Methodology for in-flight flat-field calibration of the Lyman-alpha solar telescope(LST)

Flat-field reflects the non-uniformity of the photometric response at the focal plane of an instrument,which uses digital image sensors,such as Charge Coupled Device(CCD)and Complementary Metal-Oxide-Semiconductor(CMOS).This non-uniformity must be corrected before being used for scientific research.In this paper,we assess various candidate methods via simulation using available data so as to figure the in-flight flat-field calibration methodology for the Lyman-alpha Solar Telescope(LST).LST is one of the payloads for the Advanced Space-based Solar Observatory(ASO-S)mission and consists of three instruments:a White-light Solar Telescope(WST),a Solar Disk Imager(SDI)and a dual-waveband Solar Corona Imager(SCI).In our simulations,data fromthe Helioseismic andMagnetic Imager(HMI)and Atmospheric Imaging Assembly(AIA)onboard the Solar Dynamics Observatory(SDO)mission are used.Our results show that the normal KLL method is appropriate for in-flight flat-field calibration of WST and implementing a transmissive diffuser is applicable for SCI.For the in-flight flat-field calibration of SDI,we recommend the KLL method with off-pointing images with defocused resolution of around 18′′,and use the local correlation tracking(LCT)algorithm instead of limb-fitting to determine the relative displacements between different images.

Ray tracing method for the grazing incidence flat-field imaging soft X-ray spectrometer

A ray tracing method is introduced for helping adjustment and spectra analysis of the grazing incidence flat-field imaging soft X-ray spectrometer. For a single point source, the spectra images obtained by separate components, the toroidal mirror, and the grazing incidence flat-field concave grating with varied line spaces are given respectively. The calculated spectral images of the single point source by the spectrometer are also given for comparison with measurements with different experimental alignments.

Combined Focusing and Flat-Field Spectrometer System for Extreme Ultraviolet Pulse

For reducing both extreme ultraviolet attosecond pulses energy loss in the focusing reflection process and measurement error caused by pulse focusing aberration, as well as improving the operability of pulse spectroscopy monitoring, a combined focusing and flat-field spectrometer analysis system for attosecond pulse is proposed and designed through step-by-step performance optimization. The focusing and spectrum-analyzing components are gold- coated grazing incidence to roidal mirror and grazing incidence concave focusing grating, respectively. The characteristic parameters of the system are given in details. The system proposed can find application in research platform of attosecond spectroscopy using high energy short attosecond pulse as basic probe tool.

A rapid and convenient experimental method of absolutely calibrating transmission of x-ray flat-response filter

We develop a rapid and convenient experimental method of absolutely calibrating the transmission of an x-ray flatresponse filter. The calibration experiment is performed on a small laser-target facility, and a set of high resolution holographic flat-field grating spectrometers is used as a discrimination system of the laser-produced x-ray source. Given that the holographic flat-field grating has a relatively large width, the grating is divided into two regions for use in that direction,where one region has the filter added and the other region does not. The filter transmission is determined by dividing the x-ray signal counts detected when the filter is in the line of sight by those detected when the filter is out of the line of sight.We find that the calibration results of this experiment agree with the calibration results using a synchrotron radiation source,as well as simulation results. Our method is not only highly reliable but also rapid and convenient.

Image Correction Method of Color Line-Scan System

As the development of machine vision technology, the color line-scan system is widely applied in the on-line inspection. Due to the non-uniform gray scale and color distortion of the image acquired by the system, the image correction is needed to reduce the problem of image processing and the stability system. Based on reasons mentioned above, a method that using polynomial fitting to correct the image is presented to solve the problem in this paper. The method has been used in the automatic optical inspection of PCB, and has been proved to be effective. So this method will have a potential application to the development of the color line-scan machine vision system.

EXPERIMENTAL INVESTIGATION OF DOUBLEPASS AMPLIFICATION OF X-RAY LASER IN NEON-LIKE GERMANIUM

The experimental investigations of double-pass amplification of X-ray laser in neon-like germanium were carried out by use of Shengguang laser facilities.In these experiments a molybdenum/silicon multilayer mirror Was used at normal incidence, a flat-field grating spectrograph was used to measure the intensity of lasing lines. We observed the doublepass emission intensity in the neon-like germanium at 23.2 and 23.6 nm that was 5 times larger than that of the single-pass ASE. The enhartcement of double-pass emission could be much larger if the operation period of multilayer mirror was counted in. The damage of multilayer mirror irradiated by laser plasma was measured simultaneously, the lifetime of Mo/Si multilayer mirror was about 440—700ps.In addition, we measured the beam divergence of lasing beam,the resnlts showed that the beam divergence in the vertical direction was about 22 mrad and in the horizontal direction about 12 mrad.