In most analyzers the necessary interaction length between the light beam and the sample is obtained in a multipass Herriott cell. The group has the right expertise and tecnical capabilities to realize multipass cells. An example is given in the photo, showing in foreground the back of one mirror, and in background, across the hole, the opposite mirror. The sequence of the spots of a HeNe alignment laser is well visible. Entrance and exit occurr across two peripheral holes in the background mirror. This is the reason for which a spot is missing in the low-right side of the foreground mirror. In case of entrance and exit across the same hole, this spot would be present.
Thin Adaptive Mirrors
In the frame of ESA Project LATT (Large Aperture Telescope Technology) the Group developed, in cooperation with the Optical Workshop of CNR-INO (Mr. M. Pucci), a Zerodur shell, 400 mm diameter, 5 m curvature radius, with a thickness of 1 mm only, with optical quality on both surfaces, and thickness precision of a few microns. The photo below shows one of the tests.
The mirror should survive vibrations and shocks due to launch, flight and deployment. For this reason, during all these phases the mirror is stuck on its spherical holder by electrostatic forces. In order to verify the effectiveness of this method, the mirror underwent vibration tests up to 6 G.