Determination of particle size by using the angular distribution of backscattered light as measured with low-coherence interferometry

Abstract

We employ a novel interferometer to measure the angular distribution of light backscattered by a turbid medium. Through comparison of the measured data with the predictions of Mie theory, we are able to determine the size of the scatterers comprising the medium with subwavelength precision. As the technique is based on low-coherence interferometry, we are able to examine the evolution of the angular distribution of scattered light as it propagates into the medium. The effects of multiple scattering as a function of penetration depth in the medium are analyzed. We also present various considerations for extending this technique to determining structural information in biological tissues, such as the effects of a distribution of particle sizes and the need to average out speckle contributions.

Rapid, depth-resolved light scattering measurements using Fourier domain, angle-resolved low coherence interferometry

“…Angle-resolved low coherence interferometry (a/LCI) has been developed as a means to obtain sub-surface structural information by examining the angular distribution of scattered light [1][2][3]. The a/LCI technique combines the ability of low coherence interferometry to detect singly scattered light from sub-surface sites with the capability of light scattering methods to obtain structural information with sub-wavelength precision and accuracy [2,4].…”

“…The a/LCI technique combines the ability of low coherence interferometry to detect singly scattered light from sub-surface sites with the capability of light scattering methods to obtain structural information with sub-wavelength precision and accuracy [2,4]. a/LCI has been successfully applied to measuring cellular morphology in tissues [3] and in vitro [4] as well as diagnosing intraepithelial neoplasia [5] and assessing the efficacy of chemopreventive agents [6] in an animal model of carcinogenesis.…”

“…The initial prototype a/LCI system [1,2] and the faster, second generation system [3] both relied on time domain depth scans, implemented by mechanically adjusting the length of the reference arm of the interferometer and serial scanning of the detected scattering angle. However, it has recently been shown that improvements in signal-to-noise, and commensurate reductions in data acquisition time are possible by recording the depth scan in the Fourier (or spectral) domain [7][8][9].…”

“…Indeed, recent implementations of Fourier (spectral) domain optical coherence tomography (OCT) have obtained high quality images with high frame rates [10][11][12]. While these new OCT implementations achieve 2-3 μm resolution, which is insufficient for quantitative comparisons of cellular features, light scattering based techniques can obtain structural information with sub-wavelength precision and accuracy [2,4]. This paper presents a new a/LCI technique, Fourier domain a/LCI (faLCI), which combines the Fourier domain concept with the use of an imaging spectrograph to record the angular distribution in parallel.…”

Fourier-domain low-coherence interferometry for light-scattering spectroscopy

“…7 More recently, angle-resolved low-coherence interferometry was used to obtain structural information by examination of the angular distribution of scattered light. 8,9 Angle-resolved LCI has been successfully applied to measuring cellular morphology 3 and to diagnosing intraepithelial neoplasia in an animal model of carcinogenesis. 6 The latter study was significant because it demonstrated the strength of joining LSS and LCI as a biomedical diagnostic technique.…”