We introduce an instrument for single wavelength measurement of phase retardation based on the laser feedback phenomenon.A method of multi-wavelength conversion for this instrument is proposed and the conversion resul...We introduce an instrument for single wavelength measurement of phase retardation based on the laser feedback phenomenon.A method of multi-wavelength conversion for this instrument is proposed and the conversion results are analyzed.System calibration is used to eliminate the conversion error.The experimental results show that the maximum error after conversion is 0.26°.Through the present work,the application of laser feedback instrument for single wavelength measurement of a wave plate is expanded to the multi-wavelength range.This will expand the application area of the instruments.展开更多
A sensitive method to determine the optic axis azimuth of the birefringence element is presented, which is based on laser feedback. The phase difference between the two intensities in birefringence feedback changes wi...A sensitive method to determine the optic axis azimuth of the birefringence element is presented, which is based on laser feedback. The phase difference between the two intensities in birefringence feedback changes with the angle between the optic axis of the birefringence element and laser original polarization. The phase difference is highly sensitive to the relative position of the optic axis and the laser original polarization. This method is used to highly precisely determine the optic axis azimuth, and is able to distinguish between the fast axis and the slow axis of the birefringence element. Theoretical analysis and experimental results are both demonstrated.展开更多
A new optical method based on frequency-shift feedback and laser confocal microscopy is presented to noninvasively measure a microstructure inside a sample. Due to the limit of axial resolution caused by poor signal d...A new optical method based on frequency-shift feedback and laser confocal microscopy is presented to noninvasively measure a microstructure inside a sample. Due to the limit of axial resolution caused by poor signal detection ability, conventional laser feedback cannot precisely measure the microstructure. In this Letter, the light scattered by the sample is frequency shifted before feedback to the laser to obtain a magnification. Weak signals that change with the microstructure can be detected. Together with the tomography ability of laser confocal microscopy, the inner microstructure can be measured with high axial resolution.展开更多
A method is presented for in situ resolution calibration of multiple feedback interferometers(MFIs)using two lasers with di?erent feedback levels simultaneously.The laser with weak optical feedback level generates hal...A method is presented for in situ resolution calibration of multiple feedback interferometers(MFIs)using two lasers with di?erent feedback levels simultaneously.The laser with weak optical feedback level generates half-wavelength optical fringes,whereas the laser with strong multiple feedback level generates optical nanofringes.By using this method,the number of displaced optical nano-fringes can be easily counted,and the resolution of the MFIs can be accurately determined.The integrated MFIs can be used to measure displacements and calibrate other displacement sensors.展开更多
Self-mixing interferometry (SMI) based on nanometer fringes and polarization flipping is realized. The interferometer comprises a single-mode He-Ne laser and a high-amplitude reflectivity feedback mirror. The nanomete...Self-mixing interferometry (SMI) based on nanometer fringes and polarization flipping is realized. The interferometer comprises a single-mode He-Ne laser and a high-amplitude reflectivity feedback mirror. The nanometer fringes are obtained by tilting the external feedback mirror. The fringe density is 35 times higher than that derived with conventional two-beam interference, and each fringe corresponds to a λ/70 displacement in external cavity length. Moreover, polarization flipping occurs when the external feedback mirror moves in the opposite direction. Such movement can be used to easily distinguish displacement direction. Experimental results show an optical resolution of displacement measurement of 9.04 nm with a range of 100 μm. The proposed SMI presents promising application prospects in precisely measuring displacement and calibrating other micro-displacement sensors because of its optical wavelength traceability.展开更多
The polarization state is modulated by tilting birefringence component placed in the feedback external cavity.The variation of the polarization state in one period of modulation is found to be similar to sine wave.The...The polarization state is modulated by tilting birefringence component placed in the feedback external cavity.The variation of the polarization state in one period of modulation is found to be similar to sine wave.The periods become increasingly smaller.The maximum of variation in one period decreases against the rotated angle.The experimental phenomenon is subjected to the change of optical path and secondary reflection.The phenomenon is analyzed theoretically based on geometrical optics and crystal optics.High-accuracy measurements of absolute and relative angles can be realized based on the experimental phenomenon.The angle resolution is 0.1 arcsec in theory.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 61036016the Beijing Higher Education Young Elite Teacher Project under Grant No YETP0086
基金Supported by the National Natural Science Foundation of China under Grant No 61036016Scientific and Technological Achievements Transformation and Industrialization Project by the Beijing Municipal Education Commission。
文摘We introduce an instrument for single wavelength measurement of phase retardation based on the laser feedback phenomenon.A method of multi-wavelength conversion for this instrument is proposed and the conversion results are analyzed.System calibration is used to eliminate the conversion error.The experimental results show that the maximum error after conversion is 0.26°.Through the present work,the application of laser feedback instrument for single wavelength measurement of a wave plate is expanded to the multi-wavelength range.This will expand the application area of the instruments.
