– 14 –
IEC 60904-9:2020 © IEC 2020
(integration time) of the detector shall be suitable for the pulse length of the simulator.
Caution should be taken that the spectrum of the simulator might change
during the light
pulse. In the case of spectral shifts, differences in spectral responsivities between the
irradiance monitor and the DUT will introduce spectral mismatch error. The
integration time
should be less than half of the pulse length.
The following features and parameters may determine the quality of spectral irradiance
measurement:
•
Wavelength resolution: The wavelength resolution of the spectroradiometer should be
equal or less than 5 nm in the visible range (300 nm to 900 nm) and 10 nm in the near
infrared range (900 nm to 1 200 nm). The wavelength
step setting of the
spectroradiometer should be equal to or less than the wavelength resolution. Some
apparatus using band pass filters may have wavelength resolution greater than 10 nm.
Such apparatus may be used for classification of spectral match (5.2.3), determination of
SPC (5.5), and determination of SPD (5.6). However, additional apparatus may be
required to satisfy the requirements of Clause 6 for reporting spectral irradiance.
NOTE The wavelength resolution is a measure of the ability of the spectroradiometer to separate two spectral
lines that are close together.
•
Non-linearity of sensor element(s): Spectroradiometers are
typically calibrated with
tungsten calibration lamps at low irradiance level. However, the spectral intensity of solar
simulators may differ considerably from calibration conditions.
•
Stray light or second order wavelength effects.
•
Angular response of input optics: This parameter has a great impact in the presence of
diffuse light.
Available measurement techniques are the use of:
a) a spectroradiometer comprising a monochromator and a discrete detector (typically
rotating grating);
b) a charge coupled device (CCD), complementary metal oxide semiconductor (CMOS) or
photodiode array spectrometer (typically fixed grating);
c) a multiple detector assembly with band pass filters, and
d) a single detector with multiple band pass filters.
Spectral irradiance measurement requires typically the use of two
instruments or discrete
detectors to cover the relevant wavelength range (for example with both a Si and InGaAs
detector respectively). Care shall be taken to select a suitable procedure for the combination
of both measured spectra.
Dostları ilə paylaş: