Harness Surface Morphologies for Optical Applications

Chi, Yinding

Graduate Thesis Or Dissertation

Harness Surface Morphologies for Optical Applications Public Deposited

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Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/th83kz68g

Abstract

Industrial and technology in advanced promote the development of optical system towards accessible to be high-performance, robust and easy to be tunable. Nowadays, with the development of precision manufacturing, the surface morphologies can be modified in micro scale even nano-scale which are in conformity with the requirement of the optical systems or devices. In this dissertation, several surficial morphology-based compatible and tunable optical systems have been put forward with simple dynamic actuation with the potential applications in smart window, optical diffuser and optical grating.First of all, an optimal etching time has been explored in a wrinkling-cracking based tunable smart window application. With the increased UVO etching time, the thickness of top oxidized layer enhanced a lot. As the uniaxial strain applied, the surface morphology is variable. By the comparison of different UVO etched situations, the optimal UVO treating time for smart window sample with largest tunable transmittance has be raised. Moreover, the tunable transmittance range versus UVO treating time has been developed as a consequence.Additional discover is that the micro-scaled sinusoidal surface has a scattering effect for transmitted light source when we went through the first project. Therefore, a high-performance optical diffuser with novel screwthread-like wrinkling morphology is fabricated simply and cheaply based on two arrays of micro-scaled wrinkling patterns perpendicular to each other. Such optical diffuser can scatter the light uniformly in a rectangular region, with a high haze performance. Furthermore, two-sided surface modified optical diffuser is demonstrated to enhance the optical performance with a much larger scattering region. The scattering region can also be tuned from rectangular shape to one-dimensional line via simple mechanical actuation as well.Last but not the least, a series of hierarchical surface architectures are fabricated by combining the micro-scaled wrinkling pattern with sub-micro-scaled wavy structure. Such morphology cannot only diffuse the transmitting light but also perform the tunable diffraction phenomenon for potential optical grating application. In additional, a high-performance optical diffuser (scattering angle ~60°) is exhibited via two optical grating samples stacking together.

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