Photoresist reflow method of microlens production: modeling and fabrication techniques

Abstract

The development of an inexpensive, reproducible and highly accurate method for the production of microlens arrays is of vital importance to the next generation of optics based technologies. One of the fabrication techniques used to produce microlens arrays, the photoresist reflow method, will be discussed. When lenses are produced using this method they are often found to have aspherical profiles. Aspheric lenses have applications that include beam shaping, power transfer and fiber coupling. The fabrication of these aspheric lenses currently requires an iterative experimental process as there is currently no model that accurately predicts the lens profiles from first principles. One model that shows promise is the Curvature Correction Model, CCM. In this paper we propose a novel mathematical method to solve approximately the CCM, thus enabling predictions of the expected microlens profile. This technique can then be used to determine a starting range for the fabrication parameters to design a specific lens. This novel method also provides a framework within which a number of polynomial models, that have been presented in the literature, can be examined in the context of the CCM.