Solar h alpha space telescope wavelength scaling device and method

Abstract

The wavelength calibration device and method of the solar Halpha space telescope belong to the field of space optics, effectively overcome the shortcomings of traditional wavelength calibration based on a monochromator, low spectral resolution and weak monochromatic energy. The wavelength calibration device comprises a wavelength tunable laser with high monochromaticity, high energy and ultra-narrow line width performance, a collimator, a wavemeter, a high-precision two-dimensional turntable and the like, and meets the wavelength calibration requirements of a spectral imaging system with very high spectral resolution, and is widely applied in the development, adjustment and detection of the solar Halpha space telescope, and has equal important application value in the wavelength calibration of future spectral imaging systems with very high spectral resolution, and has wide engineering application prospect.

Description

Technical Field

[0001] This invention belongs to the field of space optics, specifically relating to a wavelength calibration device and method for the solar Hα space telescope. Background Technology

[0002] The sun is closely related to human life, and its activity directly impacts Earth. Therefore, scientists closely observe solar activity. Ground-based observations are affected by atmospheric factors and weather conditions, leading to inaccurate data. To address this, a spaceborne solar Hα space telescope was developed to observe the sun in a space environment, effectively avoiding the influence of ground-based atmosphere and cloudy / rainy weather. The solar Hα space telescope consists of a full-plane imaging subsystem and an Hα spectral imaging subsystem, both sharing a front optical system. A key characteristic of the Hα spectral band is its narrow spectral range. Very high spectral resolution (half-peak bandwidth) (less than The spectral irradiance is high at each spectral line position. Traditional monochromator-based spectral wavelength calibration methods typically have a linewidth (half-peak bandwidth) of output monochromatic light that is not less than [a certain value]. Furthermore, the energy of monochromatic wavelength light is too weak to meet the wavelength calibration requirements of the Solar Ha space telescope. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a wavelength calibration device and method for the solar Hα space telescope, which effectively overcomes the shortcomings of traditional monochromator-based wavelength calibration, such as low spectral resolution and weak monochromatic energy.

[0004] The technical solution adopted by this invention to solve the technical problem is as follows:

[0005] The wavelength calibration device for the Solar Hα space telescope includes: a wavelength-tunable laser, a wavelength meter, an integrating sphere, a collimator, and the solar space telescope. The wavelength-tunable laser, after its spectral linewidth is adjusted by the wavelength meter, transmits monochromatic laser light with a spectral density less than 0.1 pm to the integrating sphere. After multiple diffuse reflections within the integrating sphere, the monochromatic laser light exits the collimator, passes through its focal plane, and enters the collimator. After beam expansion by the collimator, the light is incident on the solar space telescope, obtaining an image at the corresponding wavelength.

[0006] Preferably, it also includes a rotary table disposed below the wavelength-tunable laser to adjust the emission direction of the wavelength-tunable laser.

[0007] Preferably, it also includes a high-precision three-dimensional turntable disposed below the solar space telescope, enabling the solar space telescope to obtain images of the same wavelength laser in the entire field of view.

[0008] Preferably, the wavelength test precision of the wavemeter is less than 0.04 pm.

[0009] Preferably, the wavelength tunable laser has a line width of less than 0.1 pm, a power of 20 mW, and is continuously tunable in a spectral range of 652 nm to 658 nm.

[0010] The wavelength calibration method of the wavelength calibration device of the solar Hα space telescope comprises the following steps:

[0011] Step one: install the wavelength tunable laser on the rotating table; adjust the rotating table to align the light outlet of the wavelength tunable laser with the wavemeter;

[0012] Step two: test the wavelength of the laser output by the wavelength tunable laser by using the wavemeter, and after the wavelength is stabilized, align the light outlet of the wavelength tunable laser with the integrating sphere by using the rotating table;

[0013] Step three: the wavelength tunable laser emits monochromatic laser with a spectrum of less than 0.1 pm into the integrating sphere, the monochromatic laser is reflected multiple times in the integrating sphere, and then uniform laser is emitted through the focal plane of the collimator and enters the collimator; after being expanded by the collimator, the laser enters the solar space telescope;

[0014] Step four: set a high-precision three-dimensional turntable under the solar space telescope to rotate the solar space telescope, thereby obtaining images of the same wavelength laser in the full field of view;

[0015] Step five: change the wavelength of the wavelength tunable laser to obtain the full field of view images of each laser wavelength; by processing the image data, the functional relationship between the wavelength of the monochromatic laser and the column pixel serial number is obtained, and the wavelength calibration is completed.

