短語詞組短語focal aperture surface 焦曲面focal surface display 焦面顯示;焦平面顯示;焦點表面顯示minimal focal surface 極小焦面的the focal surface 焦曲面focal surface of a congruence 線匯的焦曲面focal surface of two sheets 雙葉焦曲面 返回 focal surface