M.Sc Thesis | |

M.Sc Student | Hatzvi Meir |
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Subject | Three Dimensional Optical Transfer of Rotating Beams |

Department | Department of Electrical and Computer Engineering |

Supervisor | PROF. Yoav Schechner |

Full Thesis text |

Much work has been done in computational imaging to increase the depth of field, i.e., decrease the depth sensitivity of a system. Towards this, aperture functions were designed. We look at the opposite problem: we wish to maximize the depth-sensing resolution of the system, in order to better discriminate object points having different axial coordinates. The object domain is volumetric, where objects can lie behind each other. Maximizing the depth resolution is achieved by designing three dimensional (3D) point spread functions (PSFs) that change fastest during axial propagation. The 3D PSF is determined by a diffractive aperture function.

Rotating beams as PSFs have become popular in 3D microscopy and in depth estimation, thanks to their significant change during axial propagation. This amount of change can be measured by the angle of rotation.

In this thesis, we analyze the 3D optical transfer function (OTF) of an imaging system for a general aperture function. In particular, we focus on Gauss Laguerre modes (GL) and rotating beams. We show two different algorithms to calculate the 3D OTF, where each algorithm has its own advantages. We show analytical consistency between these algorithms for the special case of a Gaussian beam, and show consistent simulations for several GL modes and rotating beams.

Then, we suggest a criterion for depth resolution, by defining a cutoff frequency in the axial spatial frequency. Using this criterion, we analyze some standard beams and some rotating beams. Then, by manipulating GL coefficients, we numerically maximize the transfer, yielding a higher support along the axial spatial frequency.