Popov K I, Pegoraro A F, Stolow A, Ramunno L
Department of Physics, University of Ottawa, Ottawa, Ontario, Canada.
Opt Express. 2011 Mar 28;19(7):5902-11. doi: 10.1364/OE.19.005902.
Image formation in Coherent Anti-Stokes Raman Scattering (CARS) microscopy of sub-wavelength objects is investigated via a combined experimental, numerical and theoretical study. We consider a resonant spherical object in the presence of a nonresonant background, using tightly focused laser pulses. When the object is translated along the laser propagation axis, we find the CARS signal to be asymmetric about the laser focal plane. When the object is located before the focus, there is a distinct shadow within the image, whereas the brightest signal is obtained when the object is behind the focus. This behaviour is caused by interference between resonant and nonresonant signals, and the Gouy phase shift is responsible for the observed asymmetry within the image.
通过实验、数值和理论相结合的研究，对亚波长物体的相干反斯托克斯拉曼散射（CARS）显微镜成像进行了研究。我们考虑在非共振背景下存在的共振球形物体，使用紧聚焦激光脉冲。当物体沿激光传播轴平移时，我们发现CARS信号关于激光焦平面不对称。当物体位于焦点之前时，图像内有明显的阴影，而当物体位于焦点之后时，可获得最亮的信号。这种行为是由共振和非共振信号之间的干涉引起的，古伊相移导致了图像中观察到的不对称性。
