title: Digital differential confocal microscopy based on spatial shift transformation.
abstract: Differential confocal microscopy is a particularly powerful surface profilometry technique in industrial metrology due to its high axial sensitivity and insensitivity to noise. However, the practical implementation of the technique requires the accurate positioning of point detectors in three-dimensions. We describe a simple alternative based on spatial transformation of a through-focus series of images obtained from a homemade beam scanning confocal microscope. This digital differential confocal microscopy approach is described and compared with the traditional Differential confocal microscopy approach. The ease of use of the digital differential confocal microscopy system is illustrated by performing measurements on a 3D standard specimen.
authors.affiliation: Ultra-Precision Optoelectronic Instrument Engineering Center, Harbin Institute of Technology, West Da-Zhi Street, Harbin, Heilongjiang, China.
authors.forename: J
authors.initials: J
authors.lastname: Liu
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: C
authors.initials: C
authors.lastname: Liu
authors.forename: T
authors.initials: T
authors.lastname: Wilson
authors.forename: H
authors.initials: H
authors.lastname: Wang
authors.forename: J
authors.initials: J
authors.lastname: Tan
keywords: Differential confocal microscopy; digital algorithm; multi-detectors assignment; signal to noise ratio; step edge; surface topography