Image Engineering camSPECS User Manual page 31

peak value. A failed measurement may be repeated, e.g., if a wrong filter was measured. The next filter in
the queue is highlighted in the display of the camSPECS filter matrix. After the measurement procedure is
finished, a new calibration file is created and is immediately available in the spectral response module.
Note:
The calibration device has a temporal temperature dependency, which may influence the
intensity measurement of the filters. It is, therefore, necessary to plug the device into the PC
with the USB cable at least 10 minutes before the start of measurement. This time is needed to
heat the calibration device to a working temperature.
Description of the numbered controls marked in the overview image of this chapter:
1. Click the button Scan for calibration device to scan USB devices for a connected device. In some
cases, it is necessary to disconnect and connect the calibration device from the computer and
then search again.
2. If a connected calibration device is available for measurement, some information is displayed
here: the serial number, the firmware version, and the integration time for one filter measurement.
3. In this editing field, a name for the final calibration file can be edited; it has the form
"Filter_calibration_DD-MM-YYYY by default. This name displays the spectral response module in
the menu Calibration file (chapter 4.5).
4. Put the covering cap onto the aperture of the calibration device or shade it completely by other
means. The calibration procedure is initialized with a dark measurement by clicking the start
button, and the Optimize integration time button will be active for a supported spectrometer. If
selected, directions are stated above detailing the proper sequence of dark readings and color
filter readings specified in the spectrometer_settings.txt file. If this function is selected, the default
values in the spectrometer_settings.txt will be updated with the optimized values. It is essential
not to move the spectrometer probe until the text under the spectral plot window shows that the
iterative optimization is finished, and the measurements are complete. Next, all filters must be
measured. Remove the cap from the aperture of the calibration device and measure the filters
highlighted in the image above [8].
5. Place the measurement head in the upper left hole, which is the first filter to be measured. Click
the Measure button. Check the result in the graph: The calculated center wavelength may differ
from the nominal value but generally not more than ± 2 nm. The nominal value for the current
filter is also displayed right beneath the overview image [8].
If the result is unsatisfactory, repeat the measurement by clicking the button Repeat. Only the last
measurement can be repeated. After all color filters are measured, the subsequent measurement
is the ND filters. Please remember that another dark measurement is required between each
filter.
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