第二次世界大战初期,机载瞄准系统是非常简陋的,当时的所谓瞄准具有OPL(光学成象瞄准具),它只适用于固定机枪。这看瞄准具,使瞄准镜的光学轴与距该轴较远的机枪群之射轴相一致,并以很快的响应速度工作。它的这种快速响应特性,仍被目前的雷达及激光瞄准具所利用。下图是光学瞄准具的瞄准情景。 In the early days of World War II, the airborne aiming system was very rudimentary. The so-called aiming at that time was OPL (Optical Imaging Aiming), which was only suitable for stationary machine guns. This looks at the sights so that the optical axis of the sight coincides with the axis of the machine gun cluster farther away from that axis and operates at a fast response speed. Its fast response is still utilized by current radar and laser sights. The following figure is the aiming sight of the optical sight.