PURPOSE: To improve resolution by so controlling a lens body by a vapor phase deposition method that the thicknesses of its respective glass layers are made constant and refractive index distributions change continuously in a concentrical circular shape.
CONSTITUTION: Respective deposited (glass) layers 22 are formed at varying thicknesses Kn in a reaction tube 21, and are collapsed (c) to form glass layers 25 of equal layers in such a way that Kn satisfies the equations (1), (2). Here, Ro is the inside radius of the tube 21, Kn is the thickness of the n-th glass layer, (m) is the number of the glass layers and (a) is the radius of the collapsed fiber. Controlled by a control part 31, the evaporating gases of respective vessels 40W 42 are fed together with O2 46 by Ar 45 into a reaction tube 36, where they are heated with a burner 38 and SiCl4, GeCl3, PoCl3 turn respectively to SiO2, GeO2, P2O5, thereby forming respective glass layers. These are collapsed by a glass lathe 37, whereby the fiber lens having the constant thickness of the respective glass layers and continuous refractive indice is obtained. Thereby, the resolution is improved.
MIKI MASAJI
KIKUCHI FUMI
OKADA HISANAO
