Luminescence laser scanning microscopy

Figure 8.23 (b) Confocal laser scanning microscopy image of potassium hydrogen phthalate with occluded dichlorofluorecein showing details of luminescence that has developed in the fast growing slopes of the (010) growth hillock. The vertices of the chevron-shaped hillock fossils mark dislocation cores (reproduced by permission of The Royal Society of Chemistry). 

Applications of multiwavelength TCSPC to laser scanning microscopy have been demonstrated in [35, 60]. Spectrally resolved detection in diffuse optical tomography is described in [23]. A multianode MCP PMT and an SPC-330 TCSPC module were used to resolve the luminescence of alkali halides under N, Ar, Kr, and Xe ion irradiation [266]. 

Multiphoton or two-photon laser scanning microscopy is an alternative to confocal and time-resolved microscopy for bioimaging applications. The principle has been discussed in Lanthanides Luminescence Applications and concerns a two-photon excitation from the simultaneous absorption of two photons in a single quantized event. A bioprobe that normally absorbs ultraviolet light (Xex = 350 nm) can also be excited by two photons of NIR light, at 700 nm (the wavelength is twice that required for one-photon excitation). These two photons must interact simultaneously, which means in a very small lapse time. The instrumentation requires pulse lasers to provide sufficient power, as the photon density must... 

Yu, M.X., Li, F.Y., Chen, Z.G, et al. (2009) Laser scanning up-conversion luminescence microscopy for imaging cells labeled with rare-earth nanophosphors. Analytical Chemistry, 81, 930-935. 

There arc various techniques for recording luminescence microscopy images and for improving the contrast and/or the resolution. Their description is out of the scope of this chapter. It is howevCT worth mentioning confocal microscopy. In this technique, conventional illumination in which the observed object is completely and evaily irradiated by a light source (wide field illumination) is replaced by point laser illumination. A scanning unit is inserted... 

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