On the precision of integrated photoelasticity for hollow glassware

Residual stresses in tempered glass plates can be measured with the scattered light method. Usually a rectilinear propagation of light is assumed. However, due to the gradients of the refractive index, the light rays curve. We have experimentally demonstrated this for tempered (surface stress 120 MPa and more) and annealed glass plates. For a laser beam of finite width this also results in broadening and loss of photoelastic modulation. While some features of the experimental picture (dependence of the period of modulation on depth), can be captured in the simple model of rectilinear propagation, the other observations need development of more elaborated models.

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“…Ray bending effects in transmission photoelasticity have been described before by Aben [4] and Dolovich [5]…”

Section: Introductionmentioning

confidence: 80%

Effects of Ray Bending in Scattered Light Photoelasticity for Tempered and Annealed Glass Plates

Hödemann

Kikas

Aben

et al. 2011

AMM

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“…They proposed to take the overall deflection of the light ray into consideration in refining the measurement results. Aben [32,33] investigated light ray bending in case of axi-symmetric strengthened glass. Brodland and Dolovich presented the ray tracing approach and calculated stresses in a thermally tempered glass plate [34].…”

Section: Introductionmentioning

confidence: 99%

Gradient scattered light method for non-destructive stress profile determination in chemically strengthened glass

et al. 2016

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A new non-destructive gradient scattered light method is presented for micronscale stress profile measurement in chemically strengthened (chemically tempered, ion exchanged) glass. Direct non-destructive stress measurement in the surface layer (\100 lm) of chemically strengthened glass is reported for the first time. This is accomplished by passing a narrow laser beam through the surface layer of the glass at a considerably large incidence angle of 81.9°. The theory of gradient scattered light method is based on the ray tracing of ordinary and extraordinary rays in chemically strengthened glass and calculating the optical retardation distribution along the curved ray path. The experimental approach relies on recording the scattered light intensity and calculating the optical retardation distribution from it. The stress profile is measured in a chemically strengthened (8 h at 480°C in a salt mixture of 80 mol% KNO 3 and 20 mol% NaNO 3 ) lithium aluminosilicate glass plate to illustrate the capability of the method. Measured surface compressive stress was -1053 MPa and case depth 365 lm. Method is validated with transmission photoelasticity. The method could also be used for stress profile measurement in all transparent flat materials (such as very thin thermally tempered glass slabs or polymers). Additional new applications could be: (1) enhanced version of Bradshaw's surface layer etching method for stress profile measurement in case of ultra-thin case depths \20 lm;(2) micron-scale non-destructive tomography of layered polymeric gradient-refractive-index materials. The experimental procedure is developed to the level of full automation and the measurement time is less than 10 s.

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Digital photoelasticity of glass: A comprehensive review

Ramesh

Ramakrishnan

2016

Optics and Lasers in Engineering

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On the precision of integrated photoelasticity for hollow glassware

Cited by 5 publications

References 5 publications

Effects of Ray Bending in Scattered Light Photoelasticity for Tempered and Annealed Glass Plates

Effects of Ray Bending in Scattered Light Photoelasticity for Tempered and Annealed Glass Plates

Gradient scattered light method for non-destructive stress profile determination in chemically strengthened glass

Digital photoelasticity of glass: A comprehensive review

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