Modularized broadband small astronomical spectrometer

Abstract

The utility model discloses a modularized broadband small astronomical spectrometer, which comprises a main body module, and a dispersion module, a detector module, an incident interface module, a calibration module and a star guide module which are respectively arranged on the main body module, the first reflector is used for reflecting light reflected by the surface of the slit into the star guide module, the second reflector is used for reflecting the light passing through the slit to the collimating lens, parallel light passing through the collimating lens enters the dispersion module, and the light dispersed by the dispersion module is reflected again to enter the collimating lens and is focused on the detector module by the collimating lens. The spectrometer provided by the utility model has a plurality of working modes such as direct spectrum shooting, optical fiber spectrum shooting and calibration, the dispersion module can avoid the problem of level overlapping of the grating spectrometer during broadband observation, and the number of optical elements and the spatial size of the spectrometer are effectively reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of astronomical spectroscopy, and particularly relates to a modular wide-band small astronomical spectrometer, which can be used to obtain wide-band spectral information of celestial bodies or display astronomical spectral images. Background Technique

[0002] Spectral analysis is an important means for basic research in astronomy, chemistry, biology, agronomy, etc. In the field of astronomical observation, spectral data of various target celestial bodies can be obtained by using a telescope and an astronomical spectrometer. By analyzing the intensity and relative position of characteristic spectral lines in the spectral data, important evidence can be provided for astronomical frontier research such as the origin of the universe, the formation and evolution of galaxies and stars, the search for Earth-like planets, and the revelation of the origin of elements. Spectral observation is also an important part of the basic construction of the astronomy discipline.

[0003] An astronomical spectrometer docks with the telescope focus through optical or fiber connection for spectral observation. An astronomical spectrometer usually consists of modules such as a slit, a collimator, a disperser, an imaging mirror, a detector, a guiding star, and a calibration. The slit module mainly changes the spectral resolution of the instrument by restricting the slit width. The collimator module converts the divergent incident light beam into a parallel light beam to ensure that the beam angles incident on the disperser module are consistent. The disperser module disperses the composite light into monochromatic lights of different wavelengths. The imaging mirror module converges the dispersed light beam to form a spectral image. The detector module collects the spectrum and outputs it as digital data. The guiding star module is used to monitor the position deviation between the star image converged by the telescope and the slit to ensure that sufficient starlight enters the spectrometer. The calibration module provides an artificial light source with known spectral information to the spectrometer for wavelength calibration of the celestial spectrum and other purposes.

[0004] Professional spectrometers are generally developed specifically for specific telescopes. Due to different specific requirements of different telescopes, the spectrometers carried by them are also different. At present, a large number of small-aperture telescopes are not equipped with professional spectrometers and can only perform imaging observations, greatly weakening the use value of small-aperture telescopes.

[0005] Currently, the commercially available spectrometers mainly include Fourier transform spectrometers and dispersive spectrometers. The Fourier transform spectrometer mainly consists of a Michelson interferometer and a computer. It uses the image after the interference of the light source and Fourier transform to obtain the wavelength and intensity information of the light source. The dispersive spectrometer uses a grating or a prism as a dispersive element. After the light passes through the grating or the prism, it will be dispersed into monochromatic lights of different wavelengths. The Fourier transform spectrometer has the advantages of good reproducibility, high signal-to-noise ratio, and fast scanning speed. However, it must have a high-throughput light source to work smoothly. The dispersive spectrometer can work under the condition of a low-throughput light source. The astronomical observation targets are generally various faint targets. Even for a large-aperture astronomical telescope, the intensity of the faint target light collected by it still cannot meet the working requirements of the Fourier transform spectrometer. Therefore, the spectrometers carried by current astronomical observations are generally dispersive spectrometers that use gratings and prisms as dispersive elements. Summary of the Invention

[0006] In view of the above problems in the prior art, the present utility model provides a modular wide-band small astronomical spectrometer.

