Laser Scanning System for Contact Lens Writing

Abstract

Laser machining or laser writing is a technique using mirrors and transition stages to guide a laser beam through a specific path within the target material. In this thesis, we discuss a laser scanning system consisting of a 2D galvanometer scan-head and a relay system for its specific use in contact lens writing using a process known as LIRIC (laser induced refractive index change). The characterization of this 2D galvanometer scan-head was performed using a position sensing detector (PSD) and an oscilloscope. Then, the design of this relay system is discussed along with its performance and availability (using off-the-shelf components). Next, the scan-head and relay system were combined to demonstrate their functionality for LIRIC. The main goal of this thesis was to demonstrate a low cost, short lead time laser scanning system for LIRIC writing. MATLAB code was written to process the data collected by the PSD and control the galvonometer system. Zemax was used to design the relay system, and simulation data was collected with another data processing performed with MATLAB. The energy profile of the laser beam around the target material surface is shown and discussed. A prototype was built and tested, demonstrating that a spot profile close to the diffraction limit was achieved over the full scanning field. In the end, the error from alignment is discussed and suggestions for possible future work are provided.