Portable contactless caliper

This work presents a portable optical meter for noncontact thickness measurement. The device shines a focused laser light on a thin and transparent sample, resulting in an interference between light reflecting from the top and from the bottom surface, and the interfering pattern is recorded by a linear sensor array before data analysis with an Arduino microcontroller. The device produced accurate thickness values from glass cover slips and transparent plastic sheets within a fraction of a second per measurement. Additionally, the sample's refractive index is not required a priori. Therefore, it has a high potential to be of use in real-time quality control in transparent thick-film coating and manufacturing.