FRET - Image analysis - Spillover factors (Page 7)
The CFP Spillover factor is calculated in the same manner, except the YFP tag is replaced by CFP. How often to measure the Spillover factors? The factors will reflect changes in light intensity due to the age of mercury lamp, so it is a good idea to measure the spillover factors over the lifetime of the lamp. By tracking photosensor values and changing the bulb after 100 hours of use one can minimize the change in spillover factors, as well as keep the images bright.
Once the factors are available FRETR can be evaluated.