1. Chapter 3: Preform manufacture and fiber drawing
Production of silica glass through deposition
Melting of ultrapure glass with furnace heated by radio frequency (RF) induction.

2. Flowchart of the production of ultrapure silicon dioxide from natural quartz or quartz mineral sands.

3. Deposition of silicon dioxide at high temperature in an ultrapure quartz tube in the MCVD (Modified Chemical Vapor Deposition) process.

4. Modified Chemical Vapor Deposition (MCVD)
Process description
MCVD – deposition at Acreo Fiber Lab in Hudiksvall Sweden.

5. Process description
The MCVD – process.

6. Collapse of the preform
Intense heating causes the hollow preform to soften and collapse to a solid rod.

7. Outside Vapor Deposition (OVD)
Process description: phase 1 - deposition
The OVD method for making a preform.

8. Process description: phase 2 - the sintering process
The porous preform is collapsed into a solid glass rod.

9. Process description: phase 3 – fiber drawing

10. Vapor-Phase Axial Deposition (VAD)
Production process
Schematic diagram showing the VAD method of preform manufacture.

11. Fiber drawing – principle drawing.

12. Fiber drawing Fiber drawing - top of the tower.
Typical primary coated single-mode fiber.