Electron beam control in a scanning electron microscope

TL;DR

Upgrades made to the scanning electron microscope, including a new pump and vacuum gauge, enhance its capabilities and allow for more focused imaging.

Transcript

hey everyone I thought I'd talk about some of the upgrades I've been making to my scanning electron microscope in the past few weeks uh but first I want to give a big thanks to the FEI company for helping me out with this new turbo molecular pump and also a pirani vacuum gauge that I've been using on my sputtering setup so this equipment is super h... Read More

Key Insights

• 👶 Thanks to upgrades from the FEI company, the scanning electron microscope now has a new turbo molecular pump and pirani vacuum gauge.
• 😁 The electron gun in the microscope forms a lens that helps focus the expanding beam of electrons.
• 😁 The use of electron lenses and pinholes helps create a columnated beam of electrons for imaging.
• 😁 Magnetic fields are commonly used for electron beam scanning in electron microscopes, but electrostatic deflection can be a simpler alternative.
• ⚡ The amplification circuit designed for the deflection plates allows for higher voltages and greater control over the scanning area.
• ⚡ The oscilloscope was initially used to generate deflection plate voltages, but a modified circuit was later implemented for better adaptability and higher voltage capabilities.
• ⚖️ The scanning electron microscope is capable of producing images with different scanning patterns and scales.

Questions & Answers

Q: How does the electron gun work in a scanning electron microscope?

The electron gun in a scanning electron microscope releases a stream of electrons that expand due to the repulsive force between them.

Q: How are electron lenses used in the microscope to focus the beam?

Electron lenses, along with pinholes, are used to focus the beam and create a parallel and thin beam of electrons.

Q: Why is the beam scanned across the sample in a raster pattern?

The beam is scanned in a raster pattern to create an image by filling it pixel by pixel.

Q: What are the benefits of using electrostatic deflection instead of a magnetic field?

Electrostatic deflection is easier to implement and allows for higher voltages to be used, allowing for a larger scanning area. However, it may introduce some common mode voltage changes.

Summary & Key Takeaways

• The electron gun in the scanning electron microscope sprays out a stream of electrons that naturally repel each other, causing the beam to expand.

• Electron lenses and pinholes are used to focus the beam, ultimately creating a parallel and thin beam of electrons.

• The beam is scanned across a sample in a raster pattern, allowing for the creation of an image pixel by pixel.