Biomimetic touch perception of edge finish of ophthalmic lens

Abstract

The functional texture of polished edge of an ophthalmic lens is controlled by the characteristics of the finishing process by which the surface edge is produced. In order to assess the selection of edge surface finish for production purposes, tribo-acoustic sensor that mimics human sensory perception is used. The assumptions underlying the methods are that certain sounds, such as the old and surprisingly sensitive fingernail test, have a close association with somatosensory precepts. In this paper, an existing sensor was modified and adapted, via biomimetic knowledge transfer of sensory perception in humans (touch perception). If an artificial finger with smooth surface slides over an edge of polished lenses, the friction induced micro-wear traces, waviness (termed macro-roughness) and the form (hills and valleys) population varies. In touch perception tests, we showed that the texture stimulus (friction noise) delivered to artificial finger depends on the edge finish quality. The results also revealed that the effects of the edge finish on touch are frequency dependent—only sounds with the same frequency as the vibrotactile frequency enhanced tactile detection. These results demonstrate that texture finish influences touch perception in highly systematic way and suggest that similar coding of wear traces produce by polishing may underlie the processing information of quality assessment and selection of the edge ophthalmic glass.