Goniometric characteristics of optical fibres for temperature measurement in diesel engine exhaust filters

• Published in: Measurement science & technology Vol. 14; no. 5; pp. 563 - 572
• Main Authors: Boothe, Brian J, Shih, Albert J, Kong, Jian, Roberts, William L
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.05.2003; Institute of Physics
• Subjects: Exact sciences and technology; Fiber-optic instruments; High-temperature techniques and instrumentation; pyrometry; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Optical instruments, equipment and techniques; Physics; Thermal instruments, apparatus and techniques; Optical fibers; Temperature measurement; Temperature distribution; Numerical aperture; Infrared pyrometer; Filters; Diesel engines; Geometrical configuration; Experimental study; Non contact measurement; Exhaust systems
• ISSN: 0957-0233; 1361-6501
• DOI: 10.1088/0957-0233/14/5/305

The accurate in situ, non-contact pyrometric measurement of the temperature distribution within diesel engine exhaust after-treatment filters requires the employment of optical fibres with special tip geometry. The goniometric characteristics of optical fibres with flat, 45DG angled and bent and polished tips are studied such that the specific radiation acceptance region can be determined. One 2 mm diameter fused silica and two 0.425 mm diameter sapphire optical fibres are examined. Detailed discussion of the relative intensity profiles observed for these fibres is presented. Of the 3 fibres evaluated, the 45DG angled tip geometry provides the most precise response for measuring radiation emitted from the internal filter walls. Exploiting the characteristics of total internal reflection, the 45DG angled tip fibre accepts the maximum quantity of incident radiation at an angle perpendicular to the optical axis.