the world > matter > physics > electromagnetic radiation > light > [noun] > regulator, modifier (3)
A flat vertical panel of fabric, paper, wood, etc., typically used in scientific experiments to intercept light, heat, or other radiation; a…
an electrical device which regulates the amount of light passing through it.
A pattern of opaque and transparent sections for selectively allowing light or other radiation to pass; spec. one in the shape of a disc, rotated in…