| 摘要 |
PROBLEM TO BE SOLVED: To decrease the intensity of fluorescent light due to excitation by UV rays and to obtain high transmittance for rays in a UV region by incorporating a specified amt. of Yb2O3. SOLUTION: Yb2O3 which is effective to increase the refractive index and to decrease fluorescent light is incorporated by 1 to 50 wt.% as the essential components of an optical glass. If the amt. exceeds 50 wt.%, stability against devitrification decreases. The optical glass essentially composed of Yb2O3, B2O3 and La2O3 or the like is produced by using oxides, carbonates, nitrates, metaphosphates or the like as the source material corresponding to each component, weighing these compds. in desired proportions, and mixing enough in a powder or liquid state to prepare the source material. The prepared source material is introduced into a quartz or platinum crucible in an electric furnace heated to 1100 to 1400 deg.C for example, and the source material is molten, refined, stirred and homogenized, and then cast into a preliminarily heated iron casting mold, and slowly cooled. The obtd. optical glass is useful for the optical system of a fluorescent microscope or the like in which especially fluorescence in the optical glass causes problems concerning to the observation and measurement.
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