Fibre optic beam delivery system for high peak power laser PIV illumination

Duncan Paul Hand, Jonathan D. Entwistle, Robert Raimund Josef Maier, Andreas Kuhn, Clive A. Greated, Julian David Clayton Jones

Research output: Contribution to journalArticlepeer-review

40 Citations (Scopus)


Diffractive optical elements (DOEs) are used to couple Q-switched and frequency-doubled Nd:YAG laser beams into optical fibres to achieve significantly increased damage thresholds, enabling fibre optic beam delivery for high-speed particle image velocimetry (PIV) measurements. For single fibre delivery systems, the maximum pulse energy density that can be transmitted is increased by a factor of 5-10 compared with the best that can be achieved using conventional optics, of up to 10 mJ in a 200 µm core diameter fibre at 532 nm. We also applied the DOE arrangement to our previously developed bundle delivery system, comprising nineteen 200 µm core diameter fibres. On testing, over 1000 pulses with energies of 30 mJ were successfully transmitted, with no indication of damage. This allows fibre delivery to become a practical option for many air-flow PIV applications, as demonstrated here with measurements of flow in a square duct.

Original languageEnglish
Pages (from-to)239-245
Number of pages7
JournalMeasurement Science and Technology
Issue number3
Publication statusPublished - Mar 1999


  • Fibre optic beam delivery
  • Fluid flow analysis
  • Fluid flow velocity
  • Pulsed laser illumination


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