These patented gradient-index cylindrical microlenses with Luneburg type refractive index distribution are drawn from a highly polished gradient-index fiber preform.
A simple tuning of the drawing process results in diffraction-limited microlenses in the shape of fibers or rods with precise diameters and unsurpassed surface quality. When illuminated sideways, these fibers act as perfect cylindrical lenses with 0.5 NA. The fused silica cladding and the gradient-index core of these lenses withstand very high temperatures (transition temperature is approximately 1100°C). The lenses can be used in visible and near infra red spectrum.
The rods or fibers are cut to desired length. The round cross-section of these lenses results in the large field of view and simple, cost-effective alignment with the laser diodes where most of the positioning errors result in simple focusing errors. This leads to effective "best focus" search beneficial for automated or manual positioning.
These lenses could be used either as fast-axis collimators for single laser diodes or for building cylindrical lens arrays for laser diode bars. In order to accommodate a small emitter pitch, the edge of the lens may be ground to a desired width.