The rotational modules allow to change and to measure the scattering angles of a spectrometer.
Each scattering angle, 2 θM , φ, 2 θA , corresponds to an independant module.
This module has a high precision worm gear drive which changes the scattering angle.
The Worm is deconnectable, then manual free rotation is possible.
Absolute angular encoders are mounted in the rotation axis.
Rotational modules can be made of non magnetic materials, except for the motor and encoder (on request).