Sensitivity to the quasar image brightness m_3rd of the lens search method based only on spatial extent. Wide: the group of lensed quasars with the largest separation among the pairs θ_LP >  1.5″. Narrow: the group of lensed quasars with 0.5″ <  θ_LP ≤ 1.5″. The top panels show the TPRs of each m_3rd bin, when p_thrs% = 95% and N_thrs = 9. The bottom panels show the number of mock lenses in each m_3rd bin. Our lens search algorithm can identify more than 90% of the lensed quasars with m_3rd <  21.0 mag.