Optical scan method for fine surface roughness measurement

A method is proposed for smooth surface roughness measurement. Two standard reference surfaces and two polaroids are employed to realize the measurement. The reversibility of the optical beam is overcome by using two quarter-wave plates. Measuring optical set-up is shown. The mathematical expression of the working principle of the method is derived. The uncertainty of the method is theoretically calculated and digitally simulated. Finally, the feasibility of this method is verified by measuring a standard roughness sample. The measurement result is in accordance with the standard value of the sample roughness provided by the manufacturer.