Photometric Absorbance Spectrum Analyzer of Slightly Transparent Biomaterials

Abstract

Introduction. The measurement of optical radiation, especially the intensity of the light flux passing through biological tissues or other slightly transparent (cloudy) materials and the environments is a challenging problem due to the extensive development of new light sources of different wavelengths and their use in various fields of human activity. It is important to provide high sensitivity and accuracy measurement of the output parameters of light fluxes passing through the studied material - the depth of penetration, attenuation coefficient or absorption. The known methods and devices do not provide the required sensitivity and accuracy of measuring parameters.
Main body. The aim of this study is to develop a photometric spectrum analyzer where along with the simplification of the scheme and increasing sensitivity and measurement accuracy the score of penetration depth of light flux into biological or other slightly transparent material, the determination of the attenuation coefficient and the spectrogram construction based on the analysis of two signals separated by wavelength light sources is ensured. One of the ways to increase the sensitivity and accuracy of the measurement devices is to use modulating method of the output signals transformation. Implementation of this method provides a significant reduction of the proper noises of the transformation signal path. Figure 1 shows a functional diagram of the developed by the authors device based on modulating transformation of the optical signal. It provides the measurement of the slightly transparent materials absorbance with increasing sensitivity and accuracy.
Conclusions. Considered possibilities greatly simplify the measurement process. The use of the modulating transformation of the light flux provides increase in sensitivity in the measurement accuracy because such transformation compensates the intrinsic noise level and noise of the measurement channel. The semiconductor matrix is used as the light source. It provides accommodation of two crystals at one point of light diodes with the most spaced wavelengths allowing them to be placed on the same axis with photocell and excludes collateral scattering of the light flux.