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Adaptative optics loop for pupil tracking

Roberto Russo

Adaptative optics loop for pupil tracking.

Rel. Renato Orta, Paolo Laporta. Politecnico di Torino, Corso di laurea magistrale in Ingegneria Elettronica (Electronic Engineering), 2018

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Adaptative optics loop for pupil trackingNowadays, the field of ophthalmology is permeated by a surging research to the purpose of retinal imaging with cellular resolution. The incredible rise in this research is fundamentally moved by the augmented capability to produce early diagnoses of invalidating diseases affecting the human eye. The realization of a commercial device that allows to perform the imaging of the different cells belonging to the several retina's layers is yet to come. The main reason of this lack is principally related to the complexity of the realization of such a system. One of the main element of complexity is due to the presence of eye aberrations, which introduce a phase distortion and thus implies a reduction of the achievable resolution. The eradication of this issue has old roots in a field far from ophthalmology. Indeed, a similar problem exists with the disturbances introduced by Newton's “Air's Tremors” in astronomy. The first solution proposed, which is still today one of the most applied, was in fact developed for this field. It consists in the reproduction of the Optical Transfer Function of the disturbances in order to eliminate their contribute. To perform this method generally included in the domain of Adaptive Optics, it is required to use a device that is able to perform the measurements of the disturbances, a wave-front sensor, and a device that is able to produce the correspondent countermeasures, a deformable mirror. The aim of this work will be handling the feedback loop created by the work of those two devices in order to perform the eyes' aberrations corrections, in the objective of replacing the current used proprietary software for a future perspective of integration of the Adaptive Optics Loop with all the others subsystems that handle the image acquisition. To fulfil this goal, proprietary functions provided by Imagine OpticsTM will be used to interface the two main component of the loop: the deformable mirror and the wave-front sensor, which are provided by the same producer. For the realization of this goal, several aspects have to be taken into account, from the specifications and limitations introduced by the particular devices used that have consequences on the actuation phase, to the issues related to the subject to analyse, the human eye. Indeed, the human eye is not a static object and as a consequence, countermeasures related to its movements have to be taken to improve as much as possible the acquisition procedure. In this perspective, particular attention have to be focused on the blinking phenomena. After the development of the code, several tests and validation procedures were performed with the aim of clarify the results and the limitations of the provided solution also comparing it with the performances of the existent proprietary software to replace. The developed loop resulted to solve the main issues, from the blinking handling to the proprietary software “crash” condition related to the actuation voltages increase and to the exposure setting bottleneck removal. These also providing a comparable optical behaviour.

Relators: Renato Orta, Paolo Laporta
Academic year: 2017/18
Publication type: Electronic
Number of Pages: 110
Corso di laurea: Corso di laurea magistrale in Ingegneria Elettronica (Electronic Engineering)
Classe di laurea: New organization > Master science > LM-29 - ELECTRONIC ENGINEERING
URI: http://webthesis.biblio.polito.it/id/eprint/8242
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