Analysis of Fabry-Pérot laser resonators stabilized by microlenses and applications in speckle-free imaging

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.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Electrical & Computer Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2020

Author dc:creator

• Steinforth, Austin W.

Contributors dc:contributor

• Eden, James Gary

• laser
• resonator
• speckle
• imaging
• laser array

Statement dc:rights

• Copyright 2020 Austin Steinforth

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/108106

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/108106