A non-contact laser triangulation scanning apparatus for generating a three-dimensional image of the surface of an object based on the 3D surface position and surface contrast information. The apparatus comprises a laser source, a first optical unit, a second optical unit, a photosensitive positional detector having a plurality of sensor elements, and an incident light measurement device. According to generated timing signals having a predetermined time interval, a reset timing of the sensor elements of the photosensitive positional detector is controlled. The incident light measurement device measures an amount of a certifying laser light after one timing signal. An amount of a measurement laser light is determined dependent on the measured amount of the certifying laser light. The three-dimensional image is generated by combining position data derived from signals of the positional detector with contrast data derived at least from signals of the incident light measurement device.