New infrared optical systems using diffractive optics

摘要

A method for computing the polychromatic MTF of hybrid refractive - diffractive elements is described taking into consideration the effects of not only the primary diffraction order but also the effects of additional parasitic diffraction orders. The results of this approach are compared with the more conventional single order calculation and with actual measured performance. For certain markets and applications the cost of infrared lenses are critical in order to achieve customer expectations. Two possible methods of realising this requirement are the use of moulded optics or the use of multiple kinoform optics with no refractive power. Examples of such lenses are given along with discussion of the merits and limitations that each approach entails.