RESUMO
The depth of field of an optical system can be extended through a combination of point spread function (PSF) engineering and image processing. A phase mask inserted in the back aperture of the system creates a PSF that is focus-invariant over an extended depth. A digital deconvolution is then used to restore transverse resolution. The application and analysis of this technique to fluorescence microscopy is limited in the literature. In this paper we formalize a microscopy specific imaging model, and experimentally demonstrate a total variation regularized deconvolution approach. Results are compared to the Wiener filter.
RESUMO
We have demonstrated a one-dimensional array of individually addressable electrowetting tunable liquid lenses that compensate for more than one wave of phase distortion across a wavefront. We report a scheme for piston control using tunable liquid lens arrays in volume-bound cavities that alter the optical path length without affecting the wavefront curvature. Liquid lens arrays with separately tunable focus or phase control hold promise for laser communication systems and adaptive optics.
RESUMO
Extended depth of field (EDF) microscopy, achieved through computational optics, allows for real-time 3D imaging of live cell dynamics. EDF is achieved through a combination of point spread function engineering and digital image processing. A linear Wiener filter has been conventionally used to deconvolve the image, but it suffers from high frequency noise amplification and processing artifacts. A nonlinear processing scheme is proposed which extends the depth of field while minimizing background noise. The nonlinear filter is generated via a training algorithm and an iterative optimizer. Biological microscope images processed with the nonlinear filter show a significant improvement in image quality and signal-to-noise ratio over the conventional linear filter.
