Optical choppers: modulators and attenuators

Abstract

The paper approaches the optical choppers for two of their possible functions, i.e. attenuators and modulators. An overview of the different types of optical attenuators is also achieved. Constructive and design considerations of choppers are discussed. Various possible configurations of rotating wheels are considered, in relationship with the diameter of the light bundle, in order to produce a certain signal modulation, i.e. a required profile of the transmitted flux. A source of errors regarding the use of these devices is discussed. We describe an adjustable rotating wheel that we have designed and produced to allow for the adjustment of the geometrical parameters of chopper for experiments.