METHOD AND APPARATUS FOR ACTIVE VISION IMAGE ENHANCEMENT WITH WAVE- LENGTH MATCHING

A method and apparatus for optically inspecting the geometry of a surface in an environment which is subject to the presence of external light noise perturbations. A beam of monochromatic light having a predetermined wavelength and a structured light pattern is projected onto the surface to thereby scatter the structured light beam and produce a scattered light beam which is thereafter separated into first and second scattered beam portions. The first scattered beam portion is passed through a first optical filter having a narrow bandwidth and a central wavelength corresponding substantially to the wavelength of the projected light, thereby providing a first optical output signal representative of the surface geometry and of external light noise perturbation. The second scattered beam portion is passed through a second optical filter having a narrow wavelength bandwidth and a central wavelength which is closely spaced from the predetermined wavelength of the projected light by a wavelength offset such as to reject the projected light wavelength, thereby providing a second optical output signal representative of substantially the same external light noise perturbation as that passing through the first optical filter. The first and second optical output signals are detected and converted into first and second electrical signals, respectively. The second electrical signal is then subtracted from the first electrical signal to provide a substantially noise-free electrical output signal representative of the surface geometry. The invention is particularly useful for active vision robot welding and enables arc light noise-free images to be obtained in real time.