A High Speed Tunable Etalon for LIDAR

A solid state yet rapidly tunable etalon based on liquid crystal (LC) etalon technology is constructed using minimized LC birefringence response time in an optimized electric field. The key technological innovation is the use of liquid crystal to tune the etalon.nbsp;nbsp;While this type of etalon has been in use for many years, a development effort is undertaken to reduce the time it takes to tune a LC etalon over a free spectral range from a few milliseconds (current state of the art) to 100-500 microseconds (proposed).nbsp;nbsp;Phase I results show promising ability to tune LCrsquo;s at speeds faster than 500 microseconds.nbsp;nbsp;The primary application of this technology is integration into a space based lidar (light detection and ranging) system, particularly in differential absorption lidar (DIAL) systems.nbsp;nbsp;DIAL is one of the most powerful active remote sensing techniques due to its spatial and altitude resolution, measurement precision, and insensitivity to surface emissivity.nbsp;nbsp;As such, it can be used to monitor spatial and temporal changes of minor molecular atmospheric constituents in the lower troposphere.nbsp;nbsp;The filter is designed for observing water vapor from orbit.nbsp;nbsp;An accurate assessment of global water vapor distribution is key to more precise modeling of climate feedback from clouds and improved weather forecasting.nbsp;