o type backward wave tube o 型返波管o type tube o 型超高频电子管oat 氧化物对准晶体管工艺object distance 目标距离object identification 目标识别objective 物镜objective turret 镜头转轮oblique anode 倾斜阳极oblique deposition 倾斜淀积oblique evaporation 斜射蒸镀observability 可观测性occlusion 吸气酌occupancy 占有occupation density 占有密度occupid state 填充状态octod