Search Menu
Photonics Media Photonics Buyers' Guide Photonics Spectra BioPhotonics EuroPhotonics Vision Spectra Photonics Showcase Photonics ProdSpec Photonics Handbook

Adaptive Lens Employs Liquid Crystal

Facebook Twitter LinkedIn Email Comments
Potential applications include zoom lenses in cell phone cameras.

Hank Hogan

Researchers at the University of Central Florida in Orlando have constructed a tunable-focus lens by using an electric field to vary the concentration of a liquid crystal material, which creates a gradient in refractive index.

The redistribution is performed via diffusion, which optics professor Shin-Tson Wu explained enables the lens to avoid aberration and light scattering. A problem with the approach is that the response time is proportional to the diffusion distance. Changing the focus would take minutes in a large lens. The researchers estimate that a lens with a 50-μm aperture would have a response time of about 1 s at room temperature.

In their adaptive lens, they use a transparent mixture of liquid crystal and the monomer N-vinylpyrrolidone. When subjected to an inhomogeneous electric field, the liquid crystal material moves toward the high electric field region, while the monomer moves away from it. They selected a liquid crystal material that would not undergo molecular reorientation as a consequence of the field.

They constructed an ITO electrode on a curved surface and filled the volume with a transparent polymer. A flat electrode defined the other side of the cell, and the liquid crystal and monomer mixture was introduced into the 25-μm gap.

Using a HeNe laser and a CCD camera from Santa Barbara Instrument Group Inc. in California, they measured the focal point of the lens and showed that it moved in response to changes in the applied voltage. The response time was about three minutes, which the researchers attributed to the 9-mm aperture of the lens.

The device also displayed a relatively high operating voltage and relatively low optical power. The voltage problem may be addressed by using a liquid crystal material with a larger dielectric constant. Using a liquid crystal material with a high refractive index and a monomer with a low refractive index may tackle the optical power issue.

Wu said that improvements will render the tunable lens useful in applications such as zoom lenses in cell phones equipped with cameras.

Applied Physics Letters, May 8, 2006, 191116.

Photonics Spectra
Jul 2006
energylensesliquid crystal materialopticsResearch & TechnologyTech Pulsetunable-focus lensUniversity of Central Florida

back to top
Facebook Twitter Instagram LinkedIn YouTube RSS
©2020 Photonics Media, 100 West St., Pittsfield, MA, 01201 USA, [email protected]

Photonics Media, Laurin Publishing
x Subscribe to Photonics Spectra magazine - FREE!
We use cookies to improve user experience and analyze our website traffic as stated in our Privacy Policy. By using this website, you agree to the use of cookies unless you have disabled them.