Beam configuration for light sheet application

To visualise laminar and turbulent flow patterns of gaseous or liquid fluids, the laser-light-sheet technique can be applied. The optically recorded flow images are useful for research and development of flow measuring and controlling devices. Instead of single high-power gas lasers or solid state lasers six monomode laser diodes emitting in the visible spectral range are applied. They are mounted in parallel and the individual radiation fields overlap to generate a more homogeneous intensity distribution with less coherence than with a single laser source. Therefore, disturbances due to speckle effects are reduced. The resulting light sheet has a total optical output power of 0.3 W and a thickness of 0.7 mm. The working distance amounts from 60 mm up to 160 mm with an operating area of 100 × 100 mm2. Application examples of the internal flow characteristics of a gas-pressure regulator and high-speed gas flow diagnosis in a sonic Venturi nozzle are presented and compared with computational fluid dynamics (CFD) simulations.