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Content archived on 2024-04-16

Grin material and technology R & D for gradient index optical glass lenses


The use of gradient index would significantly improve the characteristics and properties of optical mineral glass components, namely ophthalmics lenses.

The goal of the research programme is to design optical components and to develop corresponding materials for creating new glass lenses with a spatially varying (gradient refractive index)(GRIN) for use in ophthalmic optics.
Design tools were developed for optimizing image properties of lenses given the refractive index profile of the glass. An optical bench was built for measuring GRIN profiles based on deflectometry principle. The equipment is fully computerized and can be used to measure index profiles of large size blanks (up to 80 mm).
Among the three material technologies investigated (Impregnation/leaching of porous preforms, Casting of colloidal glass precursors, and High temperature interdiffusion) only the last was successful in obtaining quality glass with refractive index variation up to 0.2. The use of the developed design tools shows that the generated profiles for axial geometry are not sufficient in shape to compete with high refractive homogeneous glasses. Further development is needed for taking full advantage of the gradient index.
The work plan covers three main areas interdependent and complement one another :

-design tools will be developed to model optical ray tracing in an inhomogeneous medium and to calculate the imaging properties of gradient index lenses
-suitable glass systems will be identified and three potential ways will be investigated for processing these systems to give raw glass bodies with various radial and axial index profiles suitable for ophthalmic lenses. This task will form the largest share of the total project
-an instrument will be designed and built specifically to measure the index distribution in the raw glass bodies created in the previous activity


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Essilor International
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57 avenue de Conde
94106 Saint-Maur-des-Fossés

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Participants (4)