[0003] However, due to the very high diffraction order of the echelle grating and the very narrow spectral range utilized by each order, it is necessary to use multiple different orders to form a complete spectral range. In existing echelle grating spectrometers, there are many diffracted lights of non-utilized orders running in the optical path and reaching the detector, which is likely to cause spectral misreading. Summary of the Invention

[0004] In view of this, the present invention aims to provide an echelle grating spectrometer with high spectral resolution, which can avoid spectral misreading while ensuring the femtometer-level spectral resolution.

[0005] To achieve the above object, the technical solution of the present invention is realized as follows: An echelle grating spectrometer with high spectral resolution, which includes a prefrontal pre-dispersing module, an echelle grating dispersing module, and a spectral detection module arranged in sequence along the optical path transmission direction; The incident light is incident on the prefrontal pre-dispersing module, and the prefrontal pre-dispersing module is used to compress the spectral range of the incident light and emit a beam within a set wavelength range; The echelle grating dispersing module is located on the outgoing optical path of the prefrontal pre-dispersing module. The echelle grating dispersing module includes an entrance slit, an optical transmission component, an echelle grating, and a folding mirror group; the optical path transmission direction is in the meridional plane, and the dispersion direction of the echelle grating is in the sagittal plane; the beam passes through the entrance slit and is incident on the echelle grating through the optical transmission component for dispersion. The dispersed beam is incident on the echelle grating multiple times through the folding mirror group for dispersion. The beam after multiple dispersions is incident on the spectral detection module, and spectral information is obtained through the spectral detection module.

[0006] Further, the pre - splitting module includes an incident pinhole, a first collimating mirror, a plane blazed grating, and a first plane folding mirror; the diffraction order of the plane blazed grating is the +1 order. The incident light passes through the incident pinhole and is incident on the first collimating mirror, and the first collimating mirror is used to collimate the incident light; the collimated incident light is incident on the plane blazed grating for dispersion, so that the light of the +1 diffraction order returns to the first collimating mirror for convergence, and a beam of a set wavelength range is emitted through the first plane folding mirror to the incident slit.

[0007] Further, the first collimating mirror is a spherical mirror.

[0008] Further, the dispersion direction of the plane blazed grating is in the sagittal plane.

[0009] Further, the plane blazed grating is in the sagittal plane and can be swing - set around the center of the plane blazed grating.

[0010] Further, the optical transmission component includes a second plane folding mirror and a second collimating mirror. The second plane folding mirror is on the optical path from the incident slit to the second collimating mirror. The beam passes through the incident slit and enters the second collimating mirror through the second plane folding mirror for collimation; the collimated beam is incident on the echelle grating for dispersion. The second collimating mirror is located on the outgoing optical path of the echelle grating, so that the beam that has undergone multiple dispersions converges at the second collimating mirror, and the beam that has undergone multiple dispersions is incident on the spectral detection module through the second collimating mirror.

[0011] Further, the second collimating mirror is an off - axis paraboloid.

[0012] Further, the folding plane mirror group includes a first folding plane mirror and a second folding plane mirror. The beam that has undergone one - time dispersion is incident on the first folding plane mirror. After being reflected by the first folding plane mirror, it is incident on the echelle grating again for secondary dispersion. The beam that has undergone secondary dispersion is incident on the second folding plane mirror. After being reflected by the second folding plane mirror, it is incident on the echelle grating again for tertiary dispersion. The beam that has undergone tertiary dispersion is incident on the first folding plane mirror again. After being reflected by the first folding plane mirror, it is incident on the echelle grating again for quaternary dispersion; the beam that has undergone quaternary dispersion is incident on the spectral detection module.

[0013] Further, the spectral detection module includes a cylindrical mirror and a detector; the cylindrical mirror is located on the optical path from the echelle grating dispersion module to the detector. The beam that has undergone multiple dispersions is incident on the cylindrical mirror, and after being reflected by the cylindrical mirror, it enters the detector for spectral detection.

[0014] Further, the detector is an image intensifier charge-coupled detector.

[0015] Compared with the prior art, the present invention can achieve the following beneficial effects: In the echelle grating spectrometer with high spectral resolution of the present invention, the echelle grating spectrometer includes an echelle grating dispersion module. Among them, the optical path transmission direction is in the meridional plane, and the dispersion direction of the echelle grating in the echelle grating dispersion module is in the sagittal plane. In this way, the diffracted light corresponding to non-given wavelengths and used orders can be dispersed out of the optical path in the sagittal direction, thereby reducing the influence of the diffracted light of non-used orders on the spectral information obtained by the detector, thus avoiding spectral misreading and reducing the stray light level of the echelle grating spectrometer. At the same time, the dispersed beam is incident on the echelle grating multiple times through the folding plane mirror group for dispersion, and the beam that has undergone multiple dispersions is incident on the spectral detection module. In this way, high spectral resolution can be achieved. Therefore, the echelle grating spectrometer can avoid spectral misreading while ensuring a spectral resolution of the femtometer level. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings: Figure 1 is a schematic structural diagram of the echelle grating spectrometer according to an embodiment of the present invention; Figure 2 is a schematic optical path diagram of the echelle grating dispersion module of the echelle grating spectrometer according to an embodiment of the present invention.

