<title>Beyond image cubes: an agile lamp for practical 100% photon-efficient spectral imaging</title>

Abstract

Hardware for obtaining spectral image cubes using filters or interferometers, though capable of revealing subtle aspects of composition, is typically expensive, bulky, slow, and often provides poor spatial resolution. In addition, a great deal of computer processing is needed to extract information from the raw data: interferometers must perform FFTs on megapixel data sets; all approaches involve calculations of spectral indices in order to classify or analyze the scene into its components. Consequently, spectral imaging techniques have been adopted only by a small, pioneering community.We report on a novel agile lamp for imaging which produces illumination having any desired spectral flux distribution ranging from pure spectral bands to precisely-tailored, complex polychromatic functions. This lamp, together with a CCD camera, is suitable for use in most spectral imaging applications, and by enabling one to directly image the scene in the spectral measure of interest, it eliminates the need for computer processing. Using matched filtering, one can obtain full information from all spectral bands in a handful of exposures with optimal signal-to-noise. The lamp is long-lived and spectrally stable. It will be affordable, compact, and rugged, and its spectral output can be adjusted within one millisecond. Finally, as there is no interferometer or other optics involved, imaging is 100% photon-efficient. Use of spectrally agile lamps in various multispectral applications is expected.

Spectral imaging perspective on cytomics

“…Band‐sequential devices such as acousto‐optical tunable filters (AOTFs, (7)) liquid crystal tunable filters (LCTFs), circular or linear variable interference filters (21) can be used, as can line‐scanners coupled to gratings or to prisms. Other approaches use tunable light sources (22), and some single‐shot techniques in which spectral and spatial information are captured with a single acquisition event have also been developed (11, 23). As can be expected, all of these approaches have advantages and disadvantages, and any of them would be appropriate for acquiring spectral data for cytomics purposes.…”