Ray-based methods for simulating aberrations and cascaded diffraction in imaging systems

Abstract

To predict the quality of an optical system we need to simulate the effects of aberrations and diffraction. Aberrations can be calculated by tracing rays from a source point through a digital model of the system and evaluating the spot size of these rays on the detector. For a system without aberrations, the rays will intersect at a single point. However, the real spot size will be larger due to diffraction. This increase in size is due to the wave nature of light, which cannot be fully captured by regular ray-tracing methods. This thesis presents two ray-tracing methods that can simulate wave-optical effects by initiating secondary rays at diffracting surfaces. The first method uses rays to transport the Wigner distribution function. The second method combines the Huygens-Fresnel principle with ray tracing. The methods, particularly the latter, can be used to assess the quality of an optical system, especially when the system has multiple diffracting surfaces.