Patent ID: 9658057
Date: 2017-05-23
CPC Classifications: G01B,G01N

Claim:
1. A facility for measuring the thickness of the wall of transparent or translucent containers, delimited between an outer surface and an inner surface, including: a light source producing a light beam sent to impinge the outer surface of the wall according to an angle of incidence such that a portion of the light beam is reflected by the outer surface of the wall and that a portion of the beam is refracted in the wall and then reflected by the inner surface of the wall, a light sensor of dimension Ci, placed on a detection plane, and collecting the light for converting it into electric signals, an optical collecting and focusing system, on the detection plane of the light sensor, for collecting and focusing light beams reflected on the outer and inner surfaces of the wall, a processing unit connected to the light sensor and adapted for determining the thickness of the wall from electric signals delivered by the light sensor, characterized in that the optical collecting and focusing system combines an object field of dimension Co with the light sensor ( a first objective having the first objective's object plane located in the vicinity of the impact of the incident light beam with the wall and adapted for collecting the light beams specularly reflected by the outer and inner surfaces of the wall, with an angle (α) relatively to the optical axis O ranging from at least 20° to up to 40°, an at least translucent diffusing screen located in the image plane of the first objective, so as to physically represent the light beams collected by the first objective as hot spots (Ti), a second objective having in the second objective's object plane, the diffusing screen and in the second objective's image plane, the light sensor, so as to produce on the light sensor, an image of the diffusing screen on which the hot spots are distinguished.