Improved axial point spread function in a two-frequency laser scanning confocal fluorescence microscope.

A two-frequency laser scanning confocal fluorescence microscope (TF-LSCFM) based on intensity modulated fluorescence signal detection was proposed. The specimen-induced spherical aberration and scattering effect were suppressed intrinsically, and high image contrast was presented due to heterodyne interference. An improved axial point spread function in a TF-LSCFM compared with a conventional laser scanning confocal fluorescence microscope was demonstrated and discussed.