Light engines used in projection systems often set constraints on the design and system
application of the LED light source. In these advanced optical systems the optical extend of
the LED light source is limited due the etendue of the imager. The etendue is defined as the
product of emitting area and viewing angle. This paper shows how the LED light source is
constrained by the laws of optics and how these limits influence the light source design. To
achieve an efficient system design, the variables that must be optimized include the primary
optics, LED package design and chip technology. The LED light sources which are best
suited for these applications and requirements will also be demonstrated and discussed.