Underwater vision device
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to underwater vision devices, and more particularly, to underwater vision devices having multi-element lenses which provide neutral magnification above the surface of water and strong magnification below the surface of the water to permit a wearer to see normally both above and below the surface of the water without adjusting the device. 
     2. Description of the Prior Art 
     A variety of various types of underwater vision devices are disclosed in the prior art. U.S. Pat. No. 2,008,530 (Wick) discloses submarine glasses coupled to a spectacle-like frame and are intended to be worn by a swimmer either above or below the surface of a body of water. Each of the two optical systems of these glasses is fabricated from thin transparent celluloid and includes a sealed air chamber. These lens elements function only in the presence of water; in the air the negligible thickness of the transparent celluloid fails to have any significant refractive effect on light passing through each lens element. Because of this characteristic, the Wick submarine glasses can be worn either above or below water. 
     U.S. Pat. No. 2,088,262 (Grano) discloses underwater spectacles. Many of the various lens embodiments disclosed in the Grano patent are fabricated from glass, but several embodiments include an air filled chamber adjacent to a glass lens. 
     U.S. Pat. No. 3,040,616 (Simpson) discloses a face mask which includes an air chamber between the transparent front surface of the face mask and the face of the wearer. A complex lens system is positioned in alignment with the eye of the wearer. Each element of this lens system includes a transparent refractive material, an air cavity and a layer of water. The purpose of this invention is to permit the wearer of the device to see normally while above or below the surface of the water. 
     U.S. Pat. No. 3,672,750 (Hagen) discloses an underwater diving mask which includes a pair of lens systems which form an air chamber between the face mask and the eyes of the wearer. The central portion of each part of this mask which is aligned with an eye of the wearer includes a corrective spherical lens. This mask allows an underwater diver to have vision substantially comparable with that which he would have in an air environment. 
     The following U.S. Patents disclose optical systems which utilize various types of optical mediums of varying refractive indices: U.S. Pat. Nos. 3,976,364 (Lindemann); 2,730,014 (Ivanoff); and 3,320,018 (Pepke). 
     SUMMARY OF THE INVENTION 
     It is the principal object of the present invention to provide an underwater vision device having a first lens element including a first lens group and a second lens group separated by a chamber which fills with water when the device is submerged below the surface of water. 
     A more specific object of the invention is to provide an underwater vision device in which the second lens group is positioned at a greater distance from the eye of the wearer than the first lens group in order to provide substantially increased underwater magnification with a lens system having a comparatively large radius of curvature thus permitting a substantially wider undistorted field of vision than prior art devices. 
     Another object of the present invention is to provide an underwater vision device in which the first and second lens groups each include a sealed air chamber. 
     A further object of the present invention is to provide an underwater vision device having a compressible seal between the solid transparent lenses of each of the first and second lens groups to permit mechanical displacements of the lens elements as the device is subjected to increasingly greater underwater pressures. 
     Briefly stated, and in accord with one embodiment of the invention, an underwater vision device is supported by the nose and ears of a wearer. A frame includes a front element having a nose piece for contacting and being supported by the wearer&#39;s nose. The front element includes first and second apertures which are aligned with the wearer&#39;s eyes. A first ear piece is coupled to one end of the front element while a second ear piece is coupled to the other end of the front element. The first and second earpieces contact the wearer&#39;s ears to maintain the frame in a desired fixed position on the wearer. 
     First and second lens elements are coupled to the front element in alignment with the first and second apertures. Each of the first and second lens elements include first and second lens groups and spacer means which is coupled to the first and second lens groups for maintaining a predetermined spacing between these lens groups and for maintaining the second lens group in alignment with the first lens group. A cavity is formed between the first and second lens groups and fills with water when the device is immersed. Each lens group includes a first solid transparent lens, a second solid transparent lens, and securing means coupled to the first and second lenses for securing the first and second lenses together and for forming a sealed air chamber. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The invention is pointed out with particularity in the appended claims. However, other objects and advantages together with the operation of the invention may be better understood by reference to the following detailed description taken in conjunction with the following illustrations: 
     FIG. 1 is a perspective view of a preferred embodiment of the underwater vision device. 
     FIG. 2 is an exploded sectional view illustrating the various elements forming the underwater vision device. 
     FIG. 3 is a sectional view showing the manner in which the securing means permits the first and second solid transparent lens elements of each lens group to be compressed as the underwater vision device is submerged. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In order to better illustrate the advantages of the invention and its contributions to the art, various mechanical features of the preferred embodiment will now be reviewed in detail. 
     The underwater vision device of the present invention includes a commercially available spectacle frame having a front element 10. Nose piece 12 contacts and is supported by the nose of the wearer. Front element 10 includes first and second apertures which are aligned with the wearer&#39;s eyes when the underwater vision device is properly positioned on the wearer&#39;s head. Ear pieces 14 and 16 are coupled to front element 10 and are designed to contact the wearer&#39;s ears to maintain the underwater vision device in a desired fixed position of the wearer&#39;s head. The two ends of an elastic strap 18 are coupled as shown in FIG. 1 and assist in maintaining the device in a fixed position on the wearer&#39;s head. 
