oWhen you need to measure the size and shape of your particles, droplets or bubbles, turn to image based analysis for size distribution measurement. Our droplet sizing systems capture high-speed images of a particle cloud, spray (e.g. for water droplet size measurement) or bubble stream to give the drop size. In addition to measuring the particle diameter distribution, Oxford Lasers imaging systems also provide shape and velocity analysis.
Our powerful online analysis systems measure particle diameter, shape and velocity distributions for solids, liquids and gases suspended in any transparent medium. No other droplet sizing system is as intuitive to use as direct imaging equipment.
If you can operate a camcorder or digital camera, you can master a VisiSizer. sizing system. VisiSizer not only provides accurate diameter distributions but also records images of your subject.
VisiSizer has the unique ability to generate particle size, drop diameter, (e.g. for nozzle characterization), bubble diameter and velocity measurements, together with simultaneous images of the particles. The technique works by capturing images of the spray using a high-resolution camera together with short pulse laser illumination to freeze the motion. Software then measures the diameter and shape and calculates the diameter distribution. The non-contact online measurement means that you can add a VisiSizer particle sizing system to your current process (providing that there is suitable optical access) without causing disruption.
Air inclusion in a spray droplet
On the left is the first ever in-flight image of the output from an agricultural "air-inclusion" nozzle. From this image, taken from a VisiSize system, not only are the water drops non-spherical, but air bubbles are visible within them. Other measurement techniques such as PDA or laser diffraction would mis-size the water droplet without indicating they had done so - and you would never have known about the air inclusions
The VisiSizer range also double as very powerful laser imaging systems. As well as capturing images for sizing, the systems can image the nozzle and the break-up and drop formation processes. This can provide a very valuable insight into nozzle effects and problems. When combined with the quantitative diameter data this makes image based sizing an extremely powerful tool for R&D.
A short flash of light from a laser illuminates a screen, which acts as a bright background behind the subject spray. The short pulse from the laser freezes the motion, allowing blur-free visualization of drop size and shape. Images from the digital camera are transferred to a computer and high-speed real-time particle sizing software analyses the images obtained in order to build up the diameter distribution.
By double-pulsing the laser in a technique similar to PIV, size vs. velocity distributions may also be measured. For more information about the technique see our in-flight sizing datasheet.
Other configurations are available - for more information contact us .