折射率调制的光纤传感器可用于测量稠油热采过程中的蒸汽干度测量。当油田的油井中注入高温高压蒸汽时，从井口到井底连续地查明汽液比对节省能源和提高产出率意义重大。由于干蒸汽和水的折射率不同，汽液的比例可以从汽液两相流的折射率响应特性反映出来。研制的测量装置直接对汽液两相流的比例变化产生响应，能够应用于高温高压及狭窄工作空间的输汽环境中。在井深850m，井口蒸汽温度287℃，压力7．49MPa的油田注汽井中进行了测试。测试结果对注汽法采油的井况分析具有一定的参考作用。油田注汽井的测量数据表明，这种干度测量仪可以实现在线、连续的测量工作。

Optic-fiber sensor on refractive index modulation can be applied to measure the steam quality in the process of viscous oil heating recovery. During injecting high temperature and pressure steam into an oil well, it is useful to economize energy and raise yield if we know the vapor-to-water ratio continuously from the mouth to the bottom of the oil well. The developed device can respond to the change of vapor-to-water ratio directly, and can be used in small working space in the steam with high temperature and pressure. Tests had done in a steam injection oil well with depth of 850 m, temperature of 287℃ and pressure of 7.49 MPa at well mouth. The experimental result is helpful to analyze the downhole information of steam injection well of oilfield The tests in steam injection well show the device can acquire the figure of steam quality on the spot.