为了对斜拉桥表面缺陷进行远程检测，设计了四片式高分辨率视频摄远物镜光学系统。图像传感器是像元尺寸为1.4 μm×1.4 μm、靶面尺寸为1/2.3″的1400万像素高分辨率互补金属氧化物半导体(CMOS)摄像机。为了匹配摄像机分辨率，设计的像方分辨率为357 lp/mm的摄远物镜，焦距为320 mm，相对孔径为1/6.95，视场角为1.379°。在物方可在228 m外分辨2 mm的线宽，能够满足对普通斜拉桥拉索检测的距离和分辨率要求。

In order to realize remote detection of surface cracks of cable-stayed bridges, a four lenses high definition video telephoto objective is designed. The image sensor is a complementary metal-oxide-semiconductor (CMOS) camera with a cell size of 1.4 μm×1.4 μm, target surface size of 1/2.3″ and a definition of 14 megapixel. To match the design requirement of the camera, the definition on the image surface of the telephoto objective is designed as 357 lp/mm, with a focal length of 320 mm, the relative aperture of 1/6.95, and the angle of view field of 1.379°. On the object side, the telephoto objective has the capability to distinguish a line with width of 2 mm at a distance of 228 m, which satisfies the distance and the definition requirement for the cable detection of normal cable-stayed bridges.