Nonlinear Dark-Field Microscopy

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• 作者：Hayk Harutyunyan ; Stefano Palomba ; Jan Renger ; Romain Quidant ; Lukas Novotny
• 刊名：Nano Letters
• 出版年：2010
• 出版时间：December 8, 2010
• 年：2010
• 卷：10
• 期：12
• 页码：5076-5079
• 全文大小：276K
• 年卷期：v.10,no.12(December 8, 2010)
• ISSN：1530-6992

文摘

Dark-field microscopy is a background-free imaging method that provides high sensitivity and a large signal-to-noise ratio. It finds application in nanoscale detection, biophysics and biosensing, particle tracking, single molecule spectroscopy, X-ray imaging, and failure analysis of materials. In dark-field microscopy, the unscattered light path is typically excluded from the angular range of signal detection. This restriction reduces the numerical aperture and affects the resolution. Here we introduce a nonlinear dark-field scheme that overcomes this restriction. Two laser beams of frequencies ω₁ and ω₂ are used to illuminate a sample surface and to generate a purely evanescent field at the four-wave mixing (4WM) frequency ω_4wm = 2ω₁ − ω₂. The evanescent 4WM field scatters at sample features and generates radiation that is detected by standard far-field optics. This nonlinear dark-field scheme works with samples of any material and is compatible with applications ranging from biological imaging to failure analysis.

Keywords:

Dark-field imaging; microscopy; nonlinear wave mixing; optical sensing; detection and failure analysis