Contact lens for three dimensional visualization

This application claims the benefit of Provisional Application No. 61/026,069, filed Feb. 4, 2008, the disclosure of which is incorporated herein by reference in its entirety.

This invention is in the field of eyewear, and more particularly in the field of eyewear for stereoscopic or three-dimensional visualization.

Because the eyes of humans are in different positions on the head, they perceive slightly different views. This is the basis of stereopsis, the process by which the brain exploits the parallax due to the different views from the eye to gain different perception and estimate the distance to objects. Based on the same principle, parallax has been exploited in the engineering of devices for stereoscopic visualization.

A common method for producing stereoscopic images for a viewer is to project two sets of images, wherein the projected images are filtered such that one set of images is linearly polarized in a first direction, and the second set of images is linearly polarized in a direction perpendicular to the first direction. The two sets of images are stereoscopic, i.e., imaging the same view from slightly different positions. The images are viewed by a viewer through a pair of spectacles having polarizer (or polarized) lenses, wherein the polarization direction of the lenses are offset by about ninety degrees. The polarization directions of the projected images are similarly oriented, so that each lens is substantially transparent to one set of images, and is substantially opaque to the other set. The user's left eye, therefore, sees the first set of images, and the right eyes sees the second set of images. Using parallax, the viewer is able to perceive a stereoscopic image assembled from the left eye image and the right eye image, providing an illusion of three-dimensionality. Examples of stereoscopic imaging apparatus taking advantage of polarization are disclosed, for example, in U.S. Pat. No. 3,975,474, and in U.S. Pat. No. 7,164,529, both of which are incorporated by reference in their entirety.

However, current stereoscopic viewing technology usually requires the use of bulky devices such as 3D viewing glasses, which are often inconvenient for a viewer to carry around and keep track of. In addition, the current external stereoscopic viewing devices, such as glasses, limit the mobility of the viewer and, therefore, do not allow a complete experience in a virtual world. The present invention seeks to overcome the disadvantages of current stereoscopic visualization devices and provides further related advantages.

This invention provides contact lenses for stereoscopic visualization. In one embodiment, the invention provides a contact lens set for stereoscopic visualization using light polarization. The contact lens set includes a left contact lens and a right contact lens. The left contact lens comprises a lens substrate incorporating a first polarizer, wherein the first polarizer comprises a first plurality of parallel lines having sub-wavelength pitch and oriented in a first direction. The right contact lens comprises a lens substrate incorporating a second polarizer, wherein the second polarizer comprises a second plurality of parallel lines having sub-wavelength pitch and oriented in a second direction. The left contact lens and the right contact lens each comprises a rotational stabilization means such that, during use, the first direction is adapted to orient in an approximately orthogonal direction to the second direction.

The rotational stabilization means may include a center of gravity displaced in a direction toward the edge of the contact lens. The center of gravity of the lens may be displaced by additional weight on one side of the contact lens, which may be accomplished by thinning one side of the contact lens with respect to the other, or adding extra lens substrate volume to one side of the contact lens. The rotational stabilization means may also include at lease one identifiable marking on a surface of the contact lens, indicating the orientation of the lens in reference to the polarization direction of the lens.

In another embodiment, the present invention provides a contact lens set for stereoscopic visualization using color-coded image construction. The contact lens set includes a left contact lens and a right contact lens. The left contact lens comprises a lens substrate, wherein at least a center portion of the left contact lens is made to selectively filter or pass a first wavelength. The right contact lens comprises a lens substrate, wherein at least a center portion of the right contact lens is made to selectively filter or pass a second wavelength.

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawing, wherein:

FIG. 1 is a schematic illustration of one embodiment of the contact lens set for stereoscopic visualization using light polarization;

FIG. 2 is a diagrammatic cross section of the contact lens set of FIG. 1 along the line 2 - 2 , showing the displaced center of gravity of the lens;

FIG. 3 is a schematic illustration of a representative contact lens set using an inferior and a superior thin zone on each lens as rotational stabilization means; and

FIG. 4 is a schematic illustration of an alternative embodiment of the contact lens set for stereoscopic visualization using color-coded image construction.

Two representative embodiments of the present invention are described with reference to FIGS. 1-4 .

