| 摘要 |
A light emitted from a light emitting element (1) is introduced to the refraction surface formed in one part of a transparent body (5) to cause the light beam to refract at least once and to impinge upon a first dimensional optical position detector element (7), thereby detecting index of refraction of fuel in accordance with the position at which the light beam impinges on the first dimension optical position detector element (7) and bubbles in the fuel can be detected in accordance with the relative value relationship between the total light-receiving amounts. Alternatively, a monitor for monitoring the light emission from the light emitting element (1) may be provided, and detecting bubbles in the fuel in accordance with the relative value relationship between the total light-receiving amount and an output from the monitor means. Further, the light-emitting element (1) may be controlled by a light-emitting element control means so that the output from the total light-receiving amount detector means is maintained constant. <IMAGE> |
