A New Method For Optical Spectroscopy
Radio engineering
Abstract
New possibilities of contactless optical spectroscopy for the purpose of remote identification and quantitative analysis of substances in the optically transparent environment are studied. The detection and assessment of hazardous substances is one of the important aspects of this study. The development of a primary sensor, allowing to provide a spectral analysis of electromagnetic waves emitted from the object is of utmost importance today. Currently, such spectral distribution of electromagnetic radiation is obtained, using light filters, prisms with high precision mechanical devices and diffraction grids. The spectrophotometric systems using the listed methods and available in the market are limited in the flexibility of adding new features. They require additional devices and modifications of external computer software. These factors are making them expensive and limit their usage in various fields. A new model of portable photosensor based on double-barrier, vertically placed silicon structure has been developed. It offers capabilities of high accuracy spectral analysis. Different penetration depths of individual waves of radiation provide different degrees of photoconductivity and allow to carry out the selection of individual waves with the help of the developed algorithm. By changing the voltage applied to the photosensor, it makes it possible to register a separate absorbed wavelength and its intensity, thus obtaining information on spectral distribution of intensities of waves. The model has been tested on the experimental samples of Ag-p-Si-n-Si. The intensity distribution spectrum of red LED and the green laser have been received using the quantitative data of light’s current-voltage characteristics. Small dark currents (several dozens of pA) allow to register signals of low intensity. The results of this research open up new possibilities in the sphere of portable semiconductor spectrophotometers. It is possible to create a new type able to solve photocurrent analysis problems, be easily integrated in general and multipurpose systems such as monitoring of food, water, drugs, etc, solve security issues.
