| 摘要 |
In a system for recovering data, both prerecorded (e.g. servo track) and user data, from a reflective optical data storage medium, with the further capability of distinguishing data from foreign particulate matter on a data disk 65, a pair of detectors 71, 77 measures the fraction of light 73 (e.g. infrared laser light) reflected from and the fraction of light 75 transmitted through the data disk 65 and, knowing the fraction of light absorbed by the disk 65 distinguishes user data from prerecorded data and particulate matter. Third detector T2 samples laser 61 output the data disk 65 has different optical characteristics for prerecorded and user data, the prerecorded information being black, highly absorptive silver, while the user data consists of pits or relatively high transmissivity in a reflective field. Particulate matter is recognized by intermediate reflectivity and transmissivity. The optical characteristics of the material are enhanced or exaggerated so that the two types of data and particulate matter can be distinguished. Record carrier constructions are detailed (Figures 2, 3, 4), as are materials (silver halide emulsion type) and processing thereof. A pattern may be located in layer (29) for security purposes. A quarter wave plate is used in the (Figure 7) system. <IMAGE> |
