A multi-object spectral imaging instrument (Vol. 44 No. 6)

Imaging spectrometers acquire three-dimensional spectral data cubes (x, y, λ) to enable chemical imaging in fields ranging from microscopy and biomedicine to remote sensing. Traditional systems, employing time-sequential recording of the complete data cube, cannot record time-varying phenomena and are optically highly inefficient. Our technique enables spectra to be recorded in real time from a programmable sparse array of spots within a microscope sample. Real-time computer-controlled manipulation of the spot array enables tracking and video-rate spectroscopy of these points with the very high optical efficiency. This is achieved with a digital micro-mirror device (DMD) that deflects light from the sparse multiple points in the sample into a slitless spectrometer consisting of a dispersive prism and CCD camera. We demonstrate real-time spectra of multiple fluorescent microbeads in aqueous solution as they diffuse in the sample.