Originally Posted by plasma_fan
I suppose my question is how do we prove the reference meter is actually the reference in all circumstances?
You don't need a large number of samples for certified meters, since all certified meters have very low devations and virtually the same performance.
You need large meter samples for meter that are not coming with certificate....
The certifications of each meter proofs that is reference grade, for JETI the whole process includes:
- intake measuring check
- mechanical and optical alignment test
- wavelength check and possibly recalibration (low pressure discharge lamps HgAr, Cd, software JETI FitTool)
- sensitivity recalibration (included in software JETI LiVal, but password protected)
Spectral Radiance with OL 455 (Gooch & Housego, traceable to NIST)
Spectral Irradiance with OL 200/ UV 40 (Gooch & Housego, traceable to NIST) → Set up see below
Spectral Radiant flux with Wi40/G (Osram, traceable to PTB)
- automatic test measurements (3 times on 20 different spectra) to check device stability, device intercomparability and comparability to a reference unit (CS-2000 of Konica Minolta)
issuing of the calibration certificate (example).
As for i1PRO it's certification has to do only by measing some BCA tiles at Reflectance Mode, but to measure displays it's working at Emissive Mode and at i1PRO's certification doesn't say anything about it's accurancy in Emissive mode, you have only certification that is valid for measuring reflective light (printing/paper industry).