Aberration Invariant Optical/Digital Incoherent Optical Systems

By optimum combination of optical pre-processing and digital post-processing, or optical coding and digital decoding of the image information, incoherent optical systems invariant to numerous aberrations can be formed. The theory of aberration invariance can also be used with low-cost, low-precision optics to produce systems that image with the performance of high-cost, high-precision, or near diffraction-limited, spatial resolution. We can show that the central aberration to be controlled is second order, or misfocus. Systems that are invariant to misfocus are also invariant to chromatic aberration, astigmatism, thermal effects, and spherical aberration. This paper therefore describes, with experimental evidence, a focus-invariant optical system.