Photonics Dictionary

Luminous flux incident per unit area of a surface; luminous incidence. (The use of the term "illumination" for this quantity conflicts with its more general meaning.)

Law relating the illuminance (or irradiance) of a surface to the cosine of the angle, q, between the normal to the surface and the direction of the incident wave.

Unit of illuminance equal to one lumen per square foot. (fc).

A high-sensitivity camera is a type of camera designed to perform well in low light conditions, capturing clear and detailed images with minimal noise. These cameras typically feature advanced sensor...

The general term for the application of light to a subject. It should not be used in place of the specific quantity illuminance.

The law stating that the illuminance (or irradiance) from a point source varies as the inverse square of the distance between the source and the receiver.

SI unit of luminous incidence or illuminance, equal to 1 lumen per square meter.

The product of exposure time and irradiance or illuminance.

A device used to compare the luminous intensities of two sources by comparing the illuminance they produce.

Photocells of various kinds used to measure photometric quantities; i.e., intensity, luminance and illuminance. Meter readings are used to express illuminance and, by calibration, to measure...

An object that has a sinusoidal variation of luminance. Its image will have a sinusoidal variation of illuminance and the only effect of degeneration by the lens system will be to reduce the...

The ratio of the illuminance at the peak of the diffraction pattern of an aberrated point image to that at the peak of an aberration-free image as formed by the same optical system.

That level of retinal illuminance resulting when a surface with a luminance of 1 candela/m2 is viewed through a pupil with an area of 1 mm2.

In an optical system, the gradual reduction of image illuminance as the off-axis angle increases, resulting from limitations of the clear apertures of elements within the system.