Using Electrically Addressed Spatial Light Modulator To Achieve The Doubling Of Moire Stripes

In this paper, we put forward moire method based on electronic addressing spatiallight modulator. This method overcomes the disadvantages of traditional technique ofmoire fringe (image moire) in the optical information processing. Using spatial lightmodulator, the digital images of specimen grating can be converted into coherentoptical signals, and then the coherent optical signals are coherently processed in theFourier optical information processing system and superimpose the signals and thereference grating on the image-plane to form a clear and multiple moire fringe image.By implementing binary hole filtering on frequency-spectrum plane, the frequency ofthe specimen grating is multiplied, as a result the image of multiple moire fringe hasbeen obtained. The proposed technique takes full advantage of the virtues of opticalinformation processing. Under the condition of low grid-density grating, the techniquecan fulfill the multiplication of moire fringe, in the meanwhile it can also improve thecontrast of the image of moire fringe and filter the impurity of the signals, so it canimprove the sensitivity and accuracy of measurement. The above stated method is anadvanced technique applied originally in the optical information processing thephotomechanics and is a photoelectronic mixture processing method. It greatlyimproves the ability of processing information and the speed of calculation and getsthe images of moire fringe of U field displacement and V field displacement withample marginal information, fine contrast and high sensitivity, at the same time it canrealize automatization of the image and information processing and provide a newtechnical approach to fulfill the high sensitivity measurement by using the moiremethod.In this paper, three-point bending experiment with the pre-existing crackspolyurethane materials have been done. The experimental results adequately show that it is feasible and effective by using the spatial light modulation to acquire the moirefringe and the multiple moire fringe. Then we did the moire method experiments of twotypes of novel materials, i.e., macroscopic deformation measurement of styrene shapememory polymer and microscopic deformation measurement of NiTi multiple crystalshape memory alloy materials, and gets the information of the displacement and thestrain of the two types of novel materials.