Nikon Metrology HMX ST 225

CT scan of Pachycara

The Nikon Metrology HMX ST 225 is a versatile micro-CT scanner that can image specimens from 0.5-20 centimetres in diameter with a maximum resolution of five micrometres. It can produce a maximum accelerating voltage of 225 kilovolts.

The Nikon Metrology HMX ST 225 has two available target heads:

Reflection target

The reflection target is most commonly used. It is used for samples larger than one centimetre in diameter. One-centimetre specimens can be scanned at the highest resolution of five micrometres voxel (3D pixel) size - scanning larger specimens results in a proportionately lower voxel size.

It has the following features:

  • voxel size of 5-125µm (dependent on sample size) 
  • maximum voltage of 225kV
  • maximum sample diameter of 25cm
  • maximum sample height of 25cm (up to three scans can be concatenated together to image up to 70cm)
  • maximum weight of 30kg
  • choice of tungsten, molybdenum, silver or copper targets

Transmission target

The tungsten transmission target is used for samples between five and ten millimetres in diameter. It is requested less frequently than the reflection target and is installed for an average of one week every three months.

It has the following features:

  • voxel size of 2-5µm (dependent on sample size)
  • maximum voltage of 180kV
  • maximum sample diameter of 1cm
  • maximum sample height of 1cm (up to three scans can be concatenated together)

Data storage

During a scan over 3,000 X-ray images are collected in 16-bit quality on a four-megapixel detector. This produces large amounts of high-quality data. 

Nikon Metrology HMX ST 225

Museum lead

Dr Vincent Fernandez, CT facility manager

Key facts

  • Technique: computed tomography
  • Sample size: 0.5-20cm in diameter, with additional capacity for specimens up to 70cm in height
  • Target heads: reflection and transmission tungsten targets
  • Resolution: 5-125µm voxel size (reflection target), 2-5µm voxel size (transmission target)
  • reconstructed scan sizes vary from 5-21GB
  • total scan size (including raw X-ray images) of up to 60GB
  • image stacks of the scans can be exported in TIFF, BMP, PNG or JPEG format
  • STL, PLY and OBJ mesh files can also be produced from the scans