Pilkington Optronics has been selected to provide the Visual Systems for the three ASTUTE Class submarines, currently being built at BAESYSTEMS facility in Barrow-in-Furness. Unlike conventional periscopes, which have a direct visual path to the outside world, the Optronic Mast is non-hull penetrating and uses an electronic link to present the surface picture to the command on monitor screens as part of an integrated combat system.

The Optronic Mast represents a significant breakthrough in the design of submarine above water sensors. In addition to high resolution colour and low light cameras the Optronic Mast incorporates a thermal imaging sensor thereby providing a day and night capability, and among its many stealth characteristics is a "quick look round" facility. This allows full horizon coverage in a few brief seconds which can be examined and analysed once the mast is lowered, thereby keeping mast exposure to an absolute minimum, a key requirement for today's submariner. Radar cross section reduction measures and a streamlined shape further reduce the risk of detection.
The non-hull penetrating Optronic Mast represents the future in submarine periscope technology, providing significant advantages in submarine design flexibility, stealth and combat system integration. No longer will the positioning and layout of submarine control rooms be governed by the need to accommodate the steel tubes of the penetrating periscopes. As the submarine's primary visual sensor when operating at periscope depth. It will allow an accurate and rapid assessment of the above water tactical scene as well as providing vital targeting, navigation and submarine safety information to the command.