Quote Originally Posted by zaza
So are you saying that the reflectivity measurement will give you different values for the thickness depending on the history of the sample? i.e. if the deposition rate is fast the reflectivity measurement will give you a certain value for the thickness but if it is slow then you will get a different value for the thickness?

I don't see this as a feature in your initial function. And to be honest, I'm not really sure why this would be the case. I don't profess to be an expert in thin films, but I would have thought that issues with transmission / reflectivity would largely come about due to quality of the sample, which I wouldn't have thought to be a significant issue from this perspective for thin films.
deposition rate may affect the index of the layer, which also needs to be calculated via solver-like approximation. rate does not change drastically. typically it is 1.5-2.5 Angstroms, and change only in the second or third decimal, however it does chage.

Rate gets calculated during the first few points of data collected, after that it remains pretty much the same. So optimization has to occur in the first few seconds, thats the thing, afterwards its just kind of like keeping an eye on it.

furthermore, index can change with change in temperature, quality of coating, etc...again, in the second or third decimal, but still significant enough and needs to be tracked.

it is a significant issue, even if the quartz witness chip is off by a fraction of a degree in the fixture, or if the floor is vibrating, or if the heater is on and emitting infrared radiation...the measuring instrument will compensate, this is where fudging(coefficients ) come in.