The Application-Specific Integrated Circuit (ASIC) development plan of the astronomical CCD control system is a special chip development project launched officially by the National Astronomical Observatory of the Chinese Academy of sciences. One of the scientific objectives: Bias and Clock Driver ASIC (CDA), has been designed and manufactured twice. The test shows the performance of CDA completely reach the design requirement. Now this chip can be mass produced at low cost. We claim the CDA is successfully developed in our laboratory. CDA provides bias voltage and clock drives for CCD working. 48 DACs which produce pulse at any amplitude can be used for most CCD controller. The combination of CDA and ASIC lead to integrated multi-CCD system or sub-mini single CCD controller. This high integrated chip make the CCD controller smaller, lower power consumption, more stable and easier to be developed.
Astronomical instrumentation, in many cases, especially the large field of view application while huge mosaic CCD or CMOS camera is needed, requires the camera electronics to be much more compact and of much smaller the size than the controller used to be. Making the major parts of CCD driving circuits into an ASIC or ASICs can greatly bring down the controller's volume, weight and power consumption and make it easier to control the crosstalk brought up by the long length of the cables that connect the CCD output ports and the signal processing electronics, and, therefore, is the most desirable approach to build the large mosaic CCD camera. A project endeavors to make two ASICs, one to achieve CCD signal processing and another to provide the clock drives and bias voltages, is introduced. The first round of design of the two ASICs has been completed and the devices have just been manufactured. Up to now the test of one of the two, the signal processing ASIC, was partially done and the linearity has reached the requirement of the design.
In vacuum UV band, especially in the domain around 100nm wavelength, MCP dominates the detector realm, such as the FUSE telescope (the Far Ultraviolet Spectroscopic Explorer), the working band of which is 90.5-119.5nm. In this paper, it is introduced our work of an attempt to build a CCD system with e2v’s enhanced no-coating device as the detector to test two vacuum UV band spectrographs, of which one works at 102-170nm band and another at 160-320nm. And the working band testing result of the CCD system is showed and the potential possibility to use CCD to detect far UV image is discussed.
EMCCDs have been used in the astronomical observations in many ways. Recently we develop a camera using an
EMCCD TX285. The CCD chip is cooled to −100°C in an LN2 dewar. The camera controller consists of a driving board,
a control board and a temperature control board. Power supplies and driving clocks of the CCD are provided by the
driving board, the timing generator is located in the control board. The timing generator and an embedded Nios II CPU
are implemented in an FPGA. Moreover the ADC and the data transfer circuit are also in the control board, and
controlled by the FPGA. The data transfer between the image workstation and the camera is done through a Camera Link
frame grabber. The software of image acquisition is built using VC++ and Sapera LT. This paper describes the camera
structure, the main components and circuit design for video signal processing channel, clock driver, FPGA and Camera
Link interfaces, temperature metering and control system. Some testing results are presented.
A 10k x 10k single-chip CCD camera was installed on the first Antarctic Survey Telescope (AST3-1) at Dome A,
Antarctica in January 2012. The pixel size is 9 μm, corresponding to 1 arcsec on the focal plane. The CCD runs
without shutter but in frame transfer mode, and is cooled by thermoelectric cooler (TEC) to take advantage
of the low air temperature at Dome A. We tested the performance of the camera in detail, including the gain,
linearity, readout noise, dark current, charge transfer efficiency, etc. As this camera is designed to work at Dome
A, where the lowest air temperature could go down to −80°C in winter, we tested to cool not only the CCD
chip but also the controller which usually is operated at normal temperatures for ground-based telescopes. We
found that the performance of the camera changes a little when the controller is cooled.
In the optical position observations to the near earth objects, the differential measurement methods are commonly used to
improve positional accuracy, in which the object positions are calibrated by the star positions. However, due to the
characteristics of motion of the observed object and the restrictions on current CCD imaging technology, single
measurement accuracy of these methods for the object is not high. This is because there is relative motion between the
calibration stars and the observed object in the field of view of the telescope. This paper analyzes characteristics of
relative movement of the space objects on the Geosynchronous Earth Orbit and the stars in the field of view of an
equatorial telescope, and CCD imaging effects for these objects and stars, then present a new CCD imaging technique for
moving objects and stationary objects. One half of the CCD photosensitive area is used to acquire images of the moving
objects in the field of view in drift scan mode, the other half to take simultaneously images of the stationary objects in
the field of view in stare mode. Discussions about possibilities for developing this camera and its applications are
presented. A prototype camera controller has been developed in our laboratory. The paper also describes the structure of
the camera controller, the implementation method and skills, and some experimental results.
