Micro CT measurement of defects in light-weighted mirrors for applications in space imaging

P A Cooper, W Sun, S B Brown and C Atkins  

An additively manufactured aluminium alloy light-weighted mirror sample was measured using micro X-ray computed tomography. The additive-manufactured surface is polished or diamond turned to an optical surface quality, thus reducing surface defects is critical. The measurement was processed to investigate porosity in the sample, which can become surface defects following the polishing or turning. The porosity was most prevalent in bands approximately 0.5 mm below the original surface and in areas away from the support columns. Porosity detection was found to be sensitive to threshold parameters, showing the requirement for robust algorithms.