High framerate and high dynamic range electron microscopy
Methods and systems for acquiring transmission electron microscope video data on a rolling-shutter detector at an enhanced frame rate and without temporal distortions are described. Also described are methods to enhance the dynamic range of image and diffraction data acquired using a transmission electron microscope. The disclosed methods and systems may also be applicable to photon detection and imaging systems.
1. A system for acquiring transmission electron microscopy data, the system comprising:
a transmission electron microscope including a two-dimensional deflector configured to deflect electrons transmitted or scattered by a sample positioned at a sample plane and a two-dimensional detector array including two or more sub-regions, each sub-region configured to detect a portion of the electrons; and
a controller configured to modulate a deflector control signal such that the electrons are sequentially deflected to the two or more sub-regions of the two-dimensional detector array and to synchronize modulation of the deflector control signal with a detector array readout cycle and a shutter synchronization signal such that the electrons are directed to a sub-region within the two or more sub-regions that is not actively being read out.
2. The system of claim 1 , wherein the two-dimensional deflector is a two-dimensional electrostatic deflector or a two-dimensional electromagnetic deflector.
3. The system of claim 1 , wherein the two-dimensional detector array comprises a charge-coupled device (CCD) image sensor, a complementary metal oxide semiconductor (CMOS) image sensor, an electron direct detection (EDD) camera, or a time-of-flight (ToF) image sensor.
4. The system of claim 1 , wherein the two-dimensional detector array includes a plurality of individual detectors.
5. The system of claim 4 , wherein the two or more sub-regions of the two-dimensional detector array include distinct detectors of the plurality of individual detectors.
6. The system of claim 5 , wherein the distinct detectors have different sensitivity levels or detection capabilities.
7. The system of claim 1 , wherein a switching time for the two-dimensional deflector is less than 10 microseconds.
8. The system of claim 1 , wherein the deflector control signal is configured to modulate such that a dwell time for deflecting the electrons to each of the two or more sub-regions is different for at least one of the two or more sub-regions.
9. The system of claim 1 , wherein a dwell time for deflecting the electrons to the series of two or more sub-regions ranges from about 1 microsecond to about 100 milliseconds.
10. The system of claim 1 , wherein a duty cycle for acquiring the transmission electron microscope data is at least 90% without incurring temporal distortion of the transmission electron microscope data.
11. The system of claim 1 , wherein the controller is further configured to collect a plurality of frames of image or diffraction data and to process the plurality of frames of image or diffraction data for the two or more sub-regions, wherein the processed data is used to create video data having a framerate at least 4× faster than a read-out rate of the two-dimensional detector array.
12. The system of claim 1 , wherein the two-dimensional deflector includes a first electrode and a second electrode, wherein at least one of the first electrode and second electrode is configured to be held at a fixed voltage.
13. The system of claim 1 , wherein the two-dimensional deflector includes a first electrode and a second electrode, wherein at least one of the first electrode and second electrode is configured to differ in magnitude or have the same or opposite sign as another electrode.
14. The system of claim 1 , wherein the deflector control signal is programmable to specify a number of exposure regions, an order in which sub-regions are exposed, and a duration of exposure at each sub-region.
15. The system of claim 1 , further including a second deflector configured to reduce image or diffraction data distortion.
16. The system of claim 1 , wherein the transmission electron microscope data captured by each of the series of two or more sub-regions includes a frame of image or diffraction data.
17. The system of claim 1 , wherein the modulation synchronization is based on at least one of a sample position, a focus depth, and a convergence angle.
18. The system of claim 1 , wherein the modulation synchronization is initiated by a sending of the deflector control signal or the shutter synchronization signal to a controller.
19. A system for acquiring transmission electron microscopy data, the system comprising:
a transmission electron microscope including a two-dimensional detector array having two or more sub-regions, the transmission electron microscope configured to transmit electrons towards a sample in a sample plane and the two-dimensional detector array; and
a two-dimensional deflector configured to deflect the transmitted or scattered electrons by the sample to the two or more sub-regions of the two-dimensional detector array, wherein the deflection is synchronized with a series of recurring detector array read-out cycles, wherein the deflection of the transmitted electrons or scattered by the sample are directed to sub-regions that are not actively being read out.
20. The system of claim 19 , wherein the two-dimensional deflector is a two-dimensional electrostatic deflector or a two-dimensional electromagnetic deflector.
21. The system of claim 19 , wherein the two-dimensional detector array comprises a charge-coupled device (CCD) image sensor, a complementary metal oxide semiconductor (CMOS) image sensor, an electron direct detection (EDD) camera, or a time-of-flight (ToF) image sensor.
22. The system of claim 1 , wherein a switching time for the two-dimensional deflector is less than 10 microseconds.
23. The system of claim 1 , wherein the two-dimensional deflector includes a first electrode and a second electrode, wherein at least one of the first electrode and second electrode is configured to be held at a fixed voltage.