<p>A transparent pad having a polishing surface with an average surface roughness of 5�m or less is used as a polishing pad. An indentation is formed on the back surface of the transparent pad such that its rate of light transmission is locally changed. The transparent pad has a rate of light transmission equal to or greater than 10% or preferably 30% for light of at least one wavelength in the range of 350nm-900nm.</p>
