Baotan Jiang

A novel method to real-time offset correction for frame transfer CCD

The traditional CCD offset correction processing method is to obtain normal exposure image and dark field image respectively. In the later image processing, use normal exposure image minus the dark field image. Although traditional method can offset correction, but cannot to realize real-time offset correction. Because the traditional method is to obtain offset correction after acquire normal exposure image and dark field image, while the normal exposure image and dark field image is not acquired at the same time. This method would reduce the offset correction precision. A novel method to real-time offset correction for frame transfer CCD is proposed in this paper. The method is based on the improvement of the traditional frame transfer CCD driving timing and CCD signal processing sequence. The traditional frame transfer CCD driving timing is exposure, frame transfer and read CCD level shift register. An offset correction line is added before read CCD data storage area to acquire the offset variation of the each frame image. Take it as a normal image data. In CCD signal processing algorithm to offset calculation and correction. This novel method can correct the offset of each frame image each pixel data real time. In this way the effect on the images from the variation of the offset caused by factors such as the working temperature and the aging of electronic devices in CCD signal processing circuit of CCD camera is restrained.

Design of a multifunction astronomical CCD camera

To satisfy the requirement of the astronomical observation, a novel timing sequence of frame transfer CCD is proposed. The multiple functions such as the adjustments of work pattern, exposure time and frame frequency are achieved. There are four work patterns: normal, standby, zero exposure and test. The adjustment of exposure time can set multiple exposure time according to the astronomical observation. The fame frequency can be adjusted when dark target is imaged and the maximum exposure time cannot satisfy the requirement. On the design of the video processing, offset correction and adjustment of multiple gains are proposed. Offset correction is used for eliminating the fixed pattern noise of CCD. Three gains pattern can improve the signal to noise ratio of astronomical observation. Finally, the images in different situations are collected and the system readout noise is calculated. The calculation results show that the designs in this paper are practicable.

The digital simulation of end-to-end imaging chain in optical remote sensing system based on MTF models

The conflicts between the miniaturization of optical remote sensor and the high resolution force us to build an end-to-end simulation system, and optimize the process of the image acquisition and processing. In this paper, based on the analysis of MTF models of each link in imaging chain, a scientific visualization method of end-to-end optical remote sensing process using MTF models is presented. And, imaging simulation software is programmed with Matlab to implement the process. Using this program, the final simulated image can be generated from the original through the whole remote sensing image course according to the input parameters of each link in image chain. Through research on simulated images, we can analyze effectively the effects of each link on the quality of images, and carry out the optimization of optical remote sensor.

Research on the detection capability of space camera

Detection capability of space camera is regarded as the principal parameter in the design of space camera. On the basis of the concept of signal-to-noise ratio (SNR) and through the research of principles and derivation of theories, detection capabilities under static condition and the condition of relative motion were analyzed and compared. With a set of typical parameters given, the change of detectable magnitude with the changes of parameters was investigated. Considering the real operating environment of space camera, the necessity of temperature control in the design of space camera was discussed. The theoretical analysis provides a reference for the design of space camera.

Maximum projection and velocity estimation algorithm for small moving target detection in space surveillance

The article presents a new method to detect small moving targets in space surveillance. Image sequences are processed to detect and track targets under the assumption that the data samples are spatially registered. Maximum value projection and normalization are performed to reduce the data samples and eliminate the background clutter. Targets are then detected through connected component analysis. The velocities of the targets are estimated by centroid localization and least squares regression. The estimated velocities are utilized to track the targets. A sliding neighborhood operation is performed prior to target detection to significantly reduce the computation while preserving as much target information as possible. Actual data samples are acquired to test the proposed method. Experimental results show that the method can efficiently detect small moving targets and track their traces accurately. The centroid locating precision and tracking accuracy of the method are within a pixel.

Noise model and simulation analysis of the low noise pre-amplifier of CCD camera

The low noise video process chain design is the important guarantee of realization of CCD detection performance. While pre-amplifier locate in the front end of the video signal process of CCD camera, so the low noise preamplifier design is the important guarantee of realization of low noise CCD camera. Firstly, calculate the bandwidth and equivalent noise bandwidth of video process chain of CCD camera. Secondly, design the preamplifier circuit and build the noise model of the preamplifier. Thirdly, according to the noise model calculation the noise of the pre-amplifier. Lastly, build the noise simulation model of the preamplifier. Through theoretical calculation and PSPICE simulation result predict the noise level of the preamplifier of the CCD .The noise level of the preamplifier less than 2 electronics, it meets specification requirement.

A practical method to Extending Dynamic Range of CCD Camera

CCD (Charge Coupled Device) is the most popular detector for camera to detect low levels of light for wavelengths from 300nm to 1100nm. Contemporary CCD has read noise level equivalent to a few electrons, and Well capacity over 100,000 electrons .In order to take full advantage of these characteristics, it needs the dynamic of ADC must exceed the dynamic of the CCD. That is the number of bits provided by the ADC must exceed 16 bits. While the high reliability and inexpensive 16-20 bit A/D converter is few. In this paper, we firstly analyze CCD noise and then present the principle to extend the dynamic of the CCD in signal processing chain using two low resolution ADC with different sensitivity. At last we present a concrete example of improving the resolution of the ADC is by tow parallel low resolution ADCS with developing software to suitably process the converted analog-to-digital signal to achieve the same effect as a higher resolution ADC.