Light source device and projector

A light source device comprising:

• a light emitting element that is configured to emit light of a first wavelength band;
• a fluorescent wheel that includes a fluorescent area configured to convert the light of the first wavelength band into fluorescent light and a reflection area configured to reflect the light of the first wavelength band, the fluorescent area and the reflection area being arranged side by side in a circumferential direction;
• a mirror that is configured to reflect a component in a first polarization direction of the light of the first wavelength band and to transmit a component in a second polarization direction of the light of the first wavelength band, the second polarization direction being orthogonal to the first polarization direction;
• and
• a control unit that is configured to control the light emitting element and the fluorescent wheel,
• wherein the reflection area includes a reflecting surface and a polarization conversion layer including an optical axis and converts a polarization direction of either the incident first polarization direction or the incident second polarization direction to another polarization direction, and
• wherein the optical axis of the polarization conversion layer is inclined by 45 degrees with respect to a polarization direction of the light of the first wavelength band at an irradiation position of the light of the first wavelength band in the fluorescent wheel.