US 12,189,159 B2
Optical element, light guide element, and image display element
Yukito Saitoh, Minami-ashigara (JP); Hiroshi Sato, Minami-ashigara (JP); Katsumi Sasata, Minami-ashigara (JP); and Shigeaki Nimura, Minami-ashigara (JP)
Assigned to FUJIFILM Corporation, Tokyo (JP)
Filed by FUJIFILM Corporation, Tokyo (JP)
Filed on Aug. 13, 2021, as Appl. No. 17/401,477.
Application 17/401,477 is a continuation of application No. PCT/JP2020/005723, filed on Feb. 14, 2020.
Claims priority of application No. 2019-024295 (JP), filed on Feb. 14, 2019.
Prior Publication US 2021/0373218 A1, Dec. 2, 2021
Int. Cl. G02B 5/30 (2006.01); F21V 8/00 (2006.01)
CPC G02B 5/3016 (2013.01) [G02B 5/3041 (2013.01); G02B 6/0023 (2013.01); G02B 6/005 (2013.01)] 13 Claims
OG exemplary drawing
 
1. An optical element comprising:
a cholesteric liquid crystal layer that is obtained by immobilizing a cholesteric liquid crystalline phase,
wherein 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 birefringence in a thickness region of 80% as a center portion with respect to a thickness of the cholesteric liquid crystal layer is represented by Δn1, a birefringence in a thickness region of 10% from one surface of the cholesteric liquid crystal layer is represented by Δn2, and a birefringence in a thickness region of 10% from another surface of the cholesteric liquid crystal layer is represented by Δn3, at least one of Δn2 or Δn3 is less than Δn1.