Generally, the process is the locally heating and collapsing of a cylinder onto a core rod. It can be done online on a draw tower and offline in a separate process that yields a preform for fiber draw. Heraeus offers to do the offline process for you.
Offline RIC® process
The core rod is put into the pure silica tube. These two glass pieces, a handle and a start piece form a so-called assembly. Vacuum is applied to the void between the inner diameter and the core rod. The assembly is then locally heated to the softening point of fused silica, so that the tube collapses onto the core rod. The heat source traverses along the length of the assembly, until the tube is fully collapsed. The produced preform is then inspected and prepared for drawing. Heraeus offers to do this process for you as a service.
Online RIC® process
This process starts the same way, as the offline process, with the manufacturing of the assembly. This assembly is then brought to the draw tower and the fiber is directly drawn. This avoids the forming of the preform, saving the cost of the additional hot forming process.