Flat lens works by smooth variation of liquid crystals

The new prototype LCVL1 (liquid crystal variable lens) uses a novel approach developed at Durham University to control the parameters of liquid crystal. Known as modal addressing, the spatial properties of the device are smoothly controlled without the use of a pixellated structure. The lens aperture is typically 5mm diameter and the device operates at wavelengths greater than 400nm. The liquid crystal variable lens design is based on a standard nematic cell configuration. However modified planar electrodes allow control of the spatial distribution of the electric field within the device. Changes to the amplitude and frequency of the drive signal, produced by the purpose built control electronics, vary the refractive index profile in the liquid crystal, providing the mechanism to produce optical lensing effects and wavefront control. The refractive index change provides a controllable focal length from infinity to 50cms. Lenses with an aperture larger than 5mm diameter can be provided, on request, but with an increase in the value of the minimum focal length obtainable. Devices with 1D control of the refractive index are available for implementation of cylindrical optics. Features No moving parts Electronically controlled focal length Focal power 0-2 dioptres (infinity to 50cm) Aperture typically 5mm Switching speed typically 1s Applications Focus control Image zoom Wavefront correction Laser beam control CRL Opto Liquid Crystal Variable Lens TS