MIE.54 – Mapping the Surface Topography of Sprayed Liquids

• Jason Abraham
• Chris Ayala
• David Dragomir
• Siddharth Maiti
• Luca Murg

Spraying Systems Co. manufactures and tests specialized spray nozzles for industrial application. After a liquid is sprayed out of a nozzle and allowed to settle, the surface topography is unknown. The goal of the project is to develop a device that can measure the curvature, radius, and thickness of small droplets and/or a liquid coating to analyze the effectiveness of each nozzle. The first design alternative proposed uses a series of lenses to converge and diverge the image of the liquid on a grid, similar to a microscope. After the image is captured by a camera, the image is post-processed by code using the grid background as reference to map out the surface topography. The second design alternative works similarly, however, the need for lenses is negated due to the use of a higher resolution grid pattern. The third design alternative maps out the surface topography utilizing a stereoscopic camera. Stereoscopic cameras are combined with a point cloud system to improve measuring accuracy. Point cloud mapping projects a set of points into space, and the coordinate information is used to create a 3D mesh of the scanned surface. Each device uses code to correct for distortion caused by the lenses in the setup or camera. The functionality of the devices is tested using several methods. The first method uses objects of known heights to simulate droplets. The second method uses actual droplets on a glass slide placed above a grid pattern. An image is captured and processed by the code. Furthermore, an analysis is performed on each device to understand how light is being distorted. This is important in correcting systematic errors in readings. The final design utilizes the third device. The ability of the device to map out a liquid’s topography is validated through the use of objects of known dimensions that can closely simulate a liquid. This test ensures the customer’s needs are met as the final device can measure the surface droplet height with ± 1 mm of error.