Optical Choppers are used to mechanically modulate light sources that pass through their chopping discs. These optical choppers ship with five interchangeable chopping discs with 2, 5, 10, 30, or 200 slots, supporting chopping frequencies from 5Hz to 20kHz. These discs can be used individually or paired together to create specific chopping configurations for pulse picking applications with pulsed laser sources. Chopping frequency is adjusted by a ten-turn dial or by applying an external DC voltage to the “Control In” BNC port. A “Reference Out” BNC port provides a TTL pulse that is in-phase with the chopping action. Optical Choppers are often used with lock-in amplifiers to reduce signal-to-noise ratio in applications such as laser spectroscopy.