Analysis of Fabry-Pérot laser resonators stabilized by microlenses and applications in speckle-free imaging
Steinforth, Austin W.
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https://hdl.handle.net/2142/108106
Description
Title
Analysis of Fabry-Pérot laser resonators stabilized by microlenses and applications in speckle-free imaging
Author(s)
Steinforth, Austin W.
Issue Date
2020-04-13
Director of Research (if dissertation) or Advisor (if thesis)
Eden, James Gary
Department of Study
Electrical & Computer Eng
Discipline
Electrical & Computer Engr
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
M.S.
Degree Level
Thesis
Keyword(s)
laser
resonator
speckle
imaging
laser array
Abstract
In this work, laser arrays comprising thousands of beams are experimentally demonstrated by stabilizing macroscopic Fabry-Pérot resonators with microlens arrays. The cavity parameters are tunable to either force fundamental-mode lasing across the array or to promote oscillation of various higher-order transverse modes. The fundamental mode produced by this resonator very closely matches theoretical results calculated with standard Gaussian optics as well as numerical Rayleigh-Sommerfeld diffraction results. It was found that the beams are generally uncoupled in this arrangement, and therefore do not produce interference. The resulting emission from large arrays of lasers has a moderate degree of coherence. Therefore, this laser produces very directional light with high brightness that does not generate coherent artefacts. Because of the moderate coherence and nanosecond-scale pulse duration of the light, this laser was shown to be an ideal light source for speckle-free imaging of dynamic targets. Most notably, fruit flies were imaged while flying with high resolution and without speckle or motion blur, an otherwise challenging task because their wings can beat at frequencies up to 200 Hz.
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