The Application of CCD Pixel Positioning Subdivision in the Reach of Laser Triangulation Measurement

Miao Cao,Dandan Wang 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.1

During laser triangulation measurement, CCD image sensor is used to detect the laser spot with the measured information. Resolution and pixel size of CCD, directly affect the precision of laser scanning measurement. Based on the analysis of the gray centroid algorithm, the improvement gray centroid algorithm is proposed. By using the algorithm to solve the CCD location subdivision, the corresponding relationship between the spot position and the pixel is confirmed. The realization of the acquisition enhances the resolution through the segmentation, and the accuracy of laser triangulation measurement is improved.

Research on the Dispersion Coefficient Measurement System based on CCD Imaging Automatic Alignment Technology

Cao Miao,Yao Qinghua 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.7

In order to measure the dispersion coefficient of glass and other transparent material rapidly and accurately, the paper studies the dispersion coefficient measurement system based on CCD imaging automatic alignment technology. On the basis of consideration of the air refractive index impacting on the measurement accuracy of dispersion coefficient, this paper rebuilds the mathematical model by the traditional dispersion coefficient measurement formula. Using the measuring angle technology of precision grating, the paper realizes the digital measurement of deflection angle of refracted ray. Sub-pixel edge detection algorithm is adopted to realize the automatic alignment of double line to single line, which has reduced artificial error of the dispersion coefficient in the measurement process. Finally, the paper combined the multichannel small collimator designed technology and the modern control technology to achieve the high precision measurement of refractive index. Demarcating the measurement system by known dispersion coefficient of optical glass, testing results and error of standard is less than ±2.3×10-6 absolutely.

Research on the Dispersion Coefficient Measurement System based on CCD Imaging Automatic Alignment Technology

Cao Miao,Yao Qinghua 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.6

In order to measure the dispersion coefficient of glass and other transparent material rapidly and accurately, the paper studies the dispersion coefficient measurement system based on CCD imaging automatic alignment technology. On the basis of consideration of the air refractive index impacting on the measurement accuracy of dispersion coefficient, this paper rebuilds the mathematical model by the traditional dispersion coefficient measurement formula. Using the measuring angle technology of precision grating, the paper realizes the digital measurement of deflection angle of refracted ray. Sub-pixel edge detection algorithm is adopted to realize the automatic alignment of double line to single line, which has reduced artificial error of the dispersion coefficient in the measurement process. Finally, the paper combined the multichannel small collimator designed technology and the modern control technology to achieve the high precision measurement of refractive index. Demarcating the measurement system by known dispersion coefficient of optical glass, testing results and error of standard is less than ±2.3×10-6 absolutely.

The Study on the MRTD Measurement System of Medical Infrared Thermal Imager Based on Sub-Pixel Edge Detection Algorithm

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℃.

Effect of Interface on Mechanical Properties and Stamping Formability of Ti/Al Multilayered Composites

Miao Cao,Hui‑Qin Chen,Kun‐Kun Deng,Xing‑Wang Duan,Shuang Liu,Xin Che,Fei Li 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.5

Ti/Al multilayered composites (LMCs) with 3-layers, 5-layers and 7-layers were prepared by hot‐pressing and hot‐rolling. Theeffects of the interface on the mechanical properties and stamping formability of LMCs were revealed. The results indicatethat the TiAl3phases at the interface thicken gradually with the increase of layers. As the layers of LMCs increases, boththe grain size and the basal texture strength of Ti decrease, and Ti possesses a higher Schmid factors (SF) and more uniformSF distribution, which promotes the overall coordinated deformation of LMCs. The elongation (EL) of LMCs graduallyincreases at the expense of the strength with the increase of layers. The stress–strain transfer across the interface, the releaseof residual stress through interfacial microcracks, and the improvement of the interfacial metallurgical bonding strengthare all conducive to the coordinated deformation between Ti and Al layers, thus the strength of LMCs decreases and theEL enhances. Both the yield strength ratio (σs/σb) and plastic strain ratio (r) decrease, while the strain-hardening exponent(n) increases with the increase of layers of LMCs, which are beneficial to improve the stamping formability of LMCs. Thenumber of interface increases with the increase of layers, which hinders crack propagation. Moreover, the microcracks areeasily induced by the brittle TiAl3phase at the interface, and the main cracks deflect obviously and release part energy inthe form of secondary microcracks, thus delaying the failure of LMCs and improving their stamping formability.

Study on the Measurement Technique of the Alignment Variation of Medical Infrared Thermal Imaging System

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.

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.

Influence Analysis of Laser Spot Noise on the Measurement Accuracy of Laser Triangulation Method

Cao Miao,Wang Xiao,Yao Qinghua 보안공학연구지원센터 2016 International Journal of u- and e- Service, Scienc Vol.9 No.6

Laser triangulation method, widely used in modern industry, is able to meet the requirements of fast, real-time and on-line detection within non-contact measurement method. Laser triangulation method is affected by many factors, and the laser spot noise is the main factor to affect application field of the laser triangulation method directly. Based on the laser triangulation principle, this paper deeply analyzes the effect of laser spot noise on the measurement accuracy of laser triangulation method, such as signal flicker noise, background noise, dark current noise, thermal noise, amplifier noise and so on, and puts forward a new method to use the filtering algorithm to overcome the laser spot noise for improving the accuracy of laser triangulation.

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.

Design of Laser Scanning Optical System based on the Triangle Principle

Cao Miao,Wang Xiao,Yan Juncen,Shen Yingchun 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.3

In a three-dimensional laser scanning system, the measurement accuracy of the entire system is determined by the optical system. To improve the accuracy, this paper designs a three-dimensional laser scanning optical system. In order to improve the performance of scanning, to reduce the influence of stray light and the imaging geometric distortion is required, as far as possible to improve the distribution uniformity of the image illumination. In this paper, the semiconductor laser is chosen as the light source which is suitable for laser triangulation measurement. This system ensures accuracy in the first place, and obtain larger working distance later. The volume of the measuring system is reduced by introducing layout that the beam splitter and the normal are coaxial. The Scheimpflug conditions are deduced under this structure, and the experimental results of the laser triangulation optical system are analyzed finally.