title: Improved spatial resolution in fluorescence focal modulation microscopy.
abstract: We show that the focal modulation microscopy (FMM), which combines a spatial phase modulator with confocal microscopy, results in an improvement in spatial resolution. This technique was introduced to increase imaging depth into tissue and rejection of background from a thick scattering object. A theory for image formation in FMM is presented, and the effects of detecting the in-phase modulated fluorescence signal are discussed. Compared with conventional confocal microscopy, the width of the point-spread function for the in-phase fluorescence signal is improved by 16.4%. When applied to saturable fluorescence, the half-width at half-maximum is improved by 33.6%, 50.0%, and 62.9%, at demodulation frequencies 2omega, 4omega, and 8omega, respectively.
authors.affiliation: Division of Bioengineering, National University of Singapore, Singapore 117576, Singapore.
authors.forename: Wei
authors.initials: W
authors.lastname: Gong
authors.forename: Ke
authors.initials: K
authors.lastname: Si
authors.forename: Nanguang
authors.initials: N
authors.lastname: Chen
authors.forename: Colin J R
authors.initials: CJ
authors.lastname: Sheppard
mesh_terms: D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence / Q000295:instrumentation / Q000379:methods*