Light source apparatus and projector

A light source apparatus comprising:

• a light source configured to output first light having a first wavelength band;
• a diffuser that the first light output from the light source enters;
• an optical element that the first t light passing through the diffuser enters;
• a light collection system that the first light passing through the optical element enters;
• a wavelength converter configured to convert part of the first light into second light having a second wavelength band different from the first wavelength band;
• and
• a reflection system configured to reflect another part of the first light output from the wavelength converter,
• wherein the optical element includes a first reflection film configured to transmit the first light and reflect the second light,
• the wavelength converter includes a wavelength conversion layer having a first surface on which the first light is incident, and a second reflection film provided at the first surface and configured to separate the first light into the part and the other part, and
• the other part of the first light separated by the second reflection film enters the diffuser.