     Identical multi-element lens elements 20 and 22 are coupled in alignment with the apertures in front element 10 as is illustrated in FIGS. 1 and 2. Since the various structural elements of lens elements 20 and 22 are identical the specific structure of only one lens element will be discussed in detail. 
     Referring now to FIGS. 1 and 2, lens element 20 includes a first lens group 24. First lens group 24 includes first and second concave-convex lenses 26 and 28. The concave and convex surfaces of lenses 26 and 28 are parallel so that these lenses have virtually no refractive effect in air. Lens 28 is coupled to front element 10 of the spectacle frame as shown. Securing means in the form of a hollow plastic or Teflon tube 30 is formed in the shape of a circle. The two ends of tube 30 are sealed together to maintain a circular configuration and to maintain a sealed air cavity within the interior hollow tubular section of tube 30. An adhesive or an equivalent substance is applied around the periphery of tube 30 to couple lenses 26 and 28 and tube 30 together. Lens 28 is mechanically secured to front element 10 of the spectacle frame in a well known conventional manner. 
     A second lens group 32 includes concave-convex lens elements 34 and 36 identical in structure to lenses 26 and 28 and are adhesively coupled to tube 38 in the same manner as was discussed above in connection with first lens group 34. 
     Spacer means 40 is positioned between lens groups 24 and 32. Spacer means 40 maintains lens group 32 in alignment with lens group 24 and maintains a predetermined fixed lateral spacing between these two lens groups. If spacer means 40 takes the form of a hollow centered disc as illustrated in FIG. 2, it will also include a plurality of perforations or apertures around the periphery to permit a free flow of water into the cavity formed between surfaces 42 and 44 of lenses 36 and 26. This cavity or flooding chamber designated generally by reference numeral 46 will quickly fill with water when the underwater vision device is submerged below the surface of the water. Spacer means 40 may also take various other forms such as a plurality of spot connectors for mechanically securing lens groups 24 and 32 together or any other equivalent mechanical structure which will accomplish the same function without interferring with the wearer&#39;s line of vision through the lens system of the present invention. 
     Air chambers designated by reference numbers 48 and 50 are best seen in FIG. 3 and are formed by the air-tight coupling of the two concave-convex lenses to the tubular ring of each lens group. As a result of increasing water pressure with increasing depths, the two concave-convex lenses of each lens group are mechanically forced together, compressing tubular members 30 and 38 and increasing the air pressure within air chambers 48 and 50. This mechanical compression of the lens elements permits the air pressure and water pressure to equalize and substantially reduces the stress induced on the surfaces of the concave-convex lenses. 
     Alternatively, a collapsible air chamber positioned external to each lens system of the device could be connected to each of the air chambers between the lenses. Increasing water pressure would compress each external chamber, driving air from the chamber into the cavity between the lenses to maintain the pressure within each cavity equal to surrounding water pressure and to maintain the lenses in their same position without compression effects. The concave-convex lenses are typically made from plastic, glass or a similar hard, transparent refractive material suitable for use in an optical system. The optical qualities of the underwater vision device are only minimally affected by the compression of the various lenses in each lens group. 
     The unique configuration of the underwater vision device of the present invention specifically positions second lens group 32 at a substantial distance in front of the corneal surface of the eye of the wearer. The pairing together of lens group 24 and 32 with an intervening flooding chamber 46, substantially increases the magnification power of this device in an underwater environment. Because of this magnification enhancement resulting from this unique structure, a substantially larger radius of curvature can be utilized with the various concave-convex lenses which form each of the lens elements. This significantly minimizes peripheral distortion and therefore dramatically increases the field of vision of the present invention in comparison to prior art devices which utilize less complex lens systems having lenses with a much smaller radius of curvature. In these prior art devices the field of view is extremely limited. 
     Although the lenses 26, 28, 34 and 36 are neutral in air, each lens has refracting power when one of its surfaces is in contact with water and the other surface is still in contact with the air in chambers 46 and 50. When underwater the focal length of each lens will equal its radius of curvature times four. Since there are four lenses in first and second lens groups 24 and 32, the overall focal length of the submerged device will equal the radius of curvature of each lens. This submerged focal length will equal about three inches but will be reduced to about two inches by the lens in the wearer&#39;s own eyeball. This two inch focal length is approximately the distance between the wearer&#39;s retina and the middle of the lens system of the device. The unique structure of the present invention permits the overall optical effect of each lens element to be neutral in air, but powerful and positive when immersed in water. If desired, the elements of each lens system could be adjusted to correct for ordinary refractive errors in vision in air. Certain refractive errors such as corneal astigmatism will be corrected by the wetting of the cornea while the user is underwater. 
     It will be apparent to those skilled in the art that the disclosed underwater vision device may be modified in numerous ways and may assume many embodiments other than the preferred form specifically set out and described above. Accordingly, it is intended by the appended claims to cover all such modifications of the invention which fall within the true spirit and scope of the invention.