| 摘要 |
PURPOSE:To improve optical transmission efficiency and to enable detection with high sensitivity by using a circular cylindrical transparent member for optical transmission and setting the ratio between the diameter and length thereof at 1/50 or above. CONSTITUTION:The part facing a light incident body 13 is made of a diffusion reflecting band 14 having a width H. The band 14 is formed by roughening the surface of an optical transmission member 2 and coating BaSO4 thereon. Light exit parts 15 having a convergent shape are further provided to both ends of the member 2. The diameter D thereof is made >=20mm. when the length L of the member 2 is 1m to satisfy the relation D/L>=1/50, thereby supressing the number of reflection. The width H is set at <=10% of the periphery of the member 2. As a result, the reflectivity is increased by the BaSO4 coated on the member and the number of reflection is decreased and therefore the light is transmitted with good efficiency. |
