3D-profiling by optical demodulation with an image intensifier

The acquirement of 3D-information is currently achieved by stereophotography, line and grid projection techniques or by laser scanning in combination with a fast distance measuring device. This paper describes a new principle using a single CCD-camera with an optical demodulator in front of it. The scene is illuminated by a high frequency intensity modulated light source (i.e. a semiconductor laser). Demodulating the backscattered light by a gateable image intensifier yields a grey level image which directly corresponds to the object's form. Intensity variations within the image due to inhomogeneous object reflectivity or illumination intensity are overcome by a phase shift technology. Possible applications for such a 3D-camera include industrial automation, medical and industrial endoscopic analyses, robotics or 3D-digitalisation.