FIG. 1 shows schematically a contact lens set 100 on a viewer 90 (in phantom). The contact lens set 100 comprises a left contact lens 100 L and a right contact lens 100 R, each equipped with a linear polarizer portion, as discussed below. The polarization direction of the left contact lens 100 L is approximately orthogonal to that of the right contact lens 100 R. Each linear polarizer comprises a set of parallel metal lines or wires 101 L, 101 R produced on the surface of the lens 100 L, 100 R or embedded in the lens substrate. The parallel lines or wires 101 L and 101 R have sub-wavelength pitch P. As used herein, “sub-wavelength pitch” means that the distance between neighboring lines or wires of the polarizer is generally less than the smallest wavelength of the received light that is of interest to the user. Preferably, the pitch is less than about one-fifth of the smallest wavelength of light of interest. Therefore, for applications in the visible light spectrum preferably the pitch is equal to or less than about 60 nm.

As known in the field of microelectronic fabrication parts, the polarizer having parallel metal lines or wires 101 L, 101 R can be created through a variety of techniques including, but not limited to, e-beam lithography and nano-imprint lithography.

The capability of parallel metal lines or wires 101 R, 101 L to linearly polarize light has been reported previously in the literature. For example, the commonly used wire-grid polarizer consists of a regular array of fine parallel metallic wires. The incoming light wave with an electric field aligned parallel to the wires induces the movement of electrons along the length of the wires, such that the light wave's energy is absorbed or reflected. For an incoming light wave oriented with its electric field perpendicular to the wires little energy is lost or reflected, and the light wave is able to travel through the metallic grid. A light wave oriented with its electric field parallel to the wire is absorbed or reflected. To function, the pitch must be less than the wavelength of the incoming light wave and is typically measured as the distance between the centerline of adjacent lines. The wire width is generally a small fraction of the pitch.

Refer now also to FIG. 2 , which illustrates a cross-section of the left lens 100 L. In this embodiment, the lens substrate 105 is formed from a biocompatible polymer. In one embodiment, the lens substrate 105 comprises polymethylmethacrylate (PMMA). Other suitable biocompatible polymers include, without limitation, poly(2-hydroxyethyl methacrylate), poly(glycerol methacrylate), poly(methyl methacrylate), polyethylene oxide, polyvinyl alcohol, polydioxaline, poly(acrylic acid), poly(acrylamide), and poly(N-vinyl pyrrolidone).

In a current method, the metal lines 101 R, 101 L are fabricated on the lens substrate 105 and the metal lines are encapsulated by a capping polymer layer 107 prior to cutting and micro-molding the lens shape. Any capping polymer useful in manufacturing contact lenses would be useful in the present invention. For example, in one embodiment, a polyxylene polymer, such as parylene, is used for the capping polymer layer 107 .

After the metal lines are fabricated and encapsulated on the lens substrate, the resulting panel is cut into a desired shape, for example, to produce a generally circular contact lens. The cut portion is then micro-molded into the desired three-dimensional lens shape. A final polishing step will prepare the contact lens set 100 for use by the viewer 90 .

Still referring to FIG. 1 , when the contact lens set 100 is in use, the functionality of the contact lens set 100 for observing stereoscopic images is dependent upon the relative orientation of the polarization direction of the left lens 100 L with regard to that of the right lens 100 R. Preferably, when the lenses 100 L, 100 R are each in contact with the surface of the cornea (not shown), the direction of the parallel metal lines 101 L should be approximately orthogonal to the direction of the parallel metal lines 101 R. Rotational stabilization means constructed within each lens 100 L, 100 R serves to keep the contact lenses in a desired relative orientation during use.

Various rotational stabilization techniques are known in connection with toric contact lenses for correcting astigmatism. These rotational stabilization techniques are equally applicable to the contact lenses of the present invention. In general, rotational stabilization techniques fall into two basic categories: prism stabilization, and dynamic stabilization.

Prism stabilization involves constructing a contact lens preferentially weighted on one side, such that the center of gravity of the lens is displaced in the direction toward the edge of the contact lens. Prism stabilization is currently the most used technique for rotational stabilization of contact lenses. For example, U.S. Pat. No. 4,874,234 discloses a contact lens with a displaced center of gravity; U.S. Pat. No. 7,134,753 discloses a rotational stabilization means, such as prism ballast, and a thickness profile in a contact lens that reduces the torque imparted on the lens by the action of the eyelids, which helps to stabilize the lens; U.S. Pat. No. 6,113,236 discloses a contact lens having a posterior surface and an anterior surface, the surfaces being shaped to form a ballast to provide the desired rotational stabilization to the lens; and U.S. Pat. No. 4,573,774 discloses a contact lens utilizing a prism ballast as a means of maintaining correct axial orientation. All above references are incorporated by reference in their entirety.

