Ultrasonic sensitivity-improved fiber-optic Fabry–Perot interferometer using a beam collimator and its application for ultrasonic imaging of seismic physical models<xref rid="cpb_27_9_094218fn1" ref-type="fn">*</xref><fn id="cpb_27_9_094218fn1"><label>*</label><p>Project supported by the National Natural Science Foundation of China (Grant Nos. 61735014, 61327012, and 61275088), the Scientific Research Program Funded by Shaanxi Provincial Education Department, China (Grant No. 08JZ58), and the Northwest University Graduate Innovation and Creativity Funds, China (Grant No. YZZ17088).</p></fn>

Ultrasonic sensitivity-improved fiber-optic Fabry–Perot interferometer using a beam collimator and its application for ultrasonic imaging of seismic physical models**

Project supported by the National Natural Science Foundation of China (Grant Nos. 61735014, 61327012, and 61275088), the Scientific Research Program Funded by Shaanxi Provincial Education Department, China (Grant No. 08JZ58), and the Northwest University Graduate Innovation and Creativity Funds, China (Grant No. YZZ17088).

Shao Zhi-Hua, Qiao Xue-Guang, Chen Feng-Yi, Rong Qiang-Zhou^†

(color online) Principle of beam collimation in graded-index MMF.