Measurement of optical properties of biological tissues by low-coherence reflectometry

Abstract

We show that optical properties of dense biological tissues can be determined from backscattered power curves measured by a low-coherence reflectometer. Our measurement approach is based on a first-order scattering theory that relates the backscattered power to the total and backscattering cross sections of scatterers in a turbid medium. As a validation of the technique, measurements were made with a commercially available reflectometer on suspensions of polystyrene microspheres having known optical properties. With this reflectometer, which employs a 1300-nm LED source that emits less than 20 µW, we found that skin tissues could be probed to a depth of nearly 1 mm. Estimates of optical coefficients of human dermis and of a variety of excised animal tissues are given.

1550 nm superluminescent diode and anti-Stokes effect CCD camera based optical coherence tomography for full-field optical metrology

“…In [14] a modified laser Doppler interferometry setup was employed to measure the corneal thickness of the human eye in vivo. In [16,17] optical parameters of human and non-human dense, biological tissues, such as skin, arteries, etc.…”

Spectral-domain low coherence interferometry/optical coherence tomography system for fine needle breast biopsy guidance

“…[26][27][28][29][30] LCI is an optical ranging technique that is capable of measuring depth resolved ͑axial͒ tissue structure, birefringence, flow ͑Doppler shift͒, and spectra with a spatial resolution of several microns. LCI and OCT allow tissue characterization over a depth of 2-3 mm, which is almost one order of magnitude higher than the sampling depth of the spectroscopic approaches.…”

“…Goldberg et al 30 described an automated algorithm for differentiation of human breast tissue using low coherence interferometry. Schmitt et al 29 presented a method for the measurement of tissue optical properties based on low-coherence reflectometry. This short list of recent studies demonstrates that both LCI and OCT are being actively pursued for automated tissue differentiation.…”

Estimation of the scattering coefficients of turbid media using angle-resolved optical frequency-domain imaging

“…Many different methods have been documented for quantifying the scattering (μ s ), absorption (μ a ), total scattering coefficients (μ t =μ a + μ s ), and reduced scattering coefficients noninvasively, using approximations and inversion models of varying complexity. These methods include spatially resolved steady-state diffuse reflectance [1], time-domain diffuse reflectance [2], frequency-domain diffuse reflectance [3], confocal microscopy [4], modulated imaging [5], and optical coherence tomography (OCT) [6]. OCT and its Fourier-domain counterpart, optical frequency-domain imaging (OFDI) [7], are particularly attractive methods, as they allow measurements of heterogeneous structures in vivo.…”

“…It can be shown by a change of variables that the ensuing probability density function for ε is an exponential distribution with parameter unity [14]. It follows that the log-transformed speckle term, ε log , has the following distribution: (6) This distribution, which has no free parameters, has zero mean and variance . It allows for the exact calculation of the standard deviation of μ eff in Eq.…”