Nikon Metrology has developed a new “absolute accuracy” metrology Computed Tomography (CT) system. MCT225 provides metrology CT for a wide range of sample sizes and material densities with 9+ L/50 µm accuracy in accordance with the VDI/VDE 2630 guideline. All internal and external geometry is measured efficiently in a single non-destructive process. A full 3D visualization of the sample volume additionally provides valuable insights into part deformations and internal structural integrity.
Computed Tomography X-ray has long been used for industrial applications. With X-ray CT a number of 2D X-ray images are taken at different angles around the sample. All of the external and internal geometry is captured as the X-rays pass through the sample. CT software constructs a 3D model of the sample using these 2D images. Dimensional characteristics such as size, position and form can be measured directly using the model as well as full part-to-CAD comparison, section reporting and GD&T analysis.
MCT225 is pre-calibrated using accuracy standards traceable to the UK's national measurement institute (NPL) and verified using VDI/VDE 2630 guidelines for Computed Tomography in Dimensional Measurement. “Absolute accuracy” guarantees measurement accuracy without time consuming comparative scans or reference measurements; samples are simply placed on a rotary table inside the enclosure and measured.
A key component of the MCT225 system is the in-house developed Nikon Metrology 225 kV micro-focus X-ray source. It produces sharp images with low noise levels, enabling magnification levels up to 150x with 2µm feature detection.
High-precision linear guideways equipped with high-resolution optical encoders are error corrected using the laser interferometer mapping techniques employed for CMMs. For optimal accuracy and long term stability, Finite Element Analysis (FEA) was used during the design phase to optimize the stiffness of the manipulator.
To minimize thermal effects the interior of the MCT225 enclosure is temperature controlled, effectively creating a conditioned measurement room stable to 20°C ± 1°C.