title: Using a Hexagonal Mirror for Varying Light Intensity in the Measurement of Small-Angle Variation.
abstract: Precision positioning and control are critical to industrial-use processing machines. In order to have components fabricated with excellent precision, the measurement of small-angle variations must be as accurate as possible. To achieve this goal, this study provides a new and simple optical mechanism by varying light intensity. A He-Ne laser beam was passed through an attenuator and into a beam splitter. The reflected light was used as an intensity reference for calibrating the measurement. The transmitted light as a test light entered the optical mechanism hexagonal mirror, the optical mechanism of which was created by us, and then it entered the power detector after four consecutive reflections inside the mirror. When the hexagonal mirror was rotated by a small angle, the laser beam was parallel shifted. Once the laser beam was shifted, the hitting area on the detector was changed; it might be partially outside the sensing zone and would cause the variation of detection intensity. This variation of light intensity can be employed to measure small-angle variations. The experimental results demonstrate the feasibility of this method. The resolution and sensitivity are 3 × 10(-40) and 4 mW/° in the angular range of 0.6°, respectively, and 9.3 × 10(-50) and 13 mW/° in the angular range of 0.25°.
authors.affiliation: Institute of Applied Mechanics, National Taiwan University, No. 1, Sec. 4 Roosevelt Road, Taipei 10617, Taiwan. jang1985@msn.com.
authors.forename: Meng-Chang
authors.initials: MC
authors.lastname: Hsieh
authors.affiliation: Department of Mechatronics Engineering, National Changhua University of Education, 2, Shi-Da Road, Changhua 50074, Taiwan. jylin@cc.ncue.edu.tw.
authors.forename: Jiun-You
authors.initials: JY
authors.lastname: Lin
authors.affiliation: Institute of Applied Mechanics, National Taiwan University, No. 1, Sec. 4 Roosevelt Road, Taipei 10617, Taiwan. changco@iam.ntu.edu.tw.|College of Mechanical Engineering, Guangxi University, 100, University Road, Nanning 530004, China. changco@iam.ntu.edu.tw.
authors.forename: Chia-Ou
authors.initials: CO
authors.lastname: Chang
keywords: Gaussian beam; hexagonal mirror; laser beam shifter; small angle