PURPOSE:To shorten the wall thickness measuring time by measuring a relative position of the surface of a protective material, based on a position of a substrate by a measuring instrument provided on a through-hole of the protective material which reaches the surface of the substrate of a first wall or on a gap between the protective materials. CONSTITUTION:First of all, a light source is moved to the upper part in the vertical direction of a protective material 8 by a driving device 6 and stopped. Subsequently, a laser light 7 is radiated onto the protective material 8 and its reflected light is caught by a television camera 2, and converted to an electric signal. This signal is sent to an image processor 3, and also, analyzed by a personal computer 5. Its result is displayed on a screen of the computer 5 and a monitor television 4. After the measurement of one piece of the protective material 8 is completed, the light source 1 and the camera 2 are moved by a prescribed distance in parallel to the surface of the protective material 8 by the device 6, and the measurement is executed again. At the time of moving the light source 1 and the camera 2, they are moved in the horizontal two-dimensional direction in the case a laser beam 7 radiated from the light source 1 is a spot-like light, and in only in one direction of the plane in the direction vertical to a slit-like light in the case the laser light is a slit-like light, and the measurement is executed.
展开▼
