Abstract: An optical unit including a first electrooptical crystal element having a pyroelectric effect and first polarized faces, and a second electrooptical crystal element having a pyroelectric effect and having second polarized faces corresponding to the first polarized faces. The first and second polarized faces are electrically connected to each other such that a polarity of an electrical charge on each of the first polarized faces is opposite to that of an electrical charge on a corresponding one of the second polarized faces. The first electrooptical crystal element is positioned such that a light beam is propagated through the first electrooptical crystal element.

Abstract: An optical device including an optical bench and a plurality of optical elements. The optical bench has first and second supporting sections, separated from each other, each having at least two supporting surfaces. The optical elements secured to the first and second supporting sections have cylindrical bodies, so that these optical elements contact the sections only by lines. Therefore, the relative positions of each optical elements in the optical device are maintained for a long time without being affected by temperature variation in the atmosphere surrounding the optical device.