UNAIR NEWS – Fiber or optical fiber is well known in the world of ICT (Information and Communication Technology) as a medium to support the process of sending data on the internet. Optical fibers are cylindrical cables made of glass or plastic. Optical fiber serves to spread light waves from one place to another.
Its advantage over other media is that it is small, light, sensitive, and flexible. Furthermore, optical fiber also has a low level of vulnerability to the effects of electromagnetic interference and less risk of fire or explosion. Besides being used well in the ICT field, optical fiber is now also being utilized in the development of sensor technology.
Optical Fiber as an Alternative Sensor
Optical fiber is an alternative technology that replaces conventional cable functions as an electric signal diverter. The development of optical fiber is not only focused on telecommunications networks but also influences the field of optics, such as sensor technology. Sensors are devices that change physical quantities such as magnetic, radiation, mechanical, and thermal; or chemical becomes an electrical quantity.
In sensor technology, sensors are needed to have high sensitivity and durability. Fiber resistance to electromagnetic interference and its non-conductive property is the reason for using optical fiber as sensors. Sensing system using optical fiber have penetrated the fields of telecommunications, medical, electrical devices, and other fields.
Measuring Plate Thickness through Reflection and Transmission
Universitas Airlangga (UNAIR) Faculty of Science and Technology (FST) Lecturer, Prof. Dr. Moh. Yasin, M.Si. said that in the last few decades, thickness measurement has been increasingly important in various fields related to the development of micro to nanoscale technology. The application is very important to have a non-contact method with accurate and precise sensing and measuring systems. Optical fiber based sensors are considered very suitable for this application.
“Detection of thickness with optical fiber based on reflection and transmission is considered an interesting alternative compared to conventional sensor systems, such as mechanical and electrical based sensors because of the advantages found in fiber,” he explained.
In this optical method, he continued, no electrical signal is needed at the sensing point. Therefore, the sensor system is versatile and allows operation in an environmentally hazardous or explosion-prone environment.
All this time, most thickness measurement using the optical method usually revolve around interferometry techniques (a device for measuring frequency, length, and flexibility of waves). Low coherence interferometry method and wavelength scanning interferometry with confocal microscopes require a refractive index to determine thickness measurements. Even though it offers high measurement accuracy, this method requires critical and complex optical alignment that involves complex settings, large systems, and high costs.
“Thickness measurement of the transparent plate was also reported using lateral-shear wavelength interferometry scanning and laser beam expansion that is not expanded. However, in reality, this technique is impractical and inaccurate, “he explained.
The research conducted by Prof. Yasin in 2014 found that the best thickness measurement experimental results were obtained by transmission method with a resolution of 18 mm. He hoped that in the future there would be more optimum measurement method with smaller thickness measurement resolution until the sub-micron or nanometer scale. (*)
Reporter : Zanna Afia Deswari
Editor : Khefti Al Mawalia
Reference: Yasin, M., et al. 2014. Fiber Optic Displacement Sensor for Thickness Measurement Based on Transmission and Reflection of Transparent Plate. Journal of Optoelectronics and Advanced Materials, 16(5). p.665-671
