Transition between diffractive and refractive micro-optical components.

Optical components are usually classified into diffractive and refractive elements. In this classification, refractive components are defined as elements that are sufficiently described by geometrical optics. For micro-optics this distinction is very often not applicable. Our goal is to understand which parameters control the transition from elements that can be interpreted as refractive to those elements that are called diffractive. We investigate the linear blazed grating and focus on the wavelength dependence of its properties. For this we adopt an approach well known from the theory of echelette gratings. Our results can easily be transferred to other blazed components, such as Fresnel lenses.