Liquid crystal optical element

A liquid crystal optical element comprising:

• a transparent substrate;
• a first liquid crystal layer overlapping the transparent substrate and comprising a first cholesteric liquid crystal;
• and
• a second liquid crystal layer overlapping the first liquid crystal layer and comprising a second cholesteric liquid crystal,
• a helical pitch of each of the first cholesteric liquid crystal and the second cholesteric liquid crystal changing continuously,
• the first cholesteric liquid crystal comprising:
• a first portion close to the transparent substrate, and having a first helical pitch;
• and
• a second portion located between the first portion and the second liquid crystal layer, and having a second helical pitch different from the first helical pitch,
• the second cholesteric liquid crystal comprising:
• a third portion close to the first liquid crystal layer, and having a third helical pitch;
• and
• a fourth portion located further away from the first liquid crystal layer than the third portion, and having a fourth helical pitch different from the third helical pitch.