Double-arm high-resolution wavelength meter and light path structure

Abstract

The invention relates to the technical field of spectral analysis, in particular to a double-arm high-resolution wavelength meter and a light path structure, and the wavelength meter comprises a light splitting module, a plane grating spectrum module and an echelle grating spectrum module; incident laser is divided into first laser and second laser through the light splitting module. The first laser enters the plane grating spectrum module for pre-measurement; and the second laser enters the echelle grating spectrum module, the echelle grating spectrum module carries out adjustment according to a pre-measurement result, and then the second laser is measured to obtain the beam wavelength of the incident laser. According to the invention, the echelle grating spectrum module and the plane grating spectrum module are combined, accurate judgment of the echelle grating level is realized by adopting the plane grating spectrum module, and high-resolution spectrum measurement is realized by adopting the echelle grating spectrum module.

Description

Technical Field

[0001] The invention belongs to the technical field of spectrum analysis, and in particular relates to a double-arm high-resolution wavelength meter and an optical path structure. Background Art

[0002] Laser technology plays an important role in industrial processing, communications, medical treatment, food industry, national defense and military applications. With the continuous development of laser technology, the requirements for the measurement accuracy of laser wavelengths are getting higher and higher. In the field of optical information communication, wavelength meters can be used to monitor the specific wavelength values ​​of channels. In the military field, high-resolution wavelength meters can accurately measure wavelengths and calibrate laser weapons such as laser ranging, laser guidance, and laser aiming. In other fields, such as laser frequency stabilization, a high-resolution real-time wavelength measurement device that can quickly provide wavelength feedback is often required to calibrate wavelength drift caused by temperature or material properties.

[0003] Internationally commercialized laser wavelength measurement instruments and equipment are mainly divided into interferometry and grating dispersion measurement methods.

[0004] In the interference measurement method, the Michelson interferometer has a built-in mechanical scanning component, which makes it susceptible to vibration; the Michelson interferometer and Fabry-Perot interferometer require interference fringes generated by the reference laser and the laser to be measured to calculate the wavelength of the laser to be measured, which increases the cost of use; the Fizeau interferometer is greatly affected by temperature and air pressure, and must be under constant temperature and pressure conditions during measurement.

[0005] In the grating dispersion measurement method, high precision and compact structure cannot be achieved at the same time. Moving parts are often required to achieve high-precision wavelength measurement. When used in harsh environments, the presence of moving parts will make the measurement process difficult or the measurement results inaccurate. Summary of the invention

[0006] In view of this, the present invention aims to provide a double-arm high-resolution wavelength meter and optical path structure, in which a double-arm optical path is composed of a plane grating spectrum module and a medium-step grating spectrum module. After the plane grating spectrum module pre-measures the laser, the medium-step grating spectrum module is adjusted according to the result of the pre-measurement, and then the laser is measured to obtain a higher-resolution beam wavelength of the incident laser.

[0007] To achieve the above object, the technical solution created by the present invention is implemented as follows: A double-arm high-resolution wavelength meter comprises a spectroscopic module, a plane grating spectrum module and an echelle grating spectrum module; an incident laser is divided into a first laser and a second laser by the spectroscopic module; the first laser enters the plane grating spectrum module for pre-measurement; the second laser enters the echelle grating spectrum module, the echelle grating spectrum module is adjusted according to the result of the pre-measurement, and then the second laser is measured to obtain the beam wavelength of the incident laser.

[0008] Furthermore, the plane grating spectrum module includes a grating spectrometer module and a first planar array detector; wherein the grating spectrometer module diffracts and splits the first laser to generate a first diffracted light; the first planar array detector receives the first diffracted light and predicts the wavelength of the first diffracted light to obtain the wavelength range of the incident laser beam.

[0009] Furthermore, the plane grating spectrum module also includes a first free-form surface reflector group; the first laser is reflected into the grating spectrometer module via the first free-form surface reflector group; and the first diffracted light is reflected into the first planar array detector via the first free-form surface reflector group.

[0010] Furthermore, the echelle grating spectrum module includes a echelle grating and a second planar array detector; wherein the echelle grating diffracts and splits the second laser to generate second diffracted light, and the order of the echelle grating is selected based on the result of predicted measurement; the second planar array detector receives the second diffracted light and measures the second diffracted light based on the wavelength range of the light beam to obtain the wavelength of the light beam.

