US 4,283,145 AGranted

Optical system for the detection of flaws in bottles or the like

AssigneeKirin Beer Kabushiki Kaisha

InventorTakashi Miyazawa

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Abstract

In order to enable a laser beam to scan the complete inside surfaces of an empty bottle or the like, two mirrors oscillating about right angular axes are employed which successively reflect the laser beam. The oscillations of the two mirrors are correlated to impart an annular or spiral scanning motion to the laser beam. Subsequently passing through a converging lens, which is focused at the mouth of the bottle being tested, the laser beam enters the bottle for point-by-point scanning of its surfaces. The presence of a flaw in the bottle is sensed from the intensity of the laser beam that has penetrated, or has been reflected from, the bottle, as by an integrating sphere and a photoelectric detector mounted in position thereon. Various other embodiments of the invention and modifications are disclosed.

Claims10

Dependent claims

In a system for detecting flaws in bottles or like articles having a neck or constricted area near the top thereof, said system including a light beam generating means, a device for causing scanning motion of said light beam through an article to be tested, and a photoelectric detecting means adapted for detecting variation of said scanned light beam thereby to detect a flaw in the article the improvement wherein said system comprises:

a laser beam generating means for generating a narrow beam of light;
mirror means comprising two mirrors having respective reflective surfaces arranged so as to reflect said laser beam one after the other and supported so as to be oscillated about respective axes at right angles to each other and lying in respective planes which substantially coincide with the respective reflective surfaces for generating a scanning motion of the laser beam;
means for imparting correlated oscillations to said two mirrors whereby the beam is angularly scanned in a spiral path;
a positive lens for receiving said scanned beam and for redirecting it through a cross-over point or small region positioned within said bottle or article at said neck or constricted area;
and, a photoelectric detector means adapted for receiving said spirally scanned laser beam after it has passed through or been reflected by said article thereby to detect a flaw in the article to be tested.

2 more elements

In a system for detecting flaws in bottles or like articles having a light beam generating means, a device for causing scanning motion of said light beam through an article to be tested, and a photoelectric detecting means adapted for detecting variation of said scanned light beam thereby to detect a flaw in the article the improvements wherein:

(a) said light beam generating means is a laser beam generating means adapted to generate a narrow linearly-polarized laser beam;
(b) said device for causing scanning motion comprises optical means disposed in the path of said polarized laser beam and adapted to move in a prescribed manner for imparting angular deflections to said beam to cause it to undergo an annular or spiral scanning motion and a positive lens for receiving said scanned laser beam and for redirecting it through a cross-over point or a small region positioned within said bottle or article and above the surface to be inspected to thereby enable said beam to scan through said article;
and, (c) said photoelectric detecting means comprises means for receiving light of said laser beam which is reflected from the article, the reflected light including depolarized rays produced as a result of scattering of the polarized laser beam by a flaw of the article, means for separating the depolarized rays from the reflected light, and means for sensing the presence of the flaw in the article by receiving only the separated depolarized rays.

Dependencies are inferred from the claim text.