Skip to Content

Neutral density reference filters

Calibration of transmittance or optical density of spectrophotometer reference filters can be made in the wavelength range 280 nm to 1000 nm using a high accuracy spectrophotometer.  Clients can submit their own filters for calibration or filters can be made to the client's requirements in our optical workshop.  Neutral density glass filters are used at wavelengths greater than 400 nm.  Reflectorised metal on quartz filters can be made for use at wavelengths shorter than 400 nm but can also be used at longer wavelengths.

Wavelength calibration filters

The wavelength of maximum absorption of a number of absorption lines in holmium and didymium  filters can be calibrated using a high accuracy spectrophotometer.   Wavelength filters can also be supplied from our optical workshop.

UV-Visible Certified Reference Materials

Materials and Calibrations Supplied by MSL

Prices listed are in NZD, exclusive of GST, and are indicative only, depending on the number of items included in a report. Manufacture and Calibrate NZD Re-calibration NZD
Potassium Dichromate Filters              
       1 filter at up to 6 wavelengths   800
  each additional filter   100
Neutral Density Reference Filters    
  1 filter at up to 6 wavelengths 1300 800
  each additional filter 600 100
Wavelength Calibration Filters    
  Holmium oxide glasses(4 lines) POA 600
  Didymium oxide glasses(4 lines) POA 600
  Each extra absorption line POA 60
Stray light filters   POA


From the measurement of the spectral transmittance of filter glasses or the diffuse reflectance of materials over the visible wavelength range (360 nm to 830 nm) the CIE tristimulus values X, Y and Z, and the chromaticity coordinates x and y can be calculated for the following standard CIE illuminant sources: A, C, D55 and D65.

Measurements of transmittance are made on our high accuracy spectrophotometer using collimated light with a bandwidth up to 3 nm.

Diffuse reflectance measurements are made on the high accuracy spectrophotometer using integrating spheres in the 0°/diffuse geometry (specular reflectance excluded) or the 6°/diffuse geometry (specular reflectance included).

Contact details

For information on these services please contact Annette Koo.