VARIABLE-ENTRANCE-SLIT SYSTEM FOR PRECISION SPECTROPHOTOMETERS

An innovative variable-slit system meant for precision spectrophotomet ers has been developed and produced by combining silicon bulk-micromac hined elements with conventional mechanical parts. The key component f or varying the device entrance pupil is a silicon slit plate with its internal elastic structure actuated by a stepping motor. The double-sy mmetry beam structure has been designed to achieve millimetre-long lin ear displacements in one direction with a reproducibility of the slit centre position better than 0.01 mu m. A qualification sample of many variable-slit units has been successfully precision tested as well as fatigue tested up to ten million times and cycled between -20 and + 70 degrees C.