Non-Intrusive Calibration Target for Flow Velocimetry

A non-intrusive calibration technique for 3D velocity measurements is developed. Techniques such as Particle Image Velocimetry (PIV) require calibration to map particle images to physical space. Experimental setups that preclude access to the measurement volume make the use of a physical calibration target impossible. Here, we describe a non-intrusive, virtual calibration target, whereby a translating system of two lasers is used to create a calibration point array with precisely known point locations. This low-cost tabletop-sized system is agnostic to the index of refraction in the measurement domain, and the size of the virtual calibration target can be scaled arbitrarily. Performance of this technique is tested for both planar and stereo PIV.