AS-GROWN SINGLE CRYSTAL OF CALCIUM FLUORIDE MANUFACTURED BY CZOCHRALSKI METHOD

摘要

PURPOSE: An as-grown single crystal of calcium fluoride is provided to reduce an internal distortion and birefringence index and to reduce birefringence index non-uniformity. CONSTITUTION: A single crystal(36) of calcium fluoride in a grown state is obtained by a single crystal pulling method. The single crystal of calcium fluoride has a straight barrel part diameter of 17cm or more. A birefringence of the single crystal of calcium fluoride is same to or less than 3nm/cm. The standard deviation of the birefringence of the single crystal of calcium fluoride is not more than 2.0nm/cm. The straight barrel part has a diameter same to or greater than 5cm.