Glossary of terms

Candela: A unit of measurement of the intensity of light that is emitted by a light source in a particular direction.

Lux: The unit of luminous flux in the International System, equal to the amount of light given out through a solid angle by a source of one candela intensity radiating equally in all directions.

Lumen: A unit of measurement of the amount of brightness that comes from a light source. Lumens define “luminous flux,” which is energy within the range of frequencies we perceive as light.

Integrating Sphere: An integrating sphere is a measurement device with an entrance port that can accept all the directional light output of the device under test, or can totally enclose the device itself. The walls of the sphere should be highly diffuse with high reflectivity (>80%) and the spectroradiometer should be shielded from direct view of the device under test by a baffle system.

IP (Ingress Protection): Ingress Protection (IP) ratings specify the environmental protection the enclosure provides. The IP rating normally has two numbers (IPXX). The first number represents protection from solid objects or materials (dust) where the second number represents protection from liquids (water). With the IP rating IP 54, 5 describes the level of protection from solid objects and 4 describes the level of protection from liquids.

Rechargeable: Denotes a torch which contains rechargeable batteries and charging station. These models are shown with the rechargeable icon.