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==Phase contrast in HRTEM==
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The contrast in HRTEM comes from interference in the image plane between the phases of scattered [[electron]] waves with the phase of the transmitted electron wave.
Detectors are only able to
▲The contrast in HRTEM comes from interference in the image plane between the phases of scattered [[electron]] waves with the phase of the transmitted electron wave. When an electron wave passes through a sample in the TEM, complex interactions occur. Above the sample, the electron wave can be approximated as a plane wave. As the electron wave, or [[wavefunction]], passes through the sample, both the [[phase (waves)|phase]] and the [[amplitude]] of the electron beam is altered. The resultant scattered and transmitted electron beam is then focused by an objective lens, and imaged by a detector in the image plane.
▲Detectors are only able to directly measure the amplitude, not the phase. However, with the correct microscope parameters, the [[Interference (wave propagation)|phase interference]] can be indirectly measured via the intensity in the image plane. Electrons interact very strongly with [[crystalline]] solids. As a result, the phase changes due to very small features, down to the atomic scale, can be recorded via HRTEM.
== Contrast transfer theory ==
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