US Patent 11834899 Multi-stage prism window

A multi-stage prism window includes: a first prism configured to condense light whose angle is equal to or larger than a first predetermined angle on a reflective member and retroreflect the light; a second prism configured to condense light whose angle is equal to or larger than a second predetermined angle on an endothermic member or a reflective member and use the light for indoor heating; and a liquid control mechanism configured to fill at least one of a first space and a second space with a liquid, the first space being in contact with the first prism from an indoor side, the second space being in contact with the second prism from the indoor side.