The MFT MicroFinish Topographer is a small, lightweight and simple system for interferometrically measuring surface roughness on all sizes of optics from a few mm to meters. For large optics the MFT sits directly on the surface requiring measurement thus eliminating the need for replicas.
For small optics the MFT is inverted and a sample plate is added onto which the sample is placed on 3 nylon balls. In this way once the fringes are initially found, sample after sample maybe measured without further adjustment. Also, since the sample is directly coupled to the MFT via the 3 balls, the MFT is largely immune to vibration.


The small size and light weight of the MFT make it possible to measure substrates and configurations not possible with other instruments. The MFT has been used to make direct measurements of large substrates used in Cherenkov reflectors with delicate dielectric coatings and cylindrical X-ray mirrors where the MFT sat inside the barrel shaped mirror that was only 3 mm thick.Further the MFT is small and light enough to mount directly on a diamond turning machine for in-situ measurement of roughness and figure.


The MFT gives immediate finish feedback because it can be set on an optic during polishing without ever having to remove the optic from the polishing machine. This ability permits greater process control and evidence of meeting specification without doing excessive polishing or machining.
Recently the MFT was used for this purpose on two large telescope mirror projects.