Fast zoom portable night vision telescope based on liquid lenses and folded optical structure

Abstract

Low-light level night vision telescopes play a significant role in the fields such as emergency rescue, detection and measurement. The requirement to observe targets at different distances necessitates zoom function for night vision telescopes. However, traditional zoom mode relying on movement of lens group inevitably causes slow response speed and bulkiness. Moreover, the magnification of night vision telescopes is usually proportional to the total length of the system, resulting in a trade-off between observation distance and portability. Here, a fast zoom portable night vision telescope based on liquid lenses and folded optical structure is proposed. A zoom telescope objective lens composed of liquid lenses, solid lenses and a folded mirror group is designed, enabling reduction of total optical length and fast flexible adjustment of focal length. The focal length adjustment range of the zoom telescope objective lens is 80 mm to 120 mm with a fastest zoom response time of around 5 ms, and the total optical length is only around 91 mm. Integrating the zoom telescope objective lens, a customized image intensifier and eyepiece, the proposed night vision telescope can achieve a tunable high visual magnification ranging from 5.3× to 8.0× and a minimum angular resolution of 13″. The night vision telescope is fabricated and well-integrated, and experiments demonstrate its advantages of fast tunability, portability and strong adaptability. The proposed fast zoom portable night vision telescope is expected to be applied in multiple fields such as detection, measurement, and rescue.