Imaging with an Ultrashort Pulsed Beam

Abstract

Ultrashort pulsed laser illumination has become more and more important in modern optical microscopy. Time-resolved optical microscopy and nonlinear optical microscopy are two examples of using ultrashort pulsed laser beams in optical microscopy, which are playing a crucial role in biological studies. Due to the effect of material dispersion of a lens, diffraction patterns by a lens or an aperture, which are the topics of this chapter, may be changed in particular when the pulse width is in the range of sub-picoseconds or shorter. The method for generating ultrashort pulsed beams, called mode-locking, is first briefly described in Section 5.1. Temporal and spectral behaviours of an ultrashort pulsed beam are discussed in Section 5.2. Diffraction of an ultrashort pulsed beam by a circular aperture, an opaque disk, and a serrated aperture are given in Section 5.3. In Section 5.4, the transmittance of a lens under ultrashort pulsed beam illumination is derived. With this expression, the light distribution in a focal region of a lens is discussed in Section 5.5. Finally, the coherent transfer function and the optical transfer function for a lens are presented in Section 5.6.KeywordsPoint Spread FunctionGroup Velocity DispersionPulse BeamChromatic AberrationCircular ApertureThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.