First of all, on all comparisons the Delta E 2000 is always less than 0.1, not 0,01, sorry for the mistake.
Right - that matches my experience of an instrument that is in good shape, and is within the manufacturers short term repeatability specifications.
The phenomenon I'm referring to takes the instruments outside their specifications. Subsequent experimentation with my i1Pro2 indicates that something like short strip reads (1-5 seconds lamp on time) with about 5 seconds off time between strips is quite effective in developing this behavior.
** Have you checked your i1Pro with i1Diagnostics?, this software when checking the instrument also modify some parameters if necessary: http://www.xrite.com/product_overview.aspx?Action=support&ID=766
As far as I can see (looking at how i1Diagnostics works, and what operations it performs over USB), it doesn't do anything special - just operates the instrument like any application does. I presume it analyzes the resulting measurements in a way that normal applications do not, but it doesn't appear to modify the instrument in any way.
The report "Reflectance drift test: Successful" is intriguing - perhaps this test is looking for exactly the type of thing I've noticed >
So I tried "dirtying up" my i1Pro2 - 50 x 2 second measures with 5 secs between increased the thermal drift from 0.08 DE to 0.18 DE, and then ran i1Diagnostics on it.
But it still reported "Reflectance drift test: Successful". So either it's not testing for this, or it's error threshold is quite high.
After 60 seconds of "cleaning", it was back to 0.07 DE thermal drift.
[ Interestingly, I tried "dirtying up" one of my i1Pro RevA's, and couldn't budge it - drift stayed at 0.06 - 0.07. Either the effect is very device instance specific, or the i1Pro2 has a different type of lamp in it ? ]
** All my measurements were performed with i1Profiler software. Perhaps the software performs any correction ?. I suggest that you take the same test with i1Profiler
I've cross checked the behavior using X-Rite driver output, as well as my own driver. The driver is what feeds the measurements to applications such as i1profiler, and yes, I've checked that i1profiler doesn't manipulate the numbers it is fed by the driver. So it is a characteristic of the device, not the software (although how it is driven certainly influences the behavior.)