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.

Quasi-common-optical-path heterodyne grating interferometer for displacement measurement

2010 ◽  
Vol 21 (11) ◽  
pp. 115304 ◽  
Author(s):  
H L Hsieh ◽  
J Y Lee ◽  
W T Wu ◽  
J C Chen ◽  
R Deturche ◽  
...  
Keyword(s):  
Optical Path ◽  
Displacement Measurement ◽  
Grating Interferometer

An axial displacement measurement relying on the double-helix light beam

2014 ◽  
Vol 59 ◽  
pp. 1-6 ◽  
Author(s):  
Yitian Hu ◽  
Shuai Li ◽  
Cuifang Kuang ◽  
Peng Xiu ◽  
Jianhong Ge ◽  
...  
Keyword(s):  
Light Beam ◽  
Double Helix ◽  
Axial Displacement ◽  
Displacement Measurement

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.

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

Near Infrared Absorption of Pure Carbon Dioxide up to 3100 bar and 500 K. II. Wavenumber Range 5600 cm-1 to 7400 cm-1

1986 ◽  
Vol 41 (3) ◽  
pp. 512-518 ◽  
Author(s):  
M. Buback ◽  
J. Schweer ◽  
H. Tups
Keyword(s):  
Infrared Absorption ◽  
Near Infrared ◽  
Optical Path ◽  
Maximum Pressure ◽  
Band Maximum ◽  
High Pressure High Temperature ◽  
Pure Carbon ◽  
Density Band ◽  
Path Lengths ◽  
Pure Carbon Dioxide

Near infrared absorption of pure CO2 in the 3v1 + v3, 2v1 + 2v20 + v3, v1 + 4v20 + v3, 6v20 + v3 Fermi tetrad region around 6300 cm-1 and in the 3v3 second overtone region around 6970 cm-1 was measured at temperatures between 298 K and 500 K to a maximum pressure of 3100 bar. The 3v3 bandshape, at moderate compression up to 0.1 g · cm-3, is adequately represented by summing over individual rotation-vibration lines with half-widths proportional to the density. Band maximum positions and vibrational intensities between gaseous and liquid-like states are reported and discussed. Promising applications of high-pressure high-temperature near infrared spectroscopy to the quantitative analysis of CO2 are illustrated for the 3200 cm-1 to 7400 cm-1 region. The technique can be used for CO2 concentrations or at optical path lengths differing by several orders of magnitude.

Depth-enhanced integral 3D imaging using a polarization-multiplexed display with different optical path lengths

2004 ◽  
Author(s):  
Sungyong Jung ◽  
Jae-Hyeung Park ◽  
Yunhee Kim ◽  
Byoungho Lee
Keyword(s):  
3D Imaging ◽  
Optical Path ◽  
Path Lengths

Modeling and Analysis on Optical Path of Infrared Reflective Photoelectric Sensor

2014 ◽  
Vol 614 ◽  
pp. 312-316
Author(s):  
Zhao Yun Qiu ◽  
Zhan Xiu Cai ◽  
Ying Yuan Fan ◽  
Ren Hong Zhao
Keyword(s):  
Optical Design ◽  
Quantitative Characteristic ◽  
Model Performance ◽  
Measurement Range ◽  
Acute Angle ◽  
Optical Path ◽  
Path Model ◽  
Design Parameters ◽  
Blind Area ◽  
Photoelectric Sensor

In order to reduce the blind area and enlarge the measurement range of reflective photoelectric sensor, a simplified optical model is established to prove that the main factors affecting performance of the conventional reflective photoelectric sensor is optical design parameters defects. Through a simple pre partial emission angle design of light path and constructing the optical path model, a calculation method is given to calculate blind area and measurement range. Results show that with small blind area, wide measurement range and high sensitivity, the best measuring distance of the acute angle optical path model can be accurately calculated after the emitted light intensity reaches the set value due to its quantitative characteristic; the acute angle optical path model performance parameters are better than the right angle optical path model. The research has guiding significance for the design of reflective photoelectric sensor.

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