**Method 2005: Peak Emission Wavelength, Spectral Radiation Bandwidth and Spectrum Power Distribution**

1 Objective

Measure the peak emission wavelength, spectral radiation bandwidth and spectrum power distribution of the measuring LED device under the rated condition.

2 Test chart

Picture 11 method 2005 test chart

D：The measuring LED device

G：Current source

L：Focus lens system

G：Current source (dc or pulse)

D2,D3：Eliminate stray light diaphragm;

M：Monochromator

RM：Radiation detection system including diaphragm D1

Note: the wavelength resolution and bandwidth of the monochromator should make the test have suitable precision. The spectral response of the radiation detection system should be calibrated. For convenience of measurement, the curve peak can be expressed by using 100%. If the spectrum through rate of the monochromator and the spectrum sensitivity of the radiation detection system are not constant, the recording measurement data should be revised.

3 Test procedure

Within the scope of the spectrum needed, adjust the wavelength of the monochromator to make the radiation measuring system get to the maximum readout, the corresponding wavelength is the peak wavelength (λ p), and then adjust the monochromator peak wavelength of the λ p to half the readout value of the peak wavelength to obtain the corresponding wavelength λ 1 and λ 2, the difference of them is the spectral radiant bandwidth. According to the requirements of the wavelength interval, measure and record the spectrum power value of each wavelength that is namely the spectrum power distribution.

Picture 12 Spectral distribution bandwidth

4 Rated condition

Environment and tube temperature

Rated forward current (DC or pulse)

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