Magnetically assisted freeform optics manufacturing

MOJTABA FALAHATI

In modern optical systems, active optical components are used to modify the focal length or to correct the wavefront. For instance, wavefront control and correction has been always a critical issue in adaptive astronomical telescope. Among various active optical components, adjustable mirrors and deformable lenses, which have a wide range of focal lengths and are adjustable with a real time control system, are being used to manage wavefront formation as well as data acquisition in astronomy and aerospace science. Free form lenses are another optical corrector component which are widely used to improve the optical performance through correction of static aberration. Traditional manufacturing processes of freeform optical components such as machining, molding and casting processes demand sophisticated and expensive equipment. Hence, the main goal of this work is to introduce novel low-cost and straightforward methods in free form optics manufacturing through employing magnetic power with the aid of scientific knowledge and inspiration from natural phenomena. Meeting several objectives is essential to be able to approach this goal including development of smart materials which are responsive to magnetic stimuli, design and development of various configurations of tunable magnetic fields and utilizing versatile manufacturing techniques such as additive manufacturing. Here we propose a novel technique to incorporate magnetism and interfacial force in Additive Manufacturing for tunable rapid and low-cost fabrication of optical components such as freeform lenses and mirrors. A magnetic ink is cast or printed either on a solid substrate or within an immiscible optical elastomeric environment. The profile shapes at the liquid-fluid interface are regulated using an external adjustable magnetic field. Depending on the field configuration, various freeform optical surfaces can be generated during printing process that served as tunable magnetic molds to shape the surrounding optical elastomer into freeform optical surface after curing. An apparatus was assembled to provide different magnetic force and to control the gradient of applied magnetic field on the printed droplets. A Shack-Hartmann sensor along with a numerical analysis is employed to measure the distorted wavefront by and the surface profile of the created optical components. Extracting explicit relationships between the effective parameters such as magnetic field intensity, gradient of magnetic field, magnetic susceptibility and the final optical surface profile were included in this project. This technique can be used to form lenses, lens arrays, and mirrors with different sizes, shapes and magnifications that have applications in microscopy, imaging, mapping and sensing and can create a tremendous impact in key optical companies.

Magnetically assisted freeform optics manufacturing

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