The CDC recently recommended that everyone wear face masks whenever out in public to help protect against the further spread of coronavirus. This neat video uses an old but unusual photography technique to show the effectiveness of using face masks.
As the coronavirus pandemic continues, it is crucial that we all follow the recommendations of authorities to help prevent the further spread of the virus. LaVision recently created the above video, which shows the effectiveness of face masks, underscoring the importance of following the CDC's recent recommendation that everyone wear face masks in public. The video takes advantage of the Schlieren technique. Invented by August Toepler in 1864 to study supersonic motion, the method has remained crucial to studying airflow, with industries like aeronautics frequently employing it to visualize such dynamic processes. The technique relies on using collimated light (light that doesn't diverge with distance). Any airflow will cause density variations that change the refractive index of the air, causing the collimated light to diverge and creating areas of contrast that show the otherwise invisible airflow. It is a very clever technique, and it shows how crucial it is that we take all possible protective measures during this time. Stay safe and healthy!