Development of a Broadband Optical Seismometer: Phase 2

我们对地球内部的大量知识来自地震学：对在地球上传播的弹性波的分析。地震仪测量这些地震波，建造越来越灵敏的地震仪的科学可以追溯到许多年前。几乎所有的地震仪都是由一个悬挂在弹簧上的物体组成的。通常，当地震波产生局部振动时，电子电路会感应到质量的位移（相对于地震仪的框架）。在国家科学基金会的持续资助下，我们正在开发一种新的地震仪，它使用光学而不是电子来感知物体的运动。新的信号处理电子学使我们能够分析从地震仪质量反射的激光，并检测到小到万亿分之一米的位移。这种新技术具有多种优点，包括高动态范围和宽带宽，基于激光波长的校准，通过光纤电缆而不是电气电缆连接到传感器，并且消除了传感器封装中的电子器件。我们未来两年的研究将包括进一步降低噪音的努力，以及在除我们自己以外的地震观测站对我们的新地震仪进行独立监测测试。

A great deal of our knowledge of the Earth's interior comes from seismology: the analysis of elastic waves propagating through the Earth. Seismometers measure these waves, and the science of building more and more sensitive seismometers extends back for many years. Almost all seismometers consist of a mass suspended by a spring. Usually an electronic circuit senses the displacement of the mass (with respect to the seismometer's frame) when a seismic wave produces a local vibration. Under continuing funding from the National Science Foundation, we are developing a new seismometer which uses optics instead of electronics to sense mass motion. New signal-processing electronics allow us to analyze laser light reflected from the seismometer mass and detect displacements as small as a trillionth of a meter. A variety of advantages are afforded from this new technique, including a high dynamic range and wide bandwidth, a calibration based on the wavelength of laser light, a connection to the sensor via fiber optic cables rather than electrical ones, and elimination of electronics in the sensor package. Our research over the next two years will include further noise-reduction efforts and independently monitored tests of our new seismometer at seismic observatories other than our own.