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Descripción
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| The problem of coupling an object to be imaged perfectly through an optic is an ancient one and has evolved through the ages, from Newton¿s paraxial formulation to the very recent multi-parametric optimization techniques. This evolution has been constantly aided by developments in fabrication techniques and driven by demands posed by other fields particularly from those arising out of consumer needs and not just strictly research oriented. Initial solutions to these imaging problems were elegant and matched to the needs of specific fields at that point in time. But, with increasing demands to make the resulting systems more and more compact with form factors resembling to those of commonly used consumer devices, solving these problems with trivial solutions no longer seemed to be an option. Advancements in manufacturing techniques first led to the use of non-aspherical or aspherical surface shapes in solving common imaging problems. For example, Schwarzschild analytically proved in 1906 that two aspherical shapes are required to solve the problem of aplanatism. This paved way for more systems employing these aspherical shapes to come up with elegant solutions. With increasing complexity in the system demands and other imaging constraints, additional degree of freedoms were needed by the designer. This could in turn be solved by using more number of surfaces leading to bulkier solutions. Thankfully, with advancements in injection moulding techniques, the use of freeform surfaces seem to be the solution. Freeform surfaces were first made practical with their introduction in solving non-imaging problems where the design constraints are not so strict when compared to their imaging counterpart but was more of a mass transport problem. The resulting freeform systems were compact and thus demonstrated the significance of freeform surfaces in miniaturising optical systems. This also led to many direct design techniques to be formulated for the design of freeform optical surfaces. The next logical step in the optics community was to adapt this introduction of freeform surfaces into imaging problems. The bottleneck in this introduction was the unavailability of systems to be used as a starting point. Thus came the heavy reliance on computer-aided optimization techniques. This led to many investigations into the representations of freeform surfaces shapes which could have direct consequence in fabrication constraints to making the resultant systems more practically realisable. One such direct design method was the Simultaneous Multiple Surface method (SMS), which was initially introduced as a Non-Imaging direct design technique for the design of freeform optical surfaces. This was later extended to imaging applications where it immensely helped the designers in arriving at a good starting point for further optimisation. | |
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Tipo de Tesis
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Doctoral |
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Aprobado |
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