<title>Microjet printing of anamorphic microlens arrays</title>

Abstract

The microjet printing method of micro-optical element fabrication is being used to make arrays of high-performance hemi-elliptical and hemi-cylindrical microlenses for potential use in applications such as collimation of edge-emitting diode laser array beams. The printing method enables both the fabrication of very fast (e.g., f/0.75) microlenses and the potential for reducing costs and increasing flexibility in micro-optics manufacture. The process for fabricating anamorphic microlenses, including those of square or rectangular shape, involves the dispensing and placing of precisely sized microdroplets of optical material onto optical substrates, and then controlling their coalescence and solidification. By varying the number, diameter and spacing of adjacent microdroplets of optical materials deposited at elevated temperatures onto heated substrate, both the dimensional aspect ratios and the ratio of `fast'- to-`slow' focal lengths of a printed hemi-elliptical microlens may be varied over a very wide range. Arrays of hemi-elliptical and hemi-cylindrical microlenses on the order of 100 - 300 micrometers in width and 150 micrometers to 20 mm long, with focal length ratios (fast/slow) from 1 (circular) to 0 (cylindrical), have been printed. A model for predicting printed hemi-elliptical microlens focal lengths from printed lenslet geometry is illustrated, along with an interferometric method of detecting lenslet defects and aberrations.