GoPro Patent Puts a Mirror in a Lens Adapter to Flatten Helmet-Mounted Cameras

Bolt an action camera to a helmet and it sticks up like a fin. It catches branches, it catches wind, and it looks a bit silly. GoPro holds a US patent for a lens adapter that lets the camera lie flat while it still looks straight ahead, by folding the light path through a mirror or a prism.

The patent is US 12,699,309, “Low profile lens adapter with folded optics,” granted to GoPro on August 4, 2026. It grows out of a provisional application filed in August 2022, and the named inventor is Ian Copeland Griggs.

A periscope for an action cam

The adapter works like a small periscope. Light comes in through a front lens group that turns it into collimated light, meaning the rays travel parallel instead of converging. A mirror or prism, set at about 45 degrees, bends that beam roughly 90 degrees. It then goes into the camera’s own lens, which now points up or sideways instead of forward.

Collimating the light first is the clever part. The patent doesn’t dwell on why, but the reason is easy to see. An action camera’s lens is set up for distant scenes, and parallel rays look to it like light from far away. So the adapter can deliver the scene in a form the built-in lens already handles, with no change to the camera’s own optics.

The patent says the folding element can be a front-silvered mirror or a prism, made of glass, plastic or ceramic. A front-silvered mirror matters because a regular rear-silvered mirror gives a faint double image from its glass layer, which is the last thing you want ahead of an ultra-wide lens.

Top or side, and room for more glass

GoPro describes two ways to attach the adapter. In the top-facing setup the camera lies on its back and the adapter looks forward over the edge. In the side-facing setup the camera lies on its side. A swivel at the mount end can adjust the direction further.

The granted claim covers the mount too: a hinge that turns on a pin, built to seal the adapter against the camera. That matters for a device that lives in rain, mud and surf. The description also mentions a second mount on the front of the adapter for extra lenses with a different field of view, filters or apertures.

Why GoPro wants it

The background section spells out the reason. With a forward-facing lens, a camera on a mount protrudes awkwardly and creates air resistance. Typical lens adapters snap onto the front of the camera and leave that profile unchanged.

Anyone who has run a camera on a ski helmet, a bike helmet or a motorcycle chin mount knows the problem. A taller camera catches more wind noise and more vibration, and it has a better chance of getting knocked off. On a race car or a drone, a low profile also means less drag.

GoPro already sells lens mods for the HERO13 Black, which clip onto the front of the camera to change its field of view or add filtering. A folded-optics mod would fit that same idea of add-on glass, with a new job: changing where the camera points relative to its body.

The catch

Every extra piece of glass and every mirror costs something. A folded path adds reflections and a little light loss, and keeping a mirror perfectly aligned on a helmet that takes hits is no small task. Ultra-wide lenses make it harder still, because a very wide field of view needs a big mirror to avoid cutting off the corners. The patent doesn’t give fields of view or sizes, so there’s no way to judge yet how wide such an adapter could go.

For riders and racers it’s still an appealing idea: the same camera and the same footage, with a mount that sits low and out of the wind.

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