A scheme using microlens array for external cavity-based spectral beam combining of fiber lasers is proposed,and a spherical-profile refractive microlens array that can preliminarily collimate the output beams from the fiber array is designed.The combination potential of the beam combining system is analyzed,which shows that twelve Er3+/Yb3+ codoped fiber lasers can be combined.Using Rayleigh-Sommerfeld diffraction integral theory,the collimating effect of the microlens array is analyzed,and the...