CN109443536B - Pixel nonuniformity calibration method and device for CCD ultraviolet band of satellite-borne spectrometer - Google Patents
Pixel nonuniformity calibration method and device for CCD ultraviolet band of satellite-borne spectrometer Download PDFInfo
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Abstract
A pixel non-uniformity calibration method and device for a CCD ultraviolet band of a satellite-borne spectrometer can solve the technical problem that the traditional technology is only suitable for an optical imaging CCD but cannot meet the calibration requirement of a spectral imaging CCD. The method comprises the steps of setting up a test platform, wherein the test platform comprises a halogen lamp light source, the halogen lamp light source is arranged in a light chopper, light emitted by the light chopper passes through a grating monochromator to an adjustable slit device, and the adjustable slit device is connected with an integrating sphere through an optical fiber; the light output by the integrating sphere enters a light spot imager; the light spot imager outputs light spots to a CCD (charge coupled device) of the satellite-borne spectrometer; the invention generates light spots of different wave bands by establishing a circle-like light spot uniform irradiation light source, the diameter of the light spot covers a plurality of pixels of a CCD imaging surface, full-wave-band scanning imaging of a spectrometer is realized, the CCD imaging surface is sequentially irradiated according to the sequence of the pixels, signal distribution of the CCD pixels is obtained, and an accurate PRNU calibration equation is obtained by performing Gaussian fitting and least square processing methods on the signals.
Description
Technical Field
The invention relates to the technical field of CCD image processing, in particular to a pixel non-uniformity calibration method and device for a CCD ultraviolet band of a satellite-borne spectrometer.
Background
Scientific grade CCD has become the first choice of photoelectric detector of spectrometer, but scientific grade CCD generally image the size big, the pixel charge storage potential well is deep, causes the heterogeneity (PRNU) of pixel response easily in the imaging process, because of manufacturing process and material reason, this phenomenon is especially obvious at the ultraviolet band.
Before the satellite-borne spectrometer emits, the PRNU parameter of the CCD needs to be obtained through a ground experiment, that is, the CCD flat field calibration is generally said, and at present, the specific process of the calibration means used by people is as follows: 1. irradiating the surface of a CCD of a spectrometer by using uniform and stable white light to generate a flat-field image; 2. subtracting the offset image from the flat field image to generate an unbiased flat field frame; 3. subtracting the dark frame from the scientific image to generate a background-free scientific image; 4. the non-background scientific image is divided by the non-bias flat field frame to obtain the required target image. The effectiveness of the CCD flat field correction data is to ensure that the PRNU parameters are consistent before and after transmission, but after loading and track entry, the CCD is subjected to ultraviolet irradiation, and the PRNU state changes due to the intensity of different ultraviolet light bands. For a satellite-borne spectrometer, a spectral image is acquired on a CCD detector surface, signals of different spectral bands correspond to different lines and columns of a CCD, and if the CCD detector surface is only irradiated by simple uniform white light, the PRNU attribute of the actual working state of the CCD detector cannot be objectively reflected.
Space-borne differential absorption spectrometers typically employ differential absorption spectroscopy to resolve the spatial and temporal distribution and variation of trace gases by detecting ultraviolet/visible radiation reflected and scattered from the surface of the atmosphere or earth. In order to meet the requirements of high precision and high signal-to-noise ratio of imaging of a satellite-borne spectrometer, a scientific-grade area array CCD becomes a preferred photoelectric detector of the spectrometer. However, the imaging size of a scientific grade CCD is generally large, and the pixel charge storage potential well is deep, so that Non-Uniformity (PRNU) of pixel Response is easily caused in the imaging process, and the PRNU has a large influence on the inversion accuracy of weak spectrum signals. Because the CCD sensor takes Si as a main manufacturing material, and the absorption depth of photons in the silicon is exponentially attenuated along with the reduction of the wavelength, the collection of ultraviolet photo-generated charges in a depletion layer of the silicon is abnormally difficult; in addition, most ultraviolet photons are absorbed by a front grid structure based on a grating structure CCD, polysilicon used for manufacturing a grid material in the prior art is at least 400nm thick, and the penetration depth of ultraviolet light of 400nm is only 2nm, so that the polysilicon gate effectively shields photons generated by ultraviolet radiation in a CCD imaging area, and the attenuation of quantization efficiency is caused; meanwhile, the gate oxide layer and the passivation layer inside the CCD are both composed of SiO2, and the overlapped bands between the gate oxide layer and the passivation layer and Si can generate ionization damage and mechanical displacement damage under ultraviolet irradiation and can also influence the collection of ultraviolet photo-generated charges. The PRNU phenomenon is particularly pronounced in the ultraviolet band.
