Urgent! I knelt down and begged! Who can explain in detail what out-of-plane displacement is and how to measure it by holography? There are many rewards for answering correctly!

If bees crawl on the desktop, the distance they move is called in-plane displacement, and if bees fly out of the desktop, the height they fly is called out-of-plane displacement. The second question you asked is too big. There are no graphs and formulas in Baidu, which is unclear. You can search in VIP and Wanfang. Keywords: digital holography (or digital speckle) out-of-plane displacement, but there are few really good algorithms. It's ok to do graduation project along.