Diffractive optical elements: past, present and future

Diffractive optical elements are rapidly finding their way into many practical optical systems, and this has given rise to a spurt of research and developmental activities in this area. In this paper, the history of these elements is first traced to get a perspective on their current state- of- the- art. The important features of this rapidly advancing field are then identified so that one does not get lost and can easily stick to one's guns while browsing through the maze of publications. finally a glimpse of the fascinating future trends is given to stimulate further interest in the area.