Abrasive article having a window system for polishing wafers, and methods

A method of modifying a workpiece surface comprising:

• (a) contacting the workpiece surface with an abrasive article, the abrasive article comprising:
• (i) a textured abrasive coating comprised of a plurality of abrasive composites, each composite comprised of a plurality of abrasive particles dispersed in a binder, the abrasive composites adhered to a backing, the backing comprising a material at least partially transparent to visible light;
• (ii) a monitoring element for passage of radiation therethrough the monitoring element comprising an area of the textured abrasive coating at least partially thinned;
• (b) moving the abrasive article in relation to the workpiece surface to modify the workpiece surface;
• and
• (c) determining a degree of surface modification by:
• (i) measuring a first radiation level from the workpiece surface through the monitoring element.