Patent attributes
An image measuring system comprises a projection optical system, having a light source for emitting and projecting an illumination light through a light projection optical axis. The system further comprises a photodetection optical system, having an image pickup element, which receives a retroreflection light from an object to be measured through a photodetection optical axis, and a control arithmetic device for processing the data taken by the image pickup element. The projection optical system comprises a light projection unit for directing the light projection optical axis toward the object to be measured and projecting the illumination light, a projection angle changing means for rotating the light projection unit in an elevating and a horizontal direction and for changing a projection angle of the illumination light, and a direction detecting means for detecting a direction angle of the light projection optical axis with respect to the photodetection optical axis.