Optical Fiber Exit Angle Measurement via Differential Diameter Holder
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Solution Overview
Problem
Current methods for measuring the exit angle of optical fibers are not practical due to insufficient accuracy and cumbersome operation, with high standard deviation in repeated measurements and significant variations caused by individual differences in measurement procedures.
Innovation Solution
A method and apparatus that utilize a holder with a through hole having a small-diameter portion 0.1 µm to 1.0 µm larger than the bare fiber diameter and a large-diameter portion larger than the sheathed fiber diameter, allowing precise rotation and measurement of the optical fiber without bending, using a CCD camera for image processing to calculate the exit angle from coordinates of the locus circle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a holder with a through hole having inside diameter at least 10 μm larger than the outside diameter of the optical fiber is used, then the optical fiber can be properly inserted and rotated, but the measurement repeatability is insufficient (standard deviation of ±0.05° or more) and the operation becomes cumbersome
Solution Approach 1:
The through hole is divided into two distinct regions: a first portion with a smaller inside diameter (0.1-1.0 μm larger than bare fiber) for precise rotation guidance, and a second portion with a larger inside diameter for easy fiber insertion. This local differentiation of hole diameter allows each region to fulfill its specific function optimally.
Solution Approach 2:
The through hole is segmented into functionally distinct portions along its length. The first portion (front side) provides tight guidance for rotation, while the second portion (rear side) provides loose guidance for insertion. This segmentation resolves the contradiction by providing different clearance characteristics at different locations.
2Measurement precision
If the acceptance level is set to ±0.05° to achieve measurement repeatability of within 0.1°, then the measurement precision is improved, but the passing rate becomes very low and many acceptable products are rejected
Solution Approach 1:
The patent replaces manual measurement operations with an automated measurement system using a CCD camera and image processing. This substitution eliminates variations caused by individual differences in manual operation, achieving high measurement repeatability (within 0.1°) while maintaining a reasonable passing rate, as the automated system consistently applies the same measurement criteria.
3Ease of operation
If manual measurement operations are performed by different persons, then the ease of operation is maintained, but variations in measured values occur due to individual differences
Solution Approach 1:
The patent replaces manual measurement operations with an automated system using a CCD camera and image processing software. The automated system captures images of the optical fiber output and automatically calculates the exit angle, eliminating variations caused by different operators. This substitution maintains ease of operation in terms of system usability while dramatically improving measurement consistency.
4Ease of operation
If a retaining plate is used to fix the optical fiber by pressing with predetermined force, then the optical fiber can be fixed for measurement, but adhesion of dust particles to the groove and retaining plate causes distortion and poor repeatability
Solution Approach 1:
The patent extracts the optical fiber fixing function from the retaining plate mechanism. Instead of using a retaining plate that contacts the fiber and accumulates dust, the invention uses a through hole structure where the fiber passes through and is positioned by the differential diameter portions. This extraction of the fixing function eliminates the dust adhesion problem while maintaining the ability to secure the fiber for measurement.
Data Source
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AI summary
An object is to improve the repeatability of measurements of an exit angle of an optical fiber, facilitate a measuring operation, and accurately measure exit angles of many optical fibers in a short time. A measurement end of an optical fiber is passed through a through hole of a holder. While the optical fiber is being rotated by using the through hole as a guide, output light from the measurement end is received by light receiving means. Coordinates of at least three points on a locus circle of the output light are measured to calculate a size of the locus circle. On the basis of the calculated size, the exit angle of the optical fiber is measured. The through hole of the holder has a small-diameter portion on a front side and a large-diameter portion on a rear side. An inside diameter of the small-diameter portion is 0.1 µm to 1.0 µm larger than a diameter of a bare fiber, and an inside diameter of the large-diameter portion is larger than a diameter of a sheathed fiber. The object described above is thus achieved.