Spectroscope, optical inspection device and OCT device

A spectroscope comprising

• a first diffraction grating to which an incident light including at least a transmitted light or a reflected light from an object to be measured enters, which diffracts a first polarization component of the incident light, and which transmits a second polarization component of the incident light without diffraction, the second polarization component of the incident light being different from the first polarization component of the incident light,
• a first light-receiving element that receives a spectrum of the first polarization component of the incident light diffracted by the first diffraction grating,
• a second diffraction grating to which the second polarization component of the incident light transmitted through the first diffraction grating without diffraction enters and which diffracts the second polarization component of the incident light that is transmitted through the first diffraction grating, and
• a second light-receiving element that receives a spectrum of the second polarization component of the incident light diffracted by the second diffraction grating,
• wherein the first polarization component of the incident light received by the first light-receiving element does not pass through the second diffraction grating.