Miniaturized imaging systems

Integrated digital micro-cameras are an important feature for next generations of customer products like mobile phones and computers. Key specifications of such micro-cameras are resolution, sensitivity, power consumption, manufacturing and packaging costs-as well as the overall size. Digital micro-cameras used today 3 are rarely smaller than 5 X 5 X 5 mm(3). The recent improvements of CMOS image sensors would allow a further miniaturization. However, due to diffraction effects a miniaturization of the optics would drastically reduce resolution and image finesse. How to overcome these limitations of optics? A fascinating approach is to look how nature has successfully solved similar problems in the case of very small creatures. We will explain basics properties of miniaturized imaging systems and show how some of nature's ideas might help to further miniaturize micro-cameras. We will report on microfabrication of refractive microlens arrays, wafer-level packaging and present examples of array imaging systems used for micro-cameras and photolithography applications. (C) 2003 Elsevier Science B.V. All rights reserved.