Community Research and Development Information Service - CORDIS

Flexible wave front sensor for improving optical systems performance

An optical system can be considered to be performing at its best when it is free of aberrations such as wave front distortions. Adaptive systems have been designed to correct back to the ideal, once aberrations have been measured. This can be accomplished by a new flexible sensor developed to accurately measure these aberrations in a coherent signal that can describe the optical quality or lack thereof.
Flexible wave front sensor for improving optical systems performance
Optical systems, such as Shack-Hartmann gradient sensors have been widely used in wave front measurements for various applications, including astronomy, optical element analysis and ophthalmology. The sensor's central element is a sampling device that breaks up the incoming wave front into multiple focal spots falling on an optical detector, where it is reconstructed. Supporting sub-systems, such as beam reducers or expanders, complete the sensor's system.

Although current wave-front sensors' geometry is not flexible, it is possible to sample the wave front at different points according to the measurement conditions. This is achieved by changing the optical magnification of the sensor's relayed aperture. Aiming to improve measurement accuracy, an Israeli researcher proposed to use a flexible sensor with variable lenslets both in space and time.

The flexibility is achieved by passing the wave-front through an acousto-optic cell. Once standing sound waves have been electronically produced in this cell and launched perpendicular to the investigated beam, they cross each other at some distance down the light beam. An array of acousto-optic spots appears, just like spots behind a lenslet array. The spatial frequency of the array depends on the temporal frequency of the standing sound waves.

The innovation of the system is that, instead of mechanically changing the magnification, the sampling frequency is electronically modified when an alternative lenslet array is required. Additional benefits include significantly extended spatial and temporal dynamic range and accuracy to meet the expanding needs of ophthalmic and optometric industries. Furthermore, the system is designed for ease of manufacture and low overall product cost.

A patent is pending for this new flexible wave front sensor. Partners specialized in electro-optical and mechano-optical systems manufacturing are sought for integrating this sensor in commercial applications.
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