The SPIV is a LaVision Inc. custom-designed and built measurement system.
It consists of a 120 mJ Nd:Yag laser, submerged lightsheet generator, two 1600x1200 pixel cross-correlation cameras fitted with 50 mm f/1.8 lenses, and computer and software for data acquisition and reduction of PIV recordings.
The lenses are equipped with motors for automatic remote focusing and aperture adjustments.
The camera bodies are equipped with motors for automatic remote Scheimpflug angle adjustments.
Both cameras are arranged asymmetrically in submerged enclosures downstream of the lightsheet to minimize wave and flowfield effects of the enclosures at the measurement area.
The laser, lightsheet generator, and camera enclosures are assembled on a lightweight matrix of aluminum extrusions for adjustability and rigidity.
The SPIV system is calibrated in situ by submerging and fixing a two-tier LaVision calibration plate in the plane of the lightsheet where both camera field of views overlap.
Single images from each camera are used to create a mapping function of the plate markers which is used later to reconstruct 3D velocity vectors from particle image pairs.
The original calibration is refined iteratively with a self calibration procedure1) to account for translational or rotational misalignment of the calibration plate in the lightsheet plane.
1) B. Wieneke, "Stereo-PIV using self-calibration on particle images", Experiments in Fluids (2005) 39: 267–280
