Microlenses have been in existence for a long time. Many early lenses, including those made by Hooke and Leeuwenhoek in the 17th century, were small. A number of the applications for arrays of microlenses are also well established. Lippmann's work on integral photography at the turn of the century needed lens arrays and stimulated an interest that is very much alive today. Lens arrays played an important part in high-speed photography and various schemes have attempted to take advantage of the compact imaging properties of combinations of lens arrays. The fact that many of these ingenious schemes have not been developed fully is to a large degree due to the absence of lens arrays of a suitable quality and cost.