Preparation Of Artificial Microlenses And Their Optical Properties

In geometrical optics, a lens-based optical microscope can not resolve features of an object small than ?/2 (?, wavelength) in the far-field due to Abbe's diffraction limit. Recently, it has been found that microscale and nanoscale lenses can magnify and resolve features beyond the diffraction limit. In this thesis, by researching on the imaging system of semi-immersed silica spherical lens, we fabricate a kind of SU-8 resist lens which has the ability of super-resolution. Based on field-assisted dissolution, we fabricate gradient porous alumina films with different porous distributions and effective refractive index.Researching on the imaging system of semi-immersed silica spherical lens we find that when a microsphere lens is semi-immersed in the SU-8 resist, both the microsphere and the SU-8 resist can work as a lens. The microsphere lens forms the images from the small-k Fourier components of an object, and this image formation does not depend on the immersion of the SU-8 resist. The SU-8 resist can work as a lens and form the images from the large-k Fourier components. When the distance d between the focal spot of the SU-8 lens and the object is close, the clear large-k Fourier components image can be observed even without the microsphere.Based on field-assisted dissolution theory, we fabricate gradient porous alumina films lens with different distributions by asymmetrical anodization of Al foils. When an insulting baffle is inserted close to the anode, depending on the shape of the baffle, the current density distribution on the Al foils can be varied. Based on two different shape of baffle, two gradient porous alumina films with different pore distributions can be fabricated. One has the largest pore size and a minimum neff in the center and the smallest pore size and a maximum n-ff in the edge, while the other has the smallest pore size and a maximum neff in the center and the largest pore size and a minimum neff in the edge. This approach of asymmetrical anodization of Al foil provides us with a low-cost method to fabricate large-size gradient porous structures with different pore distributions and effective refractive index.