Abstract:
Surface roughness is one of parameters, influencing on mass stability of standard weight. 316-stainless steel is also usually used for producing the standard weight, commonly used as a transfer standard of mass unit. Thus, surface roughness of 316-stainless steel was measured in this research by using a Michelson Interferometer (MI) with a 830-nm Super Luminescence Diode (SLD). Because of a micro-scale of SLDs coherence length and a Vertical Scanning Interferometry (VSI) with a Continuous Wavelet Transform (CWT) algorithm, an accuracy micro-scale of position in z-axis could be determined from a highest intensity position of interferogram. Three 316-stainless steel artifacts were tested by applying this VSI technique in this research, and their surface roughness values were compared with ones measured from a standard equipment (TORAYs SP-500). According to the measuring results of these three samples, the calculated values of En ratio, which is an acceptable level based on ISO/IEC Guide 43-1, between surface roughness of these two methods were less than or equal to 1. Therefore, the results of this VSI with a CWT algorithm technique are acceptable. Moreover, in the end of this study, a Phase Shift Interferometry (PSI) with a Derivatives-Based (DB) algorithm was also applied to analyze the interferogram of this MI, in order to measure depth of a 1.8-m Depth Measurement Standard (DMS). PSI with DB method could get rid of the interference fringe, which led to get an envelop curve of the interferences along the shifting axis of PZT. By evaluating the image order, depth of this DMS-sample could be defined by a maximum position of the envelop curve. It was found that the error of calculated DMS depth from this research, compared with a factorys value and evaluated by data curve fitting, was 55.6 %.