Rgb Lasersysteme QWAVE UV Lux-Meter, illumination measuring device, Brightness meter, DSA491006 Datenbogen
Produktcode
DSA491006
Operation
13
To take a reference spectrum for transmission or absorption spectroscopy, turn on the
light source again, remove the sample, set an appropriate exposure time and temporal
averaging and click the “Take Reference Spectrum” button [ ]. After selecting the “Use
Reference Spectrum” button [ ], you can take spectra of your sample for measuring
absorption or transmission.
light source again, remove the sample, set an appropriate exposure time and temporal
averaging and click the “Take Reference Spectrum” button [ ]. After selecting the “Use
Reference Spectrum” button [ ], you can take spectra of your sample for measuring
absorption or transmission.
To take a reference spectrum for reflection spectroscopy, you need a white reference
sample to calibrate the setup for 100 % reflection. However, all real-world reference
samples have a reflection of less than 100 % and an uneven spectral distribution.
Therefore, for accurate measurements you also need to supply a reference spectrum for
your reference sample. To take a reference spectrum, place the white reference sample
where you’ll later place the sample to be measured. Then set an appropriate exposure
time and temporal averaging and click the “Take Reference Spectrum” button [ ]. In the
following dialog window, you can also specify a data file that includes a calibrated
spectrum of your reference sample. After selecting the “Use Reference Spectrum” button
[ ], you can measure reflectivity spectra.
sample to calibrate the setup for 100 % reflection. However, all real-world reference
samples have a reflection of less than 100 % and an uneven spectral distribution.
Therefore, for accurate measurements you also need to supply a reference spectrum for
your reference sample. To take a reference spectrum, place the white reference sample
where you’ll later place the sample to be measured. Then set an appropriate exposure
time and temporal averaging and click the “Take Reference Spectrum” button [ ]. In the
following dialog window, you can also specify a data file that includes a calibrated
spectrum of your reference sample. After selecting the “Use Reference Spectrum” button
[ ], you can measure reflectivity spectra.
The y axis of the spectrum now shows the relative intensity of the measured spectrum
compared to the reference spectrum. In the “Options” dialog from the File menu you can
choose different units for displaying the spectra:
compared to the reference spectrum. In the “Options” dialog from the File menu you can
choose different units for displaying the spectra:
• Ratio shows the ratio of the measured spectrum to the reference spectrum as in
the formula for ! λ above.
• Percentage shows the same value ! λ , but written as a percentage (i.e. multiplied
by 100).
2
This unit is usually used for transmittance.
• Absorbance shows the spectral absorbance ! λ according to the formula above.
You can choose between natural and base 10 logarithm.
These options only determine how to display the spectra in the diagram. The do not
modify the actual spectrum data.
modify the actual spectrum data.
If your light source does not cover the full range of the spectrometer, the calculated
spectrum may show large amounts of noise outside of the wavelength range of your
light source. This is normal and reflects the fact that the measurement has a large
uncertainty at these wavelengths.
spectrum may show large amounts of noise outside of the wavelength range of your
light source. This is normal and reflects the fact that the measurement has a large
uncertainty at these wavelengths.
These measurements are quite sensitive to changes of the sample illumination. If in
doubt, you may want to take another reference spectrum to check if it is still valid.
doubt, you may want to take another reference spectrum to check if it is still valid.
3.9 Calibration
The calibration for the wavelengths, dark spectra and spectral sensitivity are stored on
the device and loaded automatically during device initialization. So in contrast to almost
any other spectroscopy software, you don’t need to worry about taking dark spectra and
other calibration parameters, it’s all done automatically.
the device and loaded automatically during device initialization. So in contrast to almost
any other spectroscopy software, you don’t need to worry about taking dark spectra and
other calibration parameters, it’s all done automatically.
2
Please note that „percent“ means nothing else than “divided by 100”.