PresTo: A liquid-filled camera for low-cost imaging in the deep sea

Deep-sea imaging systems are traditionally expensive to manufacture and are physically scaled depending on the operating depth of their housing and the internal camera/lens components. Liquid and epoxy filled instrument designs are increasing in popularity as a way to reduce the cost and size of deep-sea housings. Recent advances in 3D printing have facilitated rapid prototyping of these pressure tolerant deep-sea designs. This study presents the design of PresTo, a liquid-filled pressure tolerant camera manufactured using SLA 3D printing methods. This is a compact and low-cost imaging system filled with deionized water and coated in epoxy to remove all implodable air volumes in the camera. The lens design for PresTo can be easily customized to any focal length and with zoom capabilities using a magnetically driven focus mechanism. Images taken with PresTo likely have minimal image distortions compared to other underwater cameras with flat viewports because, due to the elimination of a flat viewport solely for the reason of pressure isolation, there is an inherent reduction in the refractive indices of the surrounding environment and internal medium. The presented system has been field-tested to depths exceeding 1700 m and has been hydrostatically tested to function beyond 2600 m.