TUNABLE REJECTION LIQUID CRYSTAL FILTER

摘要

Apparatus and method for tuning a liquid crystal filter to the wavelength of incoming electromagnetic radiation (such as visible light) by exploiting the AC error signal produced by the filter when a tuning error is present.

主权项

1. Apparatus for tuning a liquid crystal filter powered by an alternating driving voltage, to reject incident light comprising:
means for deriving an electrical signal from the variation in transmission of the filter associated with the alternating driving voltage wherein the sign of the electrical signal is dependent on whether the wavelength of the incident light is greater, or less than, the rejection wavelength of the filter and means for deriving a control signal for the alternating driving voltage from the electrical signal.