[0011] Furthermore, the echelle grating spectrum module also includes a second free-form surface reflector group and an aberration-correcting lens group; wherein the second laser is reflected onto the echelle grating via the second free-form surface reflector group; the second diffracted light is reflected into the aberration-correcting lens group via the second free-form surface reflector group; and the second diffracted light enters the second array detector after passing through the aberration-correcting lens group.

[0012] Furthermore, the beam splitting module includes a beam splitter; the incident laser is split into a first laser and a second laser by the beam splitter.

[0013] An optical path structure based on a double-arm high-resolution wavelength meter comprises the double-arm high-resolution wavelength meter provided by the present invention and a front optical path; wherein the front optical path generates an incident laser and emits the incident laser to the double-arm high-resolution wavelength meter; the double-arm high-resolution wavelength meter receives the incident laser and measures the wavelength of the incident laser.

[0014] Furthermore, the front optical path includes a laser for generating incident laser light.

[0015] Furthermore, a slit is provided between the laser and the double-arm high-resolution wavelength meter, so that the incident laser enters the double-arm high-resolution wavelength meter after passing through the slit.

[0016] Compared with the prior art, the invention can achieve the following beneficial effects: (1) In the dual-arm high-resolution wavelength meter described in the invention, the echelle grating and the plane grating type spectrum module are combined, the plane grating type spectrum module is used to accurately determine the echelle grating order, and the echelle grating type spectrum module is used to achieve high-resolution, wide-band spectrum measurement; in addition, the wavelength meter does not use any moving parts, is not easily affected by vibration, and effectively improves the adaptability to the environment; (2) In the plane grating type spectrum module created by the present invention, a multi-frequency grating or a grating composed of sub-gratings with different deflection angles is used as a grating spectroscopic module, which can improve the resolution of the predicted measurement and prepare for the order gating and high-resolution measurement of the medium-step grating; at the same time, the free-form surface reflector group in the double-arm high-resolution wavelength meter in the plane grating type spectrum module and the medium-step grating spectrum module can effectively improve the imaging quality and improve the spectral resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings: Figure 1 A schematic diagram of the optical path structure of a dual-arm high-resolution wavelength meter according to an embodiment of the present invention; Figure 2 A schematic diagram of the structure of the grating spectrometer module according to an embodiment of the present invention; Figure 3 A schematic diagram of the optical path structure based on a dual-arm high-resolution wavelength meter described in an embodiment of the present invention.

[0018] Description of reference numerals: 1. Spectrometer module; 2. Grating spectrometer module; 3. First array detector; 4. First free-form surface reflector; 5. Second free-form surface reflector; 6. Echelle grating; 7. Second array detector; 8. Aberration-correcting lens group; 9. Third free-form surface reflector; 10. Fourth free-form surface reflector; 11. Laser; 12. Slit; 13. Optical fiber; 14. Sub-grating. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0020] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are 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", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0022] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" 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 a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

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

[0024] like Figure 1 As shown, the dual-arm high-resolution wavelength meter described in the embodiment of the invention includes a spectrometer module 1, a plane grating spectrum module and an echelle grating spectrum module. The incident laser is divided into a first laser and a second laser in two arms by the spectrometer module 1. The first laser enters the plane grating spectrum module for pre-measurement; the second laser enters the echelle grating spectrum module, the echelle grating spectrum module is adjusted according to the result of the pre-measurement, and then the second laser is measured to obtain the beam wavelength of the incident laser. In the embodiment of the present invention, the spectrometer module 1 includes a spectroscope, so that the incident laser irradiated to the spectroscope is divided into a first laser and a second laser.

[0025] The plane grating spectrum module adopts a non-cross-symmetrical optical path structure, including a grating spectrometer module 2 and a first planar array detector 3. The grating spectrometer module 2 diffracts the first laser, and the diffraction produces spectrometry, which in turn produces first diffracted light, and then the wavelength range of the first diffracted light is locked. Spectrometry here refers to separating light of different wavelengths in a beam of light to produce light of different orders, and light of different orders corresponds to different wavelength ranges. The first diffracted light here is the first-order diffracted light. The first planar array detector 3 receives the first diffracted light and measures the wavelength of the first diffracted light to obtain the wavelength range of the incident laser light, thereby determining the measurement range of the dual-arm high-resolution wavelength meter provided in the embodiment of the present invention.