With the advance of the PFPA technology, the design methodology of digital systems is changing. In recent years we
develop a method to implement the CCD timing generator based on FPGA and VHDL. This paper presents the principles
and implementation skills of the method. Taking a developed camera as an example, we introduce the structure, input
and output clocks/signals of a timing generator implemented in the camera. The generator is composed of a top module
and a bottom module. The bottom one is made up of 4 sub-modules which correspond to 4 different operation modes.
The modules are implemented by 5 VHDL programs. Frame charts of the architecture of these programs are shown in
the paper. We also describe implementation steps of the timing generator in Quartus II, and the interconnections between
the generator and a Nios soft core processor which is the controller of this generator. Some test results are presented in
National Astronomical Observatories of Chinese Academy of Sciences have successfully developed a universal
astronomical CCD controller, which is called Astronomical Array Control & Acquisition System (AACAS). It behaves
excellent performance and ultra low system noise. In this paper, results of E2V 4K×4K CCD203_82 characterization
using AACAS controller are presented and also the comparison with the specifications E2V supplied is given. It
concludes some important merits, such as dark current, readout noise, CTE and etc. The readout noise is smaller than 3e<sup>-</sup>
(50KHz) at -100°C working temperature. The system linearity is better than 99.99% and the full well is about 110027e<sup>-</sup>.
The horizontal and vertical CTE are 0.999993 and 0.999997, measured by Fe55 X-ray source and extended pixel edge
response (EPER) separately.
The World Space Observatory - Ultraviolet (WSO-UV) is a space astronomy project led by Russia, with contributions
from China, Germany, Italy, Spain, United Kingdom and a number of other countries in the world. WSO-UV consists of
a 1.7-meter diameter telescope and three focal plane science instruments. The Long Slit Spectrograph instrument on-board
WSO-UV will produce moderate spectral resolution (R=1000-2500) spectra in the 102nm ~ 320nm wavelength
range along a slit of 75 arcsec in length and 1 arcsec in width. The spatial resolution of the instrument will be ~1 arcsec.
A two-channel scheme is proposed to optimize performance, with each of these using a Rowland Circle optical design
with Microchannel Plate detectors in the focal plane. We will discuss the detailed design of the spectrograph and its
expected performance in this paper.
The scintillating fiber camera is a type of three-dimensional track detector. Using this camera, we can observe the scintillation track produced along the path of a charged particle, and from its scintillation yield can determine the linear energy transfer (LET) distribution of the charged particle. Such observations are also possible for recoil (charged) particles produced by fast neutrons. From these data, we can estimate the LET distribution of individual charged particles or that of recoil particles produced by neutrons; and finally, we can estimate the dose equivalent due to charged particles and/or fast neutrons. For use as a dosimeter for fast neutrons produced by the interaction between cosmic-ray particles and wall materials of a manned spaceship in space, a 52 mm cubic scintillating fiber camera with a 75 mmΦ gated-image intensifier with a maximum counting rate of 30 Hz was constructed. The dosimeter consists of a stack of scintillation fibers with a sensitive volume of 52 mm × 52 mm × 52 mm and a 75 mm diameter image intensifier for readout from the scintillation fibers. The scintillation yields were measured for high-energy heavy ions such as carbon and argon ions. An energy resolution of 12% full-width half-maximum (FWHM) was obtained for penetrated argon ions of 650 MeV/n. These results demonstrate that this type detector is very useful as a dosimeter for high-energy cosmic rays and their secondary neutrons.
In this paper, the feasibility of CMOS imagers for astronomical application was evaluated as well as evaluation methods were studied. A camera based on IBIS5 CMOS sensor was built. Evaluation results of this sensor were also presented including readout noise, gain, linearity, dark current, full well capacity and pixel nonuniformity. Experimental observations of solar flare were carried out with Hα solar telescope in Huairou Solar Observation Station (HSOS), and the solar flare in NOAA AR0742 on March 13, 2005 was successfully observed with this IBIS5 CMOS camera. The results show a favorable aspect of the CMOS imager in large dynamic range astronomical imaging.
In order to develop the detector adapted to the space solar telescope, we have built a CCD camera system capable of working in the extra ultraviolet (EUV) band, which is composed of one phosphor screen, one intensified system using a photocathode/micro-channel plate(MCP)/ phosphor, one optical taper and one chip of front-illuminated (FI) CCD without screen windows. All of them were stuck one by one with optical glue. The working principle of the camera system is presented; moreover we have employed the mesh experiment to calibrate and test the CCD camera system in 15~24nm, the position resolution of about 19 μm is obtained at the wavelength of 17.1nm and 19.5nm.
Dynamic range is a very important figure of merit to an imaging system in astronomy since it decides the range of brightness we can observe. This paper describes the design of a CMOS camera with extended dynamic range in which the CMOS sensor achieves high dynamic range by its dual slope response. We first established a model of how the dual slope response works, and gave a method to restore the image from dual slope response to linear response with the extended dynamic range. Then the data needed in the restoration to linear image was obtained in the laboratory by experiments using stable light source based on the model. At last the results of high dynamic range linear response images are shown using these experiment data.
