What Makes a Good Image?

Contrast and Brightness

All SEM data is displayed as a measure of intensity. We must adjust the greyscale histogram to optimize the display and highlight the features of interest.

Very low contrast, high brightness.

Good contrast and brightness. Contrast may be low.

Very high contrast, low brightness.

Alignment

A well aligned beam is essential. Poor stigmator alignment makes images blurry even when focused.

Some features may appear sharp even when the stigmators are misaligned.

When out of focus, the misalignment is more pronounced.

Small details are visible when well aligned.

Use Appropriate Beam Settings

Accelerating voltage matters! The last user likely needed different settings for their sample. Check the accelerating voltage (and probe current or spot size) when you start using the SEM. Try imaging with different settings for the first few sessions to learn what works best for your sample.

15kV

The image is noisy and features are blurred. Charging is strong on larger features and smaller features are not apparent.

5kV

Surface features are clearer than 15kV, but charging still blurs some features.

2kV

Surface features are clearer and charging is reduced.

2kV

Surface details are more apparent at lower voltages.

15kV

Surface details are obscured at higher voltages and edges may appear sharper.

Provide Visual Context

Capturing multiple images at different magnifications or highlighting easily recognized features helps the viewer understand what they are observing in high magnification images.

Lacking an intermediate magnification, it is difficult (if not impossible) to understand that the higher magnification image of the set below is of the interface.

High magnification images are great for showing small details.

Low magnification images help viewers understand what they see in high magnification images.

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