Researchers have developed a microscopy method that does not require mechanical scanning. The technique drastically increases the effectiveness of fluorescence lifetime microscopy (FLIM).
A major limitation to traditional fluorescence lifetime microscopy methods stems from the fact that fluorescence decay is fast-occurring — most ordinary cameras are unable to capture it. Using a single-point photodetector overcomes the issue, though the device must be scanned over the area of a sample to construct an image with each measured point. The process involves the movement of mechanical pieces, which limits the speed of image capture.
The new fluorescence lifetime microscopy method can be interpreted as simultaneously mapping 44,400 light-based ‘stopwatches’ over a 2D space to measure fluorescence lifetimes — all in a single shot and without scanning. The method uses an optical frequency comb as the excitation light for the sample; optical frequency combs are light signals composed of the sum of many discrete optical frequencies with a constant spacing between them. How the signal looks when plotted against optical frequency pertains to the “comb”: a tightly confined cluster of equidistant spikes extending from the optical frequency axis.