With its output wavelength covering the infrared penetrating window of most
biological tissues at 1200-1250 rim, the femtosecond Cr:forsterite laser s
hows high potential to serve as an excellent excitation source for the mult
iphoton fluorescence microscope. Its high output power, short optical pulse
width., high stability, and low dispersion in fibers make it a perfect rep
lacement for the currently widely used Ti:sapphire laser. In this paper, we
study the capability of using a femtosecond Cr: forsterite laser in multip
hoton scanning microscopy. We have performed the multiphoton excited photol
uminescence spectrum measurement on several commonly used bioprobes using t
he 1230 nm femtosecond pulses from a Cr:forsterite laser. Efficient fluores
cence can be easily observed in these bioprobes through two-photon or three
-photon excitation processes. These results will assist in the selection of
dichroic beam splitter and band pass filters in a multiphoton microscopic
system. We have also performed the autofluorescence spectrum measurement fr
om chlorophylls in live leaves of the plant Arabidopsis thaliana excited by
1230 nm femtosecond pulses from the Cr:forsterite laser. Bright luminescen
ce from chlorophyll, centered at 673 and 728 nm, respectively, can be easil
y observed. Taking advantage of the bright two-photon photoluminescence fro
m chlorophyll, we demonstrated the two-photon scanning paradermal and cross
-sectional images of palisade mesophyll cells in live leaves of Arabidopsis
thaliana.