Nontranslational three-dimensional profilometry by chromatic confocal microscopy with dynamically configurable micromirror scanning

Abstract

A confocal microscope profilometer, which incorporates chromatic depth scanning with a diffractive optical element and a digital micromirror device for configurable transverse scanning, provides three-dimensional (3D) quantitative measurements without mechanical translation of either the sample or the microscope. We used a microscope with various objective lenses (e.g., 40x, 60x, and 100x) to achieve different system characteristics. With a 100x objective, the microscope acquires stable measurements over a 320 microm x 240 microm surface area with a depth resolution of 0.39 microm at a 3-Hz scan rate. The total longitudinal field of view is 26.4 microm for a wavelength tuning range of 48.3 nm. The FWHM value of the longitudinal point-spread function is measured to be 0.99 microm. We present 3D measurements of a four-phase-level diffractive element and an integrated-circuit chip. The resolution and the accuracy are shown to be equivalent to those found with use of conventional mechanical scanning.