SPECTROMETRE INTERFEROMETRIQUE

摘要

Analytical radiation from a source 10 enters a Michelson-type interferometer including a beam splitter 13 and a movable reflecting member 17. Quadrature phase discrimination is employed to provide signals indicative of the position and direction of movement of a portion of member 17 within the analytical radiation path, using a beam from laser 25 directed onto beam splitter 13 and, after reflection by fixed mirror 15 (via retardation plate 27) and movable mirror 17, passed coaxially with beam 11 to detector 28. Multiple quadrature phase discrimination systems may be employed to indicate of the position and direction of movement of three portions of a flat reflecting member. One portion may be within the analytical radiation path. An initial reference indicative of the position of the movable reflecting member independently of the beam splitter and an additional quadrature phase discrimination system may be provided. The reference system may provide redundantly an indication of position and direction of movement of member 17.