Types of diving mask:
✋Older diving mask with one big window,✌Disassembled single-window, low-volume dive mask, ✌A two-window, soft-silicone dive mask without purge valve, 👀A HydroOptix Double-Dome mask, 👂Mask with bifocal lenses for reading instruments, ☝A diving mask showing the retaining strap,
👄A twin-lens, low-volume diving mask, Aqua Lung (Technisub) Sphera, with wide peripheral view of the type favoured by many Underwater Hockey players.
Early model diving masks had a single elliptical pane of glass. These masks have indentations in the skirt at the bottom on either side of the nose, into which the diver can insert a thumb and forefinger 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 around the nose, which is covered by the rubber or silicone material of the skirt. This facilitates pinching the nose when ear-clearing.
A further development is the mask with two windows, one for each eye. It can have the windows closer to the face than the one-window type, and therefore contain even less internal volume for the diver to clear or equalise. These types are often called a "low-volume mask" Participants in the sport of underwater hockey are required to use twin-lens masks of this type for their own safety - the sport uses a heavy lead puck similar to an ice hockey puck, nan but skilful players can flick the puck considerable height off the bottom when making passes which leads to the possibility of accidental puck contact with other players. Should a puck hit the lens of a single-lens mask there is a good chance it will break the glass and pass through the aperture to hit the face and eyes, but with a twin-lens mask though the glass may break the frame will prevent the passage of the puck any further.
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 a half mask with a built-in LCD head up display which displays various dive and breathing set conditions including the function of a diving computer. It is currently very expensive.
There are other related equipment.
Diver wearing a lightweight full face maskDiver wearing heavy duty Kirby-Morgan band mask
There are several specialized types of diving headgear or outerwear:
· full face diving mask - often worn by working divers who need underwater verbal communication ability.
· Lightweight diving helmet - usually worn by divers using surface supplied diving equipment.
· Copper hat - part of the old fashioned standard diving dress.
· fluid filled mask - the need to equilibrate the internal pressure in the mask by exhaling air through the nose reduces the freediver capacity to dive deep. Masks or swimming goggles with high power lenses (40-200 diopters) have been developed in this view: they are filled with water or saline fluid.
Early model diving masks had a single elliptical pane of glass. These masks have indentations in the skirt at the bottom on either side of the nose, into which the diver can insert a thumb and forefinger 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 around the nose, which is covered by the rubber or silicone material of the skirt. This facilitates pinching the nose when ear-clearing.
A further development is the mask with two windows, one for each eye. It can have the windows closer to the face than the one-window type, and therefore contain even less internal volume for the diver to clear or equalise. These types are often called a "low-volume mask" Participants in the sport of underwater hockey are required to use twin-lens masks of this type for their own safety - the sport uses a heavy lead puck similar to an ice hockey puck, nan but skilful players can flick the puck considerable height off the bottom when making passes which leads to the possibility of accidental puck contact with other players. Should a puck hit the lens of a single-lens mask there is a good chance it will break the glass and pass through the aperture to hit the face and eyes, but with a twin-lens mask though the glass may break the frame will prevent the passage of the puck any further.
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 a half mask with a built-in LCD head up display which displays various dive and breathing set conditions including the function of a diving computer. It is currently very expensive.
There are other related equipment.
Diver wearing a lightweight full face maskDiver wearing heavy duty Kirby-Morgan band mask
There are several specialized types of diving headgear or outerwear:
· full face diving mask - often worn by working divers who need underwater verbal communication ability.
· Lightweight diving helmet - usually worn by divers using surface supplied diving equipment.
· Copper hat - part of the old fashioned standard diving dress.
· fluid filled mask - the need to equilibrate the internal pressure in the mask by exhaling air through the nose reduces the freediver capacity to dive deep. Masks or swimming goggles with high power lenses (40-200 diopters) have been developed in this view: they are filled with water or saline fluid.
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