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1994
Journal Article
Title
Diffractive microlenses with antireflection coatings fabricated by thin film deposition
Abstract
Two-dimensional arrays of Fresnel zone microlenses were fabricated and coated with antireflection layers by an ion beam sputter deposition technique. The reflection of these lenses was analyzed on the basis of an angular spectrum approach for different substrate materials. A minimum reflectivity as low as 2*10-4 was realized by means of in situ controlled multilayers of TiO2 and SiO2. The lenses have a circular aperture of 2 mm and different focal lengths for the wavelengths of 1.52 and 0.63 mu m, respectively. The kinoform profile in each zone of the Fresnel zone lenses was approximated by an eight-level profile. Such stepped profiles were realized with several masks written with an electron beam and transferred by photolithographic technology. The measurements reveal that the spot sizes of the fabricated microlenses are close to the diffraction-limited values.
Keyword(s)
antireflection coatings
computer-generated holography
electron beam lithography
holographic optical elements
lenses
masks
optical workshop techniques
photolithography
reflectivity
sputter deposition
computer-generated holograms
diffractive microlenses
2d arrays
electron beam writing
thin film deposition
fresnel zone microlenses
ion beam sputter deposition
angular spectrum approach
minimum reflectivity
in situ controlled multilayers
kinoform profile
eight-level profile
stepped profiles
photolithographic technology
diffraction-limited values
1.52 micron
0.63 micron
tio2-sio2 multilayers