scholarly journals Refractive Index Measurement of Glass with Arbitrary Shape Based on Brewster’s Law and a Focusing Probe Beam

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2421
Author(s):  
Yao Hu ◽  
Jiahang Lv ◽  
Qun Hao
Keyword(s):  
Refractive Index ◽  
Incident Angle ◽  
Structural Parameters ◽  
Array Detector ◽  
Spherical Lens ◽  
Refractive Index Measurement ◽  
Optical Elements ◽  
Optical Glasses ◽  
Index Measurement ◽  
Simple Measurement

The refractive index is one of the most important parameters of optical glasses and has a significant effect on optical properties. The measurement of optical glasses, especially for optical elements such as lenses, is urgently needed. However, several presented methods require the immersion of the sample in liquid and provide indirect measurements, while others require structural parameters as priori knowledge, which is complex and time-consuming. In this study, a Brewster-Law-based direct and simple measurement method for the refractive index of glasses with arbitrary shapes is proposed, and a laser beam is focused on the surface of the sample as a probe. The incident angle of the chief ray is close to the Brewster angle. The reflected light is collected by an array detector. The refractive index is calculated from the minimum intensity position obtained with image processing. Additionally, a symmetric measurement scheme is proposed to improve the accuracy. Using these methods, a prism and four spherical lens samples with different refractive indices or radii of curvature are tested and error analyses are carried out. Results indicate that the accuracy can reach 10−4.

scholarly journals Fibre Tip Sensor with Embedded FBG-LPG for Temperature and Refractive Index Determination by means of the Simple Measurement of the FBG Characteristics

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
C. Berrettoni ◽  
C. Trono ◽  
V. Vignoli ◽  
F. Baldini
Keyword(s):  
Refractive Index ◽  
Bragg Grating ◽  
Long Period Grating ◽  
Refractive Index Measurement ◽  
Long Period ◽  
Index Measurement ◽  
Simple Measurement ◽  
The Difference ◽  
Different Response ◽  
Hybrid Configuration

A novel optical fibre sensing system based on a hybrid long period grating (LPG) and Bragg grating (FBG) configuration is proposed and demonstrated experimentally. The hybrid configuration, which uses the difference in temperature and refractive index (RI) different response of a Bragg grating and a long period grating, makes it possible to discriminate simultaneously the temperature and the refractive index of different aqueous solutions. RI (1.33 RIU–1.40 RIU) and temperature (21°C–28°C) working ranges have been experimentally determined. Experimental results show that the maximum accuracy in the refractive index measurement (0.004 RIU) with temperature compensation has been achieved within the working ranges.

scholarly journals Development of a Temperature-Controlled Optical Planar Waveguide Sensor with Lossy Mode Resonance for Refractive Index Measurement

Photonics ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 199
Author(s):  
Yu-Cheng Lin ◽  
Liang-Yü Chen
Keyword(s):  
Refractive Index ◽  
Optical Fiber ◽  
Temperature Control ◽  
Planar Waveguide ◽  
Metallic Oxide ◽  
Refractive Index Measurement ◽  
Index Measurement ◽  
Temperature Controlled ◽  
Optical Planar Waveguide ◽  
Active Temperature

The generation of lossy mode resonances (LMR) with a metallic oxide film deposited on an optical fiber has attracted the attention of many applications. However, an LMR-based optical fiber sensor is frangible, and therefore it does not allow control of the temperature and is not suited to mass production. This paper aims to develop a temperature-controlled lossy mode resonance (TC-LMR) sensor on an optical planar waveguide with an active temperature control function in which an ITO film is not only used as the LMR resonance but also to provide the heating function to achieve the benefits of compact size and active temperature control. A simple flat model about the heat transfer mechanism is proposed to determine the heating time constant for the applied voltages. The TC-LMR sensor is evaluated experimentally for refractive index measurement using a glycerol solution. The heating temperature functions relative to the controlled voltages for water and glycerol are obtained to verify the performance of the TC-LMR sensor. The TC-LMR sensor is a valuable sensing device that can be used in clinical testing and point of care for programming heating with precise temperature control.

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