I have a question that could be rather far out, but potentially doable as well. I am building a robotic book scanner and I plan on using some kind of arm to pick up an individual page in order to turn it. However, because of the nature of pages sometimes wanting to stick together, it might occur frequently that I end up picking up more than one page with my arm. I was wondering if there was a way of sensing if more than one page was lifted up. I made a rough measurement and calculation and determined that the average page thickness is .02 mm, so my sensor would need to be able to distinguish something that minuscule. Is this something that should be done optically, or would it be better to use infrared or ultrasonic methods for measurement? Even better would be a consistent method of lifting up a page that would yield an error rate of 1% and then manually rescan the few pages that were missed.