[0026] In the embodiment of the present invention, the grating spectrometer module 2 preferably adopts a multi-frequency grating or a diffraction grating composed of sub-gratings with different deflection angles, which effectively expands the measurement range and thus improves the resolution of the predicted measurement. Among them, the multi-frequency grating refers to a grating on which the line density varies, which can be understood as gratings with different line densities being spliced ​​together to achieve wide-band measurement. The resolution of the multi-frequency grating is related to the grating line density and the grating width. The multi-frequency grating in the embodiment of the present invention is divided into four parts, and the line densities of different parts are 2400l / mm, 1800l / mm, 1200l / mm, and 600l / mm, respectively, with a total area of ​​64×64mm 2 , spectral range 180-900nm. The structure of the diffraction grating composed of sub-gratings with different deflection angles is as follows Figure 2 As shown, the principle is similar to that of the multi-frequency grating, but the sub-gratings 14 with the same line density are selected and the measurement spectrum is expanded by rotating at different angles; the diffraction grating in the embodiment of the present invention is composed of four sub-gratings 14 with the same line density, and the angle between the first sub-grating 14 and the second sub-grating 14 is , the angle between the second sub-grating 14 and the third sub-grating 14 is , the angle between the third sub-grating 14 and the fourth sub-grating 14 is . In an embodiment of the present invention, in order to improve the imaging quality of the first array detector 3 and further improve the spectral resolution, a first free-form surface reflector group is preferably provided in the plane grating spectrum module, wherein the first free-form surface reflector group includes a first free-form surface reflector 4 and a second free-form surface reflector 5. In addition to realizing the functions of light reflection and light path folding, the first free-form surface reflector group can also eliminate aberrations of the light beam. Specifically, the first laser is reflected by the first free-form surface reflector 4 into the grating spectrometer module 2, and the first diffracted light generated by the grating spectrometer module 2 is reflected by the second free-form surface reflector 5 into the first array detector 3.

[0027] The echelle grating spectrum module also adopts a non-cross-symmetrical optical path structure, including an echelle grating 6 and a second array detector 7. The echelle grating 6 diffracts and splits the second laser to generate a second diffracted light. The second array detector 7 receives the second diffracted light and measures the second diffracted light according to the wavelength range of the light beam to obtain the wavelength of the light beam. Among them, the order of the echelle grating 6 is selected according to the result of the predicted measurement; among them, the echelle grating 6 has the characteristics of many orders and high resolution, and different orders correspond to different measurement ranges, so the order needs to be selected before using the echelle grating 6.

[0028] The light incident on the echelle grating 6 will have many orders when diffracted, and too many orders will cause order overlap (for example, a characteristic peak will appear three times, and a signal light may have many characteristic peaks appearing at different orders). At this time, if only the echelle grating 6 is used in conjunction with the second array detector 7 for detection, it will be seriously disturbed by the problem of order overlap. Based on the above problems, the present invention preferably designs a plane grating spectrum module in conjunction with a echelle grating spectrum module. Since the plane grating spectrum module plays the role of filtering and determines the wavelength range of the incident laser, the order of the echelle grating 6 corresponding to the echelle grating spectrum module is limited, thereby solving the problem of low detection efficiency caused by order overlap due to too many orders. The specific measurement process is that the plane grating spectrum module receives the first laser and determines that the approximate wavelength of the incident laser corresponds to a certain order of the echelle grating 6. It only needs to select a certain order on the software corresponding to the second surface detector 7, filter out other orders, and achieve accurate measurement.

[0029] In an embodiment of the present invention, in order to improve the imaging quality of the second array detector 7 and thus improve the spectral resolution, a second free-form surface reflector group and an aberration-correcting lens group 8 are preferably provided in the medium-step grating spectrum module, wherein the second free-form surface reflector group includes a third free-form surface reflector 9 and a fourth free-form surface reflector 10, and the aberration-correcting lens group 8 includes a positive lens and a negative lens. The second free-form surface reflector group completes light reflection and light path folding, and the aberration-correcting lens group 8 is combined with the second free-form surface reflector group to eliminate the aberration generated by the previous propagation process. Specifically, the second laser is reflected by the third free-form surface reflector 9 into the medium-step grating 6, and the second diffracted light generated by the medium-step grating 6 is reflected by the fourth free-form surface reflector 10 into the aberration-correcting lens group 8. The second diffracted light passes through the aberration-correcting lens group 8 and enters the second array detector 7 to complete the wavelength measurement.

