Laser radars, or lidars, are well suited for continuous monitoring of atmospheric composition. Distance measurements based on intense light pulses and their backscattering enable the collection of data on fine particles and even on nitrogen and oxygen molecules in the air. The laser radar creates a narrow and powerful light beam into the sky. The attenuation of the beam, the amount of scattered light, and changes in color provide a wealth of information about atmospheric fine particles, even from several kilometers away.
Scattering from fine particles and molecules differs in color. Separating scattering signals requires high light intensity and excellent color resolution from the receiver, but when successful, it enables the identification of particle types. Typically, spectral separation is done using optical filters and complex laser locking systems. In his research, Kim Kalmankoski chose instead to apply wind lidar technology based on optical down-conversion in a new way.
“I ended up significantly increasing both the laser power and the scope of signal processing. The new results allow for the measurement of scattering across the entire spectral range at once, without narrow optical filters. In particular, interpreting the molecular scattering spectrum could in the future enable continuous atmospheric temperature profiling”, Kalmankoski explains.
Kim Kalmankoski, originally from Pirkkala, conducted his doctoral research in the Applied Optics research group at Tampere University.
Public defence on Friday, June 6
The doctoral dissertation by M.Sc. Kim Kalmankoski in the fields of physics titled Spectral Detection of Molecular Scattering with Coherent Heterodyne Lidar will be publicly examined at the Faculty of Engineering and Natural Sciences at Tampere University at 12 o’clock on Friday, June 6, 2025, at Hervanta campus, Tietotalo building, auditorium TB109 (Korkeakoulunkatu 1, Tampere).
The Opponent will be Professor Christian Pedersen from Technical University of Denmark. The Custos will be Professor Juha Toivonen from the Faculty of Engineering and Natural Sciences at Tampere University.