| 摘要 |
PURPOSE:To obtain the titled high-quality crystal without any optical defect and to obtain an optical element for a <001> type A-O modulator in high yield by orienting the <100> axis in the pulling direction when the tellurium dioxide single crystal is grown by the pull method. CONSTITUTION:The raw material is charged. for example, into a gold crucible having 50mm internal diameter and depth, and melted at about 733 deg.C by high-fre quency heating. A tellurium dioxide single crystal having 25mm diameter and 60mm length is grown from the melt at 2.0mm/Hr pulling velocity and at 25rpm rotational speed of the crystal by using the <100> axis as the pulling aixs. Consequently, the crystal without any air bubbles, striae, and impurities at the inside and having the same high quality as the crystal obtained by the conventional <110> axis pulling method can be obtained. When the optical element for an acoustooptic (A-O) modulator used for transmitting the longitudi nal wave of a ultrasonic wave in the <001> direction is cut out, a hexahedral optical element surrounded by a (001) face, a (100) face, and a (010) face must be used. When the size is regulated to <001> axis = <100> axis = <010> axis, three elements 2 of maximum 17mm square can be cut out, and four elements 1 of 14mm square can be cut out.
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