Willem van Zyl

Willem van Zyl is an application specialist for the Thermo Scientific Phenom Desktop SEM product range at Thermo Fisher Scientific. He is excited by analytical instruments that are accessible and user-friendly, and truly believes that an SEM image is worth a kazillion words.

How to spot astigmatism in Scanning Electron Microscopy (SEM) images

By Willem van Zyl - February 28, 2019

You may have heard of astigmatism as a medical condition that causes visual impairment in up to 40% of adults [1], but how is this applicable to electron microscopy? First of all, let’s talk about what the word astigmatism, in fact, means: It is derived from the negative prefix ‘a’ (without) + ‘stigmat-’ (mark, or point, in Ancient Greek) + ‘ism’ (condition). In a perfect optical system, a lens has only one focal point, and is stigmatic. When the lens has more than one focal point, however, we refer to the lens as being astigmatic. This happens when the lens is elongated in either the sagittal (y-axis) or tangential (x-axis) plane, resulting in two focal points (= foci).

You may have heard of astigmatism as a medical condition that causes visual impairment in up to 40% of adults [1], but how is this applicable to electron microscopy? First of all, let’s talk about what the word astigmatism, in fact, means: It is derived from the negative prefix ‘a’ (without) + ‘stigmat-’ (mark, or point, in Ancient Greek) + ‘ism’ (condition). In a perfect optical system, a lens has only one focal point, and is stigmatic. When the lens has more than one focal point, however, we refer to the lens as being astigmatic. This happens when the lens is elongated in either the sagittal (y-axis) or tangential (x-axis) plane, resulting in two focal points (= foci).

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SEM trends: what is next? Automated scanning electron microscopy

By Willem van Zyl - January 17, 2019

Automated scanning electron microscopy (SEM) saves operators valuable time. Both in research and in industry this further development of SEM is in great demand and is a rapidly growing field. Thermo Fisher Scientific™ already offers innovative Phenom desktop SEM products and applications for automated imaging as well as analysis.

Automated scanning electron microscopy (SEM) saves operators valuable time. Both in research and in industry this further development of SEM is in great demand and is a rapidly growing field. Thermo Fisher Scientific™ already offers innovative Phenom desktop SEM products and applications for automated imaging as well as analysis.

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Topics: Automation

Sample preparation: how to disperse powder for amazing SEM images

By Willem van Zyl - November 16, 2018

The ability to analyze particles is becoming increasingly more important due to the rising prominence of additive manufacturing, leading to more stringent quality requirements for industrial manufacturers. Beyond maximizing yields, manufacturers need to ensure that their processes consistently deliver particles that have the appropriate size and morphology.

The ability to analyze particles is becoming increasingly more important due to the rising prominence of additive manufacturing, leading to more stringent quality requirements for industrial manufacturers. Beyond maximizing yields, manufacturers need to ensure that their processes consistently deliver particles that have the appropriate size and morphology.

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