Client : Doric Lenses Inc.
Industries: Advanced Manufacturing
We signed a strategic alliance with Doric Lenses - a company specialized in the development and fabrication of optical components and photonics assemblies - with a view to pooling our resources to develop a new family of optical components for the collimation of laser diodes for use in medical, industrial, and military applications.
In designing such optics, the problem was not to find a refractive-index profile that would correct the aberration, but rather finding a way to manufactured those microlenses in large volume and at low cost. The patented solution that we developed at INO is based on a gradient-index (GRIN) core with a homogeneous cladding. These microlenses 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 machined to a desired width.
A perfectly suited, innovative approach
The fabrication of fiber performs through modified chemical-vapor-deposition (MCVD) technology is perfectly suited for this microlenses design approach because the glass tube that is the starting point in the process of making the fiber preform is incorporated into the design. 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 microlenses having a diffraction-limited focusing quality. The diameter and shape of the rods forming the microlenses are precisely controlled and our fabrication know-how results in unsurpassed surface quality. The rods can be cut to any desired length and act as perfect cylindrical microlenses with 0.5 NA when illuminated sideways. The fused silica cladding and the gradient-index core of these microlenses withstand very high temperatures (transition temperature is approximately 1100°C). The microlenses can be used in visible and near infrared spectrum. The round cross-section of these microlenses results in the large field of view and simple, cost-effective alignment with laser diodes.