Microscale laser-induced fluorescence

Kim HJ, Kihm KD, Allen JS (2003) Examination of ratiometric laser induced fluorescence thermometry for microscale spatial measurement resolution. Int J Heat Mass Transf 46 3967-3974... 

Scalar-based flow velocimetry, where the motion of the bulk fluid is inferred from the observed velocity of a conserved scalar, has been widely applied in fluid mechanics from the work of Reynolds (1883) to the present for macro- and microscale applications [32]. The basis is the use of light emitting molecules (fluorescent or phosphorescent). In this section the laser-induced fluorescence (LIF) measurement technique will be discussed in detail. This technique tags one of the liquids by a fluorescent dye and records the fluorescence intensity originating from that dye, which is linked to the concentration of the respective liquid. In contrast to the application of fluorescence intensity techniques to macroscopic flows (LIF), the present application to microflows does not allow one to span up a light sheet and instead illuminates the complete microchannel volume. 

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