Lightredirecting

Lightredirecting is a term used to describe techniques and devices designed to alter the path of light to achieve more favorable propagation, collection, or distribution. It encompasses passive optical components and structured surfaces that reorient, concentrate, or distribute light without changing its wavelength significantly. Common approaches include refractive and reflective elements such as microlens arrays, prismatic sheets, retroreflectors, and textured or patterned surfaces, as well as waveguides and metamaterial coatings that redirect light via changes in phase, amplitude, or direction.

In solar photovoltaics, lightredirecting measures aim to increase absorption in active layers by steering incident photons toward regions with longer optical path lengths, using texturing, anti-reflection coatings, back reflectors, and scattering layers.

In displays and architectural lighting, redirecting can improve brightness and comfort by steering light toward the field of view or away from undesired directions while maintaining color and uniformity.

Implementation methods include microlens arrays to collect and redirect light, prism sheets to bend light by fixed angles, diffusers to spread light more evenly, and thin-film coatings that preferentially transmit or reflect light at specific wavelengths and angles. Dynamic variants use liquid crystals or electro-optic materials to adjust direction.

Challenges include optical losses, added complexity, material durability, and cost; performance can be sensitive to incidence angle, wavelength, and temperature.

See also: light management, optical coatings, luminescent solar concentrators.