The satellite-borne CCD ultraviolet spectrum PRNU calibration method is few at home and abroad, most research works begin from 2000 years later, and the research on the PRNU phenomenon of satellite-borne CCD ultraviolet imaging has not been carried out internationally, and related research reports have not been found at home.
The first flat field calibration of the UV channel of a spaceborne spectrometer was the ozone detector (OMI) in the American EOS (earth observation System) project, which was the first scientific planar array imagingThe CCD model is E2VCCD47-10, the pixel size is 780 × 576 (spectrum dimension × space dimension), and the ultraviolet working wave band is 264nm-383nm-4The white light source illuminates the imaging surface of the CCD of the spectrometer, and the data result shows that the PRNU effect of the white light source in the ultraviolet band reaches 5 percent and the PRNU effect in the visible band is 1 percent. According to the literature, OMI only uses a white light source on the ground for flat field calibration, and does not consider the influence of ultraviolet light with different intensities and different wavelengths on a CCD.
The CHEOPS satellite transmitted in 2017 by the European Bureau is an ultrahigh-precision spectrophotometry space telescope. CHEOPS uses a back-illuminated frame transfer CCD, model E2VCCD47-20, with pixel sizes of 1024 × 1024. In ground test, the load uses a grating monochromator to generate monochromatic light, and then the monochromatic light is generated by an integrating sphere and is projected in a CCD (charge coupled device) view field. The research group found that the PRNU phenomenon of the CCD was more pronounced the closer to the ultraviolet band. The loading working wave band is 400nm-1100nm and is just at the edge of ultraviolet, so that the ultraviolet wave band is not further researched.
The southern European astronomical stage detector group does a relatively detailed work on the PRNU variation of scientific-grade CCDs in the visible band. They reported in 2000 that imaging performance tests were performed on a variety of CCD detectors in the ultraviolet to infrared bands. The flat field images generated by the CCD device E2V44-82 at the wavelengths of 320nm, 650nm and 950nm can obviously show that the PRNU effect of the CCD is more obvious in an ultraviolet band. In a visible wave band between 400nm and 850nm, the influence of illumination on a CCD detector is basically about 2 percent and is relatively flat, but the pixel response fluctuation of 2 percent to 6 percent appears when the wave band is lower than the 400 nm. Meanwhile, the group cooperates with Hawaii university to test the imaging performance of the CCD of the echelle grating spectrometer in the UT2 telescope of the Parranner astronomical table from ultraviolet to infrared bands, the model of the CCD is CCID-20, a 15um manufacturing process is adopted, and the pixel resolution is 2 Kx 4K. Under the irradiation of ultraviolet wave length of 350nm, brick-shaped stripes appear obviously. Compared with the E2V44-82 device, the PRNU change rate reaches more than 40%. The group analyzes that the initiation of the phenomenon may be quality difference caused by the back of the CCD wafer in the laser annealing process, so that the photoelectric response of the CCD pixel in the ultraviolet band generates violent change. This phenomenon should be mitigated if the CCD manufacturing process is adjusted. This phenomenon is also explained from another point of view, and even if the quality control of CCD production is good, the PRNU effect of CCD in the ultraviolet band needs to be sufficiently emphasized.
Floris, the university of the Netherlands, and Stephen, the Isaac Newton group of Lapalma USA, also observed anomalies in the imaging of space-borne CCDs in the ultraviolet band, and performed more detailed tests on the E2V44-82 device. They used a tungsten halogen lamp as the light source, and used a slit width of 4arcsec (891um), and used a grating of H2400B, and the image plane was covered with a spectrum of 37.8nm width, so that 7 flat-field images were continuously obtained between 330nm and 570 nm. To avoid non-linear generation, the exposure time is set so that the CCD output DN value does not exceed 60000(16Bit AD). And the image is processed by IRAF software, so that the flat field data change is stable, and the ultraviolet band response obviously changes greatly.
