An optical apparatus includes a deflector configured to deflect illumination light from a light source unit to scan an object and to deflect reflected light from the object, and a controller configured to control the deflector. A first divergence angle of the illumination light in a first cross section is larger than a second divergence angle in a second cross section orthogonal to the first section. The controller controls the deflector so that the illumination light moves in the first cross section at a first speed and moves in the second cross section at a second speed higher than the first speed.