中等视场大相对孔径水下两档变焦光学系统

研究了水下两档变焦光学系统的设计方法并给出了具体设计实例。采用轴向移动变焦方式,变焦过程中相对孔径保持不变,相对孔径为1/1.4,系统变焦比为2,在水下的宽视场角为60,°有效焦距3.6 mm,用于大范围内搜索目标;窄视场角为20°,有效焦距7.2 mm,用于对目标进行具体分析。在空间42 lp/mm处的宽视场和窄视场的光学传递函数值均大于0.4,成像质量较好。既满足了水下成像对大相对孔径和较大视场的要求,又能够在大范围内搜索目标,小范围内对具体目标进行分析,满足实际应用的需要。

Underwater switch-zoom optical system with middle angle and large relative aperture

The design principle of the underwater switch-zoom optical system is analyzed, and an example has been presented. The optical system is based on the axial motion of a lens group along the optical axis. The relative aperture is a constant 1/1.4 during the zoom process. The zoom ratio is 2. In the wide-angle mode, the field of view is 60?underwater, and the effective focal length is 3.6mm, the system is used for searching for possible targets of interest. In the narrow-angle mode, the field of view is 20? and the effective focal length is 7.2mm, it is used for final target recognition and identification correspondingly. Both the wide-angle mode and the narrow-angle mode have high image quality, and the MTF of the system is larger more than 0.4 at the spatial frequency of 42lp/mm. Not only can meet the requirements of wide angle and larger aperture in underwater imaging, but also can search target on a large scale and analysis the specific target, satisfy actual application.