Vapor Phase Deposition

  Flame Hydrolysis                                                                            Chemical Vapor Deposition

  Vapor Axial Deposition                                                                  Modified chemical  

  Outside vapour phase Oxidation                                                   Plasma-  activated chemical

•       Optical fiber are made from oxide glasses and most popular is silica (SiO2) which has refractive index of 1.458 at 850 nm.

•       To produce two similar materials with slightly different refraction indices for core and cladding, either fluorine or other oxides (dopants) are added to silica

 

 

•Similar to outside vapor deposition

•Starts with a seed which is a pure silica rod

•The preform is grown in the axial direction by moving rod upward

•Rod is also rotated to maintain cylindrical symmetery

•As preform moves upward it is transformed into a solid transparent rod preform by zone melting (heating in a narrow localized zone)

•Advantages

–No central hole

                                                                        

Vapor Phase Deposition method for optical fiber grade glass preparation

Vapor Phase deposition method for optical fiber grade glass preparation
This technique is used for preparing the extremely pure optical glasses.It is now used to produce silica based fiber with a very low attenuation(a fabrication process in which a material is stretched out into a thin shape),highest transparency with optimal optical properties.
Ingredients are volatile organic compounds SiCl₄, GeCl₄,SiF₄,BCl₄,O₂,BBr_3,PoCl₃ and dopants (non silica ) are used to enhance the property of refractive index are TiO₂,GeO₂,P₂O₅,Al₂O₃,B₂O₃,F .

Vapor phase deposition

Flame Hydrolysis                                                                           Chemical Vapor Deposition Vapor Axial Deposition     Outside                           vapour phase Oxidation                                                  Modified chemical vapor phase                                                           Plasma- activate chemical

Proximate analysis of coal

Proximate analysis deals with determination of moisture contents,volatile matter, ash content and fixed carbon .It is simple and cheaper method.The better quality of coal is having a low percentage of moisture,volatile matter and ash content.