However today’s fabrication technologies allow the precise manufacturing and employment of a variety of complex surface forms:
- Diffractive optical surfaces
- Non-spherical surfaces, such as rotational-symmetric aspheres
- Non-rotational symmetric surfaces, so-called free-form surfaces
- Facetted optical surfaces, e.g. Fresnel lenses in illumination design
- TIR reflectors for collimation of LED
The optical design of systems containing such surfaces requires special tools and methods in order to employ the additional degrees of freedom and also in order to evaluate the aberrations and other relevant effects introduced by such surface forms.