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 (2) the light intensity and the light intensity distribution

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Figure 4: LED light intensity test in question

    Shown in Figure 4, the point light source in all directions uniformly in the spatial intensity distribution at different distances in different detectors receive aperture to receive the test results will not change, but the LED as the light intensity distribution such that the test results are inconsistent With the test distance and the detector aperture change. Therefore, CIE-127 test conditions presented two recommended that each LED in a light under the same conditions and evaluation test, the current condition has been CIE-127 each LED manufacturers and detection means references.

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Figure 5: CIE-127 Recommended LED light intensity test conditions

(3) spectral parameters

LED spectrum characteristic parameters include peak emission wavelength, spectral bandwidth and spectral radiant power distribution. Monochrome LED spectrum of a single peak, the peak wavelength and bandwidth characteristics, said the white LED spectrum synthesized by a variety  LED Down lights of monochromatic spectrum. All the LED spectral properties can be expressed by a spectral power distribution, the spectral power distribution of the LED to obtain color parameters can be calculated.