Method for controlling diameter of GRIN lens fiber and fiber drawing equipment

摘要

When a GRIN lens fiber is drawn from a preform, control of a fiber diameter is improved in order to increase a production yield of the GRIN lens fiber having a fiber diameter within a desired range. The problem is solved by controlling the drawing speed using a fiber diameter c, which is obtained by correcting a fiber diameter a using the fiber diameter b and a fiber diameter α. The fiber diameter a is measured using a diameter measuring instrument A that measures an outer diameter of the GRIN lens fiber, which is being elongated inside a heating furnace, the fiber diameter b is measured using a diameter measuring instrument B that measures an outer diameter of the GRIN lens fiber outside the heating furnace, and the fiber diameter α is a value of the fiber diameter a measured a specified period of time T earlier.