A laboratory demonstrator of the optoelectronic sensor employing cavity enhanced spectroscopy has been designed to detect the trace amounts of carbon monoxide. High sensitivity of this sensor is provided by the use of optical cavity consisted of dielectric mirrors with extremely high reflectance. The instrument concept was taking into consideration the latest achievement of optoelectronic technology as a part of the ‘EDEN’ project, funded by the Polish National Centre for Research and Development. Preliminary tests using the sensor concept have shown that detection of carbon monoxide is possible using the developed devices. In this configuration, the sensor is characterized by high linear sensitivity in the concentration range of 10 ppb to 2.5 ppm.
The aim of this paper is to address some of the aspects of thermal management of QCLs. Results include electrical and spectral characterization of the devices. Results show shift of QCL emission mode towards lower wavenumbers during the pulse. Characteristics were registered at different temperatures of operation and driving conditions. Registered shift rates depend on operating temperature, being the highest at room temperature. Based on spectral tuning results, temperature increase rates for different modes of operations were evaluated, delivering information on thermal dynamics of investigated devices.
The article describes an application of cavity enhanced absorption spectroscopy for nitric oxide and nitrous oxide
detection. Both oxides are important greenhouse gases that are of large influence on environment, living organisms and
human health. These compounds are also biomarkers of some human diseases. They determine the level of acid rain, and
can be used for characterization of specific explosive materials. Therefore the sensitive detectors of these gases are of
great importance for many applications: from routine air monitoring in industrial and intensive traffic areas, to detection
of explosives in airports, finally for medicine investigation, for health care, etc.
Our compact detection system provides opportunity for simultaneous measure of both NO and N2O concentration at ppb
level. Its sensitivity is comparable with sensitivities of instruments based on other methods, e.g. gas chromatography or
The paper presents a model of a free space optical transmitter operating in the wavelength range of 8-12 μm. In the
transmitter, a quantum cascade laser controlled by a special driver was applied. The driver provides the control of the
energy, repetition rate and duration of radiation pulses. In the described transmitter, generation of pulses with high duty
cycle is also provided, making it possible to use the data link with either RZ or NRZ coding. In the frame of the study,
the impact of laser working conditions on the data link operation was determined.
The paper presents an application of an optical parametric generator (OPG) for cavity enhanced absorption spectroscopy
(CEAS) technique to nitric oxide (NO) detection. The principle of this method is based on an injection of a radiation
beam into an optical cavity at a very small angle. The radiation is multiple reflected inside the resonator equipped with
spherical and high reflectance mirrors. After each reflection a part of the radiation leaves the optical cavity due to
residual transmission of mirrors. In the case of NO detection the laser emitting at around 5.26 μm was applied. During
investigation of CEAS system with OPG, two-lenses collimator was required to improve OPG beam divergence. The Ge
and ZnSe lenses were used. Thanks to this decrease of about three times in beam diameter was achieved (at the distance
of 1 m from source). It make it possible to measure output signal from the CEAS optical cavity.
The paper presents construction of broadband optical system devoted to free space optical communication using long
wavelength quantum cascade laser and a heterostructural thermally cooled HgCdTe photodetector. This system should
characterize with lower sensitivity to adverse meteorological conditions when compared with the systems operating
in near IR.
We present the study of potential application of Cavity Enhanced Absorption Spectroscopy (CEAS) for
construction of fully optoelectronic and portable NO2 detector which could replace the commonly used chemical
detectors. We demonstrate an experiment on detection of NO2 in the ambient air. The concentration of investigated
absorber was found by determination of decay time of pulse radiation trapped in the optical cavity constructed with two
mirrors of a very high reflectivity coefficient (R > 99,99%). As a light source a blue pulsed diode laser was applied. The
output signal was detected by a photomultiplier and analysed by a digital oscilloscope. For this construction the detection
limit better than 1 ppb was obtained. The cavity parameters and it's adjustment were controlled by a beam from a red
laser that is not absorbed by NO2. In order to perform the measurements in two spectral regions the special mirrors have
been developed. Study of influence of another NOx compounds (especially NO3) on final result was investigated as well.
The paper presents a detection method of laser radiation using photoacoustic converter. Mathematical-physical model of
the converter and its numerical analysis is described. Influence of selected design factors and operation conditions
on a level of a voltage signal produced at a converter output was analysed. The results of theoretical investigations have
been confirmed by the experimental ones.
Characteristics of a quality system accredited in optoelectronic testing laboratory are presented. The scope of accreditation is shown and all measurement procedures are listed. Performing with measuring equipment and basic measurement instruments are given. Some details of calibration laboratory and main characteristics of two standards of Joule and Watt of laser radiation are also presented.
The meter of average energy of holmium laser radiation is a digital measuring instrument, made on the basis of a pyroelectric detector and single-system microprocessor from the MCS- 51 family. This device enables a measurement of a defined number of light pulses, total energy of n-laser pulses as well as the number of pulses received by a detector. The frequency of sampling signal is 25 Hz, the accuracy of measurement is 5%. This meter also enables introducing the defined transmission coefficient (measurement at the back mirror of the laser resonator) to the measurement results as well as control of operation of the output diaphragm of the laser (TTL levels).
The paper presents a description of a construction of the ophthalmological set LH-58 with the holmium laser. Results of preliminary medical tests of eye lens curvature correction carried out by means of this set are given.