�� Specifications:
�� Material: SF11 grade A fine annealed optical glass
�� Dimention Tolerance: +0.0,-0.15mm
�� Clear aperture: >80% of the central area
�� Surface quality: 60/40 scratch and dig
�� Flatness: ��/8@830nm
�� Coating: MgF2 single layer on perpendicular surface
�� ��=29��7'+/-30''