Optical device and ranging device

An optical device, comprising:

• a substrate;
• a light source unit that is arranged on the substrate and emits emission light;
• a light receiving unit arranged adjacent to the light source unit on the substrate and including a semiconductor substrate having a photodiode;
• a light guide portion that is arranged in such a manner as to overlap with the light source unit and the light receiving unit in a plan view, and has a first surface close to the substrate and a second surface on an opposite side of the first surface;
• a lens group arranged in such a manner as to overlap with either one of the light source unit or the light receiving unit in a plan view;
• and
• a lens barrel that supports the lens group, wherein
• the light guide portion guides the emission light from the first surface to the second surface, and guides incident light from the lens group from the second surface to the first surface.

A ranging device, comprising:

• a light source unit that emits emission light;
• a first lens that emits the emission light;
• a second lens that projects the emission light, which is emitted by the first lens, onto an object and emits reflected light obtained by reflection of the projected emission light on the object;
• a light receiving element that receives the reflected light emitted by the second lens;
• a light guide portion that guides and emits the reflected light, which is emitted by the second lens, to the light receiving element while guiding, to the second lens, the emission light emitted by the first lens;
• and
• a ranging unit that measures a distance to the object on a basis of an image signal generated by the light receiving element on a basis of the reflected light, wherein
• the light guide portion emits the reflected light in a direction substantially parallel to the emission light emitted by the first lens.