Plastic light-folding element, imaging lens assembly module and electronic device

A plastic light-folding element, comprising:

• an incident surface configured to lead an imaging light enter the plastic light-folding element;
• an exit surface configured to lead the imaging light exit the plastic light-folding element;
• a reflective surface configured to fold the imaging light;
• a reflective optical layer disposed on a surface of the reflective surface, and comprising:
• an Ag layer configured to lead the imaging light, which enters the incident surface, reflect to the exit surface;
• a bottom layer optical film directly contacted with the Ag layer, and the bottom layer optical film closer to the reflective surface of the plastic light-folding element than the Ag layer to the reflective surface of the plastic light-folding element;
• and
• a top layer optical film, a refractive index of the top layer optical film lower than a refractive index of the bottom layer optical film, wherein the top layer optical film is not directly contacted with the Ag layer, and the top layer optical film is farther from the reflective surface of the plastic light-folding element than the Ag layer from the reflective surface of the plastic light-folding element;
• and
• at least one intermediate layer disposed between the top layer optical film and the Ag layer, and the at least one intermediate layer directly contacted to the Ag layer, wherein there is no layer disposed between the at least one intermediate layer and the Ag layer, the at least one intermediate layer comprises a metal layer excluding a silver atom, and a material of the metal layer is Ti, Cr, Ni or one of an oxide of Cr and Ni;
• wherein the refractive index of the bottom layer optical film is Nb, a thickness of the bottom layer optical film is db, the refractive index of the top layer optical film is Nt, a thickness of the top layer optical film is dt, a thickness of the Ag layer is dAg, and the following conditions are satisfied:
• 1.4<Nt<Nb<2.1;
• 1.6<Nb<2.1;
• 1.4<Nt<1.58;
• 0.05<db/dAg<1.2;
• and
• 0.2<dAg/dt<3.5.