Acousto-optic modulator for selective extraction of one or more wavelengths from randomly polarized polychromatic light beam

摘要

A polarization-independent polychromatic light modulator applies one or more pairs of predetermined RF drive frequencies to an acousto- optic transducer of an acousto-optic modulator body upon which a single beam of randomly polarized or unpolarized polychromatic input light is incident. No precursor polarization separation elements are employed. For each optical wavelength to be extracted from the incident beam, two RF drive frequencies are employed. The acoustic waves launched into the acousto- optic medium by the application of the two frequencies of a given RF drive frequency pair produce respective +1 and -1 order output beam components of the selected output wavelength (as well as a zeroth order beam for that wavelength). Because the +1 and -1 order beams depart the modulator body along spatially diverse paths, they are intercepted by a set of recombination optics, which blocks the zero order beam component and recombines the desired +1 and -1 order beams into a single composite beam containing a selected wavelength. Where the output beam is to contain a mixture of multiple wavelengths for producing a composite color output light beam, as in the case of a modulated laser projector entertainment system, multiple pairs of RF drive frequencies are applied to the acousto-optic modulator.