Multi-wavelength optical pickup with diffractive optical elements

A novel, to our knowledge, multi-wavelength diffractive optical pickup is presented. The pickup enables multi-focus imaging and increases the data transfer rate considerably. Parallel reading of two or more memory layers is possible. The different spots can be controlled independently. The optical pickup consists of different diffractive optical elements (DOEs). The measured 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-indicating good optical performance. The measured highest diffraction efficiencies of the realized DOEs are about 92%.