Simultaneous measurement of thickness and refractive index using phase shifted Coherent Gradient Sensor

作者：Disawal Reena; Suzuki Takamasa; Prakash Shashi^*

来源：Optics and Laser Technology, 2016, 86: 85-92.

DOI：10.1016/j.optlastec.2016.06.015

• Interferometry
• Fringe analysis
• Metrology
• Phase measurement

We report simultaneous measurement of thickness and refractive index (RI) using Coherent Gradient Sensing (CGS) based interferometric setup. The collimated light beam transmitted through the specimen is analyzed using two gratings in tandem and a spatial filtering arrangement. At the imaging plane, the desired orders superpose yielding interference fringes. Phase shifting interferometric (PSI) technique has been used to obtain the phase information directly. For decoding the information of thickness and RI, the specimen is rotated and the variation in interferometric phase before and after the specimen rotation determined. Simultaneous measurement on a glass plate of thickness 6.019 mm and refractive index of 1.4570 has been demonstrated. Detailed uncertainty analysis is also reported. The expanded uncertainty for thickness and RI in the measurement process was determined to be +/- 0.005 mm and +/- 0.00008 respectively.

• 出版日期2016-12