The traditional incandescent bulb is being replaced more and more by the Light Emitting Diodes (LEDs). Today the LEDs are being used as light source for general illumination applications. They do not only emit light of the desired color but its longer lifetime, low energy requirements and small dimensions make them today very attractive light sources. The spectral distribution of a LED is neither monochromatic (laser) nor broadband (incandescent lamp) but something between the two (near monochromatic source) with a spectral bandwidth of about 10 nm as shown here:
Following radiometric and spectroradiometric quantities are used to characterize LEDs performances:
A. Photometry Measurements
A.1. Average Luminous Intensity Measurements (cd)
A.2. Luminous Flux Measurements (lm)
A.3. Partial Luminous Flux Measurements (lm)
A.4. Illuminance Measurements (lx)
B. Radiometry Measurements
B.1. Average Radiant Intensity Measurements (W/sr) B.2. Radiant Power Measurements (W) B.3. Partial Radiant Power Measurements (W) B.4. Irradiance Measurements (W/m2)
C. Spectral Measurements
C.1. Spectral Distribution C.2. Colorimetric Quantities determined from the spectral Distribution C.3. Color Rendering Index C.4. Dominant Wavelength
