Engineers at the University of Wisconsin-Madison have developed a compact, single-shot, free-space-coupled spectrometer with hyperspectral imaging capabilities that can be integrated with a cellphone. The spectrometer is fabricated on top of and integrated with a CMOS chip. The miniaturized device measures 200 μm on each side and can lie directly on a sensor from a typical digital camera.
The team’s spectrometer and hyperspectral imager are based on photonic-crystal (PC) slabs. The device uses arrays of photodetectors with different responsivities, which are created by optical interference in PC slabs positioned immediately on top of the photodetector pixels. The PC slabs enable a nonscanning, single-shot imaging method on a compact chip.