A light source device comprising:
- a light source section configured to emit a first light beam which has a first wavelength band and includes light polarized in a first polarization direction and light polarized in a second polarization direction different from the first polarization direction;
- a first polarization split element which is configured to transmit the first light beam entering the first polarization split element from the light source section along a first direction and polarized in the first polarization direction toward the first direction, and is configured to reflect the first light beam polarized in the second polarization direction toward a second direction crossing the first direction;
- a second polarization split element disposed at the first direction side of the first polarization split element, and configured to reflect the first light beam which enters the second polarization split element along the first direction from the first polarization split element, and is polarized in the first polarization direction toward the second direction;
- a diffusion element disposed at the second direction side of the first polarization split element, and configured to diffuse the first light beam which enters the diffusion element along the second direction from the first polarization split element, and is polarized in the second polarization direction, and configured to emit the first light beam diffused toward a third direction as an opposite direction to the second direction;
- a wavelength conversion element disposed at the second direction side of the second polarization split element, configured to perform wavelength conversion on the first light beam which enters the wavelength conversion element along the second direction from the second polarization split element, and is polarized in the first polarization direction, and configured to emit a second light beam having a second wavelength band different from the first wavelength band toward the third direction;
- and
- an optical element disposed between the first polarization split element and the second polarization split element, and having a flat-surface area and a concave-surface area, wherein
- the second light beam enters the second polarization split element along the third direction from the wavelength conversion element, the second polarization split element transmits the second light beam polarized in the first polarization direction toward the third direction, and reflects the second light beam polarized in the second polarization direction toward a fourth direction as an opposite direction to the first direction,
- the optical element separates the second light beam which enters the optical element along the fourth direction from the second polarization split element and is polarized in the second polarization direction into a third light beam having a third wavelength band different from the second wavelength band, and a fourth light beam having a fourth wavelength band different from the second wavelength band and the third wavelength band to transmit the third light beam toward the fourth direction and reflect the fourth light beam toward the first direction, and
- the first polarization split element transmits the first light beam which is emitted along the third direction from the diffusion element, and reflects the third light beam which enters the first polarization split element along the fourth direction from the second polarization split element toward the third direction.