Simultaneous measurement of gas absorption spectra and optical path lengths in a multipass cell by FMCW interferometry

2018 ◽  
Vol 43 (12) ◽  
pp. 2872 ◽  
Author(s):  
Xiutao Lou ◽  
Chen Chen ◽  
Yabo Feng ◽  
Yongkang Dong
Keyword(s):  
Absorption Spectra ◽  
Simultaneous Measurement ◽  
Optical Path ◽  
Gas Absorption ◽  
Multipass Cell ◽  
Path Lengths

scholarly journals Compact Laser Collimation System for Simultaneous Measurement of Five-Degree-of-Freedom Motion Errors

2020 ◽  
Vol 10 (15) ◽  
pp. 5057
Author(s):  
Chuang Sun ◽  
Sheng Cai ◽  
Yusheng Liu ◽  
Yanfeng Qiao
Keyword(s):  
Simultaneous Measurement ◽  
Measurement Accuracy ◽  
Measurement Data ◽  
Optical Path ◽  
Degree Of Freedom ◽  
Experimental Setup ◽  
Collimation System ◽  
Optical Configuration ◽  
Series Of Experiments ◽  
The Common

A compact laser collimation system is presented for the simultaneous measurement of five-degree-of-freedom motion errors. The optical configuration of the proposed system is designed, and the principle of the measurement of five-degree-of-freedom errors is described in detail. The resolution of the roll and the horizontal straightness is doubled compared with other laser collimation methods. A common optical path compensation method is provided to detect light drift in real time and compensate for straightness and angle errors. An experimental setup is constructed, and a series of experiments are performed to verify the feasibility and stability of the system. Compared with commercial instruments, the pitch and yaw residuals are ± 2.5 ″ and ± 3.5 ″ without correction, and the residuals are ± 1.9 ″ and ± 2.8 ″ after correction, respectively. The comparison deviations of the horizontal straightness and vertical straightness changed from ± 4.8   μ m to ± 2.8 μm and ± 5.9 μm to ± 3.6 μm, respectively. The comparison deviation of the roll is ± 4.3 ″ . The experimental results show that the data of the five-degree-of-freedom measurement system obtained are largely the same as the measurement data of commercial instruments. The common optical path compensation can effectively improve the measurement accuracy of the system.

Quasi-Common-Path Laser Feedback Interferometers for Precision Measurement of Non-Cooperative Targets

2008 ◽  
Vol 381-382 ◽  
pp. 49-52
Author(s):  
X.J. Wan ◽  
Shu Lian Zhang
Keyword(s):  
Optical Path ◽  
Heterodyne Detection ◽  
Reference Mirror ◽  
Phase Fluctuations ◽  
Common Path ◽  
Laser Instability ◽  
Phase Variations ◽  
Path Lengths ◽  
Contact Displacement ◽  
Feedback Light

In this paper, we report a novel quasi-common-path laser feedback interferometer (QLFI) for highly stable, high-resolution and non-contact displacement measurement. QLFI measures the displacement of the target by measuring the phase of feedback light. In addition to the target-generated feedback light (frequency shifted by 2#), a reference mirror generates a reference feedback light which is frequency shifted by #. The phase variations of both feedback lights are measured by heterodyne detection simultaneously and their difference offers the phase variations caused only by target displacement. When the optical path lengths of the reference and measuring feedback light are nearly the same, the phase fluctuations caused by the environment and laser instability are effectively removed. The heat-induced deformation of a He-Ne laser tube is successfully in-line measured using QLFI.

Wavelength-modulated heterodyne grating shearing interferometry for precise displacement measurement

2014 ◽  
Vol 3 (4) ◽  
Author(s):  
Hung-Lin Hsieh ◽  
Ju-Yi Lee ◽  
Yu-Che Chung
Keyword(s):  
Light Beam ◽  
Phase Variation ◽  
Measurement Range ◽  
Optical Path ◽  
Displacement Measurement ◽  
Measurement Sensitivity ◽  
Double Refraction ◽  
Shearing Interferometry ◽  
Birefringent Crystal ◽  
Path Lengths

AbstractA wavelength-modulated heterodyne grating shearing interferometry using a birefringent crystal is proposed for two-dimensional displacement measurement. There is a difference in the optical path lengths of the p- and s- polarizations of the light beam in the birefringent crystal because of the double refraction caused by the birefringence. By passing through the unequal-path-length optical configuration, the wavelength-modulated light beam is converted into a heterodyne light beam having two frequencies. The modulated heterodyne light beam is further combined with grating-shearing interferometry based on the quasi-common-optical-path (QCOP) design concept. According to the working principle and the Jones calculation, the displacement information of a moving grating can be obtained by means of the optical phase variation resulting from the grating. Theoretical analysis shows that the measurement sensitivity of the proposed method is about 0.134°/nm. The experimental results indicate that the resolution is about 10 nm for the centimetric-level measurement range.

2D integrating cell waveguide platform employing ultra-long optical path lengths

2017 ◽  
Author(s):  
Lena Simone Fohrmann ◽  
Gerrit Sommer ◽  
Giampaolo Pitruzzello ◽  
Thomas F. Krauss ◽  
Alexander Yu. Petrov ◽  
...  
Keyword(s):  
Optical Path ◽  
Path Lengths

Effective optical path length investigation for cubic diffuse cavity as gas absorption cell

2013 ◽  
Vol 116 (1) ◽  
pp. 135-140 ◽  
Author(s):  
Jia Yu ◽  
Fu Zheng ◽  
Qiang Gao ◽  
Yinjie Li ◽  
Yungang Zhang ◽  
...  
Keyword(s):  
Path Length ◽  
Optical Path Length ◽  
Optical Path ◽  
Gas Absorption ◽  
Absorption Cell ◽  
Effective Optical Path Length

Integrating sphere effective optical path length calibration by gas absorption spectroscopy

2013 ◽  
Vol 114 (3) ◽  
pp. 341-346 ◽  
Author(s):  
Qiang Gao ◽  
Yungang Zhang ◽  
Jia Yu ◽  
Zhiguo Zhang ◽  
Shaohua Wu ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Path Length ◽  
Optical Path Length ◽  
Optical Path ◽  
Gas Absorption ◽  
Integrating Sphere ◽  
Effective Optical Path Length
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