| 摘要 |
PURPOSE:To measure precisely front minute angle scattered light intensity whose scattering angle is between 0.5 degree and about 5 degrees, by eliminating an incident primary lumnous flux which becomes a generating source of the maximum optical noise, without reflecting it to the incident side. CONSTITUTION:Scattered light separated in accordance with a scattering angle is inputted as intensity around the solid angle of its opening, by an optical fiber 6a placed in the image plane, and is detected by a photocell detector 5. Also, minute angle scattered light 10 is separated from a primary luminous flux 11 by selecting suitably a curvature of a small convex face total reflector 7, and is detected by an optical fiber 6b and the detector 5. Intensity of said minute angle scatered light 10 is corrected after detection by considering a reflection factor of a mirror 7 and a detected solid angle. The primary luminous flux which is not detected by that time, and scattered light of a more minute angle are eliminated by a light trap 9 through a lens barrel 8 having a total reflection face on the inside face. |
