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Professor Peter So's Laboratory

BEAM group (Bioinstrumentation Engineering And Microanalysis)

Two-Photon Endoscopy

Investigators: Wanrong Gao, Peter So

Two-photon fluorescence microscopic imaging has been demonstrated to be a new way to produce optical sectioned images in highly scattering medium such as tissues (ref.1 to 6). The development of a two-photon endoscope will be a critical step toward realizing non-invasive optical biopsy. It is clear that the imaging of intra-vessel structural morphology is of great clinical importance, especially the techniques that can image the tissue structural morphology beneath the surfaces of the internal biological vessels.

However, the endoscope should be as small as possible because it would be used to image the internal human organ systems. A promising way is to use single-mode and multi-mode fiber as well as GRIN lens for light delivering, focusing, scanning and collecting. To do this, one should solved the following challenge problems.

(1) Group-Velocity Dispersion,
(2) Scan methods,
(3) Small Size,
(4) High signal-to-noise ratio.

1 - Denk W., Strickler J.H., Webb W.W. (1990) Two-phone laser scanning fluorescence microscop. Science, 248: 73-76.
2 - Bird D., Gu M. (2002) Resolution improvement in two-photon fluorescence microscopy with a single-mode fiber. Applied Optics, 41, No.10: 1852-1857.
3 - Wolleschensky R., Feurer T., Sauerbrey R., Simon U. (1998) Characterization and optimization of a laser-scanning microscope. Applied Physics, B67: 87-94.
4 - Tearney G.J., Boppart S.A., Bouma B.E., Brezinski M.E., Weissman N.J., Southern J.F., Fujimoto J.G. (1996) Scanning single-mode fiber optic catheter-endiscope for optical coherence tomography. Optics Letters, 21, No. 7: 543-545.
5 - So P.T.C., Dong C.Y., Masters B.R. (2000) Two-photon excitation fluorescence microscopy.Annu. Rev. Biomed. Eng. 02: 399-429.
6 - Winfried Denk W., David W. Piston D.W., and Watt W. Webb W.W. Two-photon molecular excitation in laser scanning microscopy. Edited by James B. Plenum, New York, 1995:445-458

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