Phys.org November 14, 2024
An international team of researchers (Canada, USA – Brookhaven National Laboratory, University of Wisconsin-Madison, University of Rochester) demonstrated a laser beam acting like an object — the beam casts a shadow upon a surface when the beam is illuminated by another light source. They observed a regular shadow that could be seen by the naked eye, it followed the contours of the surface it fell on, and it followed the position and shape of the object (the laser beam). They used a nonlinear optical process involving four atomic levels of ruby. They were able to control the intensity of a transmitted laser beam by applying another perpendicular laser beam. They experimentally measured the dependence of the contrast of the shadow on the power of the laser beam, finding a maximum of approximately 22%, like that of a shadow of a tree on a sunny day. They provided a theoretical model that predicts the contrast of the shadow. According to the researchers their work opens new possibilities for fabrication, imaging, and illumination… read more. Open Access TECHNICAL ARTICLE
Photographic images of the shadow of a laser beam… Credit: Optica Vol. 11, Issue 11, pp. 1549-1555 (2024)