Hints and tips - camera integration time and gain

It is important to understand the effect of changing the camera integration time and gain on the EBSD data.

When a scanning electron microscope is set-up for an EBSD experiment, the accelerating voltage and probe current must be chosen carefully.  Higher probe currents and accelerating voltages make the diffraction pattern brighter on the phosphor screen so the camera integration time and total mapping time is less.  However, higher probe currents will reduce the spatial resolution and may result in contamination forming on the sample surface.

INCA Crystal allows the camera integration time and gain to be adjusted independently.  Increasing the gain means the integration time required to collect a pattern is reduced.  However, this also increases the noise in the diffraction pattern..   INCACrystal can easily solve noisy diffraction patterns, but there will be a point where number of unsolvable patterns in a map becomes unacceptably high.   Some experimentation for the optimum parameters for your microscope and sample will be required.

In the example below, a crystal orientation map was collected from nickel with two camera settings.  At the higher gain setting, the crystal orientation map is adequate, but the number of unsolved points has increased.

Conclusion

Choose the microscope probe current and accelerating voltage that are appropriate for the sample.  Select the shortest camera integration time and highest gain that gives diffraction patterns that are reliably solved.