Light source apparatus

A light source apparatus comprising:

• an optical amplifier configured to amplify and release light;
• a spectroscopic element configured to separate the light released from the optical amplifier according to wavelengths;
• a spatial phase modulating element including a base part and a plurality of grating elements configured to reflect the light separated by the spectroscopic element, the spatial phase modulating element being configured to relatively displace at least a part of grating elements out of the plurality of grating elements with respect to the base part and thereby perform phase modulation on the light separated by the spectroscopic element, and emit diffracted light toward the spectroscopic element along an incident optical path from the spectroscopic element regarding a part of the wavelengths within a wavelength range of the light separated by the spectroscopic element;
• and
• a controller configured to control displacement of the plurality of grating elements with respect to the base part, wherein
• the diffracted light emitted from the spatial phase modulating element generates the light having the part of the wavelengths in the spectroscopic element, and the light having the part of the wavelengths is amplified by the optical amplifier and is subsequently released toward the spectroscopic element, and
• the light having the part of the wavelengths subjected to a plurality of times of amplification by the optical amplifier is output.