Lukasz Gryko

The concept of the set to objectification of LLLT exposure

In this article authors present the developed optoelectronic set for controlled, repeatable exposure by electromagnetic radiation of biological structures in the spectral band of tissue transmission window 600-1000 nm. The set allows for an objective selection and control of exposure parameters and comparison of results for variable energetic, spectral and polarization parameters of radiation beam. Possibility of objective diagnostics of tissue state during laser treatment was provided in the presented optoelectronic set.

Digital controlling system to the set of high power LEDs

In the paper is described the concept and architecture of the multi-channel control system for set of high-power LEDs. The broadband source of radiation for prototype illuminator is dedicated to the investigation of Low Level Laser Therapy procedures. The general scheme of the system, detailed schemes, control algorithm and its implementation description in FPGA structure is presented. The temperature conditions and the opportunity to work with a microcomputer are characterized.

Optoelectronic set for measuring the absorption spectrum of the thin biological media

In the paper the authors present the developed optoelectronic system for controlled, repetitive exposure by electromagnetic radiation of biological structures in the Low Level Laser (LED) Therapy procedures. The set allows for objective selection and control of the irradiation parameters by light from spectral range of the tissues transmission window. Measurements of optical parameters of thin biological medium – spectral absorption coefficient and the amount of absorbed energy – can be implemented in the measuring chamber during irradiation treatment. The radiation source is the broadband illuminator consists of set of selected high power LEDs. The maximum optical power of single source is from 80 mW to 800 mW. Illuminator is controlled and powered by the multi-channel prototype control system, which allows independently control a current of each emitter. This control allows shaping spectral emission characteristic of broadband source in range 600-1000 nm. Illuminator allows providing in the working area of 700 cm2 a uniform distribution of optical power density, of 10 mW/cm2 for maximum. Set ensure uniform distribution of the spectral power density of up to 40 mW/nm.

Colorimetric characterization of the tunable LED-based light source at the output of the homogenizing rod

The best method to obtain uniform spectral characteristic for multi-emitter sources is to use integrating sphere as mixing element. In each point of exit window of such sphere the luminance and spectral characteristic are uniform. However price of integrating spheres are disadvantageous and the output power decreases dramatically with the increase their diameters. For this reason sometimes homogenizing rods are used when LEDs are used. In the paper we present the results of colorimetric characterization of low cost homogenizing rectangular-shaped rod applied in the tunable LEDbased source for endoscopic system. For each correlated color temperature (CCT) value we investigated changes of spectral power distribution (SPD) on the output surface of the homogenizing rod and variation of CCT while increasing the distance from the output of the rod. Results of these measurements enable efficient lighting of the working area and proper placement of optical fibers used to guide light to difficult-access objects.

Tunable white light source for medical applications

Development of light-emitting diodes has brought new possibilities in many applications, especially in terms of flexible adjustment of light spectra. This feature is very useful in construction of many devices, for example for medical diagnosis and treatment. It was proved, that in some cases LEDs can easily replace lasers during therapy of cancer without reduction of efficiency of this process. On the other hand during diagnosis process LED-based constructions can provide unique ability to adjust the color temperature of the output light while maintaining high color rendering. It allows for optimum surface contrast and enhanced tissue differentiation at the operator site. In the paper we describe the construction of the tunable LED-based source designed for application in endoscopy. It was optimized from the point of view of the color rendition for 5 different correlated color temperatures (illuminant A, D55, D65, 3500K and 4500K) with the restriction of very high (>90) values of general and specific color rendering indexes (according to Ra method). The source is composed of 13 light-emitting diodes from visible region mounted on the common radiator and controlled by dedicated system. Spectra of the components are mixed and the spectra of output light is analyzed. On the basis of obtained spectra colorimetric parameters are calculated and compared with the results of theoretical analysis.

Influence of the spectral composition of LED lighting system on plants cultivation in a darkroom

Agriculture is one of the most important areas of the world economy. However, due to dependency on weather conditions, it is strongly industrialized, for example by introducing additional lighting improving the efficiency of plants growth. Construction and operation of light-emitting diodes provides new possibilities in research and application of new concepts in agricultural lighting. The aim of the work was to investigate the effect of various spectra of light on the efficiency of photosynthesis and the growth of selected species of plants. For this purpose two grow-boxes with dedicated LED-based lighting systems were constructed and placed in the darkroom with controlled temperature. In each box lighting system provided different spectral composition of light and it was possible to adjust the ratio of blue and red as well as the irradiance level. In the paper we present the construction of the grow-boxes and the results of 3 cycles of experiments conducted with this system. During the first cycle two groups of tested plants were cultivated in the LED grow-boxes with constant irradiance level and the third group in natural light conditions. During the second cycle the irradiance in both boxes was gradually increased from 8 W/m2 to 38 W/m2. During the third cycle the irradiance was set to 38 W/m2 during the whole period (max power MRED module) to get the maximum possible intensity of photosynthesis.

