scholarly journals Research on Dual-Wavelength Absolute Ranging Technology Based on FMCW Laser Interference

2021 ◽  
Author(s):  
Bin Sun ◽  
Junfang Song
Keyword(s):  
Continuous Wave ◽  
Digital Signal ◽  
Absolute Measurement ◽  
Comparison Method ◽  
Optical Path Difference ◽  
Path Difference ◽  
Optical Path ◽  
Interference Signal ◽  
Application Range ◽  
Phase Discrimination

Abstract FMCW (Frequency-Modulated Continuous Wave) interferometer can achieve high-precision displacement measurement by phase discrimination of the interference signal. The phase needs to be superimposed continuously, so the optical path cannot be interrupted in the measurement process. To solve this problem, a new absolute ranging technology - decimal comparison method is proposed in the manuscript. According to the principle of FMCW interference, two DFB lasers with different central wavelengths are used to measure the same target. The sampled interference signal is processed by digital signal processing to calculate the integer and decimal of the synthetic wavelength period. The optical path difference of the target is calculated by the established mathematical model. The experimental results show that this method not only ensures the measurement accuracy, but also realizes the absolute measurement, and expands the application range of FMCW interferometry.

A Spectral Calibration Method in Optical Coherence Tomography Based on Interference Signal with Fixed Optical Path Difference

2018 ◽  
Vol 45 (6) ◽  
pp. 0607005
Author(s):  
王瑄 Wang Xuan ◽  
李中梁 Li Zhongliang ◽  
南楠 Nan Nan ◽  
步扬 Bu Yang ◽  
曾爱军 Zeng Aijun ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Calibration Method ◽  
Optical Path Difference ◽  
Path Difference ◽  
Optical Path ◽  
Interference Signal ◽  
Optical Coherence ◽  
Spectral Calibration

Determining optical path difference with a frequency-modulated continuous-wave method

2015 ◽  
Vol 54 (22) ◽  
pp. 6661 ◽  
Author(s):  
Ningfang Song ◽  
Xiangxiang Lu ◽  
Wei Li ◽  
Yang Li ◽  
Yingying Wang ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Optical Path Difference ◽  
Path Difference ◽  
Optical Path ◽  
Wave Method

Peak-to-peak tracking method for measurement of optical path difference: Revisited

Optik ◽  
2015 ◽  
Vol 126 (24) ◽  
pp. 5420-5422
Author(s):  
H.H. Ley ◽  
A. Yahaya ◽  
Y. Munajat
Keyword(s):  
Optical Path Difference ◽  
Path Difference ◽  
Optical Path ◽  
Tracking Method ◽  
Peak Tracking

Optical T-Bench Method for Measurement of Optical Path Difference

1963 ◽  
Vol 1 (6) ◽  
Author(s):  
Francis E. Washer ◽  
Walter R. Darling
Keyword(s):  
Optical Path Difference ◽  
Path Difference ◽  
Optical Path

Thermo-Fluid Design Simulation of Nd3+ POCl3 Transverse Flow Liquid Laser Cavity

2021 ◽  
pp. 1-31
Author(s):  
Vinod Singh ◽  
Gaurav Singhal ◽  
Prabal Talukdar
Keyword(s):  
Refractive Index ◽  
Temperature Gradient ◽  
Flow Rate ◽  
Optical Pumping ◽  
Gain Medium ◽  
Optical Path Difference ◽  
Path Difference ◽  
Transverse Flow ◽  
Optical Path ◽  
Liquid Laser

Abstract CFD based thermal design of a transverse flow optical cavity is carried out for 1 kW Nd3+ POCl3 liquid laser source to investigate temperature and velocity distribution in the optical pumping region of the cavity. Temperature gradient and turbulence both affect the refractive index of the liquid gain medium, which results in optical path difference, divergence and hence, poorer quality of the laser beam. The main purpose of this design is to achieve uniform flow and least temperature gradient in the optical pumping region so that the optical path difference can be minimized and a good beam quality can be achieved. CFD model has been developed for carrying out thermo-fluid simulations for this thermal system and based on these simulations, an optimum geometry of inlet ports along with their position from optical pumping region have been proposed. A user defined function (UDF) is incorporated for the input of spatially varying heat source term in each cell of the optical pumping region of the cavity. Variations in refractive index and optical path difference are estimated from the temperature data using another UDF. Simulation reveals that mass flow rate between 1.5 kg/s to 2.0 kg/s maintains the optical homogeneity of gain medium. Preliminary experiments have been carried out to demonstrate the effect of flow rate on the beam divergence and thereby exhibiting the importance of present simulation work.

Thermal optical path difference analysis of off-axis lens ray trace foot-print at Cassegrain telescope correct lens assembly

2012 ◽  
Author(s):  
Ming-Ying Hsu ◽  
Yu-Chuan Lin ◽  
Chia-Yen Chan ◽  
Wei-Cheng Lin ◽  
Shenq-Tsong Chan ◽  
...  
Keyword(s):  
Optical Path Difference ◽  
Path Difference ◽  
Optical Path ◽  
Difference Analysis ◽  
Lens Assembly ◽  
Ray Trace ◽  
Cassegrain Telescope
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