[0017] Description of the reference numerals: 10. Echelle grating spectrometer; 11. Pre-front-end spectroscopic module; 12. Echelle grating dispersion module; 13. Spectral detection module; 14. Entrance slit; 15. Optical transmission component; 16. Echelle grating; 17. Folding plane mirror group; 18. Entrance pinhole; 19. First collimating mirror; 20. Plane blazed grating; 21. First plane folding mirror; 22. Second plane folding mirror; 23. Second collimating mirror; 24. First folding plane mirror; 25. Second folding plane mirror; 26. Cylindrical mirror; 27. Detector. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention. Similar elements in different embodiments are labeled with related similar element numbers. In the following embodiments, many detailed descriptions are provided to enable a better understanding of the present invention. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other elements, materials, or methods. In some cases, some operations related to the present invention are not shown or described in the specification to avoid overwhelming the core part of the present invention with excessive descriptions. For those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations based on the descriptions in the specification and the general technical knowledge in the art.

[0019] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other to form various implementation manners. At the same time, the steps or actions in the method description can also be adjusted in the order that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for clearly describing a certain embodiment and do not mean that they are the necessary sequences, unless it is stated that a certain sequence must be followed.

[0020] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and 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 should not be construed as a limitation to the present invention. In addition, terms such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality" is two or more.

[0021] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

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

[0023] Referring to Figure 1 As shown, an embodiment of the present invention provides an echelle grating spectrometer 10 with high spectral resolution. The echelle grating spectrometer 10 includes a pre-pre-dispersing module 11, an echelle grating dispersion module 12, and a spectral detection module 13 arranged in sequence along the optical path transmission direction.

[0024] The incident light is incident on the pre-pre-dispersing module 11. The pre-pre-dispersing module 11 is used to compress the spectral range of the incident light and emit a beam within a set wavelength range. The pre-pre-dispersing module 11 can pre-disperse the incident light, thus avoiding spectral order aliasing.

[0025] The echelle grating dispersion module 12 is located on the outgoing optical path of the pre-pre-dispersing module 11. The echelle grating dispersion module 12 includes an entrance slit 14, an optical transmission component 15, an echelle grating 16, and a folding mirror group 17. The optical path transmission direction is in the meridional plane xoy, and the dispersion direction of the echelle grating 16 is in the sagittal plane. Among them, the sagittal plane is perpendicular to the meridional plane xoy. The beam passes through the entrance slit 14 and is incident on the echelle grating 16 through the optical transmission component 15 for dispersion. The dispersed beam is incident on the echelle grating 16 multiple times through the folding mirror group 17 for dispersion. The beam after multiple dispersions is incident on the spectral detection module 13, and spectral information is obtained through the spectral detection module 13. The optical path transmission direction is in the meridional plane xoy, and the dispersion direction of the echelle grating 16 is in the sagittal plane, which can form an optical path structure with perpendicular dispersion. The beam undergoes multiple diffractions on the echelle grating 16 and is combined with the optical path structure with perpendicular dispersion, enabling the echelle grating spectrometer 10 to achieve femtometer-level spectral resolution on the premise of low stray light, providing a new idea for the research of high-resolution spectrometers.

[0026] The echelle grating spectrometer 10 with high spectral resolution of the present invention, the echelle grating spectrometer 10 includes an echelle grating dispersion module 12. Among them, the optical path transmission direction is in the meridional plane xoy, and the dispersion direction of the echelle grating 16 of the echelle grating dispersion module 12 is in the sagittal plane. In this way, the diffracted light corresponding to the non-given wavelength and the used order can be dispersed out of the optical path in the sagittal direction, thereby reducing the influence of the diffracted light of the non-used order on the spectral information obtained by the detector 27, thus avoiding spectral misreading and reducing the stray light level of the echelle grating spectrometer 10. At the same time, the dispersed light beam is incident on the echelle grating 16 multiple times through the folding plane mirror group 17 for dispersion, and the light beam that has undergone multiple dispersions is incident on the spectral detection module 13. In this way, high spectral resolution can be achieved. Thus, the echelle grating spectrometer 10 can avoid spectral misreading while ensuring a femtometer-level spectral resolution.

