Society of Glass Technology · [Sheffield] · leaf 120
iously calculated with respect to the line ofsight. A 24-c.p. lamp furnished with a diffusing screen is placedin a proper position to send a polarised reflected ray to the observer.It is advisable to use a lens, L, before the Nicol, N, and to focus EXAMINATION OF GLASS BY POLARISED LIGHT. 59 on the… … Fig. 2. gradient is not uniform over the whole thickness of the slab.Usually at some depths, one in each side of the slab, there is a layerof no strain, shown by the presence of rather broad dark bands(Fig. 3), when the slab is examined by polarised light. If thespecimen has not very…
Glass
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