Scattering effects from optical fabrication errors of different frequency-segment limit the optical performance. But there lacks appropriate optical design software to account for these effects. In order to solve this problem and guide fabrication, Wavelet transform is used to separate errors; and then Harvey-Shack surface scatter theory is used to specify optical surface. Because of wavelet-transform's character, the corresponding region of crucial frequency segment error is also found when the optical performance cannot satisfy demand, thereby guiding fabrication. Finally, there is an experimental validation via measurement data of an aperture =500 mm mirror and design demand “the enclosed energy requirement of 70% in a 0.33 mrad enclosed region”. The experimental results show the method can set up a direct relation between frequency-segment errors, optical specification and optical fabrication effectively.