[en] Solar energy sustains ecosystems on earth, therefore solar radiation measurements are the basis for ecological research in forests. Silviculturists in particular should be aware at least of the basic principles of radiation distribution in forest vegetation. There has been a rapid development of methods and devices in the field of solar radiation measurement. In the paper, solar radiation is presented as one of the most important ecological resources and factors. The author demonstrates how significant this knowledge is in silviculture. The main topic is the presentation of recognized methods for solar radiation measurement and estimation in forests. Comparing these different methods we find Photosynthetically Usable Radiation (PUR) sensors to be very appropriate for complex research in forest vegetation. It is advantageous to use multiple PUR sensors connected to a computer for data processing. Another method for estimating radiation which has great potential is the one using hemispherical photography. The same principle is applied in a fixed horizontoscope which is particularly appropriate in silvicultural practice

[en] In order to examine ecological, floristic and structural differences between the forest stands of managed and unmanaged silver fir - Norway spruce forests (Bazzanio trilobatae-Abietetum albae), twelve sample plots (25x25 m) were established in forest reserves and managed forests. Within the plots, subplots and microplots we conducted phytosociological and pedological surveys, analyses of the stand structure, natural regeneration and estimation of solar radiation. We determined that there are no significant differences in floristic composition and ecological factors between managed forest and forest reserve stands. The only variables that were significantly different were the solar radiation variables (ISF; TSF; DSF), vertical structure (cover indexes (CI)) and stand basal area. Small differences in the composition and the structure of the vegetation indicate that, as far as ecosystematic changes are concerned, managing these forests is not as significant as the soil conditions. Solar radiation had a major influence on natural regeneration. Indirect solar radiation seemed to be more important than direct solar radiation. We found a statistically significant positive correlation between silver fir and Norway spruce regeneration and indirect solar radiation and confirmed that the management of light is a significant factor in the management of regeneration. Another trend that was detected was an increase in the number of beech, which will have quite a large proportion in the upper tree layer of the next generation, especially in forest reserves

[en] Natural regeneration of altimontane spruce forests at Jelendol is retarded due to many factors. In autumn 2003, gaps of different size and parts of the surrounding stand were covered with a 5 x 5 grid m to define sampling plots. A total of 227 plots with 1,5 x 1,5 m in size were installed to analyse general regeneration conditions and inhibitors. The following ecological parameters were estimated on each plot: micro relief, inclination, soil depth,ground cover, direct and diffuse solar radiation. Woody regeneration (density, height, height increment) and ground vegetation were recorded at each plot. Considering that N-S and E-W radiation asymmetry was explicit, the distribution of direct and diffuse radiation was divided into four groups among the plots. Spruce regeneration (28.,605 per ha) was mainly found at the edge of the large gap, though total regeneration density and radiation were not correlated. However, in both the stand and the small gaps, the lack of radiation hindered further development. This study showed that light conditions were not the only factors affecting the regeneration success at an altitude of 1,500 m. The presence of woody debris was important, while the influence of the herb layer (predominant species were Festuca altissima All. and Calamagrostis arundinacea (L.) Roth.) and soil depth proved to be negative. The impact of browsing, however, remained the main problem. (author)

[en] Hemispherical photography represents one of the most appropriate methods of estimating averages of solar radiation over extended periods of time. This method is based upon the use of extremely wide-angle fisheye lenses, which produce large projection distortion. To correctly interpret hemispherical photography we have to know the projection characteristics