OPTICAL APPARATUS, IN-VEHICLE SYSTEM, AND MOBILE APPARATUS

An optical apparatus includes a deflector configured to deflect illumination light from a light source unit so as to scan an object and configured to deflect reflected light from the object, a light guide configured to guide part of the illumination light from the light source unit to the deflector, another part to a first light receiving element, and the reflected. light from the deflector to a second light receiving element, and an optical element having an optical surface provided between the light guide and the second light receiving element. The optical surface tilts or is eccentric to a principal ray of the illumination light.