Edge Stress Meters

The quantitative determination of stress requires a calibrated relative retardation S to compensate the measured one S (S + S = 0), and we shall use from here onward the term compensator . As stated above, generally we measure a stress difference that reduces to one component only when the other one is null. This assumption is valid, at the edge of a glazing (edge stress meter), and when the light beam propagates at the surface of the glass sheet (surface stress meter). Both instruments are described in the two next sections. 

Figure 11.9 (a) Edge stress meter principle www.sharplesstress.com/.) (c) Strainoptics Inc. with a Senarmont compensator, (b) Sharpies edge stress meter. (Photograph courtesy of edge stress meter. (Photograph courtesy Strainoptics Inc., www.strainoptics.com.)... 

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