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Note that auto-range facility is not provided in the graphical display mode.
Wavelength
Photodiode heads do not have a linear response and the wavelength of the incident
radiation must be entered by the operator for meaningful measurements to be made.
The wavelength response of each detector head is stored in the head at calibration
and the correction factor is automatically applied once the wavelength has been
entered.
To enter the wavelength of incident radiation, press Menu, scroll to Wavelength
using the up arrow (8) or down arrow (2) buttons, press Enter and use the numeric
keypad to type in the wavelength in nanometres (nm). Press Enter when done. Press
Cancel instead of Enter and the data entry is removed ready for re-entry. Press
Cancel again and the display reverts to the main display.
Note that for thermal detector heads the wavelength is not required to be known and
this menu option is not available.
Peak/Average Measurement
In peak measurement mode, the display indicates the maximum value that was
reached in every approximately 0.5-second period.
In average measurement mode, the optical signal is averaged with a 200ms time
constant and will give a useful average (mean) value for steady (CW) sources or
pulse frequencies at or above 50Hz.
To set peak/average measurement in digital display mode, press menu, scroll to
Measure Mode using the up arrow (8) or down arrow (2) buttons, press enter, scroll
down the list to select the required measurement mode and press enter.
The possibility of having a variable averaging time constant is being reviewed. It is
envisaged that this would offer time constants from 100ms to 10s, so that the display
can be set to respond quickly with a short time constant or give a good average for
slow or noisy signals with a long time constant.
In waveform display mode, the actual instantaneous level is displayed and there is
no option to set peak or average mode.
