Optical filter and optical device provided with this optical filter

Abstract

Light emitted from a taking lens 20 enters a first birefringent plate 1 a to be spatially divided along a first direction extending perpendicular to the direction in which the light advances to achieve two separate rays L 10 and L 20 . The vibrational planes of the two light fluxes L 10 and L 20 emitted from the first birefringent plate 1 a are converted to a circularly polarized light by a phase plate 1 c . The two light fluxes L 10 ′ and L 20 ′ emitted from the phase plate 1 c are each spatially divided into two by a second birefringent plate id along a second direction extending perpendicular to the first direction to achieve four separate rays L 11 , L 12 , L 21 and L 22 , to be guided to an imaging plane 15 a of an imaging device 15 . At least either the first birefringent plate or the second birefringent plate is constituted of lithium niobate, rutile, Chilean nitrate, or the like.

1 . An optical filter comprising: 
 a first birefringent plate constituting an optical element that spatially divides incident light along a first direction extending perpendicular to a direction in which the incident light advances to achieve two separate light fluxes;    a vibrational plane converting plate that changes the vibrational plane of each of the two light fluxes emitted from said first birefringent plate; and    a second birefringent plate constituting an optical element that spatially divides each of the two light fluxes emitted from said vibrational plane converting plate into two light fluxes along a second direction which is different from said first direction, to achieve a total of four separate light fluxes, wherein:    at least either said first birefringent plate or said second birefringent plate is constituted of a material with a larger difference between the extraordinary ray refractive index and the ordinary ray refractive index compared to that of quartz.