LD Laser diode:
is a type of light source which generates a single frequency in the high end of the infrared spectrum and has a bandwidth of 1000 MHz. It is used in fibre optics and infrared links.

Lead acid battery:
is a type of DC power source which is similar to a car battery. It is generally used in temporary installations with DC cameras.

LED Light Emitting Device:
is a type of light source which generates an infrared frequency when stimulated by electricity. It is used in fibre optics , infrared links and as an infrared light source for monochrome cameras.

Lens calculator:
is a calculator provided by many lens manufacturers to help calculate the focal length of the lens that will provide the required scene.

Lens hunting:
is a field problem in which the iris opens and shuts alternatively. A correct ALC adjustment in the lens could rectify the problem.

Lens mount:
see C-mount or CS-mount.

Lens wheel:
see lens calculator.

Light:
is electromagnetic radiation between 400 nm and 750 nm which is detectable by the human eye.

Light sensor:
is a device which is activated by a pre-set amount of light falling on it. It can be used to switch infrared illuminators On / Off.

Limit switch:
is a device placed inside or outside the Pan Tilt head and used to limit the angles of pan and tilt.

Line:
is the basic unit of a frame or field containing the charge which is proportional to the light falling at various points on the scanning line.

Looping switcher:
is a type of switcher with looping outputs. These outputs allow the camera to be connected to another device without affecting the usage of the switcher.

Lumen:
is a measurement of light which indicates the amount of light radiated by a one candela light source.

Luminous flux:
is the rate of flow of light.

Luminance signal:
is that part of the video signal which contains the information on the brightness of the picture.

Lux:
is an international unit of illumination. It is the amount of uniform light falling on an area of 1 square meter and is measured in lumen per sq. meter.