A Method for the Evaluation of Subsurface Damage

When a glass surface is abraded there is produced a surface damage layer consisting of two somewhat independent components: a relatively rough and pitted surface structure and an underlying system of fractures. To reveal the subsurface system of fractures acid etching has been used to open up the fractures for measurement.1,2 This method, however, is unreliable to varying degrees due to non-uniform etching rates at the top and bottom of the fracture. Moreover, most information on the structure of the fractures themselves is lost in the process. We have developed a method which also uses acid etching but uses specially prepared substrates that reveal very clearly the structure and depth of the fractures. Figure 1 depicts how the substrates are prepared.