| 摘要 |
PURPOSE:To improve reliability and simplify structure by using a thin film resistor or diffused resistor which serves as both a mirror surface and a heater, and measuring variation of reflected light on the mirror surface and dew point temperature at this time. CONSTITUTION:The thin film resistor 13 which has a thin film 11 as the mirror surface 12 for reflecting light on the surface is so provided that the temperature of a substrate 1 is measured by a temperature detector 14. Then, this is fed with a pulse current from a pulse current generator 18 to detects such a change that dew is exholed and stuck on the mirror surface 12 by a photodtector 17 from variation of reflected light from a light source lamp 16, and the temperature at this time is detected by a temperature detector 14. Consequently, the dew point hygrometer of reliable and simple structure which has no malfunction due to a stain of dust, oil, etc., on the mirror surface 12, external diffused light, etc., is obtained. |
