Rainbow technique for multi-parameter measurement of absorbing cylinder--颗粒学报PARTICUOLOGY

Song, F., Xu, C., & Wang, S. (2013). Rainbow technique for multi-parameter measurement of absorbing cylinder. Particuology, 11(2), 184–188. https://doi.org/10.1016/j.partic.2012.07.004

Rainbow technique for multi-parameter measurement of absorbing cylinder

Feihu Song, Chuanlong Xu^*, Shimin Wang

Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, China

10.1016/j.partic.2012.07.004

Volume 11, Issue 2, April 2013, Pages 184-188

Received 26 October 2011, Revised 10 July 2012, Accepted 12 July 2012, Available online 20 January 2013.

E-mail: chuanlongxu@seu.edu.cn

Highlights

► Imaginary part of refractive index of the cylinder was measured with rainbow technique.

► A cylinder of red ink solution attached at a capillary tip was measured.

► Relationship between imaginary part of refractive index and ink concentration is linear.

► The relative error of the imaginary part measurement is less than 3.4%.

Abstract

Rainbow refractometry is widely used to measure the radius and real part of refractive index of a cylinder. However, studies on the detection of imaginary part of the refractive index with rainbow technique were scarce. This paper presents a new method for simultaneously measuring the radius, real and imaginary part of the refractive index of a cylinder, on the basis of the Airy theory and the Bouguer theory. The rainbows produced by the illuminated cylinder at a capillary exit are captured by a CCD camera in a lab-scale system, and then processed by the proposed method. Experimental results showed that the radius, real and imaginary part of the refractive index can be accurately determined when the SNR (signal to noise ratio) of the ripple structure is sufficiently high. However, the SNR of the ripple structure gradually decreases with decreasing scattering intensity of the cylinder, leading to larger measurement errors of the radius and real part of the refractive index. The relative error of the imaginary part of the refractive index derived from the measurement errors of the radius and real part of the refractive index, is less than 3.4%.

Graphical abstract

Keywords

Rainbow technique; Airy theory; Bouguer theory; Imaginary part of refractive index; Cylinder

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