MEASURING AND ADJUSTING OPTICAL AXIS OF A HEADLIGHT

The alignment of the optical axis of a headlight HL is examined by projecting the light from the headlamp onto a translucent screen (2). A light shielding panel (5) and an imaging screen (7) are attached to the lower portion of screen (2). Light enters the device by pinhole (6) and is reflected from mirror (8) and imaged onto screen (7). Camera (3) views both the illumination pattern on translucent screen (2) and the image of the light source on screen (7). The actual position of the headlight HL is located from the position of the source image on screen (7). A measuring area is then positioned on screen (2) and the headlamp is adjusted until a characterizing feature of the pattern on screen (2) lies within the measuring area. The optical axis may also be corrected by adjusting the headlamp so that the image of the source on screen (7) becomes a normal shape. An illuminating pattern to appear on a first screen which is disposed in front of a headlight is pictured by a camera. A light-shielding panel is disposed on substantially the same plane as the first screen. A pin hole is formed in the light-shielding panel. The light to penetrate through the pin hole is illuminated via a mirror on a second screen which is on a surface behind the lightshielding panel. On the second screen there is formed an imaginary light source image which is to be formed on a reflecting light of the headlight. This image is pictured by the camera together with an illuminating pattern on the first screen. From the position of the imaginary light source image the actual position of the headlight is located, and the position of an acceptable range, within which a reference measuring point inside the illuminating pattern falls, is corrected depending on the position of the headlight so that the reference measuring point may fall within the acceptable range. Since the shape of the imaginary light source image varies with the orientation of the optical axis, the optical axis may also be adjusted such that the imaginary light source image becomes a normal shape.