PubMed Health⌕ Search

Biomedical subjects

Tetsuya Hamamoto

Publications and source records attributed to Tetsuya Hamamoto.

2 recordsLinked to original sources
PubMed2002

High-efficiency blazed diffractive optical elements for the violet wavelength fabricated by electron-beam lithography.

Blazed diffractive optical elements (DOEs) were studied for the violet wavelength by electron-beam lithography. By optimizing electron-beam writing parameters and electron-dose distributions, we fabricated eight kinds of grating (period A = 10-0.54 microgm) with excellent blazed structure. It has been demonstrated that the measured diffraction efficiency values agreed well with the rigorous theoretical ones. For the fine period of 0.54 microm, we confirmed a peak appearance of 75.6% (TE) experimentally. A wave aberration as small as approximately 0.01 lambda (rms) was obtained for the first-order diffracted wave from the fabricated DOEs. Blazed DOEs for the violet wavelength could be used as key devices in a high-density optical disk pickup of the next generation.

Journal Article↗
PubMed2002

Polarization-multiplexed diffractive optical elements fabricated by subwavelength structures.

Polarization-multiplexed phase-only diffractive optical elements with subwavelength structures are proposed and fabricated. The differences among the phase modulations result from the differences among the effective indices exhibited in the subwavelength structures with various filling factors and surface profiles, and the phase retardations are obtained by the relief depth of the structures. The polarization-selective property is achieved by the polarization dependence of the effective indices exhibited in the one-dimensional subwavelength structures and the polarization independence exhibited in the two-dimensional structures. Additionally, the polarization contrast of our polarization-multiplexed elements, defined as the cross talk between the two polarization incidences, is independent of the relief depth. The principle of the polarization multiplexing by use of the subwavelength structures is described, and the fabrication results for the polarization-multiplexed computer-generated holograms are demonstrated.

Journal Article↗