Esta tese descreve métodos interativos para estimar e compensar erros de refração (NETRA) e opacidades ópticas (CATRA) em sistemas de imageamento usando telas de campos de luz programáveis, de alta resolução e alto contraste. Os novos métodos para oftalmologia computacional descritos aqui podem avaliar câmeras e olhos se o usuário do sistema estiver consciente do modelo de interação. A solução combina elementos ópticos baratos, interfaces interativas e reconstrução computacional. Uma tela de campos de luz, posicionada perto do olho, cria objetos virtuais em profundidades pré-definidas através de várias seções do olho. Via esta plataforma, cria-se uma nova gama de aplicações interativas que é extremamente sensível a aberrações ópticas. A capacidade de focar em um objeto virtual, alinhar padrões exibidos na tela e detectar suas variações de forma e brilho permite ao sistema estimar a função de propagação de ponto de luz para o olho e a acomodação da lente. Enquanto os sistemas convencionais requerem formação especializada, dispositivos caros, procedimentos de segurança sensíveis e normalmente não são móveis, esta tese simplifica o mecanismo, colocando o paciente no centro do teste. Ao final, a resposta do usuário calcula a condição de refração em termos de poderes esférico e cilíndrico, o eixo de astigmatismo, o poder de acomodação da lente e mapas para a opacidade, atenuação, contraste e função de espalhamento de um ponto de luz. O objetivo é permitir que o público em geral opere um sistema de iluminação portátil e obtenha uma compreensão de suas próprias condições visuais. Esta tese apresenta projetos ópticos para software e hardware para oftalmologia computacional. Avaliações com usuários e com câmeras com lentes modificadas são realizadas. Os dados compilados são usados para reconstruir visão afetada do indivíduo, oferecendo uma nova abordagem para capturar informações para o rastreio, diagnóstico e análises clínicas de anomalias visuais. / This thesis proposes light-field pre-warping methods for measuring and compensating for optical aberrations in focal imaging systems. Interactive methods estimate refractive conditions (NETRA) and model lens opacities (CATRA) of interaction-aware eyes and cameras using cost-efficient hardware apps for high-resolution screens. Tailored displays use stereo-viewing hardware to compensate for the measured visual aberrations and display in-focus information that avoids the need of corrective eyeglasses. A light-field display, positioned very close to the eye, creates virtual objects in a wide range of predefined depths through different sectors of the eye’s aperture. This platform creates a new range of interactivity that is extremely sensitive to spatially-distributed optical aberrations. The ability to focus on virtual objects, interactively align displayed patterns, and detect variations in shape and brightness allows the estimation of the eye’s point spread function and its lens’ accommodation range. While conventional systems require specialized training, costly devices, strict security procedures, and are usually not mobile, this thesis simplifies the mechanism by putting the human subject in the loop. Captured data is transformed into refractive conditions in terms of spherical and cylindrical powers, axis of astigmatism, focal range and aperture maps for opacity, attenuation, contrast and sub-aperture point-spread functions. These optical widgets carefully designed to interactive interfaces plus computational analysis and reconstruction establish the field of computational ophthalmology. The overall goal is to allow a general audience to operate portable light-field displays to gain a meaningful understanding of their own visual conditions. Ubiquitous, updated, and accurate diagnostic records can make private and public displays show information in a resolution that goes beyond the viewer’s visual acuity. The new display technology is able to compensate for refractive errors and avoid light-scattering paths. Tailored Displays free the viewer from needing wearable optical corrections when looking at it, expanding the notion of glasses-free multi-focus displays to add individual variabilities. This thesis includes proof-of-concept designs for ophthalmatic devices and tailored displays. User evaluations and validations with modified camera optics are performed. Capturing the daily variabilities of an individual’s sensory system is expected to unleash a new era of high-quality tailored consumer devices.

