Sensor for in-plane displacement measurement based on combined grating and speckle pattern phase shifting interferometry

The aim of this paper is to present a novel concept of an in-plane displacement sensor head based on grating interferometry (GI) and digital speckle pattern interferometry (DSPI) methods as complementary ones in a single device. The ultimate aim of this is to show new directions of development of microsensors for experimental mechanics purposes. In the paper, complete designs of sensor heads along with tolerance calculation required for prototyping are considered and analyzed. Their advantages are pointed out depending on application. Also theoretical analysis of the state of polarization in a cavity sensor are performed and a polarization phase shifting method for automatic fringe pattern analysis is shown. Finally, the technology demonstrators of the designed sensor head and possible directions for their further development along with a proposal of replication are presented.