Piezoelectrically scanned Fabry–Perot interferometer based on the IT-28-30 instrument with a 2.5–6 mm base

A description is given of a simple piezoelectrically scanned Fabry–Perot interferometer based on a commercially available (unscanned) IT-28-30 interferometer. The proposed construction ensures a high thermal stability of the Fabry–Perot resonator because of the mutual compensation of the thermal expansions of the separate elements of the interferometer.