Single-pixel correlation applied to background-oriented schlieren measurement

A high-spatial resolution measurement system by the background-oriented schlieren (BOS) method is proposed in this note. The single-pixel correlation method is applied for the image pairs obtained by the BOS method, and the displacement is calculated. The backgrounds are projected by a high-speed projector and changed at 900 Hz for calculation of the pixel-to-pixel correlation. This method is compared with the conventional method which utilizes the constant background and calculates the displacement by the conventional spatial correlation. The results show that the proposed system can obtain the displacement distribution in the single-pixel resolution which is eight times as high resolution as the conventional one. Graphical abstract