1990年10月30日,英国和法国的隧道两端首次连接时,是采用电光探头来测量两隧道端面的相对位置。探头是一种钻孔测量工具,用于测量钻100米深白垩时小直径孔的正确路径,保证隧道两端对齐。该探针能探测英国和法国隧道端面的位置。探头记录下两端面之间的偏差,以便及时调整掘隧道机械,保证隧道准确贯通。 On October 30, 1990, when tunnels were first connected between Britain and France, electro-optical probes were used to measure the relative positions of the two tunnel facets. The probe is a borehole measurement tool used to measure the correct path to small diameter holes drilled at 100 meters deep chalk to ensure alignment of the tunnel ends. The probe can detect the location of the tunnel face in England and France. Probe records the deviation between the two ends, in order to promptly adjust tunneling machinery, to ensure accurate tunnel through.