INTERFEROMETER DEVICE

PROBLEM TO BE SOLVED: To provide an interferometer device capable of preventing bending of an optical axis of the whole device which makes difficult a design of a device housing or the like and adjustment of an optical system, by adopting a technique for removal of a noise caused by formation of a wedge shape to two optical members having the most probability of generating an interference fringe noise in the optical system, and by integrating skillfully the wedge directions of the two optical members. SOLUTION: When a reference plate 107 is formed in a wedged shape, bending of the optical axis by the rear surface 107b is inevitable. In this case, the optical axis bent by the rear surface 107b of the reference plate 107 is bent again in the reverse direction by a half mirror 104 having a wedged shape, to roughly collimate the optical axis from a test surface 108a to the reference plate 107 with the optical axis from a light source 101 to the half mirror 104. Hereby, the optical axis of the whole device can be regarded substantially as a single axis, to avoid difficulty for the design and the adjustment of the optical system.