| 摘要 |
PURPOSE:To accurately position the light beams of wavelengths corresponding to each recording layer with a lamination type wavelength multiplex light recording device, by securing the coincidence of the interval of optical record layers and the deviation due to the wavelength difference of focus positions based on the color aberration of a convergent optical system. CONSTITUTION:The deviation of a focusing point position against the optical axis direction is caused by the color aberration of a stop-down lens. Thus the coincidence is secured between intervals d12 and d23 among multi-layer record films and the interval set between focusing positions based on the color aberration. As a result, the focusing point of a corresponding wavelength is formed on each recording layer. For instance, when the deviation of the focus position caused by the lens color aberration is 0.1mum/nm and the interval between absorbed spectrum peak wavelengths of a wavelength multiplex recording layer is at 20nm, the interval of the recording layers is 2mum. Thus each recording layer can be recorded and reproduced with high optical availability and with high stability in addition to crosstalks decreased between record layers. |
