Common path interferometer based on the modified Michelson configuration using a reflective grating

• Three interferograms can be recorded in one exposure.
• The setup is built using a modified Michelson system with a reflective grating.
• The common path configuration makes the setup more stabile and repeatable.
• Experiments are done to show the validity and stability of the proposed method.

A common-path interferometer using the modified Michelson system with a reflective grating is proposed for quantitative phase imaging. The frequency spectrum of the object beam is split into two beams using a beam splitter. One beam is diffracted into +1, 0, and −1 orders by the reflective grating to act as an object beam, and the other beam is low-filtered and diffracted by a pinhole mirror to act as a reference beam. Three phase-shifted interferograms can be simultaneously captured using the proposed interferometer, and the specimen phase can then be reconstructed from the three interferograms. Experiments are carried out to prove the precision, real-time ability, and stability of the proposed method.