Optics: measuring and testing – By configuration comparison – With photosensitive film or plate
Patent
1997-08-12
2000-04-25
Kim, Robert H.
Optics: measuring and testing
By configuration comparison
With photosensitive film or plate
356382, G01B 1106
Patent
active
060550589
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to determination of the thickness and in particular of the concentricity of the coating or jacket of an optical fiber, more particularly the deviation from a concentric position for a coating, in particular a thin plastics coating, on an optical fiber.
BACKGROUND
Conventional optical fibers comprise generally a cladding, usually of quartz (silica) glass, which is protected mechanically by a layer of a plastic forming a coating or jacket, most often of polyacrylate plastic, having a typical thickness of 60-65 .mu.m. For monitoring the concentricity of such protective coatings in the manufacture of an optical fiber most frequently an optical method is used, which uses scattering patterns, fringes, in the forward direction. However, this method does not work for fibers, which are coated with a thin layer of polyimide having a thickness of the order of magnitude of 20 .mu.m. This results from the different optical characteristics of such a thin polyimide layer, partly derived from the reduced thickness thereof, partly from the fact that polyimide materials have substantially larger refractive indices, compared to the conventional polyacrylate materials.
In U.S. Pat. No. 5,208,645, which corresponds to the published European patent application EP-A2 0 443 322, a method and a device are disclosed for optical detection of the thickness of the coatings of cylindrical objects, such as coatings on optical fibers. A fiber is irradiated with light, the intensity or energy of which is measured after a reflection by means of a photodetector. The intensity is a measure of the thickness of the coating. This document is especially focused on measurements on optical fibers coated with carbon. Two principles are described. In one, the fiber is illuminated with parallel beams orthogonally in relation to the longitudinal direction of the fiber, the reflected radiation is detected with an image detector and the thickness of the coating is finally determined from the peak levels of the intensity of light condensed by the lens effect of the fiber portion (column 2, lines 22-34). In the other method the intensity of reflected light is measured and compared to a calibration curve in order to obtain a measure of the thickness of the coating (column 3, lines 31-51 and the description of FIGS. 4a-4c).
In the published Japanese patent application JP-A 4-363612 methods similar to that described in the document discussed above are disclosed. The thickness of a coating of an optical fiber is determined by illuminating the fiber from the side and then measuring the intensity of light, which has passed through the fiber. Possibly the intensity of reflected light is also measured. The thickness of the coating is then determined by comparing the intensity of the light that has passed through, or possibly the intensity of the reflected light, to a calibration curve.
In determining the position of the coating according to U.S. Pat. No. 4,583,851 a fiber is illuminated from the side thereof and the reflected light intensity is measured in relation to the output angle. Any deviation from the symmetry of a given profile indicates an eccentric position. A light source 10 illuminates an optical fiber 12 and the intensity of the reflected light as a function of the detection angle is detected by means of a converging lens 14, an rotating mirror 16, a slit aperture 20 and a photodetector 18.
In the published Japanese patent application JP-A 63-274804 determination of the diameter of the core and the thickness of the coating of an optical fiber are determined by projecting two light beams having different wave lengths at right angles towards and through a fiber and measuring the absorption of the light beams. The principle is that one can get an estimation of the diameter of the core and the thickness of the coating from knowledge of the different absorption coefficients of the core and the coating and the measured intensity of the light which has been reflected and the measured intensity of the light which has passed t
REFERENCES:
patent: 3017512 (1962-01-01), Wolbert
patent: 4583851 (1986-04-01), Yataki
patent: 4984894 (1991-01-01), Kondo
patent: 5208645 (1993-05-01), Inoue et al.
patent: 5216486 (1993-06-01), Sullerot et al.
patent: 5570446 (1996-10-01), Zheng et al.
patent: 5572313 (1996-11-01), Zheng et al.
Borak Georges
Krahbichler Erik
Kim Robert H.
Telefonaktiebolaget LM Ericsson
LandOfFree
Method and device for determining the thickness and concentricit does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and device for determining the thickness and concentricit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device for determining the thickness and concentricit will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-997957