Proximity sensor using partial-transmissive-partial-reflective optical element and manufacturing method thereof

An optical sensing device, comprising:

• a light source, configured to emit a light beam;
• a sensing unit, configured to receive a reflected light beam;
• a light guide unit which includes a partial-transmissive-partial-reflective (PTPR) optical element, disposed in the transmission path of the light beam and the reflected light beam;
• and
• a window located between the PTPR optical element and the object, the light beam emitted from the light source and the reflected light beam passing through this same window, wherein the window is an opening of a housing;
• wherein the light beam emitted by the light source is first transmitted to the PTPR optical element, and further next is transmitted to pass through the window without passing through any optical elements,
• wherein the reflected light passing through the window is transmitted to the PTPR optical element, and further next is transmitted to the sensing unit.