Abstract: Provided is a polishing pad comprising a polishing layer made of a polyurethane resin foam containing an isocyanate-terminated prepolymer, and a curing agent, wherein the ratio (NC80/NC40) of a weight proportion (NC80) of an amorphous phase content in the polishing layer measured at 80° C. by a pulsed NMR method to a weight proportion (NC40) of the amorphous phase content in the polishing layer measured at 40° C. by the pulsed NMR method is between 1.5 and 2.5.

Abstract: A gain control section (150) controls an attenuator (101) to change the level of a signal output from the attenuator (101) to variable amplifiers (121, 131) and at the same time controls the variable amplifiers (121, 131) to adjust the gains in the variable amplifiers (121, 131). Through this adjustment, the gain control section (150) determines the respective gains in such a way that a lower limit value of the detection range of a detector (122) matches an upper limit value of the detection range of a detector (132). A detection circuit 100 having such a configuration can easily expand a dynamic range and fully realize an AGC function while preventing deterioration of the detection accuracy attributed to characteristic variations of devices such as amplifiers and detectors.