Semiconductor lasers vs LEDs in diagnostic and therapeutic medicine

Semiconductor emitters are used in many areas of medicine, allowing for new methods of diagnosis, treatment and effective prevention of many diseases. The article presents selected areas of application of semiconductor sources in UVVIS- NIR range, where in recent years competition in semiconductor lasers and LEDs applications has been observed. Examples of applications of analyzed sources are indicated for LLLT, PDT and optical diagnostics using the procedure of color contrast. Selected results of LLLT research of the authors are presented that were obtained by means of the developed optoelectronic system for objectified irradiation and studies on the impact of low-energy laser and LED on lines of endothelial cells of umbilical vein. Usefulness of the spectrally tunable LED lighting system for diagnostic purposes is also demonstrated, also as an illuminator for surface applications - in procedure of variable color contrast of the illuminated object.

Color mixing in LED illuminating system for endoscopic purposes

Endoscope equipment is used in many applications. One of them is medical diagnostics. The illuminator is an important part of the endoscope, as it enables the performance of the observed object. The quality of light is particularly important if the assessed essential feature is the colour of an object or its distribution on the surface of the object. For this reason, special attention should be paid to the quality of the illuminator in terms of colour rendering, as well as adapting it to the intended diagnostic procedure. The use of light emitting diodes allows shaping flexibly the spectral characteristics which is an innovative solution in case of endoscope equipment. In the paper the idea of the endoscope illuminator construction, based on 13 LEDs, that allows adjusting the correlated colour temperature is presented. The essential part of the paper is the issue of quality of colour mixing. Results of exemplary simulations are presented and compared with the measurement results of performed mixing elements. They are evaluated from the point of view of obtained superficial uniformity of colour mixing on the output of the element.

Optoelectronic set for measuring reflectance spectrum of living human skin

In the paper the authors present the developed optoelectronic set for measuring spectral reflectance of living human skin. The basic elements of the set are: the illuminator consists of the LED illuminator emitting a uniform distribution of spectral irradiance in the exposed field, the semispherical measuring chamber and the spectrometer which measures spectrum of reflected radiation. Measured radiation is from spectral range of tissue optical window (from 600 nm to 1000 nm). Knowledge about the reflectance spectrum of the patient skin allows adjusting spectral and energetic parameters of the radiation used in biostimulation treatment. The developed set also enables the repeatable exposures of patients in the Low Level Laser Therapy procedures.

Therapeutic and diagnostic set for irradiation the cell lines in low level laser therapy

In the paper is presented optoelectronic diagnostic set for standardization the biostimulation procedures performed on cell lines. The basic functional components of the therapeutic set are two digitally controlled illuminators. They are composed of the sets of semiconductor emitters – medium power laser diodes and high power LEDs emitting radiation in wide spectral range from 600 nm to 1000 nm. Emitters are coupled with applicator by fibre optic and optical systems that provides uniform irradiation of vessel with cell culture samples. Integrated spectrometer and optical power meter allow to control the energy and spectral parameters of electromagnetic radiation during the Low Level Light Therapy procedure. Dedicated power supplies and digital controlling system allow independent power of each emitter . It was developed active temperature stabilization system to thermal adjust spectral line of emitted radiation to more efficient association with absorption spectra of biological acceptors. Using the set to controlled irradiation and allowing to measure absorption spectrum of biological medium it is possible to carry out objective assessment the impact of the exposure parameters on the state cells subjected to Low Level Light Therapy. That procedure allows comparing the biological response of cell lines after irradiation with radiation of variable spectral and energetic parameters. Researches were carried out on vascular endothelial cell lines. Cells proliferations after irradiation of LEDs: 645 nm, 680 nm, 740 nm, 780 nm, 830 nm, 870 nm, 890 nm, 970 nm and lasers 650 nm and 830 nm were examined.