A measurement-purpose light source generates a measurement light used for
measuring an optical characteristic of an object to be measured, and the
measurement light includes a component in a wavelength range for
measurement of the optical characteristic of the object. An
observation-purpose light source generates an observation light used for
focusing on the object to be measured and checking a position of
measurement. The observation light is selected such that the observation
light includes a component that can be reflected from the object to be
measured. The measurement light and the observation light are thus
applied independently to the object to be measured, through a common
objective lens, and accordingly improvement of the precision in
measurement of the optical characteristic and facilitation of focusing on
the object to be measured are achieved simultaneously.