Since its foundation in 1817, the Senckenberg Society for Nature Research has been researching the deve­lopment of the earth and the importance of biodiversity. The Senckenberg Natural History Museum at the main site in Frankfurt am Main is one of the largest natural history museums in Europe. Senckenberg’s scientific collections – with around 41 million objects the most extensive in Germany – are as “archives of life” an in­dispensable basis for the study of our biotic and abio­tic environment.

Many of these collections are already accessible on­line and thus used all over the world. Digital technologies are crucial for this, as the way in which col­lection material is utilized has constantly evolved. Technical progress and new examination methods make it possible to elicit more and more information from the objects. For the highly accurate digitization of the unique research objects, a TomoScope® XS Plus with a new sub-microfocus tube is used, which was jointly financed with funds from the Hessian Ministry of Higher Education, Research, Science and Arts (as part of EFRE) and from the Senckenberg Society’s own funds (including SOSA).

In 2017, Werth Messtechnik presented the TomoSco­pe® XS, the first compact machine with X-ray computed tomography for fast measurements with high struc­tural resolution. The novel tube design allows the main­tenance interval for such machines to be increased to 12 months for the first time. With the first TomoScope® XS Plus – at that time still with 130 kV or 160 kV ma­ximum voltage – the measurement volume was quadru­pled. Today, the compact machine is available with up to 200 kV tube voltage. The higher voltage makes it possible to use it even for workpieces made of dense materials with long radiographic lengths that are diffi­cult to penetrate.

The Senckenberg Research Institute in Frankfurt am Main is one of the first users of the novel sub-microfocus X-ray tube (Source: Senckenberg Gesellschaft für Naturforschung)

Now Werth is introducing this type of machine with the first sub-microfocus tube in a monoblock design and long-life components. Sub-microfocus tubes used to be particularly maintenance-intensive, resulting in long downtimes and high costs. The new tubes with up to 160 kV voltage allow high availability and significantly lower maintenance costs compared to conventional sub-microfocus tubes with a separate generator.

This is the first time that a sub-microfocus tube is also available in this machine class. The maximum struc­tural resolution in the 2D transmission image is often specified as a parameter. Practically only the focal spot size of the X-ray source is relevant here, other influen­cing variables are largely neglected. This allows very small numerical values of a few hundred nanometers to be specified. For a TomoScope® XS Plus with the new sub-microfocus tube, this value is about 0.8 µm. How­ever, the correct coordination with the other machine components such as the rotary axis and detector is al­so crucial for a high structural resolution in the 3D volume. Temperature also has a major influence on resolutions in the limit range. For this reason, active temperature control to 20 °C ± 1 K is used inside the machine. In addition, there is an automatic cor­rection of temperature-related drift. All these measu­res make it possible to achieve a 3D volume structural resolution of about 1 µm, which is hardly surpassed even by conventional, so-called “nanofocus systems.”

In sub-microfocus mode, the X-ray tube allows the mea­surement of structures of a few micrometers in size with very high volume structural resolution. A high-power mode is also available and enables fast, high-resolu­tion measurements of objects with structures only a few tens of micrometers in size with the usual short measurement times of Werth TomoScope® machines.

With the help of the Werth TomoScope® XS Plus, million-year-old collection items such as this fly in amber can be digitized as an archive of life. The compound eyes are clearly visible and the thickness of the chitinous shell of 3 μm is measurable (Source: Dr. Solórzano Kraemer, Senckenberg Research Institute and Natural History Museum)