The first astronomical space telescope of China, the Space Solar Telescope (SST), of which the main optical telescope's diameter is one meter, is now being built in the National Astronomical Observatories, Chinese Academy of Sciences (NAOC). In order to obtain high precision data of solar magnetic field, long time exposure is required. Therefore, the correlation tracker technology is applied to keep the images stable during the long exposure and to ensure a high spatial resolution. In this paper, we will analyze the accuracy of the correlation tracker of SST by simulating the high-resolution ground-based observations.
By our analyses, it is found that at the spatial scale of 0.1", an accuracy of about 0.3-pixel can be achieved when using cross-correlation method together with 25-point parabolic fitting. The result is better than using only cross-correlation method. And after the quantification effect being computed, Our preliminary result shows that it will get similar result by using either higher or lower level quantification. That is, precision acquired by using 16bit quantification cannot reach much higher than by 1bit in the SST/CT.
In order to evaluate the radiation shielding efficiency on proton displacement damage for the CCDs that will be boarded space solar telescope project (SST) of China, based on the work of Janesick et. al's, a method is developed to get the stable defects produced by the incident protons. Then the proton caused degradation of the CCD specifications of charge transfer efficiency (CTE) and bulk dark current generation is calculated for SST after its 3-years-long mission on orbit and a 3mm thick aluminum shield is suggested for the CCDs of the mission. The method is a new attempt to predict the displacement-induced CTI and dark current together.
FeI 1.56 micrometers Zeeman-sensitive lines are very important and potential to measure the magnetic field of the deepest layer of the solar photosphere. The new generation polarimeter is designed and manufactured in this wavelength range. By use of the polarimeter mounted on the vertical spectrograph of the 2m solar telescope at Kitt Peak, we can observe the Stokes I, Q, U, Vv parameters simultaneously. The paper presents the introduction of the near infrared polarimeter and the polarmetry of a sunspot group.
The Solar Space Telescope (SST) is the largest scientific space project of China up to now. It engages to observe the transient and steady state solar hydrodynamic and magneto-hydrodynamic process over 2-D real time polarizing spectrum, UV, X-ray and H(alpha) image, and continuous time evolution with high spatial and temporal resolution in order to achieve a break through advance in solar physics. The EUV part of SST, the EUV telescope (EUT), consists of four telescopes with their detectors, which are parallel situated in a single telescope tube. Each telescope of the EUT adopts the normal-incidence principle with help of the multilayer technology and the primary mirror diameter is 12cm. The detectors of the EUT are constructed with EUV sensitive phosphors, fiber tapers, image intensifiers, CCDs, camera electronics and cooling blocks. Three telescopes of EUT are designed to achieve a spatial resolution of 0.5 arcsecond with a field of view (FOV) of 8.5'x8.5' in order to get the ever high-resolution image of the fine structure of the high temperature activities in solar corona and the fourth one is 85'x85' to have the full solar disk always in its field of view. In our presentation, the scientific objectives and the configuration of EUT are introduced.
Although the interest in PtSi IR focal pane array has waned due to its low quantum efficiency compared with InSb and HgCdTe arrays, it is very potential in observing brighter celestial objects. We explored the possibility of applying it to the observation of IR solar spectrum. In the paper, the methods of the simulation and calibration in our observation are introduced and discussed in detail. Using this kind of camera, a new observational band is added to the 2D Multi-band Solar Spectrograph at Yunnan Observatory. The dispersion for FeI 1.56 micrometers of the new IR solar spectrograph is 0.0722 angstrom per pixel, and each vertical pixel represents 0.51 inch of solar disk. It is specially suitable for 2D spectroscopic observation of the deepest solar photosphere. Some primary observation results are also presented.
On Mar. 6-7, 1997, a simultaneous remote observation from 6 sites was successfully carried out with the cooperation of astronomers and hobbyists in China, United States, Canada, and Great Britain. In the paper, the process and technical methods in this observation are introduced in detail. The present difficulties and brilliant prospects in the observational method under the current circumstances of Internet in China are shown as well.
The methods of evaluating the astronomy-using CCDs in Yunnan Observatory CCD-testing Lab are introduced, concerning the evaluation of linearity, noise, gain, quantum efficiency and transfer efficiency, etc.
Two remote presence observations on Dec. 25, 1995 and Mar. 7, 1997 were achieved at the 1-m telescope of Yunnan Observatory. In this paper, the observations are introduced in detail. The technical methods in the remote presence observation are also discussed under the current circumstances of hardware and software in China. The brilliant prospects of the observational method are shown as well.