To provide a light source device having high directivity.
A light source device 1 has a configuration in which a light source 2, a first refraction index layer 4, and a second refraction index layer 5 are alternately laminated, and includes a dielectric multilayer 3 that, of the light emitted from the light source 2, transmits the light of a predetermined wavelength region and reflects the light other than the light of the wavelength region. When e0 represents the energy of the light emitted from one point of the light source 2 in the direction of a first polar angle and a first azimuth angle, and e1 represents the energy of the light that transmits the dielectric multilayer 3, the relationship of e1/e0<1 is satisfied. Or in the case of e1/e0=1, when e2 represents the energy of the light that is emitted from one point of the light source in the direction of the second polar angle larger than the first polar angle and the first azimuth angle, and transmits the dielectric multilayer, the relationship of e2=0 is satisfied.
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SHIBATA SATOSHI
UTSUMI YUKA
KOBAYASHI ISATAKE
Masao Miki
Susumu Nomura
Nishizawa Kazumi
Koji Kata