Do perfect eyeglasses exist?

How Rodenstock, a world leader in ophthalmic optics, uses individual face measurement for tailor-made eyeglasses.

Rodenstock is one of the global leaders in ophthalmic optics and employs about 4,500 people. Whether it’s eyeglass lenses or eyeglass frames – the Rodenstock brand stands for products of highest technological sophistication and superb quality. There’s a good reason for this company’s leading position: Rodenstock spurs the technical advancement in ophthalmic optics with major investments in research and development. It’s the only company in the world that has been dealing with both eyeglass lenses and eyeglass frames since its foundation 125 years ago. This combined competence allows for revolutionary developments, for example, the screwless miniature cylinder joint, the newly designed spring joint or exceptionally thin glasses.

The center of all its activities consists of optimizing optical image properties, making glasses more comfortable to wear, and designs accentuating the personality of the person wearing them. In short, it’s about improving vision and looks. As the trademark in competence when it comes to ophthalmic optics, Rodenstock concentrates on its core business of eyeglasses; that is, the development, production and sale of eyeglass lenses, eyeglass frames, and sunglasses.

The company has invested in innovative solutions for eyeglass lenses, in the attractive eyeglass frame collections of Rodenstock and Porsche Design, in new manufacturing sites in and outside of Germany, as well as in new sales branches on markets where Rodenstock itself hadn’t been active before.

In German ophthalmic optics, Rodenstock is the market leader for both eyeglass lenses and eyeglass frames. The foreign proportion of its revenue amounts to more than 50%.

The current situation

In 2000 Rodenstock introduced the new generation of progressive eyeglass lenses, ImpressionILT, which for the first time allows for making individual adjustments in the calculation of eyeglass lenses by taking into account facial shape and the chosen eyeglass frame, thereby significantly improving visual quality and visual comfort.

For these glasses, which are made in Frankfurt, Rodenstock requires very precise measurements of the individual parameters of the person wearing the glasses. Individual pupil distance, cornea apex distance, frame lens angle, forward incline angle, as well as centering data.

The declared goal of Rodenstock is to be able to assist customers as best as possible in the complex selection of suitable glasses and in individual requests for matching frames, Rodenstock put into practice the idea of a 4-in-1 Integrated Service Terminal, the ImpressionIST. It provides opticians with four core functions:

  1. Interactive info terminal for the consumer
  2. Comprehensive frame consultation and presentation
  3. Worldwide unique, patented 3-D video centering system
  4. Convincing consultation regarding glasses for higher-value sales

The ImpressionIST is made available to opticians as a special customer service to selectively support them in their competence in consultations and finally to significantly boost the sales proportion of high-grade glasses, creating an attractive contribution margin in the process.

The requirements

The required stereo measurement made two cameras necessary that ensure simultaneous image capture. When it came to selecting the right cameras, the technical data and design of the AVT MARLIN proved to be perfect. The required software was to be incorporated through HALCON. As the essential challenge of the project was to guarantee top quality while staying within critical budgets, the concept by Allied Vision Technologies carried conviction in all areas.

The better idea carries conviction

The scope and order of magnitude of the project made it necessary for Rodenstock to call for bids including a multitude of competitors. They had to meet the technical requirements and come up with creative ideas for possible cost reductions. At this point, Allied Vision Technologies prevailed with a solution that combined the technical advantages of a standard product with a flexible adjustment to the specific customer requests.

To reduce additional costs without having to make sacrifices in technology, AVT chose not to consider the usual flexible board for the application, but rather a firm, unfolded core board. Furthermore, the complete housing was dispensed with and the board was used with only a mounted front flange. The IOs weren’t required either. The back lid was closed, providing only the Firewire terminal. Last but not least, the solution didn't require any additional storage, but only simple image storage in the camera.

In addition, special sensor sealing was installed against dust. The board version received a completely new, more sensitive sensor. In order to run both cameras at a high frame rate while retaining the same picture detail (preview mode), the Rodenstock cameras were equipped with special modes.

To enable Rodenstock to run the first tests in time for the important trade show Opti Munich, AVT wasted no time in designing prototypes and in setting them up to be ready for use.

The additional experience gained during the test phase at Rodenstock and requirements changed as a result thereof were also incorporated by AVT in the optimization of the system in an innovative way. In order to use the system not only for selecting suitable eyeglass lenses but also the frames, a resolution of 2 Mpixels was required for the front camera. The modular camera concept of AVT allowed for flexible adjustments based on the existing components as well.

Of course, such a major project is apt to run into problems that no one could expect during the planning phase. One of these problems was how to deal with changes in lighting. Add to that the problem with the positioning accuracy of the cameras caused by the mechanical setup. However, the AVT engineers found answers to these problems too. To deal with the changes in lighting, automatic modes of the cameras (auto gain/shutter with limit values) were implemented directly into the software. Also, the positioning accuracy of the cameras in the mechanical setup is taken care of by means of a special front flange and individual adjustments starting with the next system generation.

Customer satisfaction at AVT

Andreas Romandi, project manager at Rodenstock, proved more than satisfied with the performance of AVT: “Above all, I was delighted to see how AVT serves as a competent partner for all ideas and their implementations. Even those “minor” problems were always solved by Application Engineering and Support in a quick and solution-oriented manner. The development by AVT showed not only cooperation but also creativity in incorporating requirements into production series in the short run.The relationship between Rodenstock and AVT was characterized throughout the entire duration of the project by mutual trust in meeting the time-critical deadlines for delivery regarding the series”.

Use in practice
At this point, 20 pilot run devices have been set up in various branches of Rodenstock throughout Europe since July of this year. They serve for demonstrations and customer events. It’s all paying off: The ImpressionIST is a complete success among opticians. Even now, the sales figures are exceeding the volumes planned for year’s end by far – even though delivery of the system didn't start until early October.“I ultimately attribute the huge demand to the worldwide unique, patented threedimensional measurement of the customers”, says Andreas Romandi. “In this measuring system, the cameras play a very decisive role. Here we’ve succeeded in developing an excellent solution together with the close cooperation of Allied Vision Technologies.”