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Optical testing of progressive ophthalmic glasses based on galvo mirrors

: Stürwald, S.; Schmitt, Robert


Raghavachari, R. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Design and quality for biomedical technologies VII : 1 - 2 February 2014, San Francisco, California, United States
Bellingham, WA: SPIE, 2014 (Proceedings of SPIE 8936)
ISBN: 978-0-8194-9849-6
Paper 89360Z, 8 S.
Conference "Design and Quality for Biomedical Technologies" <7, 2014, San Francisco/Calif.>
Fraunhofer IPT ()

In production of ophthalmic freeform optics like progressive eyeglasses, the specimens are tested according to a standardized method which is based on the measurement of the vertex power on usually less than 10 points. For a better quality management and thus to ensure more reliable and valid tests, a more comprehensive measurement approach is required. For Shack Hartmann Sensors (SHS) the dynamic range is defined by the number of micro-lenses and the resolution of the imaging sensor. Here, we present an approach for measuring wavefronts with increased dynamic range and lateral resolution by the use of a scanning procedure. Therefore, the proposed innovative setup is based on galvo mirrors that are capable of measuring the vertex power with a lateral resolution below one millimeter since this is sufficient for a functional test of progressive eyeglasses. Expressed in a more abstract way, the concept is based on a selection and thereby encoding of single sub-apertures of the wave front under test. This allows measuring the wave fronts slope consecutively in a scanning procedure. The use of high precision galvo systems allows a lateral resolution below one millimeter as well as a significant fast scanning ability. The measurement concept and performance of this method will be demonstrated for different spherical and freeformed specimens like progressive eye glasses. Furthermore, approaches for calibration of the measurement system will be characterized and the optical design of the detector will be discussed.