Laser scanning microscope (LSM)

The LSM at NanoSYD is a versatile optical instrument which lets the user probe a wide range of optical characteristics of a sample. A standard inverted fluorescence microscope is used as platform for the LSM. By illuminating the sample with the mounted mercury lamp; single photon fluorescence can be detected.
By changing the excitation source to a high power femto-second laser the LSM is able to probe what is called the non-linear optical regime, e.g. two-photon fluorescence and higher harmonics. With a pair of scanning mirrors the LSM can raster the focus spot on the sample and the non-linear intensity is detected by a highly sensitive photo multiplier tube (PMT) in every scan point. The signal is processed by software to form an image of the sample. Interchanging the PMT with a spectrometer local spectroscopy can be done.
The advantage of the LSM is the small excitation volume which limits the photo-induced damage to the sample and gives a better optical resolution compared to the standard single fluorescence microscope.