He shot light from a laser out the end of the cable onto the diaphragm.
他从一激光器射出光束，正对有电缆一端的振动膜上。
2
Normally a diaphragm so thin would be transparent, allowing the laser's light to escape.
一般说来，如此超薄得振动膜应该是透明的，可允许激光束穿过。
3
Instead of letting it pass, the holes would reflect the light back toward the tip of the fibre optic cable, effectively turning the diaphragm into a mirror even as it still allowed water to pass.