A Solid-State Alternative to the Vacuum Photomultiplier Tube

There are a number of important OEM photonic applications based on the detection of low incident light levels, including flow cytometry, PET (positron emission tomography) imaging, and applied spectroscopy. In flow cytometry, a blood sample is first treated with fluorescently labeled antibodies, which preferentially adhere to different cell types. As the cells flow through the instrument in a single-file fashion, a focused laser beam excites fluorescence. The various antibody labels each have emission peaks at different points in the visible spectrum, which are separated by dichroic optical filters and detected with photodetectors. This allows several different cell types to be simultaneously counted. In this brief a novel cooled, solid-state photodetector designed to detect low light levels in flow cytometry and other applications is described.