Optronic Periscope Mast Product

Overview

The optronic mast is the digital successor to the optical periscope. A classical periscope is a 10-meter telescope through the pressure hull: a half-meter bore through the submarine's most critical structure, an optical train that fixes the control room directly beneath the sail, and one observer at an eyepiece. The optronic mast deletes all of it. A Sensor Head of cameras rides a telescoping Mast Structure housed entirely in the sail, and the only hull penetration is the Hull Penetrator — a small certified cable gland. Imagery travels as data on the Mast Data Link to any console in the boat, the control room moves to wherever the designers want it, and everyone sees what the periscope sees at once.

Sensor head

Behind the multispectral Head Protective Window — a sapphire or zinc-sulfide belt passing visible through mid-infrared while shrugging off wave slap and better than 30 bar — the head carries three imaging channels. The EO Daylight Camera is the daylight workhorse, an HDTV color channel with continuous optical zoom from wide search to ~12x identification. The IR Thermal Camera owns the night: a cooled MWIR imager whose IR Focal Plane Array focal plane, held near 80 K by an integral Cryocooler, picks out ship wakes, diesel exhausts, and aircraft through haze that blinds visible optics. The Low-Light Camera bridges dusk between them.

Around the imagers sit the sensors that exploit the exposure. The ESM Antenna sniffs for hostile radar the instant the head breaks the surface — before any optical search, because being detected by an emitter matters more than seeing. The GPS Antenna grabs a navigation fix to reset the inertial navigator, and the Laser Rangefinder puts meter-class range on a contact for the fire-control solution, replacing the old stadimeter art of reading range from masthead height.

Exposure discipline

Everything about periscope operations is governed by one fact: a raised mast can be seen. The Hoist System drives the full stroke in seconds, the Hydrodynamic Fairing cuts the wake and feather that betray a moving scope, and doctrine compresses each look to the minimum. The defining capability of the optronic mast is the automated quick-look round: the Azimuth Drive spins the head through a full 360° in about three seconds while the Video Processor records everything, the mast drops, and the crew reviews the complete horizon mosaic at leisure, submerged. Total exposure falls from the minutes a human observer needed to seconds.

Image quality during those seconds depends on the Stabilization System system. Rate gyros in the Gyro Package sense line-of-sight jitter from ship roll, mast flex, and wave slap at hundreds of hertz, and the Stabilization Controller drives the Elevation Gimbal and azimuth axis against the error, holding jitter to tens of microradians — without which the long-zoom channels would smear.

Engineering the mast

The non-penetrating architecture changes the safety calculus. A classical periscope that floods, floods the boat; a flooded Mast Tube risks only equipment in the sail. The mast rides Guide Bearing Set in the sail structure against drag loads at periscope-depth speeds, with the Mast Seal Set excluding seawater from the hoist well and the Stowage Latch holding the stowed mast rigid through shock specifications.

The head electronics live in the Pressure Housing, a machined Housing Shell rated beyond the boat's test depth, nitrogen-purged by the Desiccant/Purge System so optics never fog between −2 °C seawater and tropical air. All channels travel uncompressed down the Fiber-Optic Link, crossing the continuously rotating azimuth axis through the Slip Ring / FORJ fiber-optic rotary joint, with the Cable Chain managing the service loop as the mast strokes.

At the Control Console, the operator works a Hand Controller joystick in place of the classical periscope handles, with live EO/IR video, bearing scales, and recorded imagery on the Console Display and video repeated to the command team. The cultural shift is real: no commanding officer's eye at an eyepiece, but a shared, recorded, multi-spectral picture that several watchstanders analyze at once — and a control room freed from the geometry of a light path.