基金Project supported by the Natural Science Foundation of Beijing,China(Grant No.3091002)
文摘A sensitive method to determine the optic axis azimuth of the birefringence element is presented, which is based on laser feedback. The phase difference between the two intensities in birefringence feedback changes with the angle between the optic axis of the birefringence element and laser original polarization. The phase difference is highly sensitive to the relative position of the optic axis and the laser original polarization. This method is used to highly precisely determine the optic axis azimuth, and is able to distinguish between the fast axis and the slow axis of the birefringence element. Theoretical analysis and experimental results are both demonstrated.
基金supported by the National Natural Science Foundation of China(No.51375262)the Natural Science Foundation of Beijing(No.4152024)
文摘A new optical method based on frequency-shift feedback and laser confocal microscopy is presented to noninvasively measure a microstructure inside a sample. Due to the limit of axial resolution caused by poor signal detection ability, conventional laser feedback cannot precisely measure the microstructure. In this Letter, the light scattered by the sample is frequency shifted before feedback to the laser to obtain a magnification. Weak signals that change with the microstructure can be detected. Together with the tomography ability of laser confocal microscopy, the inner microstructure can be measured with high axial resolution.
基金supported by the Key Project of the National Natural Science Foundation of China(Nos.51375262,60827006,and 60723004)the Scientific and Technological Achievements,Transformation and Industrialization project by the Beijing Municipal Education Commission,and the Scholarship Award for Excellent Doctoral Students granted by the Ministry of Education
文摘A method is presented for in situ resolution calibration of multiple feedback interferometers(MFIs)using two lasers with di?erent feedback levels simultaneously.The laser with weak optical feedback level generates half-wavelength optical fringes,whereas the laser with strong multiple feedback level generates optical nanofringes.By using this method,the number of displaced optical nano-fringes can be easily counted,and the resolution of the MFIs can be accurately determined.The integrated MFIs can be used to measure displacements and calibrate other displacement sensors.
基金supported by the Key Project of the National Natural Science Foundation of China (Nos.60827006 and 60723004)the Scientific and Technological Achievements Transformation and Industrialization Project by the Beijing Municipal Education Commission
文摘Self-mixing interferometry (SMI) based on nanometer fringes and polarization flipping is realized. The interferometer comprises a single-mode He-Ne laser and a high-amplitude reflectivity feedback mirror. The nanometer fringes are obtained by tilting the external feedback mirror. The fringe density is 35 times higher than that derived with conventional two-beam interference, and each fringe corresponds to a λ/70 displacement in external cavity length. Moreover, polarization flipping occurs when the external feedback mirror moves in the opposite direction. Such movement can be used to easily distinguish displacement direction. Experimental results show an optical resolution of displacement measurement of 9.04 nm with a range of 100 μm. The proposed SMI presents promising application prospects in precisely measuring displacement and calibrating other micro-displacement sensors because of its optical wavelength traceability.
基金supported by the National Natural Science Foundation of China (No. 61036016)the Scientific and Technological Achievements Transformation and Industrialization Project by the Beijing Municipal Education Commission
文摘The polarization state is modulated by tilting birefringence component placed in the feedback external cavity.The variation of the polarization state in one period of modulation is found to be similar to sine wave.The periods become increasingly smaller.The maximum of variation in one period decreases against the rotated angle.The experimental phenomenon is subjected to the change of optical path and secondary reflection.The phenomenon is analyzed theoretically based on geometrical optics and crystal optics.High-accuracy measurements of absolute and relative angles can be realized based on the experimental phenomenon.The angle resolution is 0.1 arcsec in theory.
