Patent attributes
A headlight device includes a light source unit to emit first light, a first optical unit to change a light distribution pattern of incident first light, a light-reception unit to detect incident second light, a second optical unit to project the light distribution pattern in a predetermined projection direction and receive incident light traveling in a direction opposite to the projection direction, a third optical unit to emit the first light toward the second optical unit and emit incident light that has passed through the second optical unit as second light toward the light-reception unit, and a fourth optical unit to focus the second light and direct toward the light-reception unit. The light distribution pattern is controlled based on a detection result of second light in the light-reception unit.
