<title>Multispectral imaging with a liquid crystal tunable filter</title>

Abstract

We report on a new class of instrument for imaging spectral analysis, the tunable liquid crystal filter (LCTF). The LCTF is an optical filter, similar to an interference filter, whose center wavelength is electronically tunable with no moving parts, in a few milliseconds, across hundreds of nanometers. The filter is a polarization interference filter based on the Lyot design, using the electro-optic action of liquid crystals to tune the passband. Imaging quality is near the diffraction limit and there is no image shift as the filter is tuned. Bandwidths ranging from a 0.25 nm to 60 nm have been achieved, for use in high-resolution sequential RGB imaging, microscopy of multiply-tagged fluorescent samples, bathymetry, and remote sensing. LCTFs are presently being applied to agricultural quality control measurements.