02 March 2001
Optical fiber preparation
A flow imaging system using optical fiber sensors must have a good resolution to generate an image, which accurately represents the flow. It is important to ensure that the lenses have identical characteristics, and it's important to standardize the method in preparing the lenses.
Before the lens is constructed, the end of the optical fiber is polished. A simple aluminum block holds the fibers tightly in a vertical manner during the polishing process.
The fibers insert into holes located in the block so that 5 millimeters of the fiber protrude from the bottom of the block. Then the top aluminum block tightens to securely hold the fibers in place.
A range of grit papers then polishes the fibers. The polishing process ends when the fiber end is flat and smooth. Finally, industrial methylated spirit cleans the fibers.
A custom heating fixture forms the lens on the prepared flat surface. The lenses are such that all fibers have smooth surfaces and similar radii, resulting in identical characteristics with minimum differences in transmitted intensity and emission angle.
This method provides a low-cost approach to the production of optical lenses on plastic optical fibers.