Air-coupled ultrasonic scanner for Braille

This work presents an air-coupled ultrasonic scanner to digitize Braille texts. Braille is a system of touch reading for the blind whichs employs embossed dots. Air-coupled focused piezoelectric transducers for this particular application were designed, produced and characterized. A conventional 2D scan system for NDE applications was used. The ultrasonic beam scans the surface of the Braille text while some information of the reflected echo along with the spatial coordinates of the point are stored on a computer. The embossing of the paper affects the reflected signal (amplitude and delay) on the surface of the paper, therefore a reliable image of the Braille text is generated. Many Braille texts were digitized. Some of the images of different samples, generated using different techniques and resolutions are shown to illustrate the technique.