FIG. 2.

(Color online) Stone holders for each model in this study. The top shows a schematic diagram and the bottom shows a photograph of each. (A) A rectangular stone model held by a small amount of epoxy attached to a 22-gauge wire. These models were directly submerged in degassed water. (B) A chamber for containing an optical-matching fluid and fixing a cylindrical stone model. An acoustically transparent membrane is placed over the front face to contain the liquid while the optical windows on the side allow visualization with a camera. The model is held by three spring-loaded pins in the center of the chamber. ML = Matching liquid. (C) A small plastic frame (black) extending from a tissue-mimicking material holding a cylindrical artificial stone made from Begostone Plus plaster. This holder was used to suspend and support the length of the stone during fracture formation.