In this interferometer, the optical path difference is given by 

OPD = k (2d1 -2d2) 

where d1,2 are arms 1 and 2 of the interferometer and k is the wavenumber of the light used. If one mirror is moved a distance, the number of fringes that will cross the field of view is given by 

k (2Δd) = (2π/λ) (2Δd) = (2π) m 

λ = 2Δd / m = 2*0.223E-3 / 769 

λ = 579 nm

Hope this helps:)
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