Atlas of Optical Crystallography Interference figures part I

Atlas of Optical Crystallography Interference figures, part I: uniaxial crystals Olaf Medenbach Institut für Geologie, Mineralogie und Geophysik Ruhr-Universität Bochum 44780 Bochum, Germany olaf. medenbach@rub. de © by Olaf Medenbach, Ruhr-Universität Bochum

Interference Figures the same crystal viewed with objectives with different numerical apertures (n. A. ) calcite medium high low aperture, small large medium angle of of the of cone the cone of of light Olaf Medenbach, Ruhr-Universität Bochum

Interference Figures the effect of birefringence for crystals with equal thickness Quartz, n = 0. 01 Olaf Medenbach, Ruhr-Universität Bochum Calcite, n = 0. 17

Interference Figures for crystals of the same species, but different thicknesses, viewed with constant numerical aperture (same objective) calcite 30 μm Olaf Medenbach, Ruhr-Universität Bochum 1 mm 2 mm

Interference Figures of Uniaxial Crystals centered optic axis figure emergence point of the optic axis (melatope) Olaf Medenbach, Ruhr-Universität Bochum

Interference Figures of Uniaxial Crystals centered optic axis figure uniaxial cross (location of vibration directions in extinction position) Olaf Medenbach, Ruhr-Universität Bochum

Interference Figures of Uniaxial Crystals centered optic axis figure after BLOSS, 1999 isochromes (curves of equal retardation = equal interference color bands) Olaf Medenbach, Ruhr-Universität Bochum

Interference Figures of Uniaxial Crystals centered optic axis figure in circular polarized light the isogyres disappear, the melatope und the isochromes are still visible Olaf Medenbach, Ruhr-Universität Bochum

Interference Figures of Uniaxial Crystals centered optic axis figure no n Z‘ co m Re pe d nsa I to r ne‘ optic sign (+), low birefringence addition all ne‘ point towards the melatope subtraction Olaf Medenbach, Ruhr-Universität Bochum

Interference Figures of Uniaxial Crystals centered optic axis figure no n Z‘ co m Re pe d nsa I to r ne‘ optic sign (+), high birefringence addition all ne‘ point towards the melatope subtraction Olaf Medenbach, Ruhr-Universität Bochum

Interference Figures of Uniaxial Crystals centered optic axis figure no n Z‘ co m Re pe d nsa I to r ne‘ optic sign (-), low birefringence addition all ne‘ point towards the melatope subtraction Olaf Medenbach, Ruhr-Universität Bochum

Interference Figures of Uniaxial Crystals centered optic axis figure no n Z‘ co m Re pe d nsa I to r ne‘ optic sign (-), high birefringence addition all ne‘ point towards the melatope subtraction Olaf Medenbach, Ruhr-Universität Bochum

Interference Figures of Uniaxial Crystals n Z‘ co m R pe ed ns I at o r The animation starts a few seconds after the next click. optic sign (-), semi random orientation Olaf Medenbach, Ruhr-Universität Bochum

Interference figure of an uniaxial crystal cut parallel c The animation starts a few seconds after the next click. „Flash figure“: upon slight rotation of less than 10° off extinction, the isogyres have been disappeared out of the field of view. Olaf Medenbach, Ruhr-Universität Bochum