Opt. J. is a refereed open-access electronic journal for optics, lasers, optical physics, and related optical sciences. Opt. J. publishes editorials, invited opinions, and book reviews. Acceptance of submitted papers is limited only to those manuscripts that are deemed to be highly original by reviewers and the editorial board. However, once accepted, manuscripts will be published without cost to the authors. This unique policy of open-access publication, without publication charges, has been current since 2010.