A process for the production of a fluorinated quartz glass including the steps of generating SiO.sub.2 particles in a synthesis burner; depositing the resulting SiO.sub.2 particles into a body; and vitrifying the resulting body, wherein a fluorinating agent having a boiling point greater than or equal to −10° C. is supplied to the synthesis burner.

A method for joining an optical part made of quartz glass and a supporting part made of ceramic includes forming a metal layer on a surface of the supporting part by electroless plating, polishing the formed metal layer with a polishing pad to form a first smoothed face on the supporting part surface, polishing a surface of the optical part with the polishing pad to form a second smoothed face, cleaning the first smoothed face and the second smoothed face with ultrasonic cleaning water, forming a first metal film on the first smoothed face by vapor deposition and forming a second metal film on the second smoothed face by vapor deposition, and joining the first metal film and the second metal film to each other by interatomic joining by atomic diffusion between the faces at which the first metal film and the second metal film contact with each other.

A process for the production of a fluorinated quartz glass including the steps of generating SiO.sub.2 particles in a synthesis burner; depositing the resulting SiO.sub.2 particles into a body; and vitrifying the resulting body, wherein a fluorinating agent having a boiling point greater than or equal to ?10? C. is supplied to the synthesis burner.

A method for joining an optical part made of quartz glass and a supporting part made of ceramic includes forming a metal layer on a surface of the supporting part by electroless plating, polishing the formed metal layer with a polishing pad to form a first smoothed face on the supporting part surface, polishing a surface of the optical part with the polishing pad to form a second smoothed face, cleaning the first smoothed face and the second smoothed face with ultrasonic cleaning water, forming a first metal film on the first smoothed face by vapor deposition and forming a second metal film on the second smoothed face by vapor deposition, and joining the first metal film and the second metal film to each other by interatomic joining by atomic diffusion between the faces at which the first metal film and the second metal film contact with each other.