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2008
Conference Paper
Titel
Microstructuring of free-form surfaces by the use of a hybrid fast-tool-servo system
Abstract
The need for optics with increasing quality for more efficient illumination systems lead to the development of more complex optical elements. Refractive optics can be combined with diffractive microstructures to hybrid lenses, which can be produced cost-effective by ultra precision machining using diamond cutting tools. However this machining technique has to be adapted regarding machine and process properties to the requirements of micro structuring free-form surfaces. Thus this paper will discuss the development of a new Hybrid-FTS for the manufacturing of hybrid optics and the needs regarding process technology to ensure high quality microstructures. The Hybrid-FTS combines two axes with different strokes and dynamic properties into a single system to be able to machine hybrid optics. A piezo driven FTS with a bandwidth of 2 kHz and a maximum stroke of 30 mym will be integrated into a dynamic axis having 20 mm travel. The dynamic axis, which is designed like a sleeve, will be equipped with hydrostatic bearings offering good stiffness and damping properties. Due to the stroke of several millimetres a linear scale is used as measurement system. A linear motor drives the slide. In that way working frequency of 20 Hz at 5 mm stroke shall be realised. The presented concept of a Hybrid-FTS will allow the machining of micro structures on free-form surfaces. The special design of the tool guiding system in the FTS realises a high bandwidth of 2 kHz. Due to an effective mass compensation system in the FTS the direct integration into the dynamic axis is enabled. The machining of microstructures requires matched material and process characteristics to achieve burr free groove edges. Nickel-Phosphorous coatings seem to be very suitable for the machining of microstructures due to their homogenous composition. Furthermore the structure geometry influences the burr generation strongly.
Language
English