KB018 How can optical sources of interference be minimized?

The Dimetix sensors have an integrated filter glass to keep the influence of possible optical sources of interference small. This so-called band-pass filter has the task to let pass only the signal in the wavelength range of the laser (typically 650nm).

Nevertheless, especially for applications with very strong optical interference sources, an additional filter or shielding can significantly improve the measurement performance.

The following measures can help:

  • Mount an additional bandpass filter in front of the sensor optics.
    Note: Do not mount the filter perpendicular to the laser beam, see Measuring through glass.
    Filter properties: Bandpass filter with CWL: 650nm and FWHM: ~30…40nm (±15…20nm)
  • Use shielding to protect the sensor optics from optical interference sources. Example: Screening plate, pipe in front of the sensor optics.
    Attention: The laser output as well as the receiving lens of the sensor must be free and must not be covered.