Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
Browse
3 results
Search Results
Item Diode-laser-based high spectral resolution LIDAR(Montana State University - Bozeman, College of Engineering, 2021) Colberg, Luke Stewart; Chairperson, Graduate Committee: Kevin S. RepaskyThis thesis describes the design, construction, and testing of a high spectral resolution lidar (HSRL) as a part of a combined HSRL and differential absorption lidar (DIAL) system. The combined HSRL and DIAL instrument is constructed using the MicroPulse DIAL (MPD) architecture and uses distributed Bragg reflector lasers. The MPD architecture is unique because it is eye-safe and cost-effective; therefore, it is ideal for creating a network of ground-based lidars. This instrument is designed for thermodynamic profiling of the lower troposphere. A network of these instruments would be helpful for wide-scale atmospheric monitoring for weather forecasting and climate science. The purpose of the HSRL is to retrieve the optical properties of aerosols in the lower troposphere. The HSRL uses the DIAL offline laser, which has a wavelength of 770.1085 nm, and a potassium vapor cell as the spectral filter. The data retrieved from the HSRL provides the aerosol backscatter coefficient and the backscatter ratio up to an altitude of 7 km during nighttime operation and 5 km during daytime operation. The time resolution for these measurements is 5 minutes, and the range resolution is 150 m. These aerosol optical properties are valuable for aerosol studies and climate modeling; aerosols introduce the most significant degree of uncertainty in modeling the heat flux of the atmosphere. Additionally, these aerosol optical properties can be used to find the planetary boundary layer height (PBLH). The planetary boundary layer controls the exchange of heat, water vapor, aerosols, and momentum between the surface and the atmosphere. It has been demonstrated that the PBLH strongly affects turbulent mixing, convective transport, and cloud entrainment, which makes the PBLH an important parameter for weather forecasting and climate modeling. Despite its significance in atmospheric science, there is no standard method for defining the PBLH. A retrieval method for finding the daytime PBLH using HSRL data is proposed, and data comparisons to radiosonde PBLH retrievals are provided. The algorithm shows a good agreement with the radiosonde retrievals for conditions with a well-behaved boundary layer.Item The diode-pumped continuous-wave Raman laser : classical, Quantum, and thermo-optic fundamentals(Montana State University - Bozeman, College of Letters & Science, 2002) Roos, Peter AaronItem Mode-locked Raman laser in H2 pumped by a mode-locked external cavity diode laser(Montana State University - Bozeman, College of Letters & Science, 2007) Xiong, Yihan; Chairperson, Graduate Committee: John L. CarlstenIn this thesis, a theory is first presented for a far-off resonance mode-locked Raman laser in H2 with high finesse cavity enhancement. The theoretical derivation for the mode-locked Raman laser is based on semiclasscial laser theory and time-dependent continuous wave (CW) Raman theory. Numerically calculated results, including the intracavity fields' amplitude and phase evolution and output Stokes power versus input pump power are discussed in three different regimes depending on the relationship between the coherence dephasing rate and the repetition rate of the mode-locked pump laser. Then experimentally, first an actively mode-locked external-cavity diode laser (ML-ECDL) was built along with a demonstration of how to frequency lock all the longitudinal modes from the ML-ECDL to a high finesse cavity. Then a tapered amplifier diode system was designed to increase the ML-ECDL power.