[0016] Preferably, the data processing comprises the following steps:

[0017] Step one: calculate the centroid pixel row serial number corresponding to each wavelength for each column of pixels by using the centroid algorithm:

[0018]

[0019] In the formula: u k is the row serial number corresponding to the centroid of the wavelength λk position in the jth column of pixels; g(i,j) is the gray value of the ith row and jth column of pixels; i is the row serial number of the wavelength λk position in the jth column of pixels;

[0020] Step two: obtain the pixel centroid row serial numbers u1, u2, u3, …, un corresponding to the wavelengths λ1, λ2, λ3, …, λn in sequence, and obtain the functional relationship between the wavelength and the pixel serial number by using the least square method:

[0021] λ k =A j +B j ×i

[0022] In the formula: λ k For wavelength, A j B is the intercept of the linear fitting of the j-th column pixel. j Let be the linear fitting coefficients for column j, and i be the row number of the j-th column pixel.

[0023] Preferably, the wavelength measurement accuracy of the wavelength meter is less than 0.04 pm.

[0024] Preferably, the wavelength-tunable laser has a linewidth of less than 0.1 pm, a power of 20 mW, and is continuously tunable in the spectral range of 652 nm to 658 nm.

[0025] The beneficial effects of this invention are as follows: This invention employs a high-precision wavelength calibration device composed of a wavelength-tunable laser with high monochromaticity, high energy, and ultra-narrow linewidth, a collimator, a wavelength meter, and a high-precision two-dimensional turntable. This device meets the wavelength calibration requirements of spectral imaging systems with very high spectral resolution and has been widely used in the development, assembly, and testing of the solar Hα space telescope. It also has equally important application value in the wavelength calibration of future spectral imaging systems with very high spectral resolution and has broad engineering application prospects. Attached Figure Description

[0026] Figure 1 A schematic diagram of the wavelength calibration device for the solar Hα space telescope of this invention.

[0027] In the diagram: 1. Wavelength-tunable laser, 2. Rotary stage, 3. Wavelength meter, 4. Integrating sphere, 5. Collimator, 6. Solar space telescope, 7. High-precision 3D rotary stage. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0029] like Figure 1As shown, the wavelength calibration device of the solar Hα space telescope comprises a wavelength tunable laser 1, a rotating table 2, a wavemeter 3, an integrating sphere 4, a collimator 5, a solar space telescope 6 and a high-precision three-dimensional rotary table 7; the rotating table 2 is arranged below the wavelength tunable laser 1, the wavelength tunable laser 1 is first aligned with the wavemeter 3, the wavelength of the laser output by the wavelength tunable laser 1 is tested, and after the wavelength is stabilized, the wavelength tunable laser is rotated 90° by using the rotating table 2, so that the light outlet is aligned with the integrating sphere 4. The monochromatic laser with a spectral line width less than 0.1 pm is incident into the integrating sphere 4, the monochromatic laser is subjected to multiple diffuse reflections in the integrating sphere 4, and the emitted uniform light is incident into the collimator 5 through the focal plane of the collimator 5. After being expanded by the collimator 5, the light is incident into the solar space telescope 6, and an image corresponding to the wavelength is obtained. Since the laser spot can be imaged only in the local field of view in the slit direction each time, the solar space telescope 6 is placed on the high-precision three-dimensional rotary table 7, and the image of the same wavelength laser in the full field of view is obtained by horizontal rotation. The wavelength of the wavelength tunable laser 1 is changed, the full field of view image of each laser wavelength is obtained, and then the functional relationship between the wavelength and the serial number of each column of pixels is obtained through data processing, and the wavelength calibration is completed.

[0030] In the embodiment, the wavelength tunable laser 1 is in the same height and concentric with the light inlet of the integrating sphere 4, all the laser emitted by the wavelength tunable laser 1 is incident into the integrating sphere 4, the diameter of the integrating sphere 4 is Φ100 mm, the light inlet is Φ20 mm, and the light outlet is Φ20 mm. The light outlet of the integrating sphere 4 is in the same height and concentric with the focal plane position of the collimator 5. The high-precision three-dimensional rotary table 7 has the functions of high-low, pitch and horizontal rotation. The high-low of the high-precision three-dimensional rotary table 7 is adjusted, so that the solar Hα space telescope 6 is in the same height with the light outlet of the collimator 5, the pitch angle is adjusted, the laser spot is imaged in the field of view, and the laser spot image is formed on the image plane. The slit of the solar Hα space telescope 6 is long, and the laser spot occupies only part of the field of view each time. The images of each field of view in the slit direction are obtained in turn by the horizontal rotation of the high-precision three-dimensional rotary table 7 at fixed angle intervals and rotation angles (there is 20% overlap between adjacent fields of view), and then the full field of view image corresponding to the slit direction of the wavelength is obtained. The wavelength of the laser output by the wavelength tunable laser 1 is adjusted in turn, the wavelength interval is 0.1 pm, and the full field of view images corresponding to multiple laser wavelengths are obtained by the above process. The full field of view images corresponding to multiple laser wavelengths are obtained by the above process.

