An optical wedge is a strip of material that is clear at one end and gradually becomes more opaque toward the other. It is used in photography and photochemistry to study and measure the effect of varying light intensities on light-sensitive materials, such as photographic film or paper.
By exposing a sensitized material through an optical wedge, photographers and technicians can evaluate tonal response, contrast, and exposure characteristics. This tool is essential in testing, calibration, and scientific research to understand how materials react to different levels of illumination.