In summary, internationally, aiming at the PRNU effect of scientific-grade CCDs in ultraviolet band imaging, the conventional means of generating uniform light by an integrating sphere and a monochromator is mainly adopted, and the scientific image is calibrated by using a scheme of dark frames and flat-field frames. The method is suitable for the optical imaging CCD, but cannot meet the calibration requirement of the spectral imaging CCD, because the spectral CCD captures a spectral image, different line positions correspond to spectral lines with different wave bands, the characteristics of the PRNU cannot be described only by the irradiation of one monochromatic light or white light, and the response of different monochromatic lights is required to be obtained at different positions on the CCD surface to represent the characteristics of the PRNU.
Disclosure of Invention
The invention provides a pixel non-uniformity calibration method and device for a CCD ultraviolet band of a satellite-borne spectrometer, which can solve the technical problem that the traditional technology is only suitable for an optical imaging CCD but cannot meet the calibration requirement of the spectral imaging CCD.
In order to achieve the purpose, the invention adopts the following technical scheme:
a pixel nonuniformity calibration method for a CCD ultraviolet band of a satellite-borne spectrometer comprises
Firstly, a test platform is set up, the test platform comprises a halogen lamp light source which is arranged in a light chopper, light emitted by the light chopper passes through a grating monochromator to an adjustable slit device, and the test platform also comprises an integrating sphere, and the adjustable slit device is connected with the integrating sphere through an optical fiber;
the light output by the integrating sphere enters the light spot imager;
the light spot imager outputs light spots to the satellite-borne spectrometer CCD;
the calibration method comprises the following steps:
s100, recording a full-width offset frame of a CCD of the satellite-borne spectrometer under the exposure time of 0 second;
s200, recording the CCD dark background of the spaceborne spectrometer with the gain of 1 under different integration times and different working modes under the dark background;
s300, adjusting the grating monochromator to generate lambda[1，1]The wavelength monochromatic light is irradiated on a push-scanning starting point of a CCD pixel of the satellite-borne spectrometer through a light spot imager to be imaged, and data are recorded;
s400, rotating the rotary table to image at the next imaging point of the CCD of the satellite-borne spectrometer, and repeating the step S300 until lambda is generated[i，j]After the wavelength monochromatic light is finished, i represents a row number, and j represents a column number, so that light spots are subjected to push-broom imaging on a CCD imaging surface of the satellite-borne spectrometer row by row in sequence;
s500, after the whole image is scanned, splicing the spectral data according to the rows and the columns of the CCD of the satellite-borne spectrometer;
s600, matching the serial numbers of the peak position pixels of the characteristic spectral lines with the corresponding wavelengths through peak searching processing on each spectrum;
s700, performing polynomial regression analysis on the spectral line wavelength and the peak data set by adopting a least square method, and calculating a wavelength value corresponding to each pixel center to obtain a PRNU spectral calibration equation of the CCD of the satellite-borne spectrometer.
Further, the peak searching processing in step S600 includes:
determining the spectrum S by adopting Gauss function fitting of formula (1) and peak searching processingiData set of median peak position and spectral line wavelength [ x ]ij,yij]X in the arrayijRepresents the peak pixel number, yijRepresenting the corresponding characteristic peak wavelength;
wherein:
Ki: the amplitude of the ith gaussian component corresponding to the function;
xi: the central position of a Gaussian waveform;
i: a Gaussian peak half width;
y0: is constant and is determined by the CCD dark background noise.
Further, in the step S700, a wavelength value corresponding to each pixel center is calculated to obtain a PRNU spectrum calibration equation of the CCD of the satellite-borne spectrometer, which includes:
establishing a spectrum scaling equation model as formula (2), wherein the polynomial order is third order, CinIs a polynomial coefficient for wavelength calibration, and n is a polynomial order;
a pixel nonuniformity calibration device for a CCD ultraviolet band of a satellite-borne spectrometer comprises a halogen lamp light source, an integrating sphere and a light source, wherein the halogen lamp light source is arranged in a light chopper, light emitted by the light chopper passes through a grating monochromator to the adjustable slit device, and the adjustable slit device is connected with the integrating sphere through an optical fiber;
the light output by the integrating sphere faces to the inlet of the light spot imager;
the light spot imager is characterized by also comprising a satellite-borne spectrometer CCD, wherein the light spot is output to the satellite-borne spectrometer CCD by the outlet of the light spot imager.
