LED Technology Luminous intensity

LEDs are light emitting opto-electronic semiconductor components. Since decades, they are used in the field of man-machine communication to convert electrical signals into visual information.

Typical LED applications encompass household appliances, telecommunications, life sciences and signal technologies. Moreover, due to its low power consumption and excellent operational reliability LED technology partly replaces conventional lighting solutions already today.

The development of LED technology progresses at rapid pace, as light efficiency (Lumen/Watt) increases, colour qualities improve and temperature ranges get manageable. Consequentially, new territories of applications will open up, especially in the field of standard lighting.

Based on their structure, LEDs can be split into quattuor groups:

Light Technology

Light technology LED light modules of up to 350 mm Φ.

Illuminance Ev

Illuminance Ev is defined as the areal light flux density on a lighted area hit by the luminous flux Fv. Illuminance is measured in lux (lx=lm/m²), where luminous flux and area are put in as [lm] and [m²], respectively. Based on the illuminance Ev, a specific lighting solution can be calculated and designed.

Luminance Lv

Luminance is defined as the areal density of luminous intensity of a light emitting or reflecting area which radiates the luminous intensity Iv at a given angle. Luminance Lv is measured in [cd/m²].

Luminous intensity Iv

Luminous intensity Iv [cd] is among the key parameters describing an LED or LED display. It is defined as the luminous flux emanating from a point source within a solid angle W (steradian) into a particular direction. Hence, luminous intensity is the directional luminous flux Fv within a solid angle W. Today's LEDs achieve a luminous intensity of Iv=10 cd or more. As intensity depends on the radiation angle, an LED chip equipped with a 30° reflector achieves a higher luminous intensity than an identical LED chip with a 60° reflector. That is, using a 60° reflector the same luminous flux Fv has to illuminate a larger area than using a 30° reflector.

In addition to these parameters, VS Optolelectronic's in-house photometric laboratory is equipped to analyse all photometric, colorimetric and radiometric characteristics. Two in-house Gonio spectrum radiometers exactly determine the radiation characteristics of LEDs and


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