The invention includes a source stream of neutral particles (neutral atoms and neutral molecules, but not neutrons) in free molecular flow, a beam forming element disposed within the source stream having at least one small aperture located proximal to the sample allowing part of the source stream to pass through the aperture as a beam of neutral particles directed at the sample for revealing the sample, a control positioner for scanning the beam of neutral particles over or through portions of said sample surface, optionally one or more detector nozzles having an inlet positioned to collect neutral particles proceeding from or through the sample surface in free molecular flow, at least one detector, the detector arranged to sense neutral particles proceeding from the sample, and a processor connected to the detector and control positioner for generating an image of said sample.