Further, still include the revolving stage, CCD sets up on the revolving stage.
Further, the revolving stage is the high precision revolving stage of um level, and the adjustment is stepped value and is the um magnitude.
Further, the adjustable slit device generates a full width at half maximum of the single band light not exceeding 20 nm.
Furthermore, the wavelength range of the monochromatic light output by the grating monochromator is 200-400 nm
According to the technical scheme, the pixel non-uniformity calibration method and device for the CCD ultraviolet band of the satellite-borne spectrometer are different from a conventional PRNU obtaining method in that a circle-like light spot uniform irradiation light source is established, light spots of different bands are generated in different spectral dimensions in a row through a micron-sized displacement three-dimensional turntable, the diameter of each light spot covers a plurality of pixels on a CCD imaging surface, and full-band scanning imaging of the spectrometer is achieved; meanwhile, ultraviolet light is used to form elliptical light spots with small diameters, the CCD imaging surface is sequentially irradiated according to the sequence of the pixels to obtain the signal distribution of the CCD pixels, and the accurate PRNU scaling equation is obtained by performing Gaussian fitting and least square processing on the signals.
Drawings
FIG. 1 is a schematic representation of the process steps of the present invention;
FIG. 2 is a schematic structural diagram of a test platform of the present invention;
FIG. 3 is a schematic representation of spectral push-broom during light measurement according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention.
As shown in fig. 1 and fig. 2, the pixel nonuniformity calibration method for the CCD ultraviolet band of the space-borne spectrometer according to the embodiment includes first building a test platform, where the test platform includes a halogen lamp light source 1, the halogen lamp light source 1 is arranged in a light shield 2, light emitted by the light shield 2 passes through a grating monochromator 3 to an adjustable slit device 4, and further includes an integrating sphere 5, and the adjustable slit device 4 is connected with the integrating sphere 5 through an optical fiber;
the light source device also comprises a light spot imager 6, and the light output by the integrating sphere 5 enters the light spot imager 6;
the device also comprises a turntable 8, a satellite-borne spectrometer CCD7 is arranged on the turntable 8, and the light spot imager 6 outputs light spots 9 to a satellite-borne spectrometer CCD 7;
the structure of the test platform in this embodiment is shown in fig. 2, and the main functions of each structure are as follows:
1. halogen Lamp light source (Lamp): a source for generating ultraviolet light;
2. a light chopper: the light source is used for restraining the light from the light source and generating emitting light in a certain direction;
3. grating monochromator: the device is used for decomposing light generated by the halogen lamp light source into monochromatic light with continuous spectrum; the wavelength range of monochromatic light output by the grating monochromator is 200-400 nm.
4. Adjustable Slit (Adjust Slit): generating single-band light, wherein the Width of FWHM (full Width at HalfMaxima) is not more than 20 nm;
5. integrating sphere: for homogenizing the output light;
6. a light spot imager: adjusting the light output by the integrating sphere to become light spots with certain sizes; the size of the light spot can be comprehensively considered according to the spectral line precision of the required spectrometer and the size of the CCD pixel;
7. um level high-precision revolving stage: and (5) three-dimensionally adjusting the position of the focal plane of the CCD, and adjusting the stepping value to be um magnitude.
In the whole measurement process, the image output signal of the CCD of the satellite-borne spectrometer is connected into a computer for displaying, recording and processing, and referring to FIG. 1, the specific push-scan measurement process is as follows:
s100, recording a full-width offset frame of the CCD under the exposure time of 0 second;
and S200, recording the CCD dark background with the gain of 1 under different integration times and different working modes under the dark background.
S300, adjusting the grating monochromator to generate lambda[1，1]The wavelength monochromatic light is irradiated on the CCD pixel push-scanning starting point through the light spot imager to form an image, and data are recorded;
s400, rotating the precision rotary table to image at the next CCD imaging point, and repeating the step S300 until lambda is generated[i，j]Finishing the wavelength monochromatic light (i represents a row number, and j represents a column number), and enabling the light spots to be subjected to push-broom imaging on the CCD imaging surface row by row and column by column in sequence;
and S500, after the whole image is scanned, splicing the spectral data according to the rows and the columns of the CCD.
