MicroCalT24: Important Notes on Calibration

There are two calibration methods that the user should understand before ordering. First, consider the definition of transmittance:

Tλ is the spectral transmittance and Lλ is the measured flux passing through the sample (Lλ,sample) and reference (Lλ,reference). The choice of reference can significantly affect the transmittance reported.
The original calibrations (part numbers AR-MicroCalT24-CT and AR-MicroCalT24-Cal) use a blank slide (cover glass only) as the reference transmittance. Therefore the transmittance is of the slide film only. This is because the blank slide accounts for the transmittance of the glass and the cover slip. The only material left in the path of the light is the color film itself.
A more traditional method uses a reference called open port where the reference flux is equivalent to the incident flux on the sample.
For the original transmittance referencing the blank slide, use part numbers AR-MicroCalT24-CT for a new purchase calibrated slide pair and AR-MicroCalT24-Cal to recalibrate a slide pair.
For transmittance relative to the open port, use part numbers AR-MicroCalT24s-CT for a new purchase of a calibrated slide and AR-MicroCalT24s-Cal for a recalibration.
Note that both calculations for transmittance can be provided with the purchase of AR-MicroCalT24-CT or AR-MicroCalT24-Cal. The purchase of AR-MicroCalT24s-CT will contain only the color slide (no blank slide is included). Therefore only the open port reference transmittance can be provided for AR-MicroCalT24s-CT and AR-MicroCalT24s-Cal.