# Why is elastic scattering of photons (largely) non-isotropic, but inelastic scattering is isotropic?

I'm working on an experiment regarding Raman spectroscopy, and i'd like to fully understand the reasoning behind this fact. I assume it is related to the photons momentum. My apparatus has a 'collection' axis perpendicular to the laser optical axis, and I assume that this is a utilisation of this fact to reduce the elastically scattered photons incident on my optical fibre. I do however see the largest intensity, even when using a filter, on the Rayleigh (elastic) wavelength in my results. Is this because of the probability of Rayleigh scattering being way higher than that of Raman scattering?