Monday, 25 September 2017

Wind Chime Wavelength Calibration

This post describes how to perform a wavelength calibration using Wind Chime. The methodology is the same as used on the 7205 UV Diode Array:

  1. A scan of the wavelengths from 198nm to 1000nm of the output of the Xenon lamp.
  2. The data is analyzed to find all the peaks in the scan
  3. These peaks are compared against a set of reference wavelengths
  4. If there is a match you can send the corrections to the Spectrophotometer

Press START SCAN to scan each wavelength from 198nm to 1000nm, this will take some time.

Progress is shown

Once done, enter your reference wavelengths. The app will already have populated the fields with default values, to remove a reference just delete the number.

Press ANALYZE, Wind Chime will find all the peaks in the scan and then attempt to find an overlapping match with the reference peaks.

The status will show the number of peaks found, here it is 16. To find more peaks, reduce the slope threshold, to find less increase the slope threshold. Press analyze to recompute.

If you don't get a match remove one of the more troublesome reference points and press analyze again.

Once you are happy press SUBMIT PEAKS, this will first send an ERASE CALPOINTS command to the spectrophotometer and then ADD CALPOINT commands for each of the reference/match pairs.

The spectrophotometer will store the calibration data in its onboard FRAM

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