nzachri Thank you for bringing that topic to the forum!
It is of great importance to the microfedometry.
Indeed, accelerating measurements by increasing the light intensity on the sample—such as by raising the electric current through an LED source—has a serious drawback.
The reason is that the sample’s response to light is nonlinear. This means that doubling the light intensity does not simply make the sample fade twice as fast; it usually causes it to fade faster than that.
In other words, the fading rate increases more than proportionally with light intensity.
Often, an MFT is used to determine the so-called light budget for an art piece. This essentially serves as a guideline for how long, and at what light intensity, the piece can be exposed daily while keeping its photodegradation within acceptable limits. Ideally — though impractically — the measurement would use a light intensity similar to that experienced by the piece during actual exhibition. This would yield the most accurate predictions.
In practice, however, higher light intensities are typically used, which results in an overestimation of the fading rate.
This is a trade-off between measurement speed and accuracy of the result, but at least it keeps us on a safe side as far as the art piece preservation is concerned.
I would bring other people that are more experienced with that issue …
