Surface roughness is a measure of the surface fineness and irregularities in the surface texture. The varying surface roughness may be generated intentionally or may be due to artifacts during manufacturing or processing. The surface profile of the substrates is important for studying the bond strength properties in dentistry and metallographic analysis. The roughness of the surface can be described using a number of different measures, for example Ra, Rq, Rmax, Rt, Rp, Rv, R3z, R3y, Rz(JIS), Rs, Rsk, Rsm, Rku, Rc, Ry, Rmax, Rmr, etc. One commonly used roughness is often described by the parameter Ra (absolute roughness). The surface roughness parameter (Ra) is rated as the arithmetic average deviation of the surface valleys and peaks expressed in microinches or micrometers.
Prevest Research Institute is having Roughness tester Model: ISR-300, INSIZE. This tester is a handheld instrument which is simple and convenient to operate. Multi parameters can be measured with a measurement range of 320µm. When measuring the roughness, the pickup acquires the surface roughness by the sharp stylus. The roughness causes displacement of the pickup which results in change of inductive value of induction coils to generate analogue signal which is in proportion to surface roughness at the output end of phase sensitive rectifier and then processed to final result.