OPTICAL MANUFACTURING: OCT improves polymer gradient-index lens manufacture

摘要

A group at the University of Rochester (U of R; Rochester, NY), in collaboration with a number of other institutions, is using optical coherence tomography (OCT) to get high-resolution 3D images of the internal structure of a new form of gradient-index (GRIN) lens. Called the S-GRIN, the new lens has a spherical refractive-index gradient; the breakthrough in the lens itself is that it is manufacturable, leading to potential uses for lightweight single-lens cameras and other devices. The U of R team includes researchers from Synopsys (Pittsford, NY), PolymerPlus (Valley View, OH) Case Western Reserve University (Cleveland, OH), and Suranaree University of Technology (Nakhon Ratchasima, Thailand). While GRIN lenses with axial gradients (and curved surfaces) and especially those with radial gradients (often rod-shaped with flat ends normal to the optical axis) are common, S-GRIN lenses are less so, due to the difficulty of fabricating a spherical index gradient. But because such a gradient gives lens designers additional freedom to correct lens aberrations, perseverance by researchers at Case Western Reserve University has resulted in a manufacturing technique in which many polymer layers are laid down on one another. Next, they are heated, compressed, and formed into a preform with spherical concentric surfaces; the preform can then be diamond-turned to create a final lens.