The extraction of stable local features directly affects the performance of infrared face recognition al- gorithms. Recent studies on the application of scale invariant feature transform （SIFT） to infrared face reco...The extraction of stable local features directly affects the performance of infrared face recognition al- gorithms. Recent studies on the application of scale invariant feature transform （SIFT） to infrared face recognition show that star-styled window filter （SWF） can filter out errors incorrectly introduced by SIFT. The current letter proposes an improved filter pattern called Y-styled window filter （YWF） to further elim- inate the wrong matches. Compared with SWF, YWF patterns are sparser and do not maintain rotation invariance; thus, they are more suitable to infrared face recognition. Our experimental results demonstrate that a YWF-based averaging window outperforms an SWF-based one in reducing wrong matches, therefore展开更多
We report a switchable dual-wavelength fiber grating laser in linear overlapping cavity. The laser features two overlapping cavities sharing a single Yb-doped gain medium fiber and two sets of fiber Bragg gratings. A ...We report a switchable dual-wavelength fiber grating laser in linear overlapping cavity. The laser features two overlapping cavities sharing a single Yb-doped gain medium fiber and two sets of fiber Bragg gratings. A coiling fiber setup is inserted into the 1035 nm laser cavity. Given that the bending loss is inversely related to the bending radius, the cavity loss of 1035-nm can be modulated. Modulating the bending loss facilitates the switching of the fiber grating laser to a single-or dual-wavelength output at 1030 or 1035 nm and convenient tuning of the power ratio of the two wavelengths. An approximately 152.6-mW output power and up to 38-dB polarization extinction ratio are observed. The simultaneous lasing at I030 and 1035 nm is a qualified seeder source for amplification to high power scale and can be applied to difference frequency generation of a terahertz signal. This dual-wavelength fiber grating laser is a potential pump source for generating terahertz radiation using a novel approach.展开更多
基金supported by the Natural Science Foundation of Hubei Province under Grant No. 2009CDB320
文摘The extraction of stable local features directly affects the performance of infrared face recognition al- gorithms. Recent studies on the application of scale invariant feature transform （SIFT） to infrared face recognition show that star-styled window filter （SWF） can filter out errors incorrectly introduced by SIFT. The current letter proposes an improved filter pattern called Y-styled window filter （YWF） to further elim- inate the wrong matches. Compared with SWF, YWF patterns are sparser and do not maintain rotation invariance; thus, they are more suitable to infrared face recognition. Our experimental results demonstrate that a YWF-based averaging window outperforms an SWF-based one in reducing wrong matches, therefore
基金supported by the Shanghai Rising-Star Program(No.12QH1401100)the Chinese Academy of Sciences Comprehensive Strategic Cooperation Projects in Guangdong Province(No.2010B090300063)
文摘We report a switchable dual-wavelength fiber grating laser in linear overlapping cavity. The laser features two overlapping cavities sharing a single Yb-doped gain medium fiber and two sets of fiber Bragg gratings. A coiling fiber setup is inserted into the 1035 nm laser cavity. Given that the bending loss is inversely related to the bending radius, the cavity loss of 1035-nm can be modulated. Modulating the bending loss facilitates the switching of the fiber grating laser to a single-or dual-wavelength output at 1030 or 1035 nm and convenient tuning of the power ratio of the two wavelengths. An approximately 152.6-mW output power and up to 38-dB polarization extinction ratio are observed. The simultaneous lasing at I030 and 1035 nm is a qualified seeder source for amplification to high power scale and can be applied to difference frequency generation of a terahertz signal. This dual-wavelength fiber grating laser is a potential pump source for generating terahertz radiation using a novel approach.
