a system of cleaning a cmp pad used for removing copper from a substrate , the system comprising an abrasive cleaning pad , a cleaning solution delivery system that delivers a cleaning solution , an analyzing system that monitors the characteristics of the cleaning solution optically and chemically , and a carriage that allows the analyzing system to monitor the cleaning solution at a plurality of locations on the cmp pad . the use of the abrasive cleaning pad and the cleaning solution removes contaminants from the cmp pad , and the contaminants are dissolved in the cleaning solution . by measuring the concentration of contaminants in the cleaning solution , the condition of the cmp pad can be monitored . to measure the concentration of the contaminants , changes in the refractive index and absorption of light in the cleaning solution are measured , wherein the refractive index and absorption depend on the concentration of the contaminants . the concentration of the contaminants in the cleaning solution is also measured chemically . knowing the actual condition of the cmp pad during the cleaning process allows for improved condition of the cmp pad .