Figure 2.

Hyper-Rayleigh scattering optical activity is observed from a volume of ≈30 μm³. (a) A schematic of the hyper-Rayleigh scattering experimental setup. The setup comprises a quarter-wave plate (QWP), a low-pass (LP) filter, a long working distance (LWD) microscope objective with 50× magnification, and a band-pass (BP) filter. (b) Estimate of the illumination volume with our objective. The images correspond to a multiphoton microscope Z-stack scan of a fluorescent nanosphere (≈ 200 nm in diameter), situated in the XY plane, with an illumination wavelength of 730 nm.