Types of Diving Mask
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Older diving mask with one big window
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Disassembled single-window, low-volume dive mask
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A two-window, soft-silicone dive mask without purge valve
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A HydroOptix Double-Dome mask
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Mask with bifocal lenses for reading instruments
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A diving mask showing the retaining strap
Older diving masks had a single elliptical pane of glass. These masks have indentations underneath, either side of the nose. Divers can then put a thumb and forefinger in to pinch the nose, when performing a Valsalva maneuver to clear their ears. This design was improved by bringing the window closer to the face, reducing the volume of air inside the mask, thus making mask clearing easier. The window has a cutout to fit over the nose, which is covered by the rubber or silicone material of the mask. This facilitates pinching the nose when ear-clearing.
A further development is the mask with two windows, one window for each eye. It can have the windows closer to the face than the one-window type, and therefore contain even less space for the diver to have to blow water out of if the mask floods. These types are often called a "low-volume mask".
Recent innovations have produced more complex designs, intended to provide extra features:
- The double-dome mask. This was invented by HydroOptix. Double-dome masks allow a wider field of view and avoid the refraction error in perceived distance and size of objects. Underwater the curved mask windows make the diver's vision effectively more hyperopic, or less myopic, and the diver must wear special contact lenses to compensate (unless his eyes are myopic to the right amount to compensate exactly for the refraction at the curved mask windows). The diver's vision will become myopic when he puts his head out of water with the contact lenses in.
- The "Data Mask", developed by Oceanic, is an eyes-and-nose diving mask with a built-in LCD display which displays various dive and breathing set conditions including the function of a diving computer. It is currently very expensive.
Read more about this topic: Diving Mask
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