| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical material with a low refractive index and high dispersion which is indispensable for higher performance of an optical device by controlling the refractive index of a first material for the d-line and the Abbe number indicating the wavelength dispersion of a second material in the visible ray region to satisfy a specified relation. SOLUTION: The optical material is a mixture of a plurality of materials including a first material having >=1.45 refractive index for the d-line and a second material having >=25 Abbe number which indicates the wavelength dispersion in the visible ray region, and the relation between the refractive index nd for the d-line and the Abbe numberνd indicating the wavelength dispersion in the visible ray region satisfy the relation of nd<=-6.667×10-3νd+1.70. The packing rate of the material having higher wavelength dispersion is decreased, and the space is filled with the low refractive index material having a low refractive index to obtain the material having a low refractive index and a small Abbe number. By mixing the substance having a low refractive index and small wavelength dispersion (nd<=1.45) and the material having a high refractive index and high wavelength dispersion (νd<=25), the optical material having the specified relation of nd andνd can be realized.
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