The conventional masks for scuba diving have a flat front glass mounted into a frame shaped so as to be water tightly applied to a diver's face and enclosing an air volume at diver's eyes. In the simplest models, the diver is allowed to have a correct vision through said air volume and through the glass, and the air vision is almost immediately restored when the diver's head emerges from the water surface.
However, in the diving the water pressure exerts on the mask a force proportional to the depth. Such a force, not balanced by the atmospheric pressure inside the mask volume, is transmitted to the diver's face, creating a considerable discomfort, pain and even capillary vessel ruptures as well with the increase of the diving depth. To prevent any damage from the pressure increase, the diver usually compensates the pressure inside the mask by exhaling air into the mask volume from the nose or the mouth. This solution might be regarded as sufficient in the aqualung diving, wherein the diver might spend some air for this purpose. In apnea diving, the diver often does not have any chance to use the lung air in the above described way. Moreover, this solution cannot be applied to goggles covering only the diver's eyes.
For these reasons, a new concept of floodable mask has been developed, wherein the inner volume contacting the diver's eyes is essentially flooded, i.e. filled by a suitable liquid, namely physiological solution, fresh water, sea water. The liquid is basically incompressible; hence the external water pressure has no effect on the mask inner volume and on the diver's visage. However, in view of the different refractive index between air and water, the diver's vision is consequently altered, but such an optical effect is compensated by a suitable optical system placed either inside the mask volume, at the diver's eyes, or at the mask glass.
This optical system may include one or more converging lenses for each eye, embedded into the glass or internally fixed to the glass surface. In this way, during the immersion, the diver's vision is correct and the external pressure is compensated e.g. by the physiological liquid over the whole surface of the visage covered by the mask, thus avoiding the mentioned drawbacks.
Nevertheless, at re-emersion, the corrective lenses completely inhibit the normal vision in air. Such a hindrance may cause relevant difficulties in diver's orientation to locate, for instance, the other divers, a support buoy or an incumbent danger. Removing the mask when emerging from the water may not be put into practice for the necessity of having the mask volume flooded at the next plunge, and represents a serious drawback especially for free divers, which repeatedly immerge and re emerge themselves.
Innovative Aspects:
At present this is the first international patent of flooded mask for underwater and air vision that can provide a good vision to freedivers without the drawbacks of air compensation. The industry that will invest in this product will be the first on the market to produce an elite freedive mask whose invention is aimed by top athletes and recreational freedivers. The investment in new products and research could be a good presentation of customer care.
