Manufacturing method of liquid crystal optical element

A manufacturing method of a liquid crystal optical element, the method comprising:

• preparing a liquid crystal material containing a liquid crystal monomer and a polymerization initiator;
• forming an alignment film on a support substrate;
• applying the liquid crystal material onto the alignment film;
• forming a liquid crystal film by curing the liquid crystal material in a state which exhibits a cholesteric liquid crystal phase, the liquid crystal film including a first surface in contact with the alignment film and a second surface opposite the first surface;
• attaching a thermal release tape to the liquid crystal film, the whole second surface of the liquid crystal film being in contact with the thermal release tape;
• peeling the liquid crystal film from the alignment film;
• preparing a transparent substrate in which a material forming a main surface is an inorganic material, the transparent substrate being neither a retardation film nor a polarizing film;
• applying a solution containing a silane coupling agent to the main surface of the transparent substrate to form an adhesive layer;
• stacking the liquid crystal film on the silane coupling agent, the whole first surface of the liquid crystal film being in contact with the silane coupling agent and the liquid crystal film being sandwiched between the thermal release tape and the adhesive layer;
• heating the thermal release tape and the adhesive layer at a same time,
• an adhesion of the thermal release tape being reduced by heating, and
• an alkoxy group of the silane coupling agent being chemically bonded to the inorganic material forming the main surface, and a reactive functional group of the silane coupling agent being chemically bonded to a functional group of the liquid crystal film which remains in an unreacted state by heating;
• and
• peeling the thermal release tape from the liquid crystal film, wherein
• the transparent substrate, the adhesive layer and the liquid crystal film have same refractive index,
• the adhesive layer is transparent, and
• an adhesion of the adhesive layer is stronger than the adhesion of the thermal release tape after heating the thermal release tape.