S600, matching the serial number of the peak position pixel of the characteristic spectral line with the corresponding wavelength through peak searching processing of each spectrum. The peak searching process adopts Gauss function fitting as formula (1), and the spectrum S can be determined through the peak searching processiData set of median peak position and spectral line wavelength [ x ]ij,yij]X in the arrayijRepresents the peak pixel number, yijRepresenting the corresponding characteristic peak wavelength.
Wherein:
Ki: the amplitude of the ith gaussian component corresponding to the function;
xi: the central position of a Gaussian waveform;
i: a Gaussian peak half width;
y0: is constant and is determined by the CCD dark background noise.
S700, performing polynomial regression analysis on the spectral line wavelength and the peak data set by adopting a least square method, and calculating a wavelength value corresponding to each pixel center to obtain a PRNU spectrum calibration equation of the CCD. Because the spectra are approximately linearly arranged on the CCD detector, a spectrum scaling equation model is established as formula (2), wherein the polynomial order is third order, CinIs the polynomial coefficient of wavelength calibration, and n is the polynomial order.
To further illustrate the PRNU measurement process, this embodiment is further illustrated by way of example in fig. 3. Assuming that the spatial dimension resolution of the satellite-borne spectrometer corresponds to about 18 pixels of the horizontal axis of the CCD and the spectral resolution corresponds to about 14 pixels of the vertical axis, the size of the light spot generated by the light spot imager can be determined to be not larger than 14 × 18 pixels, and assuming that the image plane of the CCD is 1072 × 1032 pixels, 77 × 57 scans are required to generate a full-scale image. Obviously, the smaller the spot size, the higher the PRNU calibration accuracy, but the number of scans will increase by a factor, and as the spot size decreases, the difficulty in designing the spot imager will also increase. Therefore, in practical application, the spectral accuracy is determined according to the actual spectral accuracy required by the spectrometer.
In summary, since international space loads have been calibrated by using various methods for flat field calibration of the PRNU phenomenon of scientific-grade CCD imaging in the ultraviolet band, the conventional means of generating uniform light by an integrating sphere and a monochromator is mainly adopted to record the change of the PRNU, and the scheme of dark frame and flat field frame is used to calibrate scientific images. The method is suitable for the CCD of optical imaging, but can not meet the calibration requirement of the CCD of spectral imaging, because the spectral CCD captures a spectral image, and spectra of different wave bands corresponding to different line positions can not describe the characteristics of the PRNU only by the irradiation of one monochromatic light or white light, and the response of different monochromatic lights is required to be obtained at different positions on the CCD surface to represent the characteristics of the PRNU.
The embodiment of the invention forms elliptical light spots with small diameters by using ultraviolet light, sequentially irradiates a CCD imaging surface according to the sequence of pixels to obtain the signal distribution of the CCD pixels, and obtains an accurate PRNU calibration equation by performing Gaussian fitting and least square processing on the signal.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (3)
1. A pixel nonuniformity calibration method for a CCD ultraviolet band of a satellite-borne spectrometer is characterized by comprising the following steps: firstly, a test platform is set up, the test platform comprises a halogen lamp light source (1), the halogen lamp light source (1) is arranged in a light chopper (2), light emitted by the light chopper (2) passes through a grating monochromator (3) to an adjustable slit device (4), and the test platform also comprises an integrating sphere (5), and the adjustable slit device (4) is connected with the integrating sphere (5) through an optical fiber;
the light output by the integrating sphere (5) enters the light spot imager (6);
the system is characterized by further comprising a rotary table (8), wherein the satellite-borne spectrometer CCD (7) is arranged on the rotary table (8), and the light spot imager (6) outputs light spots (9) to the satellite-borne spectrometer CCD (7);
the calibration method comprises the following steps:
s100, recording a full-width offset frame of a CCD (7) of the satellite-borne spectrometer under the exposure time of 0 second;
s200, recording the dark background of the CCD (7) of the spaceborne spectrometer with the gain of 1 in different integration times and different working modes under the dark background;
s300, adjusting the grating monochromator (3) to generate lambda[1，1]The wavelength monochromatic light irradiates on a pixel push-scanning starting point of a CCD (7) of the satellite-borne spectrometer through a light spot imager (6) to form an image, and data are recorded;
s400, rotating the rotary table (8) to image at the imaging point of the CCD (7) of the next satellite-borne spectrometer, and repeating the step S300 until lambda is generated[i，j]When the wavelength monochromatic light is finished, i represents a row number, and j represents a column number, so that the light spots (9) are subjected to push-broom imaging on an imaging surface of the CCD (7) of the spaceborne spectrometer row by row in sequence;
s500, after the whole image is scanned, splicing the spectral data according to the rows and the columns of the CCD of the satellite-borne spectrometer;
s600, matching the serial numbers of the peak position pixels of the characteristic spectral lines with the corresponding wavelengths through peak searching processing on each spectrum;
s700, performing polynomial regression analysis on the spectral line wavelength and the peak data set by adopting a least square method, and calculating a wavelength value corresponding to each pixel center to obtain a PRNU spectral calibration equation of the CCD of the satellite-borne spectrometer.
