Variable-entrance-slit system for precision spectrophotometers

Abstract An innovative variable-slit system meant for precision spectrophotometers has been developed and produced by combining silicon bulk-micromachined elements with conventional mechanical parts. The key component for varying the device entrance pupil is a silicon slit plate with its internal elastic structure actuated by a stepping motor. The double-symmetry beam structure has been designed to achieve millimetre-long linear displacements in one direction with a reproducibility of the slit centre position better than 0.01 μm. 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 °C.