| 摘要 |
<p>An optical device (21) comprises a light-emitting element (1) and a photodetector (4), which are formed close to each other on the same substrate (9). Light L from the light-emitting element (1) is reflected by an object, and the reflection LR falls on the photodetector at an angle of incidence α(0°<α<90°).</p> |
