| 摘要 |
A refractometer and a method for measuring the refractive index of a lens (80), wherein a thin insert (86) in the form of a pad of a flexible transparent material attached to a rigid transparent sheet (82), is lightly pressed onto a surface of the lens (80) under test, such that the pad surface effectively acquires the same profile as the lens surface. The focal length or power of the lens (80) is first measured without the insert, and the measurement is then repeated with the insert positioned first in contact with one surface of the lens (80), and then in contact with the other surface. The use of equations derived from the classical lens formula then enables the refractive index of the lens (80) to be easily and quickly determined. The apparatus and method also enables the measurement of the refractive index of lenses of low power.
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