Motion Reconstruction for Optical Tomography of Trapped Objects

Peter Elbau, Monika Ritsch-Marte, Otmar Scherzer and Denise Schmutz

Optical and acoustical trapping has been established as a tool for holding and moving microscopic particles suspended in a liquid in a contact-free and non-invasive manner. Opposed to standard microscopic imaging where the probe is fixated, this technique allows imaging in a more natural environment. This paper provides a method for estimating the movement of a transparent particle which is maneuvered by tweezers (assuming that the inner structure of the probe is not subject to local movements) by making use of the assumption of a smooth movement in time. The mathematical formulation of the motion estimation leads to an infinitesimal version of the common line technique used in cryogenic electron microscopy single particle imaging to estimate the orientations of the particles in the probe.

DOI

Dual filtered backprojection for micro-rotation confocal microscopy

Danai Laksameethanasan, Sami S Brandt, Olivier Renaud and Spencer L Shorte

Micro-rotation confocal microscopy is a novel optical imaging technique which employs dielectric fields to trap and rotate individual cells to facilitate 3D fluorescence imaging using a confocal microscope. In contrast to computed tomography (CT) where an image can be modelled as parallel projection of an object, the ideal confocal image is recorded as a central slice of the object corresponding to the focal plane. In CT, the projection images and the 3D object are related by the Fourier slice theorem which states that the Fourier transform of a CT image is equal to the central slice of the Fourier transform of the 3D object. In the micro-rotation application, we have a dual form of this setting, i.e. the Fourier transform of the confocal image equals the parallel projection of the Fourier transform of the 3D object. Based on the observed duality, we present here the dual of the classical filtered back projection (FBP) algorithm and apply it in micro-rotation confocal imaging. Our experiments on real data demonstrate that the proposed method is a fast and reliable algorithm for the micro-rotation application, as FBP is for CT application.

DOI