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Contenuto archiviato il 2024-06-10

Posa-polishing of spherical lenses with high aperture angles

Obiettivo


The results of the project demonstrate that it is possible to polish lenses with high aperture angles by a modification of the Synchrospeed-kinematics. In addition it was possible to identify the main effects, which influence the reproducibility of the polishing process. The reproducibility is strongly affected by the adjustment of the pad and suspension to the glass materials. In addition a relationship between the work of the spindles and the material removal could be identified.
The mentioned result were concluded from the following items (delivered during the project):
1) Description of the kinematics by mathematical equations
2) achievable results and dominating parameters
3) reference parts representing attainable quality by other kinematics
4) measures to improve the process by using optimised tool and clamping devices
5) new machine concept "VARIOSPEED"
6) simulation software to describe the achievable accuracy using full area tools for "Synchrospeed"
7) influence of geometrical parameters and clamping device on attainable quality
8) influence of suspension, glass and pad material on polishing results and reproducibility
9) possibilities to control polishing process
10) outline potential for optimisation.
Recently, new areas of application have opened up for the optical elements with high aperture angles which are the subject of this proposal. Optical elements with extremely small dimensions are becoming increasingly important, particularly in medical technology, in minimal invasion, imaging techniques (e.g. endoscopy). Further areas of application for optics of this nature are high resolution infra red lenses which are used in monitoring, control, image processing and micro projection. Optics with high aperture angles and processing qualities are also required for collecting data at various levels in telecentric lenses and in high power diode lasers. All of these examples of applications are growth markets. The trend towards miniaturisation will strengthen its hold on the market and expand to other applications. High efficiency finish machining techniques are required in order to meet the demands imposed on optics. Polishing operations conducted on optical glass remain the Achilles heel in optics manufacturing. The high reject and re working rates bear witness to this. The need to achieve high levels of form accuracy and high quality optical surfaces result in a conflict of interests. The kinematics of the CNC polishing machines currently available, are based on the so called synchrospeed theory. This, however, loses its validity in the case of high aperture lenses. The problem affecting these optics, is the difficulty in achieving the required levels of form accuracy. Attempts have been made to extend the area of application of the machines by superimposing an oscillating motion. However, the oscillating motion results in non uniform relative speeds and to unfavourable surface pressures on the optic. The application of the oscillating motion is possible, therefore, only after extensive experience. The existing machine concept and the process technology must be optimised in order to ensure that the optics described here can be polished to a consistent level of quality. Increased consistency will lower not only the need for re working but will also reduce the level of process control required and will thus increase the economic efficiency. Expansion of the existing machine design to include adaptation of the rotational speed to suit the rotational motion and surface pressure are conceivable approaches to expanding the area in which the polishing machines can be deployed. The outcomes of the project proposed here are as follows: - The reject or re working rate resulting from form errors should be reduced from its current level of just under 50% to 15 %. - Form accuracy of l/20 should be achieved. - Surface quality should match that of a precision polished surface, in accordance with DIN 3140 On the basis of an analysis phase in which the currently existing limitations set by the techniques used, will be shown experimentally as well as theoretically, conclusions will be drawn regarding the machine related measures required, and these will then be implemented in a test facility. The effects of the machine related modifications on the polishing result and the development of machining strategies are additional priorities in this project. To conclude the investigation, the results will be verified in manufacturing plants and the economic benefits accruing to the industrial organisations will be examined. The international consortium (3 European countries), consisting of four optics producers with widely differing applications for their optics and optical systems. The consortium is complemented by the participation of a machine manufacturer with 75 years of experience in the development of optical machines. The R&D provider has been developing techniques of grinding and polishing optical glass for 15 years. The studies relate to Item 1.1.1.S Industrial and Material Technologies, Working Program, Edition 1 994

Campo scientifico (EuroSciVoc)

CORDIS classifica i progetti con EuroSciVoc, una tassonomia multilingue dei campi scientifici, attraverso un processo semi-automatico basato su tecniche NLP. Cfr.: https://op.europa.eu/it/web/eu-vocabularies/euroscivoc.

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Coordinatore

LOH Optikmaschinen AG
Contributo UE
Nessun dato
Indirizzo
Wilhelm-Loh-Strasse
35578 Wetzler
Germania

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Costo totale

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