Understanding XRM Technology


True Spatial Resolution for Your Demanding Requirements

Now you can obtain the highest resolution possible in a laboratory setting and test your samples over and over again using non-destructive X-ray computed tomography. 3D X-ray microscopy (XRM) enables a wide range of studies, but it all begins with true spatial resolution.

Spatial resolution refers to the minimum separation at which a feature pair can be resolved by an imaging system and offers a direct measurement of a system’s complete imaging capability. Emerging from attempts to describe a telescope’s resolution by the minimum separation of stars that could be resolved, spatial resolution still serves as the standard scientific measurement for many of the world’s leading imaging systems. Spatial resolution measures the output of the system—an image—accounting for all system characteristics: X-ray source spot size, detector resolution, vibrational, electrical and thermal stability, magnification geometry, and imaging conditions.

Because frequently cited parameters such as minimum voxel, nominal resolution, spot size, and detail detectability provide only partial insight into a system’s ability to resolve an image, spatial resolution provides the most meaningful method of evaluating an instrument’s performance.

Resolution Target
As feature pairs are spaced closer than a system’s resolution capability, they cannot be resolved from one another



The majority of conventional X-ray micro- and nano-computed tomography (CT) systems are projection-based and use a micro- or nano-focus X-ray source to project a geometrically magnified image of the sample on a large-pixel flat panel detector.

These conventional systems depend on high geometric magnification for resolution, which imposes limitation on sample size. Since magnification is inversely proportional to the source to center of rotation distance, achieving the highest resolution requires the sample be small and close to the source. For larger samples or samples within in situ chambers, the center of the sample rotation must move farther from the source and results in significantly reduced magnification.

ZEISS Xradia Versa Series for Submicron Imaging

In contrast to conventional CT systems, ZEISS Xradia Versa X-ray microscopes use a two-stage magnification technique.

First, the sample image is enlarged through geometric magnification, and second, after the X-rays are converted to visible light, the image is optically magnified by visible light optics. With this, dependence on geometric magnification is greatly reduced. It also provides the significant advantage of maintaining artifact-free high resolution at large working distances to increase the range and type of sample shapes and sizes that can be imaged by in a laboratory setting.

This design is rooted in the company’s synchrotron heritage and uses a patented detector system with scintillator-coupled visible light optics.

ZEISS Xradia Ultra Series for Nanoscale Imaging

The architecture of Xradia Ultra XRM is conceptually equivalent to that of an optical or transmission electron microscope (TEM) with images collected over a range of projection angles that are then reconstructed into a 3D tomographic representation. A high-brightness X-ray source is focused onto the specimen by a high-efficiency capillary condenser and Fresnel zone plate objectives image transmitted X-rays onto the detector. Multiple patents and years of experience in aligning and integrating high-quality optics enable ZEISS Xradia Ultra systems to maintain high resolution and high efficiency.

Applications and Techniques

Applications and Techniques

ZEISS Xradia Versa X-ray Microscopes – Submicron Imaging

  • True spatial resolution down to 0.7 μm
  • Resolution at a Distance (RAAD) at 50 mm working distance: 1.0 μm
  • Minimum achievable voxel*: 70 nm
  • Sample sizes: cm to mm
  • Load capacity: up to 15 kg

ZEISS Xradia Ultra X-ray Microscopes for Nanoscale Imaging

  • True spatial resolution down to 50 nm
  • Minimum achievable voxel: 16 nm
  • Load capacity: 1 kg
  • Sample sizes: micron

Spatial resolution should be assessed at working distances relevant to the user’s intended applications. To choose the correct system, users must apply consistent definitions while evaluating imaging solutions. ZEISS XRM delivers the highest spatial resolution across the widest range of working distances.

*Voxel (sometimes referred to as “nominal resolution” or “detail detectability”) is a geometric term that contributes to but does not determine resolution, and is provided here only for comparison. ZEISS Xradia XRM are specified on spatial resolution, the most meaningful measurement of instrument resolution.