Optical element and projection display device

An optical element, comprising:

• a diffractive functional layer which diffracts at least part of incident light;
• and
• a grid formed on a first surface of the diffractive functional layer, the grid including a plurality of fine wires and having a polarization separation function,
• wherein the optical element reflects a part of the incident light while transmitting another part of the incident light;
• and the first surface of the diffractive functional layer includes:
• a plurality of regions having a different height relative to a second surface of the diffractive functional layer, the second surface being an opposite surface to the first surface;
• and
• a step provided at a border between the plurality of regions.

A projection display device, comprising:

• a liquid crystal device;
• a projection lens;
• and
• an optical element arranged at an optional position in an optical path from the liquid crystal device to the projection lens;
• the optical element including:
• a diffractive functional layer which diffracts at least part of incident light;
• and
• a grid formed on a first surface of the diffractive functional layer, the grid including a plurality of fine wires and having a polarization separation function,
• wherein the first surface of the diffractive functional layer includes:
• a plurality of first regions;
• a plurality of second regions, a height thereof, relative to a second surface of the diffractive functional layer, being different from a height of the first region;
• and
• a step provided at a border between the first regions and the second regions.