2. The pixel nonuniformity calibration method for the CCD ultraviolet band of the satellite-borne spectrometer according to claim 1, which is characterized in that: the peak searching processing in step S600 includes:
determining the spectrum S by adopting Gauss function fitting of formula (1) and peak searching processingiData set of median peak position and spectral line wavelength [ x ]ij,yij]X in the arrayijRepresents the peak pixel number, yijRepresenting the corresponding characteristic peak wavelength;
wherein:
Ki: the amplitude of the ith gaussian component corresponding to the function;
xi: the central position of a Gaussian waveform;
i: a Gaussian peak half width;
y0: is constant and is determined by the CCD dark background noise.
3. The method for calibrating the nonuniformity of the pixels of the CCD (charge coupled device) of the satellite-borne spectrometer in the ultraviolet band according to claim 2, wherein the wavelength value corresponding to the center of each pixel is calculated in the step S700 to obtain a PRNU (pseudo random number) spectrum calibration equation of the CCD of the satellite-borne spectrometer, and the method comprises the following steps:
establishing a spectrum scaling equation model as formula (2), wherein the polynomial order is third order, CinIs a polynomial coefficient for wavelength calibration, and n is a polynomial order;
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| CN102508144A (en) * | 2011-10-26 | 2012-06-20 | 西安电子科技大学 | Method for measuring dark signal non-uniformity and photon response non-uniformity of photons of CCD (charge coupled device) chip |
| CN102508147A (en) * | 2011-10-26 | 2012-06-20 | 西安电子科技大学 | Method for measuring related parameters of sensitivity, linearity and dark noise of charge coupled device (CCD) chip |
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| CN106501701A (en) * | 2016-10-26 | 2017-03-15 | 上海航天控制技术研究所 | A kind of quantitative testing device of star sensor photodetector anti-radiation performance and method |
| CN107449587A (en) * | 2017-08-16 | 2017-12-08 | 中国科学院国家天文台 | The device and method of inhomogeneities in a kind of test probe pixel |
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| CN102508144A (en) * | 2011-10-26 | 2012-06-20 | 西安电子科技大学 | Method for measuring dark signal non-uniformity and photon response non-uniformity of photons of CCD (charge coupled device) chip |
| CN102508147A (en) * | 2011-10-26 | 2012-06-20 | 西安电子科技大学 | Method for measuring related parameters of sensitivity, linearity and dark noise of charge coupled device (CCD) chip |
| CN102735429A (en) * | 2012-06-13 | 2012-10-17 | 中国科学院长春光学精密机械与物理研究所 | Equipment for CCD (Charge Coupled Device) modulation transfer function test and testing method of equipment |
| CN103105286A (en) * | 2013-01-24 | 2013-05-15 | 中国兵器工业第二〇五研究所 | Imaging optoelectronic system spectral response heterogeneity measuring method |
| CN106501701A (en) * | 2016-10-26 | 2017-03-15 | 上海航天控制技术研究所 | A kind of quantitative testing device of star sensor photodetector anti-radiation performance and method |
| CN107449587A (en) * | 2017-08-16 | 2017-12-08 | 中国科学院国家天文台 | The device and method of inhomogeneities in a kind of test probe pixel |
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