Optical device

An optical device comprising:

• an emitting apparatus comprising a first aperture and which is configured to emit an excitation radiation through said first aperture, said excitation radiation comprising at least one light radiation having a wavelength included in a predefined spectral range,
• an optical guide which extends longitudinally between a first end thereof and a second end thereof and which is internally provided with a core which is configured to propagate radiation at a wavelength included in said predefined spectral range and defining an inlet aperture at said first end and an outlet aperture at said second end, said inlet aperture facing said first aperture so as to be passed through by at least a portion of said excitation radiation when said excitation radiation is emitted by said emitting apparatus, and said outlet aperture being configured to be directed towards an unknown sample when said optical device is in a first operating condition,
• wherein said optical guide comprises a reflective surface which at least partially delimits said core, said reflective surface being a regular optical surface with respect to radiation with a wavelength included in said predefined spectral range and configured to reflect the portion of the excitation radiation which is projected into said core through the inlet aperture so as to propagate said excitation radiation out of said optical guide through said outlet aperture in order to illuminate the unknown sample, wherein said optical device comprises a gap which is arranged between said first aperture and said inlet aperture, said gap being configured to receive a reference sample so that the excitation radiation emitted by said emitting apparatus through said first aperture illuminates the reference sample when said optical device is in a second operating condition, in which said reference sample is received in said gap.