POLARIZED LIGHT SWITCHING ELEMENT, LUMINOUS FLUX SPLITTING ELEMENT, OPTICAL SCANNER AND IMAGE FORMING APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide a polarized light switching element which has a large tolerance to the shift of the wavelength of incident light and an installing error of the element, and can contribute to the improvement of productivity of an optical scanner.

SOLUTION: The polarized light switching element 10 is composed of: a λ/4 plate 11; and a liquid crystal element 12 which switches the alignment direction of liquid crystal molecules into a predetermined direction by switching the direction of electric field, both arranged in this order from the incident light side. The light which is made incident to the polarized light switching element 10 is vertically polarized as shown in Figure. The incident light which was linear polarized light P1 becomes clockwise circular polarized light P2 after passing through the λ/4 plate 11. The light further becomes horizontally polarized light P3 by being added with a phase shift of λ/4 when the liquid crystal molecules of the liquid crystal element 12 are oriented in 45° direction. Further, the clockwise circular polarized light P2 after passing through the λ/4 plate 11 becomes linear polarized light P5 which vertically oscillates when the direction of the electric field applied on the liquid crystal is switched and the alignment of the liquid crystal molecules is directed to -45° as shown in (b) of the Figure.

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