Single-molecule orientation measurements with a quadrated pupil

Adam S. Backer, Mikael P. Backlund, Matthew D. Lew, W. E. Moerner

Research output: Contribution to journalArticle

Abstract

This Letter presents a means of measuring the dipole orientation of a fluorescent, orientationally fixed single molecule, which uses a specially designed phase mask, termed a "quadrated pupil," conjugate to the back focal plane of a conventional wide-field microscope. The method leverages the spatial anisotropy of the far-field emission pattern of a dipole emitter and makes this anisotropy amenable to quantitative analysis at the image plane. In comparison to older image-fitting techniques that infer orientation by matching simulations to defocused or excessively magnified images, the quadrated pupil approach is more robust to minor modeling discrepancies and optical aberrations. Precision of 1° - 5° is achieved in proof-of-concept experiments for both azimuthal ((p) and polar (0) angles without defocusing. Since the phase mask is implemented on a liquid-crystal spatial light modulator that may be deactivated without any mechanical perturbation of the sample or imaging system, the technique may be readily integrated into clear aperture imaging studies.

Original languageEnglish (US)
Pages (from-to)1521-1523
Number of pages3
JournalOptics Letters
Volume38
Issue number9
DOIs
StatePublished - May 1 2013
Externally publishedYes

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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