Method for stabilizing refractive index profiles using polymer mixtures

Abstract

A method for making an optical element comprises polymerizing a first monomer to form a first polymer, the first polymer having a spatially varying degree of cure that provides a predetermined refractive index profile; and polymerizing a second monomer in the presence of the first polymer to form a second polymer intermixed with the first polymer, the second polymer stabilizing the first polymer and the refractive index profile.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] This invention relates generally to optical elements, such as corrective lenses, and to methods for making them. More particularly, this invention relates to optical elements containing two or more polymers. [0003] 2. Description of the Related Art [0004] Many optical systems such as the human eye contain aberrations. In attempting to correct for such aberrations, it is common to assume that the light passing through the system is limited to paraxial rays, specifically, rays that are near the optical axis and that are contained within small angles. Corrective optics produced according to this assumption generally have only spherical surfaces. For example, it is typically assumed that ocular imperfections in the human eye are limited to lower order imperfections, including the imperfections commonly called “astigmatism” and “defocus”, that can be corrected by lenses having spherical surfaces. However, higher order im...

AI Technical Summary

Benefits of technology

[0007] A preferred embodiment provides an optical element comprising a first optical cover, a second optical cover, and a layer of polymeric material sandwiched between the first optical cover and the second optical cover, wherein the polymeric material comprises a mixture of a first polymer and a second polymer, the first polymer having a spatially varying degree of cure that provides a predetermined refractive index profile, and the second polymer being cured to thereby stabilize the refractive index profile.

[0010] polymerizing a second monomer in the presence of the first polymer to form a second polymer intermixed with the first polymer, the second polymer stabilizing the refractive index profile.

Problems solved by technology

However, higher order imperfections can exist, including but not limited to imperfections known as “coma” and “trefoil.” These imperfections unfortunately cannot be corrected by conventional glasses or contact lenses, leaving patients with less than optimum vision even after the best available corrective lenses have been prescribed.

Moreover, it is often difficult to simultaneously minimize all aberrations.

Indeed, corrections to an optical system to minimize one type of aberration may result in the increase in one of the other aberrations.

For example, decreasing coma can result in increasing spherical aberrations.

This process can be iterative and time consuming, requiring, as it does, assembly, alignment, and performance evaluation to identify aberrations, followed by disassembly, polishing or grinding to correct the aberrations, and then reassembling and retest.

The refractive index of the exposed polymer in the selected regions increases, but the resulting refractive index profile is not permanent, and over time, the refractive index profile changes and the amplitude of the induced refractive index change tends to decrease over time.

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