Easy method to determine refractive indices of microspheres and in micro-regions of inhomogeneous media.

We describe an innovative method which can accurately determine the refractive index (RI) of individual microspheres by immersing the microspheres in a medium and analyzing their phase-contrast microscopic images. Compared with the current techniques for microsphere RI measurement, the method has several advantages: it is simple and easy and it cannot only measure the RI of each individual microsphere but also perform measurement simultaneously on all the microspheres in the same field of view. In measurement, microspheres are not required to be suspended in a specific liquid but in any medium with known RI which is appropriate for the microspheres or even just in atmosphere.

[Study of Raman spectroscopy of optically trapped human red blood cell affected by direct current].

Laser tweezers Raman spectroscopy (LTRS) system is a combination of spectroscopy and laser tweezers; It is a new method of studying cells; It can trap single living cell and make Raman spectrum of single living cell. From the positions, intensities, and line widths of the Raman peaks in the spectra, we can get useful information about composition, structure and interactions of complexes inside the living cells. External agents may change cell's physiological state and this changed information can also be got from Raman spectra.