Patent ID: 7596070

Claim:
Appliance for reading from and/or writing to an optical recording medium, the appliance having a first laser diode for producing a first scanning beam at a first wavelength and having a second laser diode for producing a second scanning beam at a second wavelength, the scanning beams scanning an information layer on the optical recording medium and falling on a single photodetector in order to produce an information signal, with a beam combination element being arranged at a point on the optical axis for combining the scanning beams such that both scanning beams run along the optical axis towards the optical recording medium in such way as if they originated in a single virtual light source, wherein the beam combination element is a diffraction grating which is optimized for both wavelengths to a diffraction order higher than zero, and wherein the virtual light source does not coincide with either of the first laser diode and the second laser diode.