Oct 22, 2019
Optical element Clamping System
Physical Sciences, Material, Mechanical Engineering
- Constant zero-point, realignment is not needed
- High-precision clamping system
- Suitable for vacuum
The production of optics is a highly iterative process. In this process chain, not only are several machines involved and loaded one after the other, but there is also a switch back and forth between them. Components with two functional surfaces, i.e. lenses, must to be processed on their top and bottom surface, which increases the processing time and complexity. Moreover, the workpiece undergoes additional thermal and mechanical stress, caused by blocking and releasing during side change, which impairs the workpiece quality. The position and orientation of the workpiece must be ensured every time it is newly clamped. With the currently in optical manufacturing used technology this step can be done only with finite precision, which limits the achievable quality of the workpiece1.
The invention makes it possible to manufacture workpieces such as lenses in one clamping. This means that as soon as the workpiece is clamped, it is not released until the manufacturing process of both surfaces has been completed. This has the advantages:
- A constant zero-point is provided, avoiding the need for realignment;
- The clamping system guarantees, like a conventional zero-point clamping system, the highest possible accuracy in manufacturing process chains with a high number of if iterative steps.
- The clamping system is also suitable for vacuum, as the clamping mechanism is self-locking. This makes the invention suitable for production machinery such as FIB systems;
- Optionally, an integrated hydraulic control system can be installed, in order to compensate for deformations, which can be caused by the production itself and by gravity as well.
Figure: (left) blow-up drawing of the holder object of the invention. Pictured are the four main building-parts: (1) workpiece holder, (2) clamping component, (3) system closure, (4) sensors and actuators for deformations measurement and compensation. (right) sectional view of the complete system.
The invention can be used for the manufacture and handling of optical elements such as optical lenses and filters. It is also possible to process circular components of all materials. Due to the mechanical clamping and the self-locking function, the entire structure can also be used in a vacuum.
Preliminary measurements of the deformation caused by mechanical pressure exerted on the workpiece were carried out and published 2,3. A complete prototype is in preparation.
S. Sitzberger et al. “Zero-point clamping system in optical priduction”, 47 (4/9/2019 – 4/10/2019).
S. Sitzberger at al. “Workpiece self-weght in precision optics manufacturing. Compensation for workpiece deformation by a fluid bearing”, 12 (2018).
S. Sitzberger et al: “Analysis of the influence of the workpiece seof-weighting in precision optics manufacturing using FEM simulations” SPIE Proceedings, 103260 O (2017).
DE 10 2017 117 037; WO 2019/020420.