| 摘要 |
PURPOSE:To obtain single crystals having uniform diameter by compensating for the shift of focus due to variation of distance between the surface of melt and a diameter detector in accompany with displacement of crucible in the stage of growth of single crystal by Chokralsky method by the displacement of an objective lens and compensating for the change of the magnification. CONSTITUTION:A vertically movable crucible 3 is provided in a vessel 1 to maintain the melt 4 in the crucible 3. Single crystal is grown by Chokralsky method by changing the position of the surface of the melt by moving the crucible 3, and the diameter of the crystal 6 is detected by a TV camera 15 simultaneously to control the pulling speed to obtain a fixed diameter. In this stage, the displacement of the crucible 3 is calculated by integrating program signal from a program signal generator 13 for the displacement of the crucible 3, and the diameter of the single crystal is detected by controlling the position of an objective lens 17 of the TV camera 15 in accordance with the program signal. The gain is controlled in accordance with the displacement of the crucible 3 to amplify the diameter detection signal. Thus, the detection error of the diameter is compensated. |
