Provided are an illumination optical system having superior color rendering
properties while ensuring sufficient illuminance, an image display apparatus comprising
the illumination optical system and a spatial modulation device illuminated by
the illumination optical system, and a method of illuminating the spatial modulation
device. A first light source (11), a second light source (21) having
a different emission spectrum from an emission spectrum of the first light source
(11), and a replacement optical system replacing light in a specific waveband
in a luminous flux (L1) from the first light source (11) with a luminous
flux (L2) from the second light source (21) are comprised, and the
light in the specific waveband with weak light intensity in the luminous flux (L1)
from the first light source (11) is replaced with the luminous flux (L2)
with sufficient intensity from the second light source (21). Thereby, a
white balance can be kept without reducing the illuminance more than necessary,
and superior color rendering properties can be exhibited.
