Novel continuously tunable high spectral resolution optical filter for two-dimensional imaging

Abstract

Despite the existence of a variety of optical filters for the separation of spectral components in a multicolor image, a filter that is both continuously wavelength tunable and capable of high spectral resolution while preserving the spatial integrity of a two-dimensional image is not currently available. We present, in this article, the introduction of a novel optical filtering concept that permits the development of such a system. Both the concept and its implementation in an optical-fiber-based prototype that converts two-dimensional images to a one-dimensional array followed by interconversion for image reconstruction are presented. The performance of the prototype is analyzed using both a xenon arc lamp as a standard broadband illumination source as well as He–Ne and Ar lasers as sources of coherent radiation. An unoptimized throughput efficiency of approximately 30% and a bandwidth of 6 Å without spectral leakage or spatial crosstalk is obtained over the entire investigated tuning range from 430 to 807 nm. Potential applications of such an optical filtration system, with wavelength tunability on the angstrom scale and potential spatial resolutions in the micrometer range, using suitable optical imaging are discussed.