title: Diffraction response of colloidal crystals: effect of numerical aperture.
abstract: We present a quantitative experimental and theoretical study of the effect of numerical aperture (NA) on the Bragg diffraction from a dry polystyrene colloidal crystal. The diffraction peak parameters changed noticeably as the NA was increased from 0.017 to 0.5. The diffraction wavelength blueshifted 1.4% from 584 to 576 nm, and the normalized full width at half-maximum increased from 6.2% to 7.0%. These shifts occurred primarily for NA > 0.3 and agreed qualitatively with results predicted by a layered Korringa-Kohn-Rostoker method. Thus, by using focusing optics with NAs below 0.3, the diffraction response of low-photonic-strength mesostructures may be compared with normal-incidence experimental and theoretical data.
authors.affiliation: Department of Materials Science and Engineering, Beckman Institute for Advanced Science and Technology, Urbana, Illinois 61801, USA.
authors.forename: Yun-Ju
authors.initials: YJ
authors.lastname: Lee
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Pruzinsky
authors.forename: Paul V
authors.initials: PV
authors.lastname: Braun