Luminous flux is a total emitted light energy that a light source sent out the light to the around space. Different light source sent out luminous flux in distribution space is different. The basic unit of luminous intensity is the candela, it indicates that the surface for point light source form the angle sent out the luminous flux.1cd = 1lm/1sr.
The luminous intensity of LED is usually refers to the luminous intensity on normal direction. If the radiation intensity is (1/683) W/sr, so glow 1 candela.
Due to the structure characteristics of the LED, in order to improve the luminous efficiency, fitted reflector at the bottom, in fact itself a lamps and lanterns.
Requirements for the LED luminous intensity measuring instrument:
A. Correct measurement Angle dΩ＝0.001sr(A) dΩ＝0.01sr
B. Correct measurement mechanical axis
C. Effectively prevent stray light design
D. Precision V (lambda) light detector
E. Provide V (lambda) light detector spectral data, facilitate the correct measurements
F. Equipped with high stability power supply.