Super-heterodyne laser interferometer using femtosecond frequency comb for linear encoder calibration system

2007 ◽  
Author(s):  
Mariko Kajima ◽  
Hirokazu Matsumoto
Keyword(s):  
Laser Interferometer ◽  
Frequency Comb ◽  
Calibration System ◽  
Linear Encoder ◽  
Heterodyne Laser Interferometer

Model and Measurement Method of Optical Nonlinearities Caused by the Heterodyne and Homodyne Interference Terms in the Heterodyne Interferometer

2014 ◽  
Vol 613 ◽  
pp. 58-63
Author(s):  
Hai Jin Fu ◽  
Jiu Bin Tan ◽  
Peng Cheng Hu ◽  
Zhi Gang Fan
Keyword(s):  
Measurement Method ◽  
Laser Interferometer ◽  
Optical Nonlinearity ◽  
Laser Source ◽  
Optical Nonlinearities ◽  
Laser Polarization ◽  
Heterodyne Interferometer ◽  
Optical Mixing ◽  
Ultra Precision ◽  
Heterodyne Laser Interferometer

The heterodyne laser interferometer is widely applied in ultra-precision displacement measurement, but its accuracy is seriously restricted by the optical nonlinearity which arises from the optical mixing in the reference and measurement arms. In an ideal heterodyne laser interferometer, the beam from the laser source consists of two orthogonally linear-polarized components with slightly different optical frequencies and the two components can be completely separated by the polarizing optics, one traverses in the reference arm, the other traverses in the measurement arm, both of them are in the form of a pure optical frequency. However, in a real heterodyne laser interferometer, due to the imperfect laser polarization, the optics defect and the misalignment, the two components of the laser beam cant be perfectly separated, therefore both of the reference arm and the measurement arm contain a portion of the two laser components, which leads to an optical mixing in the two arms of the heterodyne interferometer and causes the cyclic nonlinearity of several to tens of nanometers.

A digital heterodyne laser interferometer for studying cochlear mechanics

2009 ◽  
Vol 179 (2) ◽  
pp. 271-277 ◽  
Author(s):  
Stefan Jacob ◽  
Cecilia Johansson ◽  
Mats Ulfendahl ◽  
Anders Fridberger
Keyword(s):  
Laser Interferometer ◽  
Cochlear Mechanics ◽  
Heterodyne Laser Interferometer

A heterodyne laser interferometer for dilatometer measurements

2009 ◽  
Vol 52 (12) ◽  
pp. 1319-1327 ◽  
Author(s):  
V. P. Kulesh ◽  
L. M. Moskalik ◽  
A. A. Sharov
Keyword(s):  
Laser Interferometer ◽  
Heterodyne Laser Interferometer

scholarly journals Seismic Discrimination between Earthquakes and Explosions Using Support Vector Machine

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 1879
Author(s):  
Sangkyeum Kim ◽  
Kyunghyun Lee ◽  
Kwanho You
Keyword(s):  
Support Vector Machine ◽  
Hough Transform ◽  
Laser Interferometer ◽  
Kernel Functions ◽  
P Wave ◽  
Support Vector ◽  
Nonlinearity Error ◽  
Seismic Discrimination ◽  
Heterodyne Laser Interferometer ◽  
Discrimination Method

The discrimination between earthquakes and explosions is a serious issue in seismic signal analysis. This paper proposes a seismic discrimination method using support vector machine (SVM), wherein the amplitudes of the P-wave and the S-wave of the seismic signals are selected as feature vectors. Furthermore, to improve the seismic discrimination performance using a heterodyne laser interferometer for seismic wave detection, the Hough transform is applied as a compensation method for the periodic nonlinearity error caused by the frequency-mixing in the laser interferometric seismometer. In the testing procedure, different kernel functions of SVM are used to discriminate between earthquakes and explosions. The outstanding performance of a laser interferometer and Hough transform method for precision seismic measurement and nonlinearity error compensation is confirmed through some experiments using a linear vibration stage. In addition, the effectiveness of the proposed discrimination method using a heterodyne laser interferometer is verified through a receiver operating characteristic curve and other performance indices obtained from practical experiments.

scholarly journals Earthquake Magnitude Estimation Using a Total Noise Enhanced Optimization Model

Sensors ◽  
2019 ◽  
Vol 19 (6) ◽  
pp. 1454 ◽  
Author(s):  
Kyunghyun Lee ◽  
Jinhwan Oh ◽  
Hyukwoo Lee ◽  
Kwanho You
Keyword(s):  
Seismic Waves ◽  
Laser Interferometer ◽  
Optimal Solution ◽  
Ground Vibration ◽  
Earthquake Magnitude ◽  
P Wave ◽  
Total Noise ◽  
Acceleration Amplitude ◽  
Precise Prediction ◽  
Heterodyne Laser Interferometer

In this paper, a heterodyne laser interferometer, which is used as a sensor for high-precision displacement measurement, is introduced to measure ground vibration and seismic waves as a seismometer. The seismic wave is measured precisely through the displacement variation obtained by the heterodyne laser interferometer. The earthquake magnitude is estimated using only the P-wave magnitudes for the first 3 s through the total noise enhanced optimization (TNEO) model. We use data from southern California to investigate the relationship between peak acceleration amplitude ( P d ) and the earthquake magnitude ( M g ). For precise prediction of the earthquake magnitude using only the P d value, the TNEO model derives the relation equation between P d and the magnitude, considering the noise present in each measured seismic data. The optimal solution is obtained from the TNEO model based objective function. We proved the performance of the proposed method through simulation and experimental results.

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