IRVINE, Calif., Feb. 18, 2015 — The 75160NF phase-locked optical chopper system from Oriel Instruments is suited for spectroscopy applications. It combines a chopper controller with an enclosed chopper head and includes four interchangeable chopper wheels. The enclosure prevents scattering and blocks unchopped background light, improving the signal-to-noise ratio. The system integrates with the company’s light sources and monochromators. Optical choppers function by introducing a periodic interruption into the light path in an optical experiment, resulting in an amplitude modulation. This is useful for many low-signal optical detection schemes. The chopping frequency range is adjustable from 4 Hz to 2.0 kHz, using either the internal frequency synthesizer or an external source as the reference. When locked to an external reference, it is possible to chop for harmonics or subharmonics.