EFFECT OF FABRICATION ERRORS ON MULTILEVEL FRESNEL ZONE LENSES

Blazed Fresnel zone lenses for the 1.5-mum wavelength were fabricated in quartz glass by means of microstructuring technology. The blazed pr ofile in each zone of the lenses was approximated by two, four, and ei ght discrete levels. The effects of fabrication errors, such as depth and alignment errors, on the diffraction efficiency of the different F resnel zone lenses were investigated. Further the location and intensi ty of the parasitic foci appearing due to the discrete level approxima tion are calculated. Theoretical results along with experimental measu rements are presented.