A scanning charged particle microscope includes a layered charged particle beam column package; a sample holder; and a layered micro-channel plate detector package located between the column package and the sample holder. The outer sleeve has ports connected thereto for the admission of pressurized fluid and the delivery of pressurized fluid from the pressure control valve to the work or back to a sump. The localized Zernike moment includes a projection of the local iris region into a space of Zernike polynomial orthogonal basis functions.