| 摘要 |
<p>PURPOSE:To optically detect the turning and moving position of a susceptor without badly affecting a film formation operation by a constitution wherein a through hole is made in the susceptor and a beam or light which has passed the through hole is detected by means of a photosensor. CONSTITUTION:A beam of light 100 from a halogen lamp 81 makes its way into a shielding member 51 from a U-shaped curved surface 85 at an edge 84. While it is being reflected totally on the surface inside the shielding member 51, it is propagated. One part of it is radiated as a beam of scattered light 102 to the outside of the shielding member 51 by a V-shaped groove 86; the rear side of a susceptor 62 is irradiated with it. At this time, the susceptor 62 is turned; a through hole 90 is moved and reaches a position faced with the V-shaped groove 86; one part of the beam of scattered light 102 passes the through hole 90; a photosensor 89 is irradiated with a beam of passed light 104; the photosensor 89 detects the beam of light. Thereby, it is detected that the susceptor 62 has reached its turning and moving position. Consequently, the turning and moving position of the susceptor 62 can be detected even in the situation that a film has been formed on the surface of the susceptor and that the surface has been made deep-black.</p> |
