Freeform Surfaces
Opportunities and challenges for optical lens manufacturing
Optical lenses made of plastic, glass and crystals are traditionally made in manufacturing processes such as milling, turning, grinding and polishing. High-quality lenses are very demanding when it comes to surface quality and dimensional accuracy.
A particularly good choice to achieve high surface quality in precision optics is the use of removal mechanisms with an undefined cutting edge, such as grinding and polishing. Using these processes, spherical lenses, with their simple geometry, can be manufactured in high quality with relatively simple kinematics.
Summary
Lenses with freeform surfaces undoubtedly offer a very high potential. Several optical functions can be combined in one lens to create more compact and lighter systems. Complex applications can only be realised with freeform surfaces.
Just as the potential of freeform surfaces increases, so does the complexity of the entire process chain. The description of the freeform surface is much more complex and the demands on the geometric accuracy increase significantly. The more demanding tool path and the necessary dynamics significantly increase the demands on the processing machines.
The point contact between tool and lens, the resulting small overlap area and the necessary grid make the conditions for highest surface qualities difficult. Due to the more complex surface topography, the measurement required for the iterative manufacturing process is also more complex and significantly more time-consuming.
For optimal surface quality and highest accuracy, a polishing tool is required that leaves minimal structures and can correct errors as accurately as possible. The combination of ADAPT tool and ADAPT-Freeform software was developed for this task. With the help of the modelled material removal function and the measured geometric deviation, the software calculates a precise trajectory curve with the corresponding dwell time of the tool at each path point.
Picture shows Application example for freeform surfaces: Headup
display. Source: GettyImages/Mike Mareen
An article by:
Dr. Max Schwade
Managing Director, Bazell Technologies
AR Coatings for complete eye protection
08.2023
During everyday activities, we are exposed to light from many different sources: the sun, tablets, digital notebooks, cell phone and TV screens, lamps, etc. Light radiation from all of these sources is not always beneficial.
Freeform Surfaces - Opportunities & challenges
04.2022
This article presents a comprehensive evaluation of actual available technologies & thier challenges for the production of freeform optics. Freeform optics refers to the fabrication of optical elements with non-traditional shapes, allowing for enhanced optical performance and versatility in various applications.
The vital role of the Coolant Management System
05.2023
When concerned with effective lens production, it’s imperative for labs to consider not only the most efficient, productive and cost-effective methods, but also those which will not cause negative environmental repercussions.
The art of generating - a technological challenge
03.2018
Clear vision is crucial for various daily tasks, making glasses essential for billions of people worldwide. To obtain the right pair, individuals consult an optician who then typically orders lenses from an ophthalmic manufacturing lab.
The road to a sustainable and profitable lens production
09.2022
Sustainability entails assessing production's environmental impact alongside economic, environmental, and social aspects. To advance sustainable lens production, labs must prioritize meeting present needs without jeopardizing future generations' abilities.