[0027] In one embodiment, the pre-pre-dispersing module 11 includes an incident pinhole 18, a first collimating mirror 19, a plane blazed grating 20, and a first plane folding mirror 21. In one embodiment, the first collimating mirror 19 is a spherical mirror. The diffraction order of the plane blazed grating 20 is +1 order. The incident light passes through the incident pinhole 18 and is incident on the first collimating mirror 19, and the first collimating mirror 19 is used to collimate the incident light. The collimated incident light is incident on the plane blazed grating 20 for dispersion, and can be dispersed according to the grating equation for dispersion. Among them, is the grating constant of the plane blazed grating 20, is the incident angle of the plane blazed grating 20, is the diffraction angle of the plane blazed grating 20, is the offset angle incident on the plane blazed grating 20, is the wavelength of the incident light, is the diffraction secondary of the plane blazed grating 20. In this way, the light of the +1 order diffraction order can return to the first collimating mirror 19 for convergence, and the light beam within the set wavelength range is emitted through the first plane folding mirror 21 to the entrance slit 14. The spectral range of the light beam incident on the echelle grating dispersion module 12 can be controlled by adjusting the width of the entrance slit 14. Since the echelle grating 16 works at a relatively high diffraction secondary, the free spectral range of each secondary is very small, and the phenomenon of spectral order overlap is likely to occur. In order to avoid the influence of this factor, the present invention compresses the spectral range of the incident light through the pre-pre-dispersing module 11, so that the light beam within the set wavelength range emitted by the pre-pre-dispersing module 11 is within the free spectral range of the given wavelength and used order of the echelle grating 16.

[0028] In one embodiment, the optical path transmission direction is in the meridional plane, and the dispersion direction of the planar blazed grating 20 is in the sagittal plane. In this way, the light of the +2 diffraction order can be dispersed out of the optical path in the sagittal direction of the sagittal plane, and only the light of the +1 diffraction order returns to the first collimating mirror 19 for convergence.

[0029] In one embodiment, the planar blazed grating 20 is in the sagittal plane and is swingably arranged around the center of the planar blazed grating 20. In this way, wide-spectrum range scanning can be achieved by the swing of the planar blazed grating 20.

[0030] In one embodiment, the optical transmission assembly 15 includes a second planar folding mirror 22 and a second collimating mirror 23. In one embodiment, the second collimating mirror 23 is an off-axis paraboloid. In this way, the collimation and imaging quality can be guaranteed. The second planar folding mirror 22 is on the optical path from the incident slit 14 to the second collimating mirror 23. The light beam passes through the incident slit 14 and enters the second collimating mirror 23 through the second planar folding mirror 22 for collimation. The collimated light beam is incident on the echelle grating 16 for dispersion. The second collimating mirror 23 is on the outgoing optical path of the echelle grating 16, so that the light beam that has undergone multiple dispersions is converged by the second collimating mirror 23, and the light beam that has undergone multiple dispersions is incident on the spectral detection module 13 through the second collimating mirror 23.

[0031] In one embodiment, the folding mirror group 17 includes a first folding mirror 24 and a second folding mirror 25. The light beam that has undergone one dispersion is incident on the first folding mirror 24. After being reflected by the first folding mirror 24, it is incident on the echelle grating 16 again for secondary dispersion. The light beam that has undergone secondary dispersion is incident on the second folding mirror 25. After being reflected by the second folding mirror 25, it is incident on the echelle grating 16 again for tertiary dispersion. The light beam that has undergone tertiary dispersion is incident on the first folding mirror 24 again. After being reflected by the first folding mirror 24, it is incident on the echelle grating 16 again for quaternary dispersion. The light beam that has undergone quaternary dispersion is incident on the spectral detection module 13.

[0032] In order to make the light beam that has undergone one dispersion be incident on the echelle grating 16 for dispersion multiple times through the folding mirror group 17 while ensuring the diffraction efficiency of the echelle grating 16, a bias angle is introduced in the meridional plane when the light beam is incident on the echelle grating 16 , that is, the light beam is incident on the echelle grating 16 in a quasi-Littrow form through the optical transmission assembly 15 for dispersion. At this time, the dispersion law of the echelle grating 16 satisfies . Among them, is the grating constant of the echelle grating 16, is the incident angle when the light beam is first incident on the echelle grating 16, is the diffraction angle of the light beam when it first enters the echelle grating 16, is the wavelength of the light beam, is the diffraction order of the echelle grating 16. Thus, the angular dispersion of the light beam after four dispersions can be expressed as:

[0033] where, is the offset angle when first entering the echelle grating 16, is the offset angle when second entering the echelle grating 16, is the offset angle when third entering the echelle grating 16, is the offset angle when fourth entering the echelle grating 16, is the angular dispersion of the light beam after one dispersion.

