US 10,890,429 B2
Automatic calibration optical interferometer and automatic calibration method of optical interferometer
Hung Chih Chiang, Chiayi (TW); Cheng Yi Chang, New Taipei (TW); Ting Wei Chang, New Taipei (TW); and Chi Shen Chang, Zhubei (TW)
Assigned to INDUSTRIAL TECHNOLOGY RESEARCH INSTITUTE, Hsinchu (TW)
Filed by INDUSTRIAL TECHNOLOGY RESEARCH INSTITUTE, Hsinchu (TW)
Filed on Apr. 9, 2019, as Appl. No. 16/379,721.
Claims priority of application No. 107147454 A (TW), filed on Dec. 27, 2018.
Prior Publication US 2020/0208958 A1, Jul. 2, 2020
Int. Cl. G01B 9/02 (2006.01)
CPC G01B 9/0209 (2013.01) [G01B 9/02067 (2013.01); G01B 9/02071 (2013.01)] 9 Claims
OG exemplary drawing
 
1. An automatic calibration optical interferometer, comprising:
a light source configured to emit a low coherent light;
an optical interference assembly coupled to the light source and configured to divide the low coherent light into a first incident light and a second incident light, wherein the optical interference assembly is implemented by a coupler or a splitter;
an optical sampling assembly coupled to the optical interference assembly, wherein the optical sampling assembly comprises a first end and a second end, the first end couples to the optical interference assembly to receive the first incident light, the second end is configured to face a test sample, a partially reflective window at the second end is configured to divide the first incident light into a first reflected light and a first penetrating light, and the first penetrating light is configured to be emitted to the test sample;
an optical reference assembly coupled to the optical interference assembly, wherein the optical reference assembly comprises a reference mirror and an actuator, the optical reference assembly receives the second incident light and emits the second incident light to the reference mirror so as to generate a second reflected light, and the actuator is configured to move the reference mirror;
a polychromator coupled to the optical interference assembly, wherein the polychromator is configured to output a displacement signal according to an optical path difference variation which is derived from the first optical path of the first reflected light and the second optical path of the second reflected light; and
a displacement controller electrically connecting to the polychromator and configured to control the actuator according to the displacement signal, wherein the reference mirror is moved with the optical path difference variation by the actuator, and a modified optical path of the second reflected light equals to a sum of a second optical path of the second reflected light and the optical path difference variation.