Extraction of optical properties from a turbid medium using fiber probe for spectral and spatial diffuse reflectance measurement

Abstract

Diffuse reflectance technique is popular in the study of tissue physiology through the change in optical properties in a noninvasive manner. Diffuse reflected light intensity is commonly collected either from a single distance with spectral measurement or from a single wavelength with different spatial distances. Improving existing systems is necessary in order to obtain information from greater depths and in smaller volumes. In this paper, we propose a fast and compact fiber probe-based diffuse reflectance method for combining the spectral measurements in the range of 400–950 nm and spatial information up to 1.33 mm from the illumination source. First, we chose the most appropriate analysis model for the proposed distances between the fiber probe and tested it on solid phantoms with varying scattering and absorption components. The measurements are compared to the scattering coefficients according to Mie theory and the absorption according to spectrophotometer measurements. Next, we measured two-layer phantoms with constant scattering and absorption contrast in different layer thicknesses. We extracted the penetration depth from the measured effective absorption coefficient. In the near-IR, we were able to detect the absorption coefficient of the bottom phantom layer behind a top layer of up to 5 mm. We achieved a maximum penetration depth of 5.7 mm for 5 mm top layer thickness at 900 nm. Our fiber probe diffuse reflectance system can be used in the near future for skin lesion detection in clinical studies.

Diffused reflectance measurements to detect tattoo ink location in skin using the crossover point

“…The collected intensity ( R ( r )) was plotted as the logarithm of the product between the reflected intensity and distance [ln ( R ( r ) × r )] vs distance. The slope was extracted from the linear region of the DR intensity profile (detailed information [24]). Using these slopes, we can calculate the reduced scattering coefficient () given the absorption coefficient ( μ a ).…”

Bottom layer absorption coefficients extraction from two-layer phantoms based on crossover point in diffuse reflectance

“…The homogeneous solution was poured into tissue culture plates (with a diameter of 60 mm and a height of 10 mm) and cooled under vacuum conditions (to avoid air bubbles). 15 …”

“…The slope was extracted from the linear region of the intensity profile and described in detail in our previous work. 15 The reduced scattering coefficient ( ) is calculated from Eq. (2) using the slope values and the known absorption coefficient ( ).…”

Noninvasive Nanodiamond Skin Permeation Profiling Using a Phase Analysis Method: Ex Vivo Experiments

“…Figure 6b Another aspect that should be discussed is the characterization of the IMOPE technique as an absorption coefficient sensing technique in comparison with other techniques. In order to compare IMOPE with other methods we measured ink-based phantoms by diffusion reflection (DR) 44 and IMOPE. We compared both results with a spectrophotometer measurement of varying ink concentration.…”