Optical: systems and elements – Lens – Fluid
Patent
1998-03-02
2000-05-30
Epps, Georgia
Optical: systems and elements
Lens
Fluid
351 41, 351159, 351169, G02B 106, G02C 702, G02C 706
Patent
active
060697423
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an optical apparatus and method of adjusting an optical apparatus for correcting defective eyesight. In particular, the invention relates to an optical apparatus comprising at least one liquid lens or flexible membrane mirror, and more particularly to a pair of spectacles constituted by or including such an apparatus.
2. Related Art
It is known to provide a liquid lens in the form of one or more transparent, circular, flexible membranes clamped about a peripheral zone to define a cavity. The cavity is filled with a transparent liquid, the pressure of which is adjustable by means of a positive displacement pump such as a syringe.
Adjustments of the pressure of fluid in the cavity cause variations in the curvature of the lens defined by the membranes and fluid, thereby giving rise to a lens of infinitely variable optical power.
U.S. Pat. No. 4,890,903 gives further details of liquid lenses, and of optical instruments such as spectacles incorporating such lenses. The entire disclosure of U.S. Pat. No. 4,890,903 is incorporated herein by reference.
The history of liquid lenses goes back several decades, yet there has not previously been a proposal for a truly practical sight-correcting device incorporating such lenses.
SUMMARY OF THE INVENTION
According to a first aspect of the invention, there is provided an optical apparatus comprising: lens or mirror; flow of liquid therebetween; and cavity attains a desired value, whereby to render the lens or mirror subsequently non-adjustable.
The principal advantage of such an arrangement over previous apparatuses is that the liquid lens or lenses become non-adjustable after adjustment of the lens or lenses to a desired setting. This is in contrast to previous apparatuses, in which the liquid lenses have remained perpetually adjustable. Thus, previous liquid lens apparatuses could not be incorporated into spectacles partly because of the cumbersome nature of the pumps needed for adjustment of the lenses; and partly because of the risk of the optical power of the lenses deviating from optima tailored for the wearer of the spectacles.
Thus, an apparatus according to the invention confers a robustness and practicality not achievable with previous liquid lens designs.
Preferably the closure includes a portion of the duct plastically deformable to close the duct. In particularly preferred embodiments, the duct is plastically deformable when compressed and or when heated. A further possibility is for the duct to be plastically deformable when subjected to ultrasonic excitation.
The foregoing features mean that apparatus according to the invention can readily be adjusted to a preferred optical power of the lenses, and easily set at the preferred optical power.
Conveniently, the pump is a positive displacement pump capable of increasing and decreasing the pressure of liquid in the cavity. In particular preferred embodiment, the pump is a syringe.
Syringes are mass-produced at extremely low cost, and therefore they provide a simple, inexpensive means of setting the power of the lenses of an apparatus according to the invention, eg. in a harsh environment.
In some embodiments of the invention, the closure preferably includes a member retentively deformable to close the duct. One form of such a member is a resiliently deformable bung closing the duct. For use with such a bung, the pump may include or be operatively connected to a further duct capable of removably piercing the bung to permit the flow of liquid between the pump and the cavity, the resilience of the bung (a) creating a liquid-tight seal about the further duct when the bung is pierced thereby; and (b) causing closure of the aperture pierced by the further duct on removal thereof from the bung.
In particular preferred embodiments, the further duct is a hollow needle.
Thus it is possible to devise embodiments of the invention in which the pump is a conventional syringe having a conventional hypodermic needle secured thereto, in order to
Epps Georgia
Schwartz Jordan M.
Silver Joshua David
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