Spectral imaging in a snapshot

We describe a new filter that simultaneously achieves spectral filtering and image replication to yield a two-dimensional, snapshot spectral imager. Filtering is achieved by spectral demultiplexing; that is without rejection of light; so optical throughput efficiency is, in principle, unity. The principle of operation can be considered as a generalisation of the Lyot filter to achieve multiple bandpasses. We report on the design and experimental implementation of an eight-band system for use in the visible. Proof-of-concept demonstrations are reported for imaging of the ocular fundus and microscopy of fluorescently labelled living cells.