title: Effects of spatial coherence in diffraction phase microscopy.
abstract: Quantitative phase imaging systems using white light illumination can exhibit lower noise figures than laser-based systems. However, they can also suffer from object-dependent artifacts, such as halos, which prevent accurate reconstruction of the surface topography. In this work, we show that white light diffraction phase microscopy using a standard halogen lamp can produce accurate height maps of even the most challenging structures provided that there is proper spatial filtering at: 1) the condenser to ensure adequate spatial coherence and 2) the output Fourier plane to produce a uniform reference beam. We explain that these object-dependent artifacts are a high-pass filtering phenomenon, establish design guidelines to reduce the artifacts, and then apply these guidelines to eliminate the halo effect. Since a spatially incoherent source requires significant spatial filtering, the irradiance is lower and proportionally longer exposure times are needed. To circumvent this tradeoff, we demonstrate that a supercontinuum laser, due to its high radiance, can provide accurate measurements with reduced exposure times, allowing for fast dynamic measurements.
authors.forename: Chris
authors.initials: C
authors.lastname: Edwards
authors.forename: Basanta
authors.initials: B
authors.lastname: Bhaduri
authors.forename: Tan
authors.initials: T
authors.lastname: Nguyen
authors.forename: Benjamin G
authors.initials: BG
authors.lastname: Griffin
authors.forename: Hoa
authors.initials: H
authors.lastname: Pham
authors.forename: Taewoo
authors.initials: T
authors.lastname: Kim
authors.forename: Gabriel
authors.initials: G
authors.lastname: Popescu
authors.forename: Lynford L
authors.initials: LL
authors.lastname: Goddard