Optical filter and optical device provided with this optical filter

a a cc d a Light emitted from a taking lens enters a first birefringent plate to be spatially divided along a first direction extending perpendicular to the direction in which the light advances to achieve two separate rays L and L. The vibrational planes of the two light fluxes L and L emitted from the first birefringent plate are converted to a circularly polarized light by a phase plate . The two light fluxes L′ and L′ emitted from the phase plate are each spatially divided into two by a second birefringent plate along a second direction extending perpendicular to the first direction to achieve four separate rays L, L, L and L, to be guided to an imaging plane of an imaging device . At least either the first birefringent plate or the second birefringent plate is constituted of lithium niobate, rutilo, Chilean nitrate, or the like.