[0007] To achieve the above object, the present utility model provides the following technical solutions:

[0008] A modular wide-band small astronomical spectrometer includes a main body module, a dispersive module, a detector module, an incident interface module, a calibration module, and a guiding star module respectively installed on the main body module. Among them, the incident interface module and the calibration module are selectively installed according to the required detection mode. A first reflector, a slit, a second reflector, and a collimating lens are arranged inside the main body module. Light is introduced into the interior of the main body module through the incident interface module. The first reflector is used to reflect the light reflected from the surface of the slit into the guiding star module. The second reflector is used to reflect the light passing through the slit to the collimating lens. The parallel light passing through the collimating lens enters the dispersive module. The light dispersed by the dispersive module is reflected again into the collimating lens and focused on the detector module by the collimating lens.

[0009] Further, a reflective film is coated on the surface of the slit.

[0010] Further, the collimating lens consists of a lens group composed of a first cemented lens and a second cemented lens.

[0011] Further, the dispersive module includes a echelle grating and a triangular prism. The parallel light emitted from the collimating lens obtains a one-dimensional dispersion spectrum in the X direction after passing through the triangular prism. Then the light is reflected by the echelle grating and obtains a two-dimensional dispersion spectrum A in the Z direction. The light passes through the triangular prism again and obtains a two-dimensional dispersion spectrum B in the X direction.

[0012] Further, the detector module includes a detector and a focusing mechanism for receiving the spectrum and converting it into a digital signal.

[0013] Furthermore, the incident interface module includes a lens barrel, a first lens, a second lens, and an optical fiber. Light first enters the second lens and then enters the main body module through the first lens.

[0014] Furthermore, the lens barrel is connected to the main body module through a threaded interface.

[0015] Furthermore, the guiding star module includes a third cemented lens, a fourth lens, a fifth lens, and a guiding star camera, which are arranged in sequence along the optical path.

[0016] Furthermore, a calibration module is also included. The calibration module includes an argon-neon lamp, a third lens, a guide rail, and a third reflector. The lens converges the light generated by the argon-neon lamp, and the third reflector is installed on the guide rail and is used to reflect the light converged by the third lens to the slit inside the main body module.

[0017] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0018] The present utility model includes multiple functional modules such as a dispersion module, a detector module, a calibration module, and a guiding star module. Users can install different modules according to their usage requirements, so that the spectrometer has working modes such as direct spectral photography, fiber optic spectral photography, and calibration. The present utility model uses a triangular prism and a grating as dispersion elements to achieve dispersion in two dimensions, which can avoid the problem of order overlap existing in grating spectrometers during wide-band observation. At the same time, the present utility model reduces the design of the detector camera lens by passing the light reflected by the echelle grating through the collimator twice, effectively reducing the number of optical elements and the spatial size of the spectrometer. Description of the Drawings

[0019] Figure 1 is a schematic structural diagram of the spectrometer of the present utility model;

[0020] Figure 2 is a schematic structural diagram of the main body module;

[0021] Figure 3 is a schematic structural diagram of the dispersion module;

[0022] Figure 4 is a schematic structural diagram of the incident interface module;

[0023] Figure 5 is a schematic structural diagram of the calibration module;

[0024] Figure 6 is a schematic structural diagram of the guiding star module;

[0025] Figure 7 is a schematic diagram of the direct spectral photography mode;

[0026] Figure 8 It is a schematic diagram of the fiber optic spectrum shooting mode.

[0027] Markings in the figure: 1. Main body module; 2. Dispersion module; 3. Detector module; 4. Incident interface module; 5. Calibration module; 6. Guide star module; 1-1. Guide star module interface; 1-2. Dispersion module interface; 1-3. Tripod interface; 1-4. Detector module interface; 1-5. Calibration module interface; 1-6. Incident module interface; 1-7. Main body; 1-8. First reflector; 1-9. Slit; 1-10. Second reflector; 1-11. First cemented lens; 1-12. Second cemented lens; 2-1. Outer frame of the dispersion module; 2-2. Echelle grating; 2-3. Prism; 2-4. One-dimensional dispersion spectrum; 2-5. Two-dimensional dispersion spectrum A; 2-6. Two-dimensional dispersion spectrum B; 4-1. Lens barrel; 4-2. First lens; 4-3. Second lens; 4-4. Optical fiber; 5-1. Argon-neon lamp; 5-2. Third lens; 5-3. Guide rail; 5-4. Third reflector; 5-5. Light source housing; 6-1. Guide star lens barrel; 6-2. Third cemented lens; 6-3. Fourth lens; 6-4. Fifth lens; 6-5. Guide star camera; 7. Spectrometer; 8. Connecting ring; 9. Telescope. Specific implementation mode

[0028] The following further elaborates on the present utility model in conjunction with the attached drawings.

