1. Your submission of the filters with following information:  

• Article no.
• Serial no.
• Wavelength to be measured
• Slit width(s) to be measured
• Documentation of measurement prior to cleaning (yes/no)
• Quotation no., if you have already received a quotation from us
• If you have an order number, please note that on your delivery note
• Billing address
• Delivery address (if different from billing address)
• Special request e.g. additional wavelengths, etc.

2. Verification of the filter material

3. Determination of recertification parameters

4. Checking of the filter regarding integrity, scratches, etc.

5. Perform recertification

6. Creation of certificate

7. Return of the recertified filters incl. DAkkS certificate

How often do I have to recertify my certified reference material?

It is recommended to recertify it regularly to ensure the validity of the calibration results of the certified reference materials. The periodicity of this recertification is up to the user and is also specific to the laboratory environment in which it is used. To establish a statistical basis for setting this recertification interval, it is recommended to have the filters recertified every 12 months in the first three years of use. After that, at a periodicity considered appropriate for the specific laboratory environment where the interval between the calibrations is determined from the data obtained in the first three years.

A review of this process should be part of any formal control of the system and any major changes in the laboratory environment should be evaluated with respect to the impact on the unit’s calibration.