[0030] Based on the dual-arm high-resolution wavelength meter described in the embodiment of the invention, the embodiment of the invention further provides an optical path structure based on the dual-arm high-resolution wavelength meter, such as Figure 3As shown, it includes the dual-arm high-resolution wavelength meter described in the invention embodiment and the front optical path. The front optical path generates incident laser and transmits the incident laser to the dual-arm high-resolution wavelength meter. The dual-arm high-resolution wavelength meter receives the incident laser and measures the wavelength of the incident laser.

[0031] In the embodiment of the present invention, the front optical path includes a laser 11 for generating incident laser light, and a slit 12 is provided between the laser 11 and the spectroscopic module 1 of the dual-arm high-resolution wavelength meter. The incident laser light generated by the laser 11 enters the slit 12 through the optical fiber 13, and the slit 12 controls the amount and angle of the light and transmits the adjusted incident laser light to the dual-arm high-resolution wavelength meter.

[0032] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A dual-arm high-resolution wavelength meter, characterized in that: It comprises a spectroscopic module, a plane grating spectrum module and an echelle grating spectrum module; the incident laser is divided into a first laser and a second laser by the spectroscopic module; the first laser enters the plane grating spectrum module for pre-measurement; the second laser enters the echelle grating spectrum module, the echelle grating spectrum module is adjusted according to the result of the pre-measurement, and then the second laser is measured to obtain the beam wavelength of the incident laser.

2. The dual-arm high-resolution wavemeter according to claim 1, characterized in that: The plane grating spectrum module includes a grating spectrometer module and a first planar array detector; wherein the grating spectrometer module diffracts the first laser to generate a first diffracted light; the first planar array detector receives the first diffracted light and predicts the wavelength of the first diffracted light to obtain the beam wavelength range of the incident laser.

3. The dual-arm high-resolution wavemeter according to claim 2, characterized in that: The plane grating spectrum module also includes a first free-form surface reflector group; the first laser is reflected into the grating spectrometer module via the first free-form surface reflector group; the first diffracted light is reflected into the first planar array detector via the first free-form surface reflector group.

4. The dual-arm high-resolution wavemeter according to claim 2, characterized in that: The echelle grating spectrum module includes an echelle grating and a second planar array detector; wherein the echelle grating diffracts the second laser to generate second diffracted light, and the order of the echelle grating is selected according to the result of the predicted measurement; the second planar array detector receives the second diffracted light and measures the second diffracted light according to the light beam wavelength range to obtain the light beam wavelength.

5. The dual-arm high-resolution wavemeter according to claim 4, characterized in that: The echelle grating spectrum module also includes a second free-form surface reflector group and an aberration-correcting lens group; wherein the second laser is reflected onto the echelle grating via the second free-form surface reflector group; the second diffracted light is reflected into the aberration-correcting lens group via the second free-form surface reflector group; and the second diffracted light enters the second planar array detector after passing through the aberration-correcting lens group.

6. The dual-arm high-resolution wavemeter according to claim 1, characterized in that: The beam splitting module includes a beam splitter; the incident laser light is split into the first laser light and the second laser light by the beam splitter.

7. An optical path structure based on a double-arm high-resolution wavelength meter, characterized in that: It comprises a dual-arm high-resolution wavelength meter as described in any one of claims 1 to 6, and a front optical path; wherein the front optical path generates the incident laser and emits the incident laser to the dual-arm high-resolution wavelength meter; the dual-arm high-resolution wavelength meter receives the incident laser and measures the wavelength of the incident laser.

8. The optical path structure based on the dual-arm high-resolution wavelength meter according to claim 7, characterized in that: The front optical path includes a laser that generates the incident laser.

9. The optical path structure based on the dual-arm high-resolution wavelength meter according to claim 8, characterized in that: A slit is provided between the laser and the dual-arm high-resolution wavelength meter, so that the incident laser passes through the rear slit and enters the dual-arm high-resolution wavelength meter.

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