A topographer for mapping the central portion as well as the peripheral portion
of the corneal surface is disclosed. The topographer includes a chart image generating
part for producing a chart image to fixate the gaze of an eye under test; a measuring
light source for projecting concentric ring-shaped measuring lights to the cornea
of the eye; a light detector for detecting the image of the measuring light reflected
from the cornea; and a vertex measuring optical system. The vertex measuring optical
system comprises a vertex measuring light source for radiating a vertex measuring
light; a vertex beam splitter for separating the vertex measuring light into two
beams; a vertex measuring light projector for projecting one of the two beams to
the corneal vertex of the eye, and capable of moving along the surface of the corneal
vertex; a collimator for projecting the other beam to a scanning mirror; and a
vertex measuring light detector for detecting a light signal produced by superimposing
and interfering the two beams reflected from the scanning mirror and the corneal vertex.
