Detection and correction of system responses in real-time

A system, comprising:

• an electron beam tool including:
• an electron beam emitter configured to emit electrons in an electron beam towards a specimen;
• a stage configured to hold the specimen;
• an electron detector configured to detect secondary and/or backscattered electrons emitted by the specimen to obtain electron data, wherein the electron data defines a detection signal;
• and
• a controller in electronic communication with the electron beam tool, the controller having a processor;
• wherein the controller is configured to:
• instruct the electron beam emitter to modulate the electron beam to obtain a beam signal wherein the modulating is based on a wave that controls the beam signal, and wherein the modulating includes adjusting a beam current that reaches the specimen;
• determine a comparison between the wave controlling the beam signal and a wave for the detection signal;
• and
• filter the detection signal using the comparison.

A non-transitory computer-readable storage medium, comprising one or more programs for executing the following steps on one or more computing devices:

• instructing an electron beam tool to emit an electron beam towards a specimen;
• modulating the electron beam to obtain a beam signal, wherein the modulating is based on a wave that controls the beam signal, and wherein the modulating includes adjusting a beam current that reaches the specimen;
• receiving electron data from an electron detector detecting secondary and/or backscattered electrons emitted by the specimen, wherein the electron data defines a detection signal;
• determining a comparison between the wave controlling the beam signal and a wave for the detection signal;
• and
• filtering the detection signal based on the comparison to obtain a filtered detection signal.