scholarly journals Two-Wavelength Laser Interferometer System Which Reduces the Uncertainty Caused by the Fluctuation of the Refractive Index of Air

2011 ◽  
Vol 5 (2) ◽  
pp. 126-131 ◽  
Author(s):  
Kaoru Miyata ◽  
◽  
Hidekazu Oozeki ◽  
Hideyuki Nakagawa ◽  
Hiroki Masuda ◽  
...  
Keyword(s):  
Refractive Index ◽  
Uncertainty Analysis ◽  
Measurement Accuracy ◽  
Laser Interferometer ◽  
Optical Path ◽  
Highly Sensitive ◽  
Industrial Use ◽  
Laser Interferometers ◽  
532 Nm

Laser interferometers are widely used to measure highly sensitive length and displacement, e.g., in which refractive index fluctuations of air adversely affect measurement accuracy. To compensate for these effects, the two-wavelength interferometer studied has not yet proved practical in industrial use. We studied the interferometer’s performance and practicality, using uncertainty analysis to extract its features. Based on our results, we developed a two-wavelengthMichelson interferometer with wavelengths of 1064 nm and 532 nm. It was calibrated and evaluated using a highprecision laser interferometer whose optical path was in a vacuum. Results confirmed measurement accuracy of 100 nm/50 mm (k=2) under unstable air conditions - superior to a traditional laser interferometer.

scholarly journals Highly Sensitive D-Shaped Plasmonic Refractive Index Sensor for a Broad Range of Refractive Index Detection

2021 ◽  
Vol 13 (1) ◽  
pp. 1-11
Author(s):  
Emranul Haque ◽  
Abdullah Al Noman ◽  
Md. Anwar Hossain ◽  
Nguyen Hoang Hai ◽  
Yoshinori Namihira ◽  
...  
Keyword(s):  
Refractive Index ◽  
Refractive Index Sensor ◽  
Highly Sensitive ◽  
Refractive Index Detection

scholarly journals Hybrid Grating in Reduced-Diameter Fiber for Temperature-Calibrated High-Sensitivity Refractive Index Sensing

2019 ◽  
Vol 9 (9) ◽  
pp. 1923
Author(s):  
Biqiang Jiang ◽  
Zhen Hao ◽  
Dingyi Feng ◽  
Kaiming Zhou ◽  
Lin Zhang ◽  
...  
Keyword(s):  
Refractive Index ◽  
Simultaneous Measurement ◽  
Surrounding Medium ◽  
High Sensitivity ◽  
Fiber Grating ◽  
Bragg Resonance ◽  
Core Mode ◽  
Promising Alternative ◽  
Sensing Applications ◽  
Highly Sensitive

We propose and experimentally demonstrate a hybrid grating, in which an excessively tilted fiber grating (Ex-TFG) and a fiber Bragg grating (FBG) were co-inscribed in a reduced-diameter fiber (RDF). The hybrid grating showed strong resonances due to coupling among core mode and a set of polarization-dependent cladding modes. This coupling showed enhanced evanescent fields by the reduced cladding size, thus allowing stronger interaction with the surrounding medium. Moreover, the FBG’s Bragg resonance confined by the thick cladding was exempt from the change of the surrounding medium’s refractive index (RI), and then the FBG can work as a temperature compensator. As a result, the Ex-TFG in RDF promised a highly sensitive RI measurement, with a sensitivity up to ~1224 nm/RIU near the RI of 1.38. Through simultaneous measurement of temperature and RI, the temperature dependence of water’s RI is then determined. Therefore, the proposed hybrid grating with a spectrum of multi-peaks embedded with a sharp Bragg resonance is a promising alternative for the simultaneous measurement of multi-parameters for many RI-based sensing applications.

scholarly journals A Highly Sensitive SPR Sensors Based on Two Parallel PCFs for Low Refractive Index Detection

2018 ◽  
Vol 10 (4) ◽  
pp. 1-10 ◽  
Author(s):  
Famei Wang ◽  
Chao Liu ◽  
Zhijie Sun ◽  
Tao Sun ◽  
Banghua Liu ◽  
...  
Keyword(s):  
Refractive Index ◽  
Highly Sensitive ◽  
Low Refractive Index ◽  
Refractive Index Detection

scholarly journals Improved Refractive Index Sensitivity Utilizing Long-Period Gratings with Periodic Corrugations on Cladding

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Anthony Lim ◽  
Wen Bin Ji ◽  
Swee Chuan Tjin
Keyword(s):  
Refractive Index ◽  
Cost Effective ◽  
Experimental Results ◽  
Refractive Index Sensitivity ◽  
Long Period ◽  
Specimen Collection ◽  
Long Period Gratings ◽  
Highly Sensitive ◽  
Index Sensitivity

A new structure of Long-Period Gratings (LPGs) sensor is introduced as a sensitive ambient RI sensor. This structure consists of creating periodic corrugations on the cladding of the LPG. The experimental results show that this LPG structure has good performances in terms of linearity and sensitivity and serves as a highly sensitive and cost-effective sensor. It also has the advantage of portability as the corrugation can also serve as the reservoir for the specimen collection to be tested.

TDC Implementation Based on Internal Delay Module of FPGA

2013 ◽  
Vol 816-817 ◽  
pp. 1063-1068
Author(s):  
Rou Gang Zhou ◽  
Yun Fei Zhou ◽  
Guang Dou Liu ◽  
Xiao Tu
Keyword(s):  
Nuclear Physics ◽  
Measurement Accuracy ◽  
Laser Interferometer ◽  
Interpolation Method ◽  
Time Measurement ◽  
Clock Signal ◽  
Signal Delay ◽  
Digital Conversion ◽  
Sampling Points ◽  
Stable Performance

Currently the time to digital converter (TDC) integrated in FPGA performs time-to-digital conversion in the carry chain mode and inter-slot offset is caused to be severe by internal wiring in the FPGA. Based on the carry chain interpolation method, this paper proposes the method for using a delay module in FPGA to achieve accurate signal delay. By calculating the phase difference of multi-clock signal between two latch sampling points, the interval between two sampling points was obtained. Experimental results indicate a measurement accuracy of 78ps or 52ps can be reached by precisely collecting time through the delay module in FPGA. Compared to the carry chain interpolation method, this method is significantly advantageous in small inter-slot offset, stable performance and convenient design and can meet the requirement for time measurement or requirement by laser interferometer with a nm-level accuracy in nuclear physics.

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