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LED Luminous Intensity

By: DeRun   Views:5527  

The luminous intensity of the concept requires a light source is a point light source, or requiring the size of the light source and detector area is small enough compared with the distance from the light detector.

However, in many practical applications of the LED measurement, often is not long enough to measure the distance, the size of the light source is too large or is too large solid angle constituted by the LED and detector surface, in this near-field conditions, and not very to ensure that the law of the inverse square of the distance, the actual measurement of luminous intensity values ??vary with the type of the several factors, thus, strictly speaking, does not measure the real LED luminous intensity.

To solve this problem, so that the measurement results can be generic comparison, the average luminous intensity of the concept of the CIE recommended: V of the light flux irradiated in the light detector at a certain distance from the LED, and the ratio of the solid angle constituted by the detector. Wherein the solid angle may be the area S of the detector divided by the measured the square of the distance d is calculated.

From a physical point of view, the concept of the average luminous intensity is no longer associated with the concept of luminous intensity so close, and more to do with the design of the luminous flux measurements and institutions. CIE about the the LED measurement of near field conditions, there are two recommended standard conditions: the CIE standard conditions A and CIE standard conditions B. These two conditions are required, the detector has an area of ??1cm2 (corresponding diameter 11.3mm) circular entrance aperture .