The Michelson arrangement on the carrier plate (Fig. 2)
consists of two surface mirrors S1 and S2 which are positioned
at right angles to each other. Mirror S1 is fixed, but
can be tilted about two axes which are perpendicular to
each other by means of adjusting screws on the back of it.
Mirror S2 can be moved in a direction perpendicular to itself
by means of a micrometer screw and a 1:10 reduction
lever. One graduation on the micrometer screw therefore
corresponds to a mirror displacement of 1 μm.
The partially silvered mirror S3 is positioned at the intersection
of the normals to the two mirrors. It serves to divide the
incident beam into two equal beams.
A holder between S1 and S3 accepts a measuring cell for
the examination of gases. The rods supplied can be fitted
into the threaded bore in the underside of the carrier plate.