| 摘要 |
<p>A beam splitting unit (31) and a reflection mirror (32) are fixed to a lens barrel (12) in a state where a distance between the unit and the mirror is maintained constant. A laser beam emitted from a light source is guided to the beam splitting unit through an optical fiber (33), and split into a measurement beam and a reference beam by a beam splitter, and a synthesized beam of the measurement beam and the reference beam, which have reciprocated between the beam splitting unit and the reflection mirror in a liquid (Lq), is guided to a light receiving system through the optical fiber. In the light receiving system, the measurement beam and the reference beam are permitted to interfere with each other, and based on a photoelectric conversion signal of the interfering beam, a change of the optical path length of the measurement beam is measured. Thus, a change of the refractive index of the liquid can be optically measured.</p> |
