| 摘要 |
PURPOSE:To inspect the shape of a parabolic antenna easily even in an actual installation position, by irradiating an optional point on the parabolic surface with an optical beam of the vertical direction and detecting its converging conditions. CONSTITUTION:A laser tube 3 is supported freely suspensively and emits always the optical beam downward in the vertical direction. A photodetector 4 which measures the illuminance of the reflected light of the optical beam due to the parabolic surface is attached temporarily near the focus of the parabolic surface. In this constitution, when the laser tube 3 is moved optionally to emit the optical beam toward the parabolic surface in the vertical direction, the optical beam is reflected by the parabolic surface and reaches the focus. In this case, if the parabolic surface has prescribed dimensions, the optical beam is made incident to the photodetector 4 uniformly. But, if dimensions of the parabolic surface are different from prescribed dimensions, the intensity of the optical beam incident to the photodetector 4 is not uniform. Consequently, the output value of the photodetector 4 is analyzed to obtain information of positions, whose correction is required, of the parabolic surface and the correcting method. |
