A displacement/quantity of light converter in which sensitivity to a micro displacement
due to sound of a diaphragm, or the like, can be enhanced easily. In the displacement/quantity
of light converter where a light emitting part (2) and a light receiving
part (3) are disposed oppositely to a diaphragm (1), light emitted
from the light emitting part (2) and reflected off the diaphragm (1)
is received at the light receiving part (3), and a displacement of the diaphragm
(1) is converted into an output from the light receiving part (3),
a concave diaphragm is used and the concave face is directed toward the light emitting
part (2) and the light receiving part (3). According to the arrangement,
light emitted from the light emitting part (2) and reflected off the diaphragm
(1) impinges efficiently on the light receiving part (3) in the form
of focused light.