The main objective of HARMOPLUS is to demonstrate SHG and THG at sub-diffraction resolution using a novel approach inspired from the Re-scan Confocal Microscope (RCM). HARMOPLUS will build and test a prototype system for Re-scan HHG (incorporating also regular RCM) which will provide 40% improved resolution, and 4x increased sensitivity compared to the current state-of-the-art commercial systems for HHG imaging.