Referring back to FIG. 1 , the center of gravity of the lens may be displaced by adding extra lens substrate volume to one side of the contact lens 100 R, 100 L, resulting in a thickened area 110 R, 110 L. As shown in FIG. 2 , the thickened area 110 R, 110 L may have a shape of a hanging drop and may not reach as far as to the lower edge 120 R, 120 L of the lens. The additional volume of the lens substrate may be added during the microfabrication process. Alternatively, the center of gravity may be displaced by thinning one side of the contact lens with respect to the other side. The thinning process may be carried out during the polishing process.

Still referring to FIG. 1 , for the contact lens set 100 to function properly, the center of gravity of each lens 100 R, 100 L must be displaced in a controlled fashion such that, during use, the polarization direction of the left lens 100 L stays approximately orthogonal to the polarization direction of the right lens 100 R. To accomplish that, the thickened area 110 R is placed perpendicular to the parallel metal lines 101 R; and the thickened area 110 L is placed parallel to the parallel metal lines 101 L. During use, the displaced center of gravity of each lens 100 R, 100 L naturally rotates to the bottom position, keeping the parallel metal lines 101 R in a vertical position and the parallel metal lines 101 L in a horizontal position. This leads to the orthogonal orientation between the polarization directions of the lenses.

Dynamic stabilization, by contrast, relies on interaction between the eyelids and the lens to achieve the desired alignment of the lens. For example, the rotational stabilization may be achieved by designing a contact lens with an inferior and a superior thin zone outside the optical zone (i.e., the area overlying the user's iris). FIG. 3 shows another embodiment of a contact lens set 200 including a left lens 200 L and a right lens 200 R, each having an inferior thin zone 210 L, 210 R and a superior thin zone 220 L, 220 R outside of the optical zone 205 L, 205 R. The lens may have symmetrical or asymmetrical thin zones. The thin zones serve as rotational stabilization means and are placed in such a way that, during use, the polarization direction of the left lens 200 L stays at an approximately orthogonal direction to that of the right lens 200 R.

Various dynamic stabilization techniques for use on contact lenses have been developed. For example, U.S. Pat. No. 5,650,837 discloses a non-ballasted, rotationally stabilized contact lens, in which the lens is positionally and rotationally stabilized in the eye through the interaction between the lens and the eyelid; U.S. Pat. No. 5,500,695 discloses a contact lens using waveform contours on the lens periphery to enable proper location and orientation of the lens by interaction between the lens, the eye, and the eyelid. See also, U.S. Pat. Nos. 6,176,578; and 7,152,975. All these references are incorporated by reference in their entirety.

It is contemplated that, in order to facilitate the proper placement of the contact lens inside an eye, the lens may further include at least one identifiable marking on the surface of the contact lens, indicating the orientation of the lens in reference to the polarization direction of the lens. The marking may be tiny, almost invisible markings, such as dots, lines, or dents on the lens, preferably located at the edge of the lens. These markings may be formed by known techniques. When placing the lens on the cornea of an eye, the marking provides guidance on the proper orientation of the lens.

In another embodiment, the present invention provides a contact lens set for stereoscopic visualization using color-coded image construction. In this embodiment, each contact lens filters for a specific wavelength. The projected images for the contact lens set have two separate image components programmed according to the wavelength of each lens. Therefore, each lens only allows the image component having the corresponding wavelength to go through, letting the viewer perceive two different images simultaneously.

Various known methods may be used to selectively filter a desired wavelength through a contact lens including, for example, the incorporation of dyes or multilayer dielectric filters. The prior art discloses various methods for making color contact lenses including, for example, U.S. Pat. Nos. 7,296,891, and U.S. Patent Publication No. 2005/0128433, both of which are hereby incorporated by reference in their entirety.

FIG. 4 shows a representative contact lens set 300 using color-coded image construction on a viewer 90 (in phantom). Referring to FIG. 4 , the contact lens set 300 includes a color-coded left lens 300 L and a color-coded right lens 300 R. The center portion 310 L, 310 R of each lens that overlies the iris is colored. The center portion 310 L is colored with a different color than the center portion 310 R. For example, the center portion 310 L may be colored a first color such as red, and the center portion 310 R may be colored a second color, such as blue. An image generated in the first color is filtered through the left lens 300 L to reach the left eye, and an image generated in the second color is filtered through the right lens 300 R to reach the right eye. By assembling the left eye image and the right eye image, the viewer will see a stereoscopic image.

While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.