Effects of defocus on the transfer function of coherence scanning interferometry

Rong Su, Matthew Thomas, Richard Leach, Jeremy Coupland
2017 Optics Letters  
Coherence scanning interferometry (CSI) offers threedimensional (3D) measurement of surface topography with high precision and accuracy. Defocus within the interferometric objective lens, however, is commonly present in CSI measurements and reduces both the resolving power of the imaging system and the ability to measure tilted surfaces. This Letter extends the linear theory of CSI to consider the effects of defocus on the 3D transfer function and the point spread function in an otherwise ideal
more » ... an otherwise ideal CSI instrument. The results are compared with measurements of these functions in a real instrument. This work provides further evidence for the validity of the linear systems theory of CSI.
doi:10.1364/ol.43.000082 pmid:29328211 fatcat:ms4m6cjqtfc5paohnj5yiaspqa