Based on the telluric field data from a Sino-France cooperation station and analysis of the linear characteristic of telluric field polarization, this paper puts forward a new method, called vertical projection to the...Based on the telluric field data from a Sino-France cooperation station and analysis of the linear characteristic of telluric field polarization, this paper puts forward a new method, called vertical projection to the polarization, to recognize seismic electrical anomaly from observation background. Through careful analysis of polarization variation in different time intervals, it is determined that the best time interval for the regression of polarization is 24 h. Telluric observational data from two earthquakes, one is Yongdeng M_s=5.8 earthquake on July 22, 1995, the other is west Tianzhu M_s=5.4 earthquake on June 1, 1996, are processed by this new method, it is interesting to discover that abnormal electrical signals appeared 28 days and respectively. The limit condition of using this method is discussed finally.展开更多
A position sensor based on grating projection with spatial filtering and polarization modulation is presented. A grating is projected onto the object to be measured through a 4f optical system with a spatial filter. A...A position sensor based on grating projection with spatial filtering and polarization modulation is presented. A grating is projected onto the object to be measured through a 4f optical system with a spatial filter. After reflected by the object, the grating projection is imaged on a detection grating through another 4f optical system to form moiré fringes, The polarization modulated moiré signal is detected to obtain the position information of the object. In the position sensor, the moiré signal varies sinusoidally with the position of object. The measurement is independent of the incident intensity on the projection grating and the reflectivity of the object to be measured, In experiments, the effectiveness of the position sensor is proved, and the root mean square （RMS） error at each measurement position is less than 13 nm.展开更多
文摘Based on the telluric field data from a Sino-France cooperation station and analysis of the linear characteristic of telluric field polarization, this paper puts forward a new method, called vertical projection to the polarization, to recognize seismic electrical anomaly from observation background. Through careful analysis of polarization variation in different time intervals, it is determined that the best time interval for the regression of polarization is 24 h. Telluric observational data from two earthquakes, one is Yongdeng M_s=5.8 earthquake on July 22, 1995, the other is west Tianzhu M_s=5.4 earthquake on June 1, 1996, are processed by this new method, it is interesting to discover that abnormal electrical signals appeared 28 days and respectively. The limit condition of using this method is discussed finally.
文摘A position sensor based on grating projection with spatial filtering and polarization modulation is presented. A grating is projected onto the object to be measured through a 4f optical system with a spatial filter. After reflected by the object, the grating projection is imaged on a detection grating through another 4f optical system to form moiré fringes, The polarization modulated moiré signal is detected to obtain the position information of the object. In the position sensor, the moiré signal varies sinusoidally with the position of object. The measurement is independent of the incident intensity on the projection grating and the reflectivity of the object to be measured, In experiments, the effectiveness of the position sensor is proved, and the root mean square （RMS） error at each measurement position is less than 13 nm.
