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Research on NETD Test System of Medical Infrared Thermal Imager Based on CCD Imaging Technology
Miao Cao,Wenjie Cui 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.3
Under the conditions that the target and background are bold and the transmission loss in atmosphere between systems is neglected, the SNR of the thermal imaging system, the radiation flux of the target and the NETD expression are derived. On this basis, the NETD test system of the modern infrared thermal imager is studied. The system is constructed by a Newton type reflecting parallel light tube, and the off-axis parabolic reflector is as the main body, which provides infinity infrared observation target for infrared thermal imager being tested. The target is composed of the infrared reticle located at the focus of off-axis parabolic reflector and the high precision temperature blackbody at the back of the reticle. The image of infinity infrared target is displayed on its own screen by the infrared thermal imager. CCD shoots the screen of infrared thermal imager, and NETD value is obtained by processing the camera's video signal. The experimental results show that the accuracy of NETD synthesis can reach 0.03℃ in this paper.
The Design of All Fiber Laser Heterodyne Detection System
Cao Miao,Cui Wenjie,Yao Qinghua 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.5
The traditional method of heterodyne detection is improved in this paper based on the principle of laser heterodyne detection. The laser heterodyne detection system is designed with all-fiber laser radar in all fiber system, and the laser, the optical system, the receiving device and so on are connected via the passive component. The system can mix the local oscillation light with signal light of measured object information in the photodetector surface, and the difference frequency signal is obtained. Then the signal is filtered and amplified by the signal processing technique to eliminate the DC component, and the desired difference frequency signal is obtained. Through the analysis of the performance of all fiber laser heterodyne detection system, the system has a strong ability to detect weak signal, high conversion gain and signal to noise ratio, and has a good filtering effect. The system is very suitable for the application of laser ranging and so on.
Cao Miao,Cui Wenjie,Yao qinghua 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.7
MRTD (minimum resolvable temperature difference) is an important parameter to evaluate the infrared thermal imager. MRTD is not only related to the spatial resolution of the system, but also to many factors such as optical system, detector array and so on. The measurement technique and principle of the medical infrared thermal imager’s MRTD is deeply analyzed, and the MRTD measurement model is established in this paper. The MRTD measurement system of infrared thermal imager based on CCD imaging technology is designed. CCD is used to carry on the interpretation of temperature difference in this system instead of the human eye, which can avoid the effect of some factors on the subjective image quality evaluation, such as the contrast, the human interference flaw and so on. The sub-pixel edge detection algorithm is used to deal with the four-bar target image, which can effectively suppress the interface of the random noise on four-bar target image. The experimental results show that the MRTD testing accuracy of the system can reach 0.055℃.
Miao Cao,Wenjie Cui 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.1
The change cause of the thermal imager alignment and its detection principle are analyzed in this paper. On this basis, an infrared thermal imaging is designed for the shortcomings of the traditional detection method, that alignment change detection system is based on CCD imaging technology. The cross pinhole target is used to establish the measurement space coordinate system for the digital image interpretation program in this system. The interpretation software is called about aiming at the baseline variation in the data processing system. According to the position relationship of the 5 pin hole in the field of the infrared thermal imager, the alignment change can be measured. The experimental results show that the system can effectively test the change in the baseline of the thermal imager, and the uncertainty of the test is better than 0.05mil.