[0034] In one embodiment, the spectral detection module 13 includes a cylindrical mirror 26 and a detector 27. The cylindrical mirror 26 is located on the optical path from the echelle grating dispersion module 12 to the detector 27. The light beam after multiple dispersions is incident on the cylindrical mirror 26, and after being reflected by the cylindrical mirror 26, it enters the detector 27 for spectral detection. The light beam after multiple dispersions enters the detector 27 after being reflected by the cylindrical mirror 26, and the astigmatism of the optical system can be reduced by the cylindrical mirror 26.

[0035] In one embodiment, the detector 27 is an image-intensified charge-coupled device 27 (ICCD, Intensified Charge-Coupled Device), so as to ensure the sensitivity of the echelle grating spectrometer 10 in a weak light environment.

[0036] It should be understood that various forms of the processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in the disclosure of the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution disclosed in the present invention can be achieved. No limitations are imposed herein.

[0037] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A echelle grating spectrometer with high spectral resolution, characterized in that, It includes a pre - pre - dispersion module, an echelle grating dispersion module, and a spectral detection module arranged in sequence along the optical path transmission direction; The pre - pre - dispersion module is used to compress the spectral range of the incident light and emit a light beam within a set wavelength range; The echelle grating dispersion module is located on the outgoing optical path of the pre - pre - dispersion module. The echelle grating dispersion module includes an entrance slit, an optical transmission component, an echelle grating, and a folding flat mirror group; the optical path transmission direction is in the meridional plane, and the dispersion direction of the echelle grating is in the sagittal plane; the light beam passes through the entrance slit and is incident on the echelle grating through the optical transmission component for dispersion. The dispersed light beam is incident on the echelle grating multiple times through the folding flat mirror group for dispersion. The light beam after multiple dispersions is incident on the spectral detection module, and spectral information is obtained through the spectral detection module.

2. The echelle grating spectrometer with high spectral resolution according to claim 1, characterized in that, The pre - pre - dispersion module includes an entrance pinhole, a first collimating mirror, a plane blazed grating, and a first plane folding mirror; the diffraction order of the plane blazed grating is +1 order; The incident light passes through the entrance pinhole and is incident on the first collimating mirror, and the first collimating mirror is used to collimate the incident light; The collimated incident light is incident on the plane blazed grating for dispersion, so that the light of the +1 diffraction order returns to the first collimating mirror for convergence, and a light beam within a set wavelength range is emitted to the entrance slit through the first plane folding mirror.

3. The echelle grating spectrometer with high spectral resolution according to claim 2, characterized in that, The first collimating mirror is a spherical mirror.

4. The echelle grating spectrometer with high spectral resolution according to claim 2, characterized in that, The dispersion direction of the plane blazed grating is in the sagittal plane.

5. The echelle grating spectrometer with high spectral resolution according to claim 4, characterized in that, The plane blazed grating is arranged in the sagittal plane and can be swing - set around the center of the plane blazed grating.

6. The echelle grating spectrometer with high spectral resolution according to claim 1, characterized in that, The optical transmission component includes a second plane folding mirror and a second collimating mirror; The second plane folding mirror is on the optical path from the entrance slit to the second collimating mirror. The light beam passes through the entrance slit and enters the second collimating mirror through the second plane folding mirror for collimation; The collimated light beam is incident on the echelle grating for dispersion; The second collimating mirror is located on the outgoing optical path of the echelle grating, so that the light beam after multiple dispersions converges at the second collimating mirror, and the light beam after multiple dispersions is incident on the spectral detection module through the second collimating mirror.

7. The echelle grating spectrometer with high spectral resolution according to claim 6, characterized in that, The second collimating mirror is an off - axis paraboloid.

8. The echelle grating spectrometer with high spectral resolution according to claim 1, characterized in that, The folding flat mirror group includes a first folding flat mirror and a second folding flat mirror; The light beam after one - time dispersion is incident on the first folding flat mirror. After being reflected by the first folding flat mirror, it is incident on the echelle grating again for secondary dispersion; The light beam after secondary dispersion is incident on the second folding flat mirror. After being reflected by the second folding flat mirror, it is incident on the echelle grating again for tertiary dispersion; The light beam after tertiary dispersion is incident on the first folding flat mirror again. After being reflected by the first folding flat mirror, it is incident on the echelle grating again for quaternary dispersion; the light beam after quaternary dispersion is incident on the spectral detection module.

9. The echelle grating spectrometer with high spectral resolution according to claim 1, characterized in that, The spectral detection module includes a cylindrical mirror and a detector; the cylindrical mirror is located on the optical path from the echelle grating dispersion module to the detector, and the beam that has undergone multiple dispersions is incident on the cylindrical mirror, and after being reflected by the cylindrical mirror, it enters the detector for spectral detection.

10. The echelle grating spectrometer with high spectral resolution according to claim 9, characterized in that, The detector is an image-intensified charge-coupled detector.

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