Nowadays the technique of analog contact potential difference probes well developed. Due to the influence of various parasitic factors, analog probes has substantial errors. The integration time for automatic CPD compensation should be at least several seconds to achieve high accuracy measurements. The speed and the accuracy are essential, for example, for Scanning Kelvin Probes. The purpose of this paper is to develop a digital contact potential difference probe, with a higher accuracy and speed of measurements as compared to analog probe. The digital probe made on base of 32-bit microprocessor with a Cortex M4 core. Measuring cycle consists of at least two successive determinations of the output signal amplitude at different compensation voltage generated by the microcontroller. It allows synchronizing of the generated oscillations and reading of the measuring signals. Data arrays processed in real time of the Digital Signal Processing by microprocessor. In this case is possible computation of the root mean square value or determination of the desired spectral line of the signal after fast Fourier transformation. Both methods permit eliminate of random noise and spurious harmonics. The method provides the digital contact potential difference probe operation in large signal mode and with a large signal/noise ratio. This eliminates the error associated with the zero signal finding. Also the integration time for automatic CPD compensation of the measured value is not necessary, which significantly reduces the measurement time and eliminates errors of compensation and DAC. In addition, the microcontroller could control the movement of the probe during scanning and transfer data to the host computer on interface USB, etc.

Modern measuring transducers for optical diagnostic system should perform automatic parameter estimation of optical signal and automatic switching between different energetic and optical sensitivity ranges. Traditional solution of this problem lies in the field of multi-sensory systems, complex optical schemes and complex signal processing algorithms. The paper aims at the development of new measuring transducers for optical diagnostic system on a basis of multifunctional unitary photovoltaic converters built on semiconductors with low-concentration deep dopants that form multiple energy levels for different charge states in the band gap. Relative complexity of physical processes accompanying the recharge of several energy levels of multiply-charged deep dopant makes it possible to realize the multifunctionality of a photoelectric converter albeit simple sensor design.The proposed unitary photovoltaic converters proved to have extended functional characteristics and increased ranges of energetic characteristic (by dozens dB) and spectral sensitivity characteristic with possible shifts of red margin by 2 to 4 μm in the spectral sensitivity range of 1–10 μm. Energetic and spectral sensitivity characteristic ranges could be switched either by measurement signal itself or by additional control inputs. Possible materials for resistive or barrier photovoltaic converter structure are Germanium, Silicon, А3В5 systems and other semiconductors including that compatible with «non-silicon» technologies and structures on sapphire substrate.

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One of the ways to solve multiple problems of optical diagnostics is to use photovoltaic converters based on semiconductors with intrinsic photoconductivity slightly doped with deep impurities which form several energy levels with different charge states within the semiconductor′s bandgap. Peculiarities of physical processes of recharging these levels make it possible to construct photodetectors with different functionality based on a range of simple device structures.The aim of this work is to analyze peculiarities of conversion characteristics of single-element photovoltaic converters based on semiconductors with intrinsic photoconductivity, to systematize their properties and to represent structures of photovoltaic convertors as a device structures suitable for implementation in measurement transducers of optical diagnostics systems.Based on the analysis of the characteristics of the conversion characteristics of single-element photovoltaic converters based on semiconductors with intrinsic photoconductivity and the requirements for their design, a dash series of photovoltaic converters was developed for use in the measuring transducers of optical diagnostics systems. The possibility of constructing functional measuring transducers for multiparameter measurements of optical signals is shown.