Laser micromachining of high-density optical structures on large substrates

A new laser mask projection technique, Synchronised Image Scanning (SIS), has been developed for the efficient fabrication of dense arrays of repeating microstructures on large area substrates. This paper details the technique and provides specific examples of the type of structures that can be produced. SIS is a laser micro-machining technique where the information for the ablation of a specific 3D feature is stored as a linear array on a chrome-on-quartz mask. The feature is then written by synchronised motion and laser firing, such that the firing frequency of the laser corresponds to the spatial pitch of the features. This requires highly accurate laser triggering with low-jitter signals, and accurate stages with high resolution encoders. An add-in for CAD software has been developed to generate the mask pattern efficiently and error-free, using the 3D designs. SIS allows for major improvements in the accuracy and speed with which 3D patterns can be created over large areas by laser ablation. Feature sizes down to a few microns can be produced with excellent surface quality. Large areas of microstructures have wide ranging applications in many areas. One example is the machining of large polymer master panels for electroforming to produce moulds for replication of display enhancement films

Advanced laser micro-structuring of super-large-area optical films

A novel laser micro-machining technique to produce high density micro-structures called Synchronized Image Scanning (SIS) was introduced a couple of years ago. Over this period of time, the technique was refined in a major effort to meet the needs of various industries. There is an increasing demand for micro-structuring of large and super large area optical films, e.g. for Rear Projection TV, anti counterfeit packaging material and 3D displays. Especially in the display industry, where the screens are ever increasing in size, established micro-structuring methods like e-beam milling, diamond turning or the reflow technique struggle to keep up with the development. This paper explains how it is possible to direct laser etch hundreds of millions of lenses into a 2 m x 1.5 m substrate. It looks at the advances made in SIS in recent years regarding seam reduction, overall accuracy and precision when structuring super large area optical films, and it presents the tools and subsystems needed to generate the features in those films. Furthermore, the potential of this exciting laser micro-machining technique for rapid prototyping for all sorts of optical and non-optical structures is mapped out