Optical imaging in presence of scattering.

This project represents a step towards the overarching aim of imaging scattering specimens. In such samples, the contrast and sharpness of optical images is severely reduced since a large fraction of the light is scattered and manifests itself as a uniform background. In optical projection tomography it has been demonstrated previously that the scattered background can be separated from the image-forming light by capturing only the first arriving photons with ingenious ultrafast gated optical set-ups [1-3]. The goal of this project is to investigate if the same can be achieved for optical microscopy using a gated camera and a low-cost laser.

In addition, this project aims to be to quantitatively stating how much the image quality can be improved using a time gated optical set-up and to enhance a 3D reconstruction of a biological tissue.

In order to accomplish the objectives, several programs and/or experiments which facilitates the everyday work in the lab were developed: like a way to orchestrate a camera, a laser, and an oscilloscope; testing two super-resolution techniques; and finding way to record data from an oscilloscope.

In short, the aforementioned set-ups are based on the same fact: if light is passed through a sample and only the first portion of the photons coming out of it are integrated to form an image, the negative effects of light scattering are reduced. To simplify the notation, I shall only refer to this idea as ‘time -gated’. This idea will be explained in detail, after the concepts of light microscopy and scattering are first introduced in this thesis.

After it, the equipment that was used in order to develop the time-gated set-up will be elucidated. These two elements makes up the introduction, the first of the five blocks onto which the text is structured. The introductory block contains all the information that was available beforehand, and after reading it, the reader should be able understand the expectations and motivations of the time-gated system before it was tested.