The paper presents a new construction of an optical pulse amplitude monitoring unit (PAMU) used in a transceiver of Free Space Optics. It consists of a buffer, constant fraction discriminator (CFD), delay line, and a sample and hold (S&H) circuit. In the design FSO system, the PAMU provides to monitor transmitted and received optical pulses with duration of few ns. Using this device, there is no need to apply complicated and expensive digitizing systems. The unique aspect of its construction is to control S&H circuit using the CFD. The lab model of this unit allows to perform tests to define some virtues of constant fraction and leading-edge discriminators. The results were implemented in optical signal monitoring of FSO system. The unit was prepared to cooperate with two different detection modules. Using this setup, it was possible, e.g. to determine operation characteristics of FSO transmitter, identify interruption of transmission, and control light power to provide high safety of work.
The paper presents verification of a peak detection method cooperating with infrared radiation detector module applications. The work has been divided into parts including SPICE simulations and presentation of results obtained with the constructed prototype. The design of the peak detector dedicated to applications with very short pulses requires a different approach than that for standard solutions. It is mainly caused due to the ratio of pulse width and time period. In the described application this ratio is less than 10%. The paper shows testing of an analogue circuit which is capable to be inserted in these applications.
Optoelectronic technology plays an important role in medical diagnosis. In the paper a review of some optoelectronic sensors for invasive and non-invasive human health test is presented. The main attention is paid on their basic operation principle and medical usefulness. The paper presents also own research related to developing of tools for human breath analysis. Breath sample unit and three gaseous biomarkers analyzer employing laser absorption spectroscopy designed for clinical diagnostics were described. The analyzer is equipped with sensors for CO, CH4 and NO detection. The sensors operate using multi-pass spectroscopy with wavelength modulation method (MUPASS-WMS) and cavity enhanced spectroscopy (CEAS).
The article presents state of work in technology of free-space optical communications (Free Space Optics − FSO). Both commercially available optical data links and their further development are described. The main elements and operation limiting factors of FSO systems have been identified. Additionally, analyses of FSO/RF hybrid systems application are included. The main aspects of LasBITer project related to such hybrid technology for security and defence applications are presented.
Biocompatible coatings produced on the basis of the chemically extracted natural hydroxyapatite (HAp) from the animal bones were deposited using multiplex method comprising glow discharge nitriding (GDN) of the titanium alloy substrate and pulsed laser deposition (PLD) of HAp on the formerly fabricated titanium nitride layer (TiN). The TiN interlayer plays an important role improving adhesion of HAp to substrate and preserves the direct contact of the tissue with metallic substrate in the case of possible cracking of HAp coating. Surface morphology of deposited layers, crystallographic texture and residual stress were studied in relation to the type of laser applied to ablation (Nd:YAG or ArF excimer), laser repetition, temperature of substrate and atmosphere in the reactive chamber.
The paper describes an integrated laser absorption system as a potential tool for breath analysis for clinical diagnostics, online therapy monitoring and metabolic disorder control. The sensors operate basing on cavity enhanced spectroscopy and multi-pass spectroscopy supported by wavelength modulation spectroscopy. The aspects concerning selection of operational spectral range and minimization of interference are also discussed. Tests results of the constructed devices collected with reference samples of biomarkers are also presented. The obtained data provide an opportunity to analyse applicability of optoelectronic sensors in medical screening.
Sensing technology has been developed for detection of gases in some environmental, industrial, medical, and scientific applications. The main tasks of these works is to enhance performance of gas sensors taking into account their different applicability and scenarios of operation. This paper presents the descriptions, comparison and recent progress in some existing gas sensing technologies. Detailed introduction to optical sensing methods is presented. In a general way, other kinds of various sensors, such as catalytic, thermal conductivity, electrochemical, semiconductor and surface acoustic wave ones, are also presented. Furthermore, this paper focuses on performance of the optical method in detecting biomarkers in the exhaled air. There are discussed some examination results of the constructed devices. The devices operated on the basis of enhanced cavity and wavelength modulation spectroscopies. The experimental data used for analyzing applicability of these different sensing technologies in medical screening. Several suggestions related to future development are also discussed.
The paper is a review of analog and digital electronics dedicated to monitor nanosecond pulses. Choosing the optimal peak detector construction depends on many factors for example precision, complexity, or costs. The work shows some virtues and limitations of selected peak detection methods, for example standard peak detector with rectifier, sample and hold circuit with triggering units and ADC fast acquisition. However, the main attention is paid to problems of results from effective triggering signal for sample and hold operation. The obtained results allow for designing a peak detector construction as an alternative for costly and very complex fast acquisition systems based on ADC and FPGA technologies.
This paper presents some construction analysis and test results of a Free Space Optics system operating at the wavelength of 9.35 μm. In the system, a quantum cascade laser and a photoreceiver with mercury cadmium telluride photodetectors were used. The main parameters of these elements were discussed taking into account a data link operation. It also provides to determine a data range for various weather conditions related to scattering and scintillation. The results of numerical analyses defined the properties of currently available FSO technologies working in the near infrared or in the short infrared range of spectrum versus the performances of the developed system. The operation of this system was verified in three different test environments. The obtained results may also contain important issues related to the practical application of any FSO system.