Wide-field fluorescence tomography with composited epi-illumination of multi-frequency sinusoidal patterns.

We present a spatial-frequency domain (SFD) fluorescence tomography (FT) for acquiring three-dimensional fluorophore distribution in turbid media. The approach uses a composited epi-illumination of multi-frequency sinusoidal patterns on a sample of semi-infinite geometry and demodulates the measured data with a generalized phase shifting scheme to calculate the modulation transfer function (MTF) at each frequency. This method results in a significantly reduced number of the optical field measurements, as compared to those with separate illumination of single-frequency sinusoidal patterns, and, thereby, achieves a fast data acquisition that is desired for a dynamic imaging application. Fluorescence yield images are recovered with the normalized Born formulated inversion of the diffusion model by simultaneously using the multi-frequency MTFs. Simulative and experimental reconstructions are performed in comparison with the single-frequency scheme to validate the proposed algorithm. The results suggest that adoption of the multi-frequency strategy to the SFD-FT can substantially improve the reconstruction quality, as well as its imaging resolution and quantitative accuracy.