ABSTRACT
The Simultaneous Multiple Surface (SMS) design method allows to design two optical surfaces simultaneously that couple two input wavefronts onto two output wavefronts. This chapter considers the limit case, in which the etendue of the light captured by an optic goes to zero. When that happens, the emitter and receiver sizes become infinitesimal. The chapter examines infinitesimal etendue optics with circular symmetry. Aplanatic optics may be designed using a simple method in which we proceed in very small steps, building both optical surfaces simultaneously. Fresnel Optics is possible to design infinitesimal etendue optics with Fresnel optical surfaces. Infinitesimal etendue designs may also be used as a basis design to be further improved by aplying the SMS design method.
