• Neutral Density Filter (66.7161961367%)

    Neutral Density Filter

Neutral Density Filter

These references can be used to qualify the absorbance accuracy and linearity of visible spectrophotometers with a spectral bandwidth of 6.5 nm or less, over the wavelength range 440 -635 nm.
Measurements made with these references will be accepted as evidence of instrument qualification by:

  • United States Pharmacopoeia
  • American Society for Testing and Materials
  • Therapeutic Goods Administration (Australia)
  • British Pharmacopoeia

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Schott NG-type glasses have been used for over thirty years for the validation of the absorbance scale and linearity of spectrophotometers in the visible region. Filters with a wide range of transmission and absorbance values can be produced

The spectrum of these filters is essentially flat over the range of calibration.


A range of 18 filters is available from Starna, covering absorbance values from approximately 0.04 A to 3.5 A, calibrated at 440 nm,  465 nm 546.1 nm 590 nm and 635 nm.


A Certificate of Calibration and Traceability and full instructions for use are provided with each Reference Material. Starna Scientific is accredited to both ISO Guide 34 (4001) as a Reference Material producer, and ISO 17025 (0659) as a Calibration Laboratory for optical reference measurements. Starna offers a Lifetime Guarantee on all its Reference Materials.