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 Incoming links: Born approximation

The Rytov approximation writes a total wave field as

ψ = ψ_{i} e^{ϕ}

and linearizes the equation for the complex logarithmic perturbation

ϕ

. At first order,

ψ_{i} ϕ

ψ_{R} = ψ_{i} exp (ψ_{s, B} / ψ_{i}) .

It can remain useful when phase accumulation is appreciable but local scattering is weak.