Abstract
An angular filter includes a louver film including a plurality of dark regions alternately arranged with a plurality of clear regions, incorporating spatial smoothing, or apodization, at boundaries between the dark regions and the clear regions. Spatial smoothing may be accomplished with an edge treatment in the form of discrete grey regions interposed between adjacent dark regions and clear regions. The edge treatment may include blurred grey regions interposed between the adjacent dark and clear regions. The edge treatment may include corrugated regions interposed between adjacent dark and clear regions. In some examples, the angular filter includes a two-dimensional louver film, including a first louver film overlaid on a second louver film, in which, a longitudinal direction of plurality of dark and clear regions of the first louver film is substantially orthogonal to that of the second louver film. Angular filters can be positioned in an optical path to allow incident light to pass through the filter in one direction, while filtering out, or blocking, the incident light in other directions. Some optical systems employ angular filters to narrow the viewing angle of a display to a range that is visible by a single user. Some optical systems employ angular filters to control stray light, such as when a light source emits light at an angle that is greater than the numerical aperture of a subsequent optical component.
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Recommended Citation
Hoekman, Thomas Leonard, "Optical Angular Filter With Reduced Diffraction Artifacts Background", Technical Disclosure Commons, (March 27, 2025)
https://www.tdcommons.org/dpubs_series/7940