Light geometry

The Alchemy of Light Geometry and Optics in Late Renaissance Alchemical Illustration... 

Szulakowska, Urszula. The alchemy of light geometry and optics in late Renaissance alchemical illustration. Leiden, Boston Brill, 2000. xxii, 246 p. ISBN 9004116907... 

Figure 7. Target light geometries used commonly for different clinical applications, (a) surface irradiation, (b) interstitial irradiation, (c) intraluminal (endoscopic), (d) intracavity or intraoperative.

Fig. VI-4. Illustration of the surface force apparatus with the crossed-cylinder geometry shown as an inset. The surface separations are determined from the interference fringes from white light travelling vertically through the apparatus. At each separation, the force is determined from the deflection in the force measuring spring. For solution studies, the entire chamber is filled with liquid. (From Ref. 29.)...

The early Hartley model [2, 3] of a spherical micellar stmcture resulted, in later years, in some considerable debate. The self-consistency (inconsistency) of spherical symmetry witli molecular packing constraints was subsequently noted [4, 5 and 6]. There is now no serious question of tlie tenet tliat unswollen micelles may readily deviate from spherical geometry, and ellipsoidal geometries are now commonly reported. Many micelles are essentially spherical, however, as deduced from many light and neutron scattering studies. Even ellipsoidal objects will appear... 

This birefringence coupled with spherical geometry produces light extinction along the axis of each of the Polaroid filters, hence the 90° angle of the Maltese cross. 

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