pubmed.ncbi.nlm.nih.gov

Switchable electro-optic diffractive lens with high efficiency for ophthalmic applications - PubMed

  • ️Sun Jan 01 2006

. 2006 Apr 18;103(16):6100-4.

doi: 10.1073/pnas.0600850103. Epub 2006 Apr 5.

Affiliations

Switchable electro-optic diffractive lens with high efficiency for ophthalmic applications

Guoqiang Li et al. Proc Natl Acad Sci U S A. 2006.

Abstract

Presbyopia is an age-related loss of accommodation of the human eye that manifests itself as inability to shift focus from distant to near objects. Assuming no refractive error, presbyopes have clear vision of distant objects; they require reading glasses for viewing near objects. Area-divided bifocal lenses are one example of a treatment for this problem. However, the field of view is limited in such eyeglasses, requiring the user to gaze down to accomplish near-vision tasks and in some cases causing dizziness and discomfort. Here, we report on previously undescribed switchable, flat, liquid-crystal diffractive lenses that can adaptively change their focusing power. The operation of these spectacle lenses is based on electrical control of the refractive index of a 5-mum-thick layer of nematic liquid crystal using a circular array of photolithographically defined transparent electrodes. It operates with high transmission, low voltage (<2 Vrms), fast response (<1 sec), diffraction efficiency > 90%, small aberrations, and a power-failure-safe configuration. These results represent significant advance in state-of-the-art liquid-crystal diffractive lenses for vision care and other applications. They have the potential of revolutionizing the field of presbyopia correction when combined with automatic adjustable focusing power.

PubMed Disclaimer

Conflict of interest statement

Conflict of interest statement: No conflicts declared.

Figures

Fig. 1.
Fig. 1.

Adaptive liquid-crystal diffractive lens. (a) Dashed line, phase profile of a conventional refractive lens; dotted line, phase profile to achieve a diffractive lens; staircase structure, multilevel quantization approximates the continuous quadratic blaze profile. a.u., arbitrary units. (b) Layout of the one-layer electrode pattern (two central zones shown). Adjacent zones are distinguished by color. An electrical insulation layer with vias is added (vias shown with white dots). Each bus connects to one electrode (subzone) in each zone. Dimensions of the vias, the bus line, and the gap between electrodes are illustrated in the lower right. (c) Processing steps for fabrication of the patterned electrodes and the conductive lines. The structure of the liquid-crystal lens is shown in the lower right, where k is the wave vector, and E is the polarization state of the incident light.

Fig. 2.
Fig. 2.

Characterization of the 1-diopter lens. (a) Electro-optic response of the lens obtained with polarized microscope. (b) Diffraction efficiency as a function of the beam diameter. (c) Interferogram obtained with the Mach–Zehnder interferometer. The interference pattern has very good fringe modulation across the lens. A close-up view of the interferogram shows that the eight subzones in each zone have different grayscale intensities, and the pattern is periodic. (d) Unwrapped phase map for a 10-mm aperture. (e) Phase map of the unwrapped phase minus tilting and focusing. (f) MTF of the lens. The green line is obtained from the measurement data, and the blue line is for a diffraction-limited lens. The value at low spatial frequency is determined by the diffraction efficiency of the lens.

Fig. 3.
Fig. 3.

Hybrid imaging using the 1-diopter electroactive diffractive lens with the model eye. The function of the diffractive lens is to provide near-vision correction to the model eye. (a) The object is placed at a reading distance (≈30 cm). The image is severely out of focus in the model eye when the diffractive lens is off. (b) When the diffractive lens is activated, the object is imaged clearly.

Fig. 4.
Fig. 4.

A prototype of the assembled adaptive eyewear.

Similar articles

Cited by

References

    1. Smith G., Atchison D. A. The Eye and Visual Optical Instruments. Cambridge, U.K.: Cambridge Univ. Press; 1997.
    1. Sato S. Jpn. J. Appl. Phys. 1985;18:1679–1684.
    1. Fowler C. W., Pateras E. S. Ophthal. Physiol. Opt. 1990;10:186–194. - PubMed
    1. Sato S., Sugiyama A., Sato R. Jpn. J. Appl. Phys. 1985;24:L626–L628.
    1. Kowel S. T., Cleverly D. S., Kornreich P. G. Appl. Opt. 1984;23:278–289. - PubMed

Publication types

MeSH terms