Methods and systems for event modulated electron microscopy
A method for measuring an electron signal or an electron induced signal may be provided. The method may include providing a threshold number of events or a threshold event rate for a pixel on a detector. The method may include collecting from the detector the threshold number of events or determining that the threshold event rate is achieved, wherein a signal at the detector is an electron signal or an electron induced signal from a sample. The method may include modulating an intensity of an electron source directed to the sample in response.
1. A method for measuring an electron signal or an electron induced signal, the method comprising:
(a) providing a threshold number of events or a threshold event rate for an element, a pixel, or a portion of a detector;
(b) collecting from the detector the threshold number of events or determining that the threshold event rate is achieved, wherein a signal at the detector is an electron signal or an electron induced signal from a sample; and
(c) modulating an intensity of an electron source or an ion source directed to the sample in response to the collecting in (b).
2. The method of claim 1 , wherein (c) further comprises directing the electron source or the ion source to another position on the sample.
3. The method of claim 1 , wherein (c) further comprises turning off the electron source or the ion source.
4. The method of claim 1 , wherein (c) further comprises deflecting a path of the electron source or the ion source.
5. The method of claim 1 , wherein (c) is performed in substantially real time.
6. The method of claim 1 , wherein (c) is performed within an electron counting interval of the detector.
7. The method of claim 1 , wherein the threshold number of events or the threshold event rate is determined based at least in part on information about the sample.
8. The method of claim 1 , wherein (c) further comprises modulating an electron or ion dose waveform based at least in part on a number of events determined from the signal.
9. The method of claim 8 , wherein the electron or ion dose waveform comprises a continuously variable temporal profile.
10. The method of claim 9 , wherein the electron or ion dose waveform comprises an arbitrarily defined temporal profile.
11. The method of claim 10 , wherein the arbitrarily defined temporal profile comprises a temporal resolution of less than 10 nanoseconds (ns).
12. The method of claim 10 , further comprising receiving an indication of the arbitrarily defined temporal profile from a user.
13. The method of claim 8 , wherein the electron or ion dose waveform comprises a series of waypoints.
14. The method of claim 13 , wherein the series of waypoints are individually or collectively selectable to construct the arbitrarily defined temporal profile.
15. The method of claim 13 , wherein the series of waypoints comprises greater than 1000 waypoints.
16. The method of claim 1 , further comprising recording a time to achieve the threshold number of events or the threshold event rate at the pixel, the element or the portion of the detector.
17. The method of claim 16 , further comprising forming an image based at least in part on the time to achieve the threshold number of events or the threshold event rate for a plurality of pixels, elements, or portions of the detector.
18. The method of claim 16 , further comprising collecting from the detector the threshold number of events or determining that the threshold event rate is achieved, wherein a signal at the detector is an electron or ion signal or an electron-induced or ion-induced signal from or through the sample.
19. The method of claim 1 , wherein the threshold number of events or the threshold event rate is a mutual information threshold.
20. The method of claim 1 , further comprising, subsequent to (c), providing the threshold number of events or the threshold event rate for a second element or a second portion of the detector.