Guo Baoping

A Real-Time Vision System for Defect Detection in Printed Matter and Its Key Technologies

A vision inspection system with high speed and on line is proposed to detect defects in printed matter, such as smudges, doctor streaks, pin holes, character misprints, foreign matters, hazing, and wrinkles, etc. Any tiny defect would be developed by using the high and low illumination angles design and anti-blooming techniques. A new image reference method based on morphological pre-processing eliminates all false defects brought by slight distortion of printed matter and chromatography mistake. The fast objects searching algorithm based on run-length-encoding can locate the coordinates of defects and define the shape of the defects. The C/S parallel network structure was used, image data were processed distributed and quality data is managed centralized. Experimental results verify the speed, reliability and accuracy of proposed system.

An Automation System for High-Speed Detection of Printed Matter and Defect Recognition

An automation system for high-speed detection of printed matter and defect recognition is proposed to detect defects in printed matter, such as smudges, doctor streaks, pin holes, character misprints, foreign matters, hazing, and wrinkles, etc. Any tiny defect would be developed by using the high and low illumination angles design and anti-blooming techniques. A new image reference method bused on morphological preprocessing eliminates all false defects brought by slight distortion of printed matter and chromatography mistake. The fast objects searching algorithm based on run-length-encoding can locate the coordinates of defects and define the shape of the defects. The C/S parallel network structure was used, image data were processed distributed and quality data is managed centralized. Experimental results verify the speed, reliability and accuracy of proposed system.

Time-resolved two-photon excitation fluorescence spectroscopy and microscopy using a high repetition rate streak camera

We present a time-resolved two-photon excitation fluorescence spectroscopy and a simultaneous time-and spectrum-resolved multifocal multiphoton microscopy system that is based on a high repetition rate picosecond streak camera for providing time-and spectrum-resolved measurement and imaging in biomedicine. The performance of the system is tested and characterized by the fluorescence spectrum and lifetime analysis of several standard fluorescent dyes and their mixtures. Spectrum-resolved fluorescence lifetime images of fluorescence beads are obtained. Potential applications of the system include clinical diagnostics and cell biology etc.

Effect of annealing on photoluminescence and microstructures of InGaN/GaN multi-quantum well with Mg-doped p-type GaN

InGaN/GaN multi-quantum well structure with Mg-doped p-type GaN was grown by low-pressure metalorganic vapour phase epitaxy. After rapid-thermal-annealing at 700 and 900 degrees C, both the red-shift and the blue-shift of the photoluminescence (PL) peak, the decreased and the enhancement of the PL intensity were observed. The transmission electron microscopic images showed that InGaN multi-quantum-dots-like (MQD-like) structures with dimensions less than 5×10nm were formed in InGaN wells. The changes of PL spectra could be tentatively attributed to the competition between the red-shift mechanism of the quantum-confined Stark effect and the blue-shift mechanism of the quantum size effect due to MQD-like structures.

Influence of Growth Temperature and Trimethylindium Flow of InGaN Wells on Optical Properties of InGaN Multiple Quantum-Well Violet Light-Emitting Diodes

An InGaN multiple-quantum-well (MQW) violet-light-emitting diode (LED) is grown by low-pressure metalorganic chemical vapour deposition. It is found that photoluminescence wavelength of the InGaN MQW violet LED is lengthened with increasing growth temperature and with the increasing trimethylindium flow of the InGaN wells. The electroluminescence peak wavelength of the violet LED are about 401 nm with full width at half maximum of 14 nm, and the output power in injection current of 20 mA at room temperature is 4.1 mW.