Application Note: Evolution of Gemini electron optics: The next chapter in sub-nanometer imaging below 1 kV
2 December 2020

In the last 20 years, a major thrust of research in scanning electron microscopy (SEM) has been driving the performance of systems towards higher resolution at lower voltages. Key to the performance of any SEM, conventional or field emission SEM (FE-SEM), is its electron optical column. ZEISS FE-SEMs are based upon the Gemini column design which has seen a number of technological advancements since it was first launched in 1993. Low acceleration voltage imaging is attractive in that it reduces the interaction volume in the specimen, which allows surface sensitive information to be extracted. Additionally, the charging of insulating samples by SEM investigation can be avoided by reducing the electron energy used to probe the sample. The reduced radiation damage from low energy SEM imaging is also essential for imaging sensitive specimens such as biological samples and semiconductor devices.