Cole Daniel, Young Gavin, Weigel Alexander, Sebesta Aleksandar, Kukura Philipp
Physical and Theoretical Chemistry Laboratory, University of Oxford , South Parks Road, OX1 3QZ Oxford, U.K.
ACS Photonics. 2017 Feb 15;4(2):211-216. doi: 10.1021/acsphotonics.6b00912. Epub 2017 Jan 18.
Our ability to optically interrogate nanoscopic objects is controlled by the difference between their extinction cross sections and the diffraction-limited area to which light can be confined in the far field. We show that a partially transmissive spatial mask placed near the back focal plane of a high numerical aperture microscope objective enhances the extinction contrast of a scatterer near an interface by approximately , where is the transmissivity of the mask. Numerical-aperture-based differentiation of background from scattered light represents a general approach to increasing extinction contrast and enables routine label-free imaging down to the single-molecule level.
我们对纳米级物体进行光学探测的能力，取决于它们的消光截面与远场中光可被限制的衍射极限区域之间的差异。我们表明，在高数值孔径显微镜物镜的后焦平面附近放置一个部分透射的空间光阑，可将界面附近散射体的消光对比度提高约 ，其中 是光阑的透射率。基于数值孔径的背景光与散射光区分，是提高消光对比度的通用方法，能够实现常规的单分子水平无标记成像。