[0029] A modular wide-band small astronomical spectrometer of the present utility model mainly includes a main body module 1 and five accessory modules (dispersion module 2, detector module 3, incident interface module 4, calibration module 5, guide star module 6), as shown in the attached Figure 1 . By replacing different accessory modules, spectral images with different resolutions can be obtained to achieve different functions.

[0030] Among them, the main body module 1 is mainly used to realize functions such as light reception, folding, collimation, and focusing, and can be connected to each accessory module. Its structure is as Figure 2As shown, it includes the main body 1-7, and inside the main body 1-7, there are a first reflector 1-8, a slit 1-9, a second reflector 1-10, a first cemented lens 1-11, and a second cemented lens 1-12. The main body 1-7 is provided with interfaces for docking with accessory modules (including a guiding module interface 1-1, a dispersion module interface 1-2, a tripod interface 1-3, a detector module interface 1-4, a calibration module interface 1-5, and an incident module interface 1-6). Light is introduced into the instrument through the incident interface module 4. The first reflector 1-8 can reflect the light reflected from the surface of the slit 1-9 into the guiding module 6; the slit 1-9 can block excess stray light, and by replacing slits with different apertures, the resolution of the spectrometer can be changed. On the surface of the slit plate of the present utility model, a reflective film is also electroplated to reflect the light onto the first reflector 1-8; the second reflector 1-10 can reflect the light passing through the slit 1-9 into the lens group composed of the first cemented lens 1-11 and the second cemented lens 1-12; the two cemented lenses in the lens group can convert the received light into parallel light, and the parallel light passing through the lens group will enter the dispersion module 2. The dispersion module 2 can reflect the dispersed light back into the lens group again and focus it on the detector of the detector module 3. The slit 1-9 of the present utility model preferably uses the scheme of a circular aperture slit, and this scheme has a higher target surface efficiency than a long-slit spectrometer. The present utility model realizes the purpose of guiding star monitoring by plating a reflective film on the surface of the slit. The tilt angle of the slit is not limited to a specific value, as long as it ensures that the reflector does not block the light path. The present utility model uses lenses with different materials and parameters to form a collimating lens group, which can effectively reduce the degradation of imaging quality caused by chromatic aberration. The combination of lenses in the imaging and collimating lens group is not limited to a specific form, as long as the final imaging quality can be ensured.

[0031] Among them, the dispersion module 2 is connected to the main body 1-7 of the main body module 1 through the dispersion module interface 1-2, and its structure is as Figure 3As shown in the figure, it includes the outer frame 2-1 of the dispersion module, the echelle grating 2-2 and the prism 2-3. Different resolutions can be achieved by replacing the prism and echelle grating with different parameters. The dispersion module 2 mainly relies on the echelle grating 2-2 and the prism 2-3 to achieve dispersion in two directions. The parallel light undergoes primary dispersion in the X direction after passing through the prism 2-3, and at this time, a one-dimensional dispersion spectrum A 2-4 is obtained; then the light is reflected by the echelle grating 2-2 and undergoes primary dispersion in the Z direction, and at this time, a two-dimensional dispersion spectrum A 2-5 is obtained; finally, the light will pass through the prism 2-3 again and undergo secondary dispersion in the X direction, and at this time, a two-dimensional dispersion spectrum B 2-6 is obtained. This spectrum undergoes secondary dispersion in the X direction, so it has a higher resolution than the two-dimensional dispersion spectrum A 2-5. The utility model uses the cooperation of the echelle grating and the prism to achieve dispersion in two directions. The spectrum is arranged two-dimensionally on the target surface, and the characteristics of the echelle grating and the prism are used to achieve high resolution and wide-band one-time imaging of the spectrometer. The utility model utilizes the characteristics of the reflective echelle grating, so that the light diffracted by the grating passes through the collimator and the prism again. The collimator and the imaging lens use the same set of lenses, effectively reducing the number of optical elements.

