High-speed focal modulation microscopy using acousto-optical modulators.

Focal Modulation Microscopy (FMM) is a single-photon excitation fluorescence microscopy technique which effectively rejects the out-of-focus fluorescence background that arises when imaging deep inside biological tissues. Here, we report on the implementation of FMM in which laser intensity modulation at the focal plane is achieved using acousto-optic modulators (AOM). The modulation speed is greatly enhanced to the MHz range and thus enables real-time image acquisition.

Focal modulation microscopy: a theoretical study.

Focal modulation microscopy is an emerging fluorescence microscopy technique for in vivo imaging of thick biological tissues. Here, we present a theoretical study to assess its performance. The scalar diffraction theory is combined with Monte Carlo simulation to evaluate the signal-to-background ratio at various depths.

Focal modulation microscopy.

We report a novel light microscopy method for high resolution molecular imaging of thick biological tissues with one photon excited fluorescence. Effective optical sectioning and diffraction limited spatial resolution are achieved when imaging deep inside a multiple-scattering medium by the use of focal modulation, a technique for suppressing the background fluorescence signal excited by scattered light. Our method has been validated with animal tissue and an imaging depth around 600 microns has been demonstrated.

Simple spatial phase modulator for focal modulation microscopy.

Focal modulation microscopy (FMM) is an emerging microscopy technique for fluorescence imaging of thick biological tissue in vivo. A spatial phase modulator is a critical component whose characteristics have a significant impact on the performance of a FMM system. We have designed a simple spatial phase modulator based on a tilting glass plate that provides superb modulation stability.

Binary-phase spatial filter for real-time swept-source optical coherence microscopy.

We report a novel scheme to optimize the focusing condition for real-time, swept-source optical coherence microscopy. The axial and lateral behaviors of four-zone binary-phase spatial filters are presented numerically. A nearly constant axial intensity distribution along an extended depth of focus of 1.