Imaging freeform optical systems designed with NURBS surfaces
Author(s)Chrisp, Michael P.; Echter, Michael A.; Primeau, Brian C.
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The designs of two imaging freeform systems using nonuniform rational basis-spline (NURBS) optical surfaces are described. The first system, a 10 deg×9 degf/2 three-mirror anastigmat has four times higher spatial resolution over the image plane compared with the equivalent conventional rotational aspheric design, and 2.5 times higher resolution compared with a 10th-order XY polynomial freeform design. The mirrors for the NURBS freeform design have more than twice the asphericity than the conventional rotational and XY polynomial designs. In the second system, a Ritchey–Chretien telescope followed by a two-mirror NURBS freeform corrector is compared to a four-mirror Korsch telescope, for imaging to a visible-infrared imaging spectrometer. The freeform corrector design had 70% smaller spot sizes over the field and eliminated the large tertiary required in Korsch type design. Both of these NURBS freeform designs are possible due to a custom optical design code for fast accurate NURBS optimization, which now has parallel raytracing for thousands of NURBS grid points.
Chrisp, Michael P., Brian Primeau, and Michael A. Echter. “Imaging Freeform Optical Systems Designed with NURBS Surfaces.” Optical Engineering 55.7 (2016): 71208.
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