Polymer Structure Characterization: From Nano to Macro ...
https://books.google.com/books?isbn=184973433X
Richard A. Pethrick - 2013 - Science
On entering the crystal, each reflecting plane aligned to satisfy the Bragg condition ... These waves interact with each other and set up standing wave fields.___________________________________________________________
Use of Crystals to satisfy the Bragg condition and create a standing wave field: One instrument that uses a single source of light and generates standing waves is a crystal. For our electronic Structure we can use Polymer or Molecular Crystals.
We align three crystals together. As Crystal resonates, electromechanical standing waves are created. Notice that all rays with larger angle of incidence than the red colored ray, such as the blue colored one, do not transmit into the lower index medium. (A red colored ray's angle of incidence is the critical angle.) Total internal reflection is the phenomena that allows wave guides to deliver waves from one point in space to another with little or no attenuation. Wave energy is created but does not disperse.
In the visible region of electromagnetic spectrum a wave guide is called an optical fiber. We create an electroactive polymer, or EAP, which is a class of materials that change their shape when excited by an electric field. When we create EAPs, they convert electrical energy into motion, and also conversely, they can be used to convert mechanical energy into electrical energy. Thus, we create a standing wave.
