Hung-Ying Chang

An Ultra-Sensitive Liquid-Level Indicator Based on an Etched Chirped-Fiber Bragg Grating

A novel ultra-sensitive liquid-level indicator using an etched chirped fiber Bragg grating is experimentally demonstrated with a sensitivity of 1.214 nm/mm for detecting tens of micro-meter liquid-level variation. The operation mechanism is based on the superposition wavelength-peak shift created by the overlap between the spectrum of the etched CFBG section immersed in the liquid and the spectrum of the rest of the grating in air. This sensor may be used to precisely measure the liquid-level variation in bio-hazardous systems or industrial containers that demand accurate interrogation of the amounts of the contents.

A Highly Sensitive Two-Dimensional Inclinometer Based on Two Etched Chirped-Fiber-Grating Arrays

We present a novel two-dimensional fiber-optic inclinometer with high sensitivity by crisscrossing two etched chirped fiber Bragg gratings (CFBG) arrays. Each array is composed of two symmetrically-arranged CFBGs. By etching away most of the claddings of the CFBGs to expose the evanescent wave, the reflection spectra are highly sensitive to the surrounding index change. When we immerse only part of the CFBG in liquid, the effective index difference induces a superposition peak in the refection spectrum. By interrogating the peak wavelengths of the CFBGs, we can deduce the tilt angle and direction simultaneously. The inclinometer has a resolution of 0.003° in tilt angle measurement and 0.00187 rad in tilt direction measurement. Due to the unique sensing mechanism, the sensor is temperature insensitive. This sensor can be useful in long term continuous monitoring of inclination or in real-time feedback control of tilt angles, especially in harsh environments with violent temperature variation.

High Sensitive Two-Dimension Tilted-Meter Based on Chirped Fiber Bragg Gratings

A high sensitive two-dimension tilted-meter using the two etched chirped fiber Bragg gratings (CFBGs) is experimentally demonstrated. The sensitivity of tilted angle is 0.303 nm/°, corresponding to the resolution of 0.033°. The proposed 2D tilted meter can be used for measuring the tilted angle and directional angle with the tilted angle ranging from 0° to 35° and the direction angle ranging from 0° to 360°. The operation mechanism is based on the two CFBGs with the superposition wavelength peak shift created by the overlap between the spectra from a CFBG in the liquid and the air region.

A Fiber Bragg Grating-Based Anemometer

A novel fiber anemometer based on two pairs of fiber gratings is experimentally demonstrated and can simultaneously detect wind speed and wind direction. One pair of gratings, which are separated by 90° in space, is fixed on a small stainless steel pipe driven by a rotating disc for measuring the wind-direction angle. The other pair is composed of a sensing and a matched grating. The frequency of the spectrum-shifted of the sensing grating to overlap with that of the matched grating is employed for determining the wind speed. The errors in the wind-speed and wind-angle measurements are experimentally demonstrated to be less than 1%. The proposed fiber anemometer with a simple and durable structure can be applied in wind-powered electricity generators.

Rotational speed sensors based on a fiber Bragg grating

A novel rotational speed sensor consisting of a fiber Bragg grating is proposed. As the grating glued to the surface of a metal rod was driven by a disc, the grating wavelength was shifted back and forth to cause the change of reflection power for measuring the frequency of on-off change for obtaining the rotational speed.

A three-dimension tilt-meter based on fiber gratings

A tilt-meter consists of two long-period gratings mounted axially on the inner wall of a cylindrical container and has a nice linearity in the tilt range from 0 to +20 degree in a random direction.