Two-photon microscopy is a new technique which combines laser scanning con-focal microscopy and two-photon excitation technique. Two- photon fluorescence microscopy has the advantages of little light damage,small bleaching area,strong penetrability,high resolution,high fluorescence collection efficiency,and high image contrast. It is suitable for dark field imaging and multi-labeled compound measurement,and has been widely used in small animals in vivo optical imaging,such as research for tumour,gene therap...