Confocal microscopy addresses two significant challenges in biological imaging that conventional fluorescence microscopy cannot overcome. Firstly, biological specimens are 3-dimensional structures so to fully understand them we often need to construct 3-dimensional images. Secondly, many processes biologists would want to study occur inside biological structures, but other cell features can block a clear view.
Confocal microscopy uses optical sectioning to take multiple, thin, 2-dimensional slices of a sample to construct a 3-dimensional model from them. This is made possible through the addition of a pinhole into the same focal plane as the sample to block out-of-focus light. Spinning disk confocal microscopy increases the speed of this technique by using multiple pinholes etched into an opaque disk which, when spun, scans the pinholes across the entire image.
Compared to other optical sectioning techniques, spinning disk confocal microscopy is high-speed, high-sensitivity and simple to implement. This makes it a very common choice for studying 3-D structure, fast dynamic processes, long-term time-lapse or details inside the cell membrane, all possible with live cells.