(mathematics) A mathematical problem, asking whether a room with mirrored walls can always be illuminated by a single-point light source, allowing for repeated reflection of light off the mirrored walls. It was solved in 1958: there are such rooms that cannot be thus illuminated.

Alternative spelling of overillumination

(computer graphics) The realistic lighting of a rendered scene by means of algorithms that take into account not only the direct illumination from light sources but also the indirect cases where light is reflected between surfaces in the scene.

(physics) The projection of a grid of lines onto a target in order to obtain information of its structure, typically by analysing the Fourier transform of the reflected light

plural of oblique illumination

A microscopic technique where light is projected at the specimen from an oblique, slanting angle to reveal features with higher contrast.

(informal, Britain, simile) Very brightly lit.

A form of microscopy that employs structured illumination to observe biological structures smaller than the wavelength of the light used