Voltage controlled variable optical attenuator. This is a used unit mfg. by Xerox for use with a linear polarized Helium Neon laser. The unit uses a electro-optic element and a stationary optic to variably attenuate the laser output power. A simple 0 to 3 VDC low current (less than 1mA) input is all that is needed to operate. The laser output can be fully attenuated at 0 volts or 3 volts depending on the light input plane of polarization and can produce an attenuation ratio of around 50:1. The assembly also has a beam splitter and a photodiode that taps a small amount of the attenuated light for use in a feedback loop circuit. The front optic is a cylindrical lens that can be removed if desired.
