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The use of optical parametric oscillator for harmonic generation and two‐photon UV fluorescence microscopy
Author(s) -
Kao FuJen
Publication year - 2004
Publication title -
microscopy research and technique
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 118
eISSN - 1097-0029
pISSN - 1059-910X
DOI - 10.1002/jemt.20026
Subject(s) - second harmonic generation , laser , optical parametric oscillator , optics , excitation , ultrashort pulse , materials science , two photon excitation microscopy , optoelectronics , high harmonic generation , fluorescence , photon , ultraviolet , wavelength , microscopy , sapphire , physics , quantum mechanics
Ultrafast lasers have found increasing use in scanning optical microscopy due to their very high peak power in generating multiphoton excitations. A mode‐locked Ti:sapphire laser is often employed for such purposes. Together with a synchronously pumped optical parametric oscillator (OPO), the spectral range available can be extended to 1,050–1,300 nm. This broader range available greatly facilitates the excitation of second harmonic generation (SHG) and third harmonic generation (THG) due to better satisfaction of phase matching condition that is achieved with a longer excitation wavelength. Dental sections are then investigated with the contrasts from harmonic generation. In addition, through intra‐cavity doubling wavelengths from 525–650 nm are made available for effective two‐photon (2‐p) excitation with the equivalent photon energy in the UVB range (290–320 nm) and beyond. This new capacity allows UV (auto‐) fluorescence excitation and imaging, for example, from some amino acids, such as tyrosine, tryptophan, and glycine. Microsc. Res. Tech. 63:175–181, 2004. © 2004 Wiley‐Liss, Inc.