Development of Precise Stress-strain Measurement System by Employing Electronic Speckle Pattern Interferometry

研究的目的是利用电子散斑干涉（ESPI）技术，研制一种新型的地壳应变和应力测量系统，该系统与全息干涉技术一样，可以在不接触物体的情况下，根据激光波长定量测量物体的二维或三维变形。与全息干涉术相比，电子散斑干涉术还具有曝光时间短、不需湿照相等优点，因为它不用全息干板，而用摄像机记录干涉条纹图。1992年1月，在日本兵库县平木矿的坑道中，首次进行了ESPI钻孔应力计的现场试验。

The aim of research is to develop a new type of crustal-strain and -stress measurement system by employing the technique of Electronic Speckle Pattern Interferometry (ESPI), which enables, as well as holographic interferometry, two or three dimensional deformation of object to be measured quantitatively in terms of the wavelength of laser light without any contacting the object. Moreover, the ESPI technique has some attractive feature compared with holographic interferometry, i.e, short exposure time and no need for wet photographic processing, because this technique does not use a holographic plate instead a video camera to record interference fringe patterns.In 1991, we developed a borehole module of the ESPI stress measurement system. The module is designed to be very compact (10cm in diameter and about 50cm in length) and to be used in a small borehole.In January, 1992, The first field experiment using the ESPI borehole stressmeter was carried out in a tunnel at the Hiraki mine, Hyogo Prefecture.