| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical recording medium having good Bragg selecting performance while using a laminated structure body by using a technique by which the selecting performance is equal to or less than a specified amount even though the medium thickness of a single active area is changed by equal to or more than the specified amount. SOLUTION: A function for writing and re-constituting many holograms (that is, equal to or more than L/5λ) depends on a fact that the technique having unchanging selecting performance is adopted. L is defined as the thickness of the single active layer, andλis defined as the wavelength of light to be used. The laminated medium has at least two active areas 3, and the areas 3 are separated by inactive areas 1 and 2. The thickness of the areas 3 versus the thickness of the areas 1 and 2 is <=10:1, and desirably <=5:1. Thus, the writing technique used for performing recording uses the laminated medium having the unchanging performance. The decision must be done in the case thickness of an area where a signal beam and a reference beam are superposed each other is equal to or more than the thickness of the medium. |
