Development of a next-generation imager/sounder requires advances in optics, focal planes, mechanical systems and
electronics. Technologies exist today to meet the requirements of next generation imager/sounders, but they allow a
wide range of configurations. On one hand, the instrument aperture can be as small as diffraction will allow, but this
will require a very large field of view of the optical system and a large focal plane assembly. On the other hand, the
aperture can be large, minimizing the field of view and number of detectors. In this paper, we examine the relationship
between aperture size, field of view of the optical system and focal plane assembly size and the number of detector
elements needed to meet the requirements of a next generation imager/sounder system.