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1993
Conference Paper
Titel
Thin film deposition: An alternative technique for the fabrication of binary optics with high efficiency
Abstract
Binary optics were fabricated by an ion-beam sputter deposition technique on different substrate materials for the wavelengths of 1.52 mu m and 0.63 mu m respectively. The blazed profile of thin film dielectric gratings was approximated by a 2 and 4 phase level profile and the kinoform profile in each zone of the Fresnel zone lenses was approximated by a 2,4,8,16 and a 32 level profile. Such stepped profiles were realized with several masks, written with electron-beam and with photolithographic technology. The microlenses were coated with an anti-reflection coating. The reflection of these lenses was optimized on the basis of an angular spectrum approach. A minimum reflectivity as low as 1*10-4 was realized using in situ controlled multilayers of TiO2 and SiO2. The measurements reveal, that the spot-sizes of the fabricated microlenses are close to the diffraction limited values. The highest measured diffraction efficiencies for the 32 level structures are 97%. The effects of fabrication errors, such as level heights, alignment and linewidths errors, on the diffraction efficiency of Fresnel zone lenses were discussed.
Language
English
Tags
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computer-generated holography
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electron beam lithography
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holographic gratings
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holographic optical elements
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lenses
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optical workshop techniques
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optical zone plates
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photolithography
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sputter deposition
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ion beam sputter deposition
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thin film deposition
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electron beam writing
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alignment errors
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fabrication
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binary optics
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high efficiency
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blazed profile
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thin film dielectric gratings
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kinoform profile
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fresnel zone lenses
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stepped profiles
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photolithographic technology
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anti-reflection coating
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angular spectrum approach
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minimum reflectivity
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in situ controlled multilayers
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spot-sizes
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fabrication errors
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level heights
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linewidths errors
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1.52 micron
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0.63 micron
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tio2-sio2 multilayers