The High Energy cosmic-Radiation Detection (HERD) facility is one of several space astronomy payloads of the cosmic light house program onboard China's Space Station, which is planned for operation starting around 2020 for about 10 years. Beam test with a HERD prototype, to verify the HERD specifications and the reading out method of wavelength shifting fiber and image intensified CCD, was taken at CERN SPS in November, 2015. The prototype is composed of an array of 5*5*10 LYSO crystals, which is 1/40th of the scale of HERD calorimeter. Experimental results on the performances of the calorimeter are discussed.
Spectral imaging technology has made great achievements in applications of earth observation and space target detection, with the further development of research, the requirement that People tend to get more material properties about target is also improving rapidly, so getting more characters of the target is continuous pursuit goal for the instruments of optical remote sensing. Polarization is one of the four main physical properties of light including intensity, frequency and phase . It has very important significance for remote sensing observations such as improving the accuracy of target recognition. This paper proposes on a spectropolarimeter system based on Sagnac interferometer, and introduces the main aspects related to System components, working principle, optical design, adaptive spectrum extraction algorithm, state of polarization extraction methods. Also get the data of polarization spectral imaging by using the instruments designed by the principle .By processing these data I have got the combined polarization image and target spectral curves, achieved a good result. It is a new attempt to obtain polarization spectral image by integrated measuring system. Then thoroughly solve the traditional shortcoming of spectropolarimeter, such as asynchronous detecting, poor stability and vibration, poor energy efficiency. It can be applied to many kinds of fields. Simultaneously the paper puts forward some relevant new points in the future research for this kind of principle.
The High Energy cosmic-Radiation Detection (HERD) facility is one of several space astronomy payloads of the cosmic lighthouse program onboard China's Space Station, which is planned for operation starting around 2020 for about 10 years. The main scientific objectives of HERD are indirect dark matter search, precise cosmic ray spectrum and composition measurements up to the knee energy, and high energy gamma-ray monitoring and survey. HERD is composed of a 3-D cubic calorimeter (CALO) surrounded by microstrip silicon trackers (STKs) from five sides except the bottom. CALO is made of about 104 cubes of LYSO crystals, corresponding to about 55 radiation lengths and 3 nuclear interaction lengths, respectively. The top STK microstrips of seven X-Y layers are sandwiched with tungsten converters to make precise directional measurements of incoming electrons and gamma-rays. In the baseline design, each of the four side SKTs is made of only three layers microstrips. All STKs will also be used for measuring the charge and incoming directions of cosmic rays, as well as identifying back scattered tracks. With this design, HERD can achieve the following performance: energy resolution of 1% for electrons and gamma-rays beyond 100 GeV, 20% for protons from 100 GeV to 1 PeV; electron/proton separation power better than 10-5; effective geometrical factors of >3 m2sr for electron and diffuse gamma-rays, >2 m2sr for cosmic ray nuclei. R and D is under way for reading out the LYSO signals with optical fiber coupled to image intensified CCD and the prototype of one layer of CALO.
The low light level imaging and ultrafast detection system is a high performance ICCD composed of imaging intensifier and high-frame-rate CCD, the important readout system of the semi-digital 3D-imaging calorimeter for space observation of cosmic ray and dark matter that has the function of intensifying, delaying, imaging and memorizing, making rapid response to the ultrafast low light signals that is transmitted by tens of thousands of wavelength shifting fibers, generated by the semi-digital 3D-imaging calorimeter when cosmic ray is passing through. Using the images of ICCD and the semi-digital information reconstruction method, the particle type, energy and direction of cosmic ray can be obtained. By solving some key technologies such as coupling techniques of optical parts, low noise and high speed imaging of high-frame-rate and large-area CCD, the high speed gating system of imager intensifier, the prototype of high performance ICCD is developed. The prototype of ICCD can meet the requirements: up to 400 frames per second, detection ability for low light about 10 photons, linear dynamic range more than 300.Performances verification of the prototype is carried out by using a single photon test system. In this paper we will describe the requirement of ICCD for the ground cosmic detection system which is used to verify the theory of Herd (High Energy Cosmic-Radiation Detection), the key techniques used to achieve perfect performances, and test method and result of the ICCD.
Hyperspectral remote sensing images are affected by different types of noise. In addition to typical random noise, nonperiodic partially deterministic disturbance patterns appear in the data. The strips usually found in images acquired by push-broom sensors, which are characterized by a high degree of spatial and spectral coherence. Many strips-reduction approaches such as histogram matching and moment matching have been developed. These methods assume that all sensor elements observe similar subscenes in a given image and adjust the distributions of values acquired by each sensor to some reference distribution by means of a histogram or moment matching, but this assumption usually is failure in many scenes which contain diverse materials. The formation of strips has close connection with the image formation process of push-broom imaging spectrometers. Many causes such as the uniformity of the pixels, the push-broom mode and the asymmetric width of thin slit at the entrance of imaging spectrometers can induce the strips in the images. Comparing with the dispersive spectrometers, interferometer spectrometers acquire the interference data, obtaining the spectrum by using the Fast Fourier Transformation (FFT). By analyzing the generating mechanism of strips in push-broom interferometer imaging spectrometers, we proposed an approach that corrects the strips using relative calibration factor directly computed from the acquired image. Once the relative calibration factor is determined, all the images acquired by the same imaging spectrometers can be corrected. So the methodology is an efficient one to reduce the strips. A formula is set up to describe the connection between gray values of pixels in images and relative calibration factor. The developed methodology is tested on data acquired by HJ-1A Hyperspectral Imaging Spectrometers, which is an interferometer spectrometer put into operation in 2008. The shortwave bands of HJ-1A HSI have severe strips. Results show excellent rejection of the noise with respect to the original HJ-1A HSI images, improving the removal in those scenes with diverse materials as well as being high efficient.