[0032] Among them, the detector module 3 is mainly composed of a detector (CCD or CMOS) and a focusing structure, etc., and is used to receive the spectrum and convert it into a digital signal. The spectrometer of the utility model uses a commercial CMOS as the detector, and the user can also replace different detectors according to needs; the detector module also includes an attached focusing structure. The utility model adopts a common screw focusing structure and installs a spring to eliminate the screw clearance. Similar focusing structures are adopted in various commercial camera lenses and will not be elaborated here. If the detector in the detector module 3 is replaced with a projection lens, the spectrum projection function can also be realized.

[0033] Among them, the incident interface module 4 is used to introduce the light converged by the telescope into the spectrometer. The incident interface module 4 of the utility model is divided into two methods, namely, the direct connection of the connecting ring and the fiber coupling two incident methods. Figure 2 The incident module interface 1-6 in is a threaded interface, and currently common small and medium-sized telescopes are designed with threaded interfaces at the exit end. Therefore, only a connecting ring 8 needs to be added between the telescope 9 and the spectrometer 7 to connect the two, which is the direct connection method of the connecting ring 8, as shown in Figure 7 shown. Considering different usage requirements, the utility model also provides an incident interface module 4 in the fiber coupling method as shown in Figure 4 shown, which mainly includes a lens barrel 4-1, a first lens 4-2, a second lens 4-3, and an optical fiber 4-4. The lens barrel 4-1 is provided with threads and can be directly connected to the incident module interface 1-6 on the main body module 1. The other end of the optical fiber 4-4 is connected to the telescope 9, as shown in Figure 8 shown.

[0034] Among them, the calibration module 5 is used to provide an artificial light source that can supply known spectral information to the spectrometer. Its structure is as Figure 5 shown, including an argon-neon lamp 5-1, a third lens 5-2, a guide rail 5-3, a third mirror 5-4, and a light source housing 5-5. The argon-neon lamp 5-1 can generate light of a certain wavelength. The third lens 5-2 can converge the light generated by the argon-neon lamp 5-1. The guide rail 5-3 is used to install and move the third mirror 5-4. The light source housing 5-5 can be connected to the calibration module interface 1-5 on the main body module 1. When the third mirror 5-4 moves to a suitable position, it can reflect the light converged by the third lens 5-2 to the slit 1-9 in the main body module 1 to ensure that the spectrometer completes the subsequent calibration spectrum shooting.

[0035] Among them, the guiding star module 6 mainly includes a guiding star lens and a guiding star camera, and is used to ensure that light accurately passes through the slit. Figure 6 A feasible structure of the guiding star module is given. This guiding star module mainly includes a guiding star barrel 6-1, a third cemented lens 6-2, a fourth lens 6-3, a fifth lens 6-4, and a guiding star camera 6-5. A flange is designed on the guiding star barrel 6-1, and it can be directly connected to the guiding star module interface 1-1 on the main body module 1.

[0036] The spectrometer of the present utility model has functions such as guiding star, calibration, direct observation of the telescope, and fiber optic observation. The present utility model can realize the switching between two modes of fiber optic spectrum shooting and direct observation by replacing the fiber optic lens and the telescope connection component; it can also realize the switching between two modes of spectrum shooting and spectrum projection by replacing the detector and the imaging lens.

[0037] Figure 7 It is a working schematic diagram in the direct spectrum shooting mode, which mainly includes a spectrometer 7, a connecting ring 8, and a telescope 9. In the direct spectrum shooting mode, the spectrometer is connected to the telescope 9 through the connecting ring 8 and rotates with the telescope. At this time, the slit of the spectrometer is located at the focus of the telescope. In the case of installing the calibration module 5, spectrum calibration can also be completed in the direct shooting mode.

