| 摘要 |
<p>PROBLEM TO BE SOLVED: To conduct distinguishing of sodium glass and non-sodium glass by an optical device. SOLUTION: An interference filter 7 passing only light flux having a wavelength of 2800nm±5% is provided between a light projecting portion 21 and a light receiving portion 22 so as to form a first optical path 11, and a second optical path 12 having no interference filter 7 is provided in parallel thereto. A glass piece 6 is arranged extending over both optical paths 11, 12, in the first optical path 11 the light flux having a wavelength of an infrared range penetrated the interference filter 7 is irradiated on the glass piece 6, and in the second optical path 12 visible light itself is irradiated. In the first optical path 11 sodium glass and non-sodium glass are judged, in the second optical path 12 stain and the like on the surface of the glass piece 6 are detected, and considering the degree of the stain, misjudgement between the sodium glass and the non-sodium glass in the first optical path 11 is prevented.</p> |
