Even though gaseous methane (CH4) is a comparatively sparse constituent in Earth’s atmosphere, it is the third most impactful greenhouse gas after water vapor and carbon dioxide, and the second most important in terms of anthropogenic drivers. Methane is some 60 times more effective than CO2 in absorbing long-wavelength radiation, because the methane absorption lines in that part of the spectrum are less saturated and have less overlap with water vapor lines. Natural and agricultural sources of methane continue to dominate, but are difficult to separate and quantify. World-wide, rice cultivation, biomass burning, ruminant farm animals, and fossil fuel mining and usage have long been the most powerful drivers, but with climate change these sources could be dwarfed in the future by the release of enormous quantities of methane from melting permafrost and/or methane hydrates currently buried deep in ocean sediment. Innovative new remote sensing technologies need to address the atmospheric methane concentration measurement problem for NASA and other applications.
Beyond Photonics proposes to investigate specific very compact pulsed oscillator/amplifier designs near the 1.645-micron wavelengths of interest by NASA for atmospheric methane (CH4) and potentially coherent winds in the same nominal wavelength region. Specifically, methane concentration measurement from operational platforms of NASA’s choice will be our focus; this application puts particular emphasis on decreasing size, weight, and prime power (SWaP) and eliminating active laser component cooling. Particular emphasis will also be placed on ensuring that the laser/lidar designs are compatible with scaling to space qualification in future programs. Emphasis will also be placed on technical approaches with good operational flexibility in terms of pulse energy and duration, frequency agility, and application to other IR and SWIR wavelengths.
Potential NASA applications include quantification of atmospheric methane sources and sinks on a finer spatial scale than currently possible, immediately valuable for climate model improvement and atmospheric sciences. Coherent winds can be readily added to such an instrument for further functional enhancement and utility. Single frequency Q-switched Er:YAG lasers developed in this effort will also be applicable to aerosol backscatter measurement and Doppler winds measurement applications.
Non-NASA applications greatly interest Beyond Photonics in terms of low cost, compact DIAL product development, as evidenced in our use of company IRAD to further the proposed effort. These laser/lidar technologies relate to development of robust high-efficiency remote sensing instruments for commercial and military use including spectroscopy, aerosol backscatter measurements, and wind sensing.