Hörmann Martin, Visentin Federico, Chakraborty Suman Kumar, Nayak Biswajeet, Sahoo Prasana Kumar, Cerullo Giulio, Camargo Franco V A
Opt Express. 2024 Jun 3;32(12):21230-21242. doi: 10.1364/OE.525581.
Many applications of ultrafast and nonlinear optical microscopy require the measurement of small differential signals over large fields-of-view. Widefield configurations drastically reduce the acquisition time; however, they suffer from the low frame rates of two-dimensional detectors, which limit the modulation frequency, making the measurement sensitive to excess laser noise. Here we introduce a self-referenced detection configuration for widefield differential imaging. Employing regions of the field of view with no differential signal as references, we cancel probe fluctuations and increase the signal-to-noise ratio by an order of magnitude reaching noise levels only a few percent above the shot noise limit. We anticipate broad applicability of our method to transient absorption, stimulated Raman scattering and photothermal-infrared microscopies.
超快和非线性光学显微镜的许多应用需要在大视场范围内测量微小的差分信号。宽视场配置极大地缩短了采集时间；然而，它们受到二维探测器低帧率的影响，这限制了调制频率，使得测量对过量激光噪声敏感。在此，我们介绍一种用于宽视场差分成像的自参考检测配置。利用视场中没有差分信号的区域作为参考，我们消除了探测波动，并将信噪比提高了一个数量级，达到仅比散粒噪声极限高几个百分点的噪声水平。我们预计我们的方法在瞬态吸收、受激拉曼散射和光热红外显微镜方面具有广泛的适用性。
