OPTICAL ELEMENT, IMAGE DISPLAY APPARATUS, HEAD-MOUNTED DISPLAY, SENSING APPARATUS, AND EYE TRACKING APPARATUS

• Main Authors: SAITOH, Yukito, SATO, Hiroshi
• Format: Patent
• Language: English
• Published: 28.03.2024
• Subjects: OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHYSICS

The present invention provides an optical element in which the occurrence of sidelobe is suppressed and a reflectivity is high, an image display apparatus, a head-mounted display, a sensing apparatus, and an eye tracking apparatus. The optical element according to the present invention includes: at least one reflecting layer pair that is a combination of two reflective layers where turning directions of circularly polarized light to be reflected are opposite to each other and at least a part of reflection wavelength ranges is an overlapping part, in which the reflective layer includes a cholesteric liquid crystal layer obtained by immobilizing a cholesteric liquid crystalline phase, the cholesteric liquid crystal layer has a liquid crystal alignment pattern in which a direction of an optical axis derived from a liquid crystal compound changes while continuously rotating in at least one in-plane direction, and in a case where a depth position corresponding to 10% of a total helical pitch number of the reflective layer from one surface to another surface side of the reflective layer is set as a depth position X, a depth position corresponding to 90% of the total helical pitch number of the reflective layer from the one surface to the other surface side of the reflective layer is set as a depth position Y, a region from the one surface to the depth position X is set as a first region, a region from the depth position X to the depth position Y is set as a second region, and a region from the depth position Y to the other surface is set as a third region, at least one of birefringences in the first region and the third region is less than a birefringence in the second region.