Human vision is one of the most important senses, but recently near-sightedness is growing among the population. To investigate this progression, the pheripery of the eye is being studied. Therefore, new methods are developed to examine peripheral vision. This study compares two such instruments: A newly developed for commercial use (Double-Pass) is tested against an established lab setup (Hartmann-Shack Dual-Angle). Measurements of mean focus and astigmatism were taken both foveally and peripherally on 15 people, to examine if the two instruments give the same values. The comparison between the systems shows that a correlation exists, but the data handling algorithm of the Double-Pass system can be fine-tuned to obtain a more consistent result. In addition to this, a university course in optics is investigated in order to develop a homework assignment to make the students engage with the course material and get more students to pass the course. The choice of task is based on the most challenging concepts of previous exams, focusing on peer assessment and formative feedback. From this, a material was developed with a typical exam task combined with a proposed solution that the students used to give feedback to each other. The material was test-run with two former students and updated based on their comments. The assignment was appreciated, but seeing a peer’s assignment can be stressful if the students themselves feel unsure about the material. This will hopefully be avoided when given during the course, where the students can discuss with each other. The upcoming course round will test the assignment with a whole class. / Synen är ett av människans viktigaste sinnen, men den senaste tiden har närsynthet blivit allt vanligare. För att undersöka den ökade förekomsten av myopi utvecklas nya metoder för att undersöka synen i periferin, då denna verkar ge ledtrådar om uppkomsten av närsynthet. I denna studie görs en jämförelse mellan två sådana instrument, ett nyutvecklat mot kommersiellt bruk (Double-Pass) testas mot en etablerad labuppställning (Hartmann-Shack Dual-Angle). Mätningar av medelfokus och astigmatism gjordes både fovealt och periferiellt på 15 personer för att se om instrumenten ger samma resultat. Jämförelsen mellan systemen visar att en korrelation existerar, men att datahanteringsalgoritmen för Double-Pass instrumentet kan finjusteras för att få ett mer överensstämmande resultat. Utöver detta undersöks en universitetskurs i optik för att utveckla en hemuppgift som ska hjälpa studenterna att arbeta med kursmaterialet och hjälpa fler att klara kursen. Valet av uppgift grundar sig i vilka koncept som varit utmanande i tidigare tentor och fokus ligger på kamratbedömning och formativ återkoppling. Från detta utvecklades ett material med en tentatypisk uppgift kombinerat med ett lösningsförslag som studenterna använder för att ge återkoppling till varandra. Materialet testkördes med två tidigare studenter och uppdaterades efter deras kommentarer. Uppgiften uppskattades, men att se en kamrats uppgift kan vara stressande om studenterna själva känner sig osäkra på materialet. Detta undviks förhoppningsvis när uppgiften ges under en kurs då studenterna har möjlighet att diskutera med varandra. Uppgiften kommer testköras i helklass under kommande kursomgång.

Η παρούσα διπλωματική εργασία πραγματεύεται την ανάπτυξη ενός αποδοτικού συστήματος ελέγχου που θα επιτυγχάνει τον ακριβή έλεγχο της θέσης ενός λαπαροσκοπικού ρομποτικού εργαλείου που χρησιμοποιεί ‘έξυπνα μορφομνήμονα κράματα’ ως τένοντες-επενεργητές. Το γεγονός ότι το εργαλείο που χρησιμοποιείται είναι με πλεονάζοντες βαθμούς ελευθερίας, καθιστά ιδιαίτερα δύσκολο πρόβλημα την επίλυση της αντίστροφης κινηματικής. Στόχος της παρούσας εργασίας είναι, μέσω τεχνικών υπολογιστικής όρασης, να επιλυθεί προσεγγιστικά η αντίστροφη κινηματική ανάλυση της θέσης των αρθρώσεων του ρομποτικού εργαλείου. Ο προτεινόμενος νόμος ελέγχου χρησιμοποιεί την αριθμητική επίλυση των γωνιών των αρθρώσεων από την αντίστροφη κινηματική για την επιτυχή παρακολούθηση της επιθυμητής τροχιάς του ρομποτικού εργαλείου. / This thesis deals with the development of a robust control system responsible for the precise position control of an innovative, SMA-based tendon-driven endoscopic robotic surgical tool. Given the hyper-redundant features of this robotic tool, the solution to the inverse kinematics problem is quite complicated. Henceforth, the main objective of this thesis is the numerical solution of the joints' positions using image processing techniques. The proposed control law utilizes this information for trajectory tracking purposes of the tool's end-effector.