A problem in terms of the accuracy of noninvasive measurement of blood glucose with near-infrared（NIR） spectroscopy is mainly caused by the weak glucose signal and strong background variations.We report the existence of the radial reference point in a floating-reference method,which is supposed to solve this problem.Based on the analysis of the infinite diffusion theory,the local condition of the reference point is deduced theoretically.Then the experiments using the intralipid solutions are constructed to testify the existence of the reference point.In order to further validate our results,Monte Carlo simulations are performed to calculate the diffused light distribution according to the variation of the glucose concentration in the intralipid solutions.All the reference points existing in three-layer skin model are also listed at the wavelength of 1200-1700 nm.
Tissue optical clearing by use of optical clearing agents(OCAs)has been proven to have potential to reduce the highly scattering effect of biological tissues in optical techniques.However,the difference in tissue samples could lead to unreliable results,making it difficult to quantitatively control the dose of OCAs during the course of tissue optical clearing.In this work,in order to study the effects of optical clearing,we customized tissue-like phantoms with optical properties of some biological tissue.Diffuse reflectance and total transmittance of tissue-like phantoms with different OCAs(DMSO or glycerol)and porcine skin tissues were measured.Then optical property parameters were calculated by inverse adding-doubling(IAD)algorithm.Results showed that OCAs could lead to a reduction in scattering of tissue-like phantoms as it did to porcine skin tissue in vitro.Furthermore,a series of relational expressions could be fit to quantitatively describe the relationship between the doses of OCAs and the reduction of scattering effects.Therefore,proper tissue-like phantom could facilitate optical clearing to be used in quantitative control of tissue optical properties,and further promote the application potential of optical clearing to light-based noninvasive diagnostic and therapeutic techniques.
