| In the measurement process of the gauge block,higher than the second grade and K level gauge length must be measured with the interference absolute method. Using fringe method,two-dimensional FFT method and Virtual grating phase-shifting Moire Fringe method,the fraction of central fringes of gauge block can be got.Besides,interference fringes fraction coincident method use different wavelength source,in a limited field of view,to obtain the accurate integer-part of central fringes of gauge block.Finally,after the ambient parameters( air temperature,gauge surface temperature,atmospheric pressure and absolute humidity) correction calculating,the central length of gauge block can be obtained in standard state.This paper is based on computer image processing and the interference measurement.At first,theoretical simulation of the entire measurement process which proves the accuracy of fringe method and two-dimensional FFT method has been done.In the way of Fringe,dgital image processing technology and the FFT method are used to process interference fringe method, get rid of fringe noise, thin interference partterns, and read the fraction of central fringes of gauge block by automatically.In another way of 2D FFT,Criminisi algorithm is used to spread the interference. Centroid algorithm and regional approximation algorithm have been applied to determine the position of the+1 spectrum which aggrees to sub-pixel level. At last, in order to make the measurement process more and more automatic and intelligent, PTU300 and 1560 black stack automatic measurement procedures are writted.Large amounts of data show that the algorithm can automatically calculate the fraction of the central fringe of gauge block. Measurement repeatability and uncertainty of central length of gauge block are consistent with the requirement of second grade gauge block,which can realize accurate and rapid test process and greatly improve the test efficiency. |
PDF Full Text Request