Project: Intelligent advanced design and mapping of ophthalmic lenses
The ophthalmic spectacle lens manufacturing industry is undergoing significant change due to the widespread introduction of digital free form surface process technology. This technology provides the manufacturers of finished lenses, the so called RX labs, with an opportunity to compete with larger corporations dominating the spectacle lens market as it allows to produce lenses at the same cost as conventional cast molding technology which is still the most widely used lens manufacturing process today. Free form processing allows customizing every lens so that it meets the needs of each individual patient._x000D_Free form lenses are produced based on a prescription issued by an optician or ophthalmologist. These prescriptions define the required optical performance of a lens needed to correct defects in the patient's vision. Based on this prescription, the RX lab will issue a production specification in order to generate a finished lens. Finished lenses are COly manufactured starting from semi finished lenses, i.e. lenses with only one optically cut surface. The RX lab will then use free form technology to shape the opposite surface. The combination of both surfaces is supposed to yield a lens with the desired optical properties corresponding to the initial prescription._x000D_To generate the correct lens surface shape, the RX lab will perform calculations prior to the start of the production. Such calculations take into account a large number of variables such as the front surface radii of the semi-finished lens, the refraction index, values for minimum lens thickness as well as the physical dimensions of the mounting structure. To perform these complex calculations RX labs use lens design software. At the end of the production process, the correct finishing of the lens is assessed by analyzing the optical performance using lens mappers. These are optical instruments capable of determining the shape of the front and back surface of a lens and relate surface shape to the optical performance of the lens._x000D__x000D_Problem_x000D_RX labs cannot exploit free form technology in full. For a start, RX labs cannot compare and correlate data from the lens design software with data from the lens mapper. This is because the mathematical models used to describe the lens surfaces in the lens design software and in the lens mapper are different. The lens design software simulates the lens behavior 'on-the-eye', whereas a lens mapper analyzes the lens using collimated light parallel to the lens optical axis. The consequence is that the manufacturer cannot compare this data and gets confused as to whether he has produced the correct lens. Moreover none of these data correlate with the production specifications for the free form generator. In almost all of the smaller RX labs, there is no real means today to provide direct feedback to the production equipment._x000D_Furthermore, none of the existing lens mappers on the market today combine sufficient resolution with speed of analysis and a large enough field of view to meaningfully analyze the entire lens during production. Some lens mappers will measure all parameters over a small area of the lens only, other mappers such as focimeters, evaluate average values of just one single parameter over a larger area._x000D__x000D_To solve these problems, the present Eurostars project intends to develop:_x000D_(1) an in-process free form lens mapper capable of analyzing relevant optical properties, surface shape and surface finish quality across the entire lens surface, and capable of exchanging its data with_x000D_(2) a decision support software programme that will compare inputs from the lens design software and lens mapper, and provide feedback and propose corrective actions to the free form process._x000D__x000D_Consortium_x000D_The consortium consists of the two Ps, both are suppliers of services and products to lens manufacturers. The combination of the know-how present at both Ps related to the free form lens market is clearly complementary and allows a holistic approach to solve the problems cited._x000D__x000D_Indizen Optical Technologies S.L. (IOT), Madrid, Spain is specialized in developing spectacle lens design software for RX labs. 51% of the shares of IOT are held by Younger Optics, a major supplier of semi-finished spectacle lenses. The IOT design software is being used by over 60 independent RX labs worldwide._x000D__x000D_Lambda-X S.A. (LX), Nivelles, Belgium, is an independent optical engineering R&D performing SME specialized in conceiving and assembling scientific and industrial optical metrology instrumentation. Typical applications include aerospace, defence and ophthalmic optics. LX has supplied its instruments to over 20 different lens manufacturers worldwide.
| Acronym | IMAPS (Reference Number: 7019) |
| Duration | 13/03/2012 - 12/09/2014 |
| Project Topic | Free form spectacle lens manufacturers lack closed feedback support systems to correct process equipment settings. The aim of this project is to provide a closed feedback process to free form lens producers by developing a new decision support system software and a new lens mapper. |
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Project Results (after finalisation) |
Results of the project are summarized per workpackage below: _x000D_• An error database has been defined based on the different error patterns that can be viewed used a lens mapper. This database has been fed with 2000 items and can be fed continuously;_x000D_• An algorithm has been developed in order to sort the different errors based on the power maps measurement. This algorithm is based on a learning strategy and it has been demonstrated to converge;_x000D_• Lens mapper requirements have been established. These are met with the current version of NIMO from Lambda-X. Minor modifications have been considered such as extension for polarized lenses measurement and lens support modification for measuring contoured lenses;_x000D_• Lens mapper software has been modified to meet the industry standards. The processing part of the lens mapper software has been extracted into separate software to allow processing of previously-acquired measurements. This software makes measurements much easier due to alignment constraint removal. It also generates files fully compatible with the industry standard and the decision support center; _x000D_• An interface has been developed for the decision support center developed in WP2. This interface software shows a user-friendly GUI and is fully compatible with industry standards; _x000D_• Lens mapper from Lambda-X has been compared to other instruments (mapper) in the industry. Measurements from the NIMO have also been correlated with a profilemeter. Interfaces with the different algorithms have been used in the course of the project and are then validated as such. _x000D_ |
| Network | Eurostars |
| Call | Eurostars Cut-Off 7 |
Project partner
| Number | Name | Role | Country |
|---|---|---|---|
| 2 | Indizen Optical Technologies S.L. | Partner | Spain |
| 2 | Lambda-X S.A. | Coordinator | Belgium |