Optical waveguides – Optical fiber bundle – Fiber bundle plate
Reexamination Certificate
1999-05-05
2001-03-27
Ngo, Hung N. (Department: 2874)
Optical waveguides
Optical fiber bundle
Fiber bundle plate
C385S034000, C385S083000
Reexamination Certificate
active
06208787
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to fabrication of microlens arrays and its application to produce long period gratings.
2. Description of Prior Art
The invention relates more particularly to methods of producing a low cost microlens array with a length longer than 200 mm. Chosen forms of those microlens arrays are, according to this invention, used to write long period gratings with germanosilicate fibres, which fibres are themselves readily commercially available. Hitherto such long period gratings have been normally produced by using amplitude masks that must selectively blocks off laser radiation leading to inefficient use of power. Commercial micro-optics arrays constructed with UV grade fused silica is an alternative as it focuses the laser beam into a periodic pattern and thus requires much less energy from the laser. Unfortunately, the extremely high cost of such microlens arrays normally prohibits their use in long period grating fabrication.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a method of producing low cost microlens arrays and/or overcoming or at least reducing the disadvantages referred to above.
According to one aspect of the invention there is provided a method of making a microlens array comprising preparing a plurality of short lengths of transparent fibre, holding the fibres side by side and fixing their ends to a rigid body having an open region across which the fibres extend and through which radiation may pass.
The method may include the step of gluing the ends of the fibres to fix them to a planar surface of the rigid body.
The gluing is preferably carried out using epoxy resin.
The fibres may be prepared by taking commercially available UVGFS fibre, removing its outer protective coating and cutting off short lengths.
The method may include polishing one side of the microlens array so that each fibre has a generally semicircular cross-section.
According to another aspect of the invention there is provided a microlens array formed of a plurality of transparent fibres that are held together side by side and extend across an opening in a rigid body.
The fibres are preferably prepared by removing an outer protective coating of commercially available UVGFS fibre from a length of fibre, and cutting that fibre into short lengths.
According to a further aspect of the invention there is provided a method of making a long period grating which comprises placing a strand of silica fibre across and below a microlens array described above, and radiating the strand via the lens with UV radiation.
REFERENCES:
patent: 5446815 (1995-08-01), Ota et al.
patent: 5980119 (1999-11-01), Furuyama
patent: 5991492 (1999-11-01), Ota et al.
patent: 6002819 (1999-12-01), Saito et al.
Leydig Voit & Mayer Ltd
Ngo Hung N.
The Hong Kong Polytechnic University
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