The 39213 Focusing Lens is used with the 77330 Focusing Lens Assembly. It is a 1 inch (25.4 mm) diameter, Borosilicate Crown Glass, Bi-convex Lens with a 33 mm Focal Length. Bi-convex lenses are for imaging with little change in magnification. 330 to 2200 nm wavelength range.

39213聚焦透镜与77330聚焦透镜组件一起使用。它直径1英寸(25.4毫米),硼硅酸盐皇冠玻璃,双凸透镜,焦距33毫米。双凸透镜适用于放大率变化不大的成像。330 ~ 2200 nm波长范围。