[0038] Figure 8 It is a working schematic diagram in the fiber optic observation mode, which mainly includes a spectrometer 7, an incident interface module 4 (specifically fiber optic coupling incidence), a fiber optic 4-4, and a telescope 9. At this time, the light is introduced into the spectrometer 7 by the fiber optic 4-4 and the fiber optic coupling incidence module and the shooting is completed. Similar to the direct spectrum shooting mode, the fiber optic spectrum shooting mode can also be compatible with the calibration mode, and only need to install the calibration module 5.

[0039] In addition, regardless of the above-mentioned mode, when the light converges at the slit, the light that does not pass through the slit will be reflected by the slit plate and the mirror into the guiding module. By observing the image captured by the guiding camera, it can be ensured that the light accurately passes through the slit. In the direct spectral imaging mode, in addition to the light of the target celestial body passing through the slit, the other celestial bodies observed by the telescope will be imaged in the guiding camera. Therefore, the spectrometer of the present utility model also has the function of partial imaging observation.

[0040] In summary, the spectrometer of the present utility model adopts a modular design to meet various usage requirements, and users can independently select the required components according to their needs. Through optical design and structural optimization, miniaturization of the instrument is achieved. The spatial dimensions of the spectrometer of the present utility model are less than 350mm×200mm×85mm, and the weight is less than 4 kg. Compared with spectrometers that only use gratings as dispersion elements, the present utility model can avoid the problem of order overlap and can achieve one-time imaging in a wide wavelength band. Compared with spectrometers that only use prisms as dispersion elements, the present utility model has a higher resolution.

[0041] The above are only the preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model.

Claims

1. A modular wide-band small astronomical spectrometer, characterized in that It includes a main body module, as well as a dispersion module, a detector module, an incident interface module, and a guiding star module respectively installed on the main body module. A first mirror, a slit, a second mirror, and a collimating lens are arranged inside the main body module. Light is introduced into the interior of the main body module through the incident interface module. The first mirror is used to reflect the light reflected from the surface of the slit into the guiding star module. The second mirror is used to reflect the light passing through the slit to the collimating lens. The parallel light passing through the collimating lens enters the dispersion module. The light dispersed by the dispersion module is reflected again into the collimating lens and is focused by the collimating lens on the detector module.

2. The modular wide-band small astronomical spectrograph according to claim 1, characterized in that, A reflective film is coated on the surface of the slit.

3. A modular wide-band small astronomical spectrometer according to claim 1, characterized in that, The collimating lens consists of a lens group composed of a first cemented lens and a second cemented lens.

4. A modular wide-band small astronomical spectrometer according to claim 1, characterized in that, The dispersion module includes a echelle grating and a prism. The parallel light emitted from the collimating lens obtains a one-dimensional dispersion spectrum in the X direction after passing through the prism. Then the light is reflected by the echelle grating and obtains a two-dimensional dispersion spectrum A in the Z direction. The light passes through the prism again and obtains a two-dimensional dispersion spectrum B in the X direction.

5. A modular wide-band small astronomical spectrograph according to claim 1, characterized in that, The detector module includes a detector and a focusing mechanism, which is used to receive the spectrum and convert it into a digital signal.

6. The modular wide-band small astronomical spectrometer according to claim 1, characterized in that, The incident interface module includes a lens barrel, a first lens, a second lens, and an optical fiber. Light first enters the second lens and then enters the main body module through the first lens.

7. A modular wide-band small astronomical spectrometer according to claim 6, characterized in that, The lens barrel is connected to the main body module through a threaded interface.

8. A modular wide-band small astronomical spectrometer according to claim 1, characterized in that The guiding star module includes a third cemented lens, a fourth lens, a fifth lens, and a guiding star camera arranged in sequence along the optical path.

9. A modular wide-band small astronomical spectrometer according to claim 1, characterized in that, It further includes a calibration module. The calibration module includes an argon-neon lamp, a third lens, a guide rail, and a third mirror. The lens converges the light generated by the argon-neon lamp. The third mirror is installed on the guide rail and is used to reflect the light converged by the third lens to the slit inside the main body module.

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