The optical department produced a lens with a numerical aperture of F/O=.68, through which a large circular graticule was projected onto a circular glass reflector screen 76 mm (3 in) in diameter.

• 光学部门制造了数值孔径F/O=.；68的镜头，通过这个镜头投射一个宽大的圆形分划到一个圆直径76毫米（3英寸）形的玻璃反射屏。