Scitec Instruments has released an optical chopper using 200mm diameter discs, which allows modulation of larger diameter beams. Model 340CD Optical Chopper enables optical beams of up to 78mm diameter to be modulated at frequencies of up to 220Hz.
Two discs are available: a two-slot disc provides chopping frequencies from 5 to 110Hz and a four-slot disc provides chopping frequencies from 10 to 220Hz. The system consists of a control unit with frequency display, a chopper head, an interconnecting cable and a choice of either a two-slot or four-slot 200mm diameter disc.