Apparatus and method for manufacturing glass preform

A method for manufacturing a glass preform, the method comprising:

• preparing a dummy tube section and a glass tube section, the dummy tube section having a first end and a second end opposite to the first end, the glass tube section having an inner wall and being provided at the second end of the dummy tube section;
• arranging an alkali metal compound or an alkaline earth metal compound in the dummy tube section;
• heating and vaporizing the alkali metal compound or the alkaline earth metal compound at a predetermined temperature using a first heat source;
• allowing a dry gas containing oxygen to flow into the dummy tube section from the first end of the dummy tube section;
• cooling and condensing vapor of the alkali metal compound or the alkaline earth metal compound with movement of the dry gas in the dummy tube section, and thereby generating particles of the alkali metal compound or the alkaline earth metal compound;
• heating the particles of the alkali metal compound or the alkaline earth metal compound carried to the glass tube section with the movement of the dry gas by use of a second heat source which performs traverse;
• and
• making oxides of the alkali metal compound or the alkaline earth metal compound be deposited on the inner wall of the glass tube section and dispersed inside the glass tube section.