[0031] The calibration method based on the wavelength calibration device of the solar Hα space telescope comprises the following steps:

[0032] Step one: install the wavelength tunable laser 1 on the rotating table 2; adjust the rotating table 2 to align the light outlet of the wavelength tunable laser 1 with the wavemeter 3;

[0033] Step two: test the wavelength of the laser output by the wavelength tunable laser 1 by using the wavemeter 3, until the wavelength is stable, then rotate the wavelength tunable laser 1 by 90° by using the rotating table 2, so that the light outlet of the wavelength tunable laser 1 is aligned with the integrating sphere;

[0034] Step three: the wavelength tunable laser 1 emits monochromatic laser with a spectral width of less than 0.1 pm into the integrating sphere 4, the monochromatic laser undergoes multiple diffuse reflections in the integrating sphere 4, and then the uniform light exits the integrating sphere 4 and enters the collimator 5 through the focal plane of the collimator 5; after expanding by the collimator 5, the light enters the solar space telescope 6;

[0035] Step four: set a high-precision three-dimensional turntable 7 under the solar space telescope 6, so that the solar space telescope 6 rotates, thereby obtaining images of the same wavelength laser in the full field of view;

[0036] Step five: obtain the functional relationship between the wavelength of the monochromatic laser and the serial number of each column of pixels by processing the images, and complete the wavelength calibration.

[0037] The data processing includes the following steps:

[0038] Step one: calculate the centroid pixel row serial number corresponding to each wavelength for each column of pixels by using the centroid algorithm:

[0039]

[0040] In the formula: u k is the row serial number corresponding to the centroid of the wavelength λk position in the jth column of pixels; g(i,j) is the gray value of the ith row and jth column of pixels; i is the row serial number of the wavelength λk position in the jth column of pixels;

[0041] Step two: obtain the pixel centroid row serial numbers u1, u2, u3, …, un corresponding to the wavelengths λ1, λ2, λ3, …, λn in sequence, and obtain the functional relationship between the wavelength and the pixel serial number by using the least squares method

[0042] λ k = A j +B j ×i

[0043] In the formula: λ k is the wavelength, A j is the linear fitting intercept of the jth column of pixels, and B jis the linear fitting coefficient of the jth column of pixels, and i is the row number of the jth column of pixels.

Claims

1. A wavelength calibration method for the Solar Hα space telescope, characterized in that, The system includes a wavelength calibration device comprising: a wavelength-tunable laser, a wavelength meter, an integrating sphere, a collimator, and a solar space telescope; a rotating stage positioned below the wavelength-tunable laser to adjust its emission direction; and a high-precision three-dimensional rotating stage positioned below the solar space telescope to enable it to obtain images of the same wavelength laser across the entire field of view. After the wavelength meter adjusts the spectral linewidth, the wavelength-tunable laser transmits monochromatic laser light with a spectral density less than 0.1 pm to the integrating sphere. The monochromatic laser undergoes multiple diffuse reflections within the integrating sphere, exits through the focal plane of the collimator, and then enters the collimator. After beam expansion by the collimator, the light is incident on the solar space telescope, obtaining an image of the corresponding wavelength. The method includes the following steps: Step 1: Mount the wavelength-tunable laser on the rotating platform; adjust the rotating platform so that the output port of the wavelength-tunable laser is aligned with the wavelength meter; Step 2: Use the wavelength meter to test the laser wavelength output by the wavelength-tunable laser until the wavelength stabilizes, then use the rotating stage to align the output port of the wavelength-tunable laser with the integrating sphere. Step 3: The wavelength-tunable laser emits monochromatic laser light with a spectrum less than 0.1 pm, which enters the integrating sphere. After multiple diffuse reflections within the integrating sphere, the monochromatic laser light exits the collimator and passes through its focal plane before entering the collimator. After being expanded by the collimator, the light enters the solar space telescope. Step 4: A high-precision three-dimensional turntable is set up under the solar space telescope to rotate the solar space telescope, thereby obtaining an image of the same wavelength laser in the entire field of view; Step 5: Change the wavelength of the wavelength-tunable laser to obtain a full field-of-view image for each laser wavelength. Then, through data processing, obtain the functional relationship between the wavelength and the pixel number of each column to complete the wavelength calibration. The data processing includes the following steps: Step 1: Calculate the centroid pixel row number corresponding to each wavelength for each column of pixels using the centroid algorithm: In the formula: wavelength The row number corresponding to the centroid of the pixel located in the j-th column; For the first Line 1 The grayscale values ​​of the cells in the column; wavelength Position at The row number of the column cell; Step 2: Obtain the corresponding wavelengths sequentially. Pixel centroid row number Using the least squares method, the functional relationship between wavelength and pixel index is obtained: In the formula: For wavelength, For the first Column pixel linear fitting intercept, for Column pixel linear fitting coefficients, For the first The row number of the column cell.

2. The method according to claim 1, characterized in that, The wavelength measurement accuracy of the wavelength meter is less than 0.04 pm.

3. The method according to claim 1, characterized in that, The wavelength-tunable laser has a linewidth of less than 0.1 pm, a power of 20 mW, and is continuously tunable in the spectral range of 652 nm to 658 nm.

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