Hi everyone I have been told that gravitational lensing affects CMB power spectra (TT, TE, EE) for high values of l (i.e. the least, low peaks on the right, say l>1000). But how? Isn't the effect of the varying gravitational potential along the line of sight the cause of Integrated Sachs-Wolfe effect which affects the spectrum, on the contrary, for low values of l (say, l< 30)? How can we know that the lensing is caused in an accelerating universe scenario? And how can gravitational lensing constrain DE, both in density and in equation of state?