Lasers in space often suffer from light absorbing deposits forming inside the resonator. This effect is commonly called laser-induced contamination (LIC), and its mechanism can be compared with laser chemical vapor deposition. LIC experiments were carried out in a dedicated vacuum chamber using a q-switched 355-nm laser, hafnia- or silica-coated fused silica samples and contamination by epoxy adhesive outgassing, or toluene vapor in vacuum. The typical deposit formation was observed at different experimental conditions and analyzed by in situ laser-induced fluorescence imaging and ex situ white light interference microscopy. We determined the average growth rate during the first growth stage (bump-shaped growth) and analyzed it as a function of the laser fluence, sample nature, and used contamination. The data show that the band gap of the sample is important for the LIC process in the first growth stage. The light absorbed in the sample leads to a temperature rise that drives the deposit growth. This knowledge opens a new pathway to minimize LIC that is complementary to studies that aim to reduce the adsorption of contaminant molecules by making chemical surface treatments. |
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CITATIONS
Cited by 3 scholarly publications.
Contamination
Laser induced fluorescence
Absorption
Adhesives
Epoxies
Silica
Astronomical imaging