Four filling recesses 14 are formed on an inner peripheral surface of
a fitting groove 5, which is formed concentrically with a light passage
hole in a holder 3, at intervals of 90 degrees in a circumferential direction.
A bottom surface 14a of each filling recess 14 is inclined
from one end face 3a of the holder 3 toward a lens receiving
seat 6, such that a longitudinal sectional shape of each filling recess
14 is formed in a substantially triangular shape.
