美国 Aerodyne公司开发的一种光学设备正用来帮助保存美国“自由宪章”的原本。这些文件包括宪法、自由宣言和权利法案 ,目前正在华盛顿特区展出。仪器以红外吸收微分光谱为基础 ,提供一种非侵入性光学传感器 ,用于监测密封空间中的湿度以及痕量氧气的存在。仪器用微分吸收技术 An optical device developed by the U.S. Aerodyne company is being used to help preserve the original U.S. Charter of Freedom. These documents, including the Constitution, the Declaration of Freedom and the Bill of Rights, are currently on display in Washington, D.C. Based on Infrared Absorption Differential Spectroscopy, the instrument provides a noninvasive optical sensor for monitoring the humidity in sealed spaces and the presence of traces of oxygen. Instrument differential absorption technology