Multi-wavelength optical pickup with diffractive optical elements

A novel, to our knowledge, multi-wavelength diffractive optical pickup is p resented. The pickup enables multi-focus imaging and increases the data tra nsfer rate considerably. Parallel reading of two or more memory layers is p ossible. The different spots can be controlled independently. The optical p ickup consists of different diffractive optical elements (DOEs). The measur ed full-width at half-maximum (FWHM) spot intensity for the DOE-pickup is 0 .76 mu m-close to the diffraction limited predicted value of 0.71 mu m-indi cating good optical performance. The measured highest diffraction efficienc ies of the realized DOEs are about 92%.