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Currently, two-photon uorescence (2PF) microscopy is the most common technique used in combina-
tion with second harmonic generation (SHG) microscopy. Making use of the various endogenous uo-
rophores found in bio-tissues, 2PF microscopy can provide more cellular, morphological, and molecular
information regarding these tissues in addition to the SHG-revealed information; moreover, it can also
help localize the SHG signals and identify the contrast sources of these signals. However, since 2PF
microscopy is a uorescence-based technique, issues of photodamage and photobleaching due to mul-
tiphoton absorption are always of concern in the i ...