Observation cone aperture

Equation 8 shows that the wavelength of the n th harmonic will vary with the observation angle 0. From this and from the dependence of spectral width on (nN) at 0 = 0, it can be shown that in order to prevent line broadening due the 0 effect, the observation cone aperture has to be smaller than an angle 0m> where ... 

Angle aperture The angle of the cone of light exiting a sample observed by microscopy. 

This equation quantifies the axial distortions arising from the use of media with different refractive indices between the immersion oil and the sample. This implies that, for the entire light cone to be focused, NA must be less than ns. For objectives with high numerical apertures, NA>ns, and when nsliving cells with an 1.4 NA oil immersion objective) the numerical aperture falls below ns and some of the light is lost due to reflection to the medium interface. 

I = scattered light intensity K = defined by Equation [11] N = number of events NA = numerical aperture R = distance between scattering molecule and observer S = surface area S/N - signal to noise ratio a = half angle of light cone = isotropic Raman invariant aG = isotropic ROA invariant due to the optical activity tensor = anisotropic Raman invariant =j8(G )2 = anisotropic ROA invariant due to the optical activity tensor <5 = f A) = anisotropic ROA invariant due to the quadrupole tensor fiQ = permeability of the vacuum to = angular frequency. 

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