Diffraction pattern detection in a transmission charged particle microscope

A transmission charged particle microscope comprising:

• a specimen holder, for holding a specimen;
• a charged particle beam column, for producing a charged particle beam and irradiating at least a portion of the specimen therewith;
• an imaging system, for collecting charged particles that traverse the specimen during said irradiation, and directing them onto a detector configured to record a diffraction pattern of said irradiated portion of the specimen;
• and
• a controller, for controlling at least some operational aspects of the microscope, configured to:
• operate said detector in particle counting mode;
• record said diffraction pattern iteratively in a series of successive detection frames, and sum said frames;
• and
• during recording of each frame, invoke a scanning assembly to effect relative motion of said diffraction pattern and said detector so as to cause each local intensity maximum in said pattern to trace out a locus on said detector.

A method comprising:

• operating a detector of a charged particle microscope in a particle counting mode;
• irradiating a sample with a charged particle beam;
• iteratively recording, by the detector, a diffraction pattern of the irradiated sample in a series of successive detection frames, the diffraction pattern formed in response to the charged particle beam traversing the sample;
• and
• while recording each frame of the series of successive detection frames, causing, by a scanning assembly, relative motion of the diffraction pattern and the detector to cause each local intensity maximum of the diffraction pattern to trace out a path on the detector.