Patent ID: 6957493

Claim:
An automatic tracking apparatus for a reflector, comprising: a surveying machine body; an illumination portion disposed in said surveying machine body for illuminating a measurement light toward a reflector; a light receiving portion which is disposed in said surveying machine body and which has an image sensor including a plurality of pixels for receiving a reflection light image of the measurement light illuminated toward said reflector; an arithmetic device configured to calculate a position of the reflection light image from said reflector in an area of said image sensor; a rotation mechanism for rotating said surveying machine body so as to position said reflector on a light receiving optical axis of said light receiving portion based on the position obtained by said arithmetic device; and a distance measuring portion for measuring a distance from the reflector to the surveying machine body, wherein the area of the image sensor is provided with a first light receiving area, which is set to be larger than the reflection light image, and a second light receiving area surrounding the first light receiving area, as scanning areas of the reflection light image, and areas of the first light receiving area and the second light receiving area are changed in accordance with the distance from the reflector to the surveying machine body.