| 摘要 |
<p>A sufficiently large light detection value can be obtained to determine a concentration of a target component in a desired section, without using a laser emitter of a high laser intensity or a large light collector. By changing an orientation of a laser emitter 3 about a horizontal axis or a height of the laser emitter 3, a laser irradiation position on a ground or water surface 5 is switched between a first irradiation position 5a and a second irradiation position 5b. A photodetector 9 detects first scattered light resulting from scattering of first laser beam at the first irradiation position 5a, second scattered light resulting from scattering of second laser beam at the first irradiation position 5a, third scattered light resulting from scattering of the first laser beam at the second irradiation position 5b, and fourth scattered light resulting from scattering of the second laser beam at the second irradiation position 5b. A concentration calculator 11 calculates a concentration of a target component between the first irradiation position 5a and the second irradiation position 5b, based on detection values of the first, second, third, and fourth scattered light obtained by the photodetector 9.</p> |
