Light source device and projector

A light source device comprising:

• a light emitting device that outputs a first light having a first wavelength in a first polarization direction;
• a first optical element having a first area that transmits or reflects the first light and a second area that reflects the first light when the first light is transmitted through the first area or transmits the first light when the first light is reflected by the first area;
• a second optical element into which the first light output from the first area of the first optical element is entered, converting the first light into a circularly-polarized second light having the first wavelength;
• a diffuser element into which the second light output from the second optical element is entered;
• and
• a wavelength conversion element into which the first light output from the second area of the first optical element is entered, wherein
• the light output from the diffuser element and entered into the second optical element is converted into a third light having the first wavelength in a second polarization direction by the second optical element,
• the third light output from the second optical element and entered into the first area of the first optical element is output from the first area,
• the light output from the diffuser element and entered into the second area of the first optical element is output from the second area of the first optical element, and
• a fourth light output from the wavelength conversion element and entered into the first area and the second area of the first optical element and having a second wavelength is output through the first area and the second area of the first optical element.