Alignment method and system for use in manufacturing an optical filter
AssigneeOki Electric Industry Co., Ltd.
InventorAkihiko Nishiki
Life of this patent
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Abstract
A photosensitive optical fiber being scanned by an ultraviolet beam to form an optical filter is aligned with the beam by detecting fluorescence produced in the fiber. The relative position of the fiber and beam is made to oscillate in a direction cutting across the scanning direction. Misalignment is corrected according to the phase relationship between the fluorescence detection signal and the oscillation, permitting the alignment to be controlled accurately regardless of the beam dimensions, scanning distance, scanning rate, and natural fluorescence variations.
Claims18
An alignment system for maintaining correct alignment between a photosensitive optical fiber and an ultraviolet beam illuminating the photosensitive optical fiber through a phase mask, while the ultraviolet beam is scanned along the photosensitive optical fiber in a first direction to create an optical filter in the photosensitive optical fiber, comprising:
- a positional transducer causing an oscillation in relative position between said photosensitive optical fiber and said ultraviolet beam in a second direction differing from said first direction;
- an optical transducer coupled to an end of said photosensitive optical fiber, receiving from said photosensitive optical fiber light produced by fluorescence in said photosensitive optical fiber when said photosensitive optical fiber is illuminated by said ultraviolet beam, and converting said light to a first signal, said first signal having an oscillating component due to said oscillation in relative position;
- and
- a control circuit coupled to said optical transducer, comparing phases of said first signal and said oscillation in relative position, and adjusting the relative position of said photosensitive optical fiber and said ultraviolet beam in said second direction according to a phase relationship between said first signal and said oscillation in relative position.
A method of maintaining correct alignment between a photosensitive optical fiber and an ultraviolet beam illuminating the photosensitive optical fiber through a phase mask, while the ultraviolet beam is scanned along the photosensitive optical fiber in a first direction to create an optical filter in the photosensitive optical fiber, comprising the steps of:
- producing an oscillation in relative position between said photosensitive optical fiber and said ultraviolet beam in a second direction differing from said first direction;
- detecting light produced by fluorescence in said photosensitive optical fiber when said photosensitive optical fiber is illuminated by said ultraviolet beam;
- converting said light to a first signal having an oscillating component due to said oscillation in relative position;
- detecting a phase relationship between said first signal and said oscillation in relative position;
- and adjusting the relative position of said photosensitive optical fiber and said ultraviolet beam in said second direction according to said phase relationship.
Dependencies are inferred from the claim text.