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The use of refractometers to investigate the nature of liquids is very common. Here it is shown that surface relief diffraction gratings can be used to measure the refractive index of liquids. Calibration plots showing the relation between first order intensity as a function of refractive index are shown. We also developed a microfluidic device behaving as a grating which is used as refractometer where a very small amount of liquid (microliters) is used.

In this work, several tests of the performance of 3,3’-thiodipropanol (TDP) as a mounting medium for fluorescence microscopy of biological samples were performed. Besides optical properties like the dispersion curve of TDP and the effect of the embedding medium on the fluorescence of commonly used dyes, the interaction with biological specimens, including the labeling of filamentous actin with fluorescent phalloidins, was tested: TDP showed to represent an interesting alternative to commercial mounting media. By mixing TDP with 2,2’-thiodiethanol (TDE), it was possible not only to fine tune the refractive index of the resulting solution, but to preserve the compatibility with fluorescent phalloidins.