Amazing stuff! Without a shadow of a doubt! 😊
"... In Optica, researchers describe how they used a ruby crystal and specific laser wavelengths to show that a laser beam could block light and create a visible shadow due to a nonlinear optical process. This effect occurs when light interacts with a material in an intensity-dependent way and can influence another optical field. ..."
"... "What's particularly fascinating is how closely this laser shadow behaves like a traditional shadow," ..."
From the abstract:
"Light, being massless, casts no shadow; under ordinary circumstances, photons pass right through each other unimpeded. Here, we demonstrate a laser beam acting like an object — the beam casts a shadow upon a surface when the beam is illuminated by another light source. We observe a regular shadow in the sense it can be seen by the naked eye, it follows the contours of the surface it falls on, and it follows the position and shape of the object (the laser beam). Specifically, we use a nonlinear optical process involving four atomic levels of ruby. We are able to control the intensity of a transmitted laser beam by applying another perpendicular laser beam. We experimentally measure the dependence of the contrast of the shadow on the power of the laser beam, finding a maximum of approximately 22%, similar to that of a shadow of a tree on a sunny day. We provide a theoretical model that predicts the contrast of the shadow. This work opens new possibilities for fabrication, imaging, and illumination."
uOttawa physicists make laser cast a shadow (original news release)
Shadow of a laser beam (open access) "In a recent study, researchers from the University of Ottawa have demonstrated a remarkable new phenomenon: a laser beam casting a visible shadow."
Fig. 1. Photographic images of the shadow of a laser beam. A high-power green laser beam (the object), travelling through a cube of ruby, is illuminated from the side by blue light.
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