INSPECTION OF MOIRÉ FRINGES PERIOD AND ITS ORIENTATION IS DONE CONVENTIONALLY BY TWO APPROACHES; PARAMETRIC EQUATION METHOD AND FOURIER ANALYSIS APPROACH. IN SOME CASES THEY YIELD DIFFERENT RESULTS. IN THIS ARTICLE, THIS INCONSISTENCY IS REMOVED BY REVISION IN DERIVING THE PARAMETRIC EQUATION. SUPERIMPOSITION OF COMPUTER GENERATED GRATINGS, WITH SUITABLE PERIODS, VERIFIES THE RESULTS.