Shoei's new prototype helmet features a built-in heads up display

[MotoNews]

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Shoei’s new experimental, prototype helmet, the Opticson, comes with an integrated heads up display in its visor, so what are the benefits?

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[Skywagon]

My car has HUD. Not sure if they all do this but if you wear polarized sunglasses you can not see it. When not wearing sunglasses I rarely notice it. It can display all kinds of info. The only time I really use it is in heavy traffic in a place I’m not familiar. It gives me a better view of the gps. 

[BrianM]

On 4/29/2022 at 9:43 AM, Skywagon said:

My car has HUD. Not sure if they all do this but if you wear polarized sunglasses you can not see it. 

HUDs use reflection off the windshield. Reflected light will tend to polarize along the direction of the surface (horizontal for the windshield since source is in the dash and shining upwards.) from which is it is reflecting. The polarization is total at the Brewster angle (tangent of the Brewster angle = index of refraction of the glass - would work in this case). Polarized sunglasses are design to remove reflected light that is horizontally polarized (most surfaces reflecting light are horizontal). So the reflected HUD is blocked by polarized sunglasses.

 

For Shoei, it depends upon how the HUD is displayed. If it is reflected from the side, polarized glasses may not block the reflection.

Personally I do not like polarized sunglasses looking through a plastic face shield. Any imperfections (internal stresses) can alter the polarization of the light passing through which can then be seen with polarized glasses.