title: Design and fabrication of diffractive optical elements by use of gray-scale photolithography.
abstract: Diffractive optical elements (DOEs) are key components in the miniaturization of optical systems because of their planarity and extreme thinness. We demonstrate the fabrication of DOEs by use of gray-scale photolithography with a high-energy-beam sensitive glass photomask. We obtained DOE lenses with continuous phase profiles as small as 800 microm in diameter and 5.9 microm in the outermost grating pitch by selecting a suitable optical density for each height level and optimizing the process variables. Microlenses patterned with eight levels and replicated by UV embossing with the polymer master mold showed a diffraction efficiency of 81.5%, which was sufficiently high for the devices to be used as optical pickups. The effects of deviations in diffraction efficiency between the DOE height and profile design were analyzed.
authors.affiliation: School of Information Storage Engineering and Center for Information Storage Devices, Yonsei University, Sudaemoon-Ku, Seoul 120-749, Korea.
authors.forename: Jin-Seung
authors.initials: JS
authors.lastname: Sohn
authors.forename: Myung-Bok
authors.initials: MB
authors.lastname: Lee
authors.forename: Wan-Chin
authors.initials: WC
authors.lastname: Kim
authors.forename: Eun-Hyung
authors.initials: EH
authors.lastname: Cho
authors.forename: Tae-Wan
authors.initials: TW
authors.lastname: Kim
authors.forename: Chan-Young
authors.initials: CY
authors.lastname: Yoon
authors.forename: No-Cheol
authors.initials: NC
authors.lastname: Park
authors.forename: Young-Pil
authors.initials: YP
authors.lastname: Park