Fault-detecting surface scanner using a laser light source

Claim 1

Apparatus for inspecting a moving web for surface defects with a single flying spot of light, said web having a width substantially greater than 15 inches, said inspection apparatus comprising a web inspection station, means for transporting a web past said inspection station, laser means for generating a continuous substantially nondiverging beam of coherent light, a rotating reflector having a diameter less than about 6 inches, said rotating reflector having a multiplicity of peripheral planar reflector surfaces each having a width less than about one-half inch arranged to reflect said beam of light towards said web at said inspection station and to sweep said beam across said web with an included scanning angle of less than about 20*, said rotating reflector being spaced from said web a distance greater than the width of the web and arranged to direct said light beam toward the surface of said web at an angle thereto whereby said beam is reflected from the surface of the web in a direction away from said rotating reflector, means for directing said beam reflected from the surface of the web to substantially a single point, and beam detector means disposed at said single point arranged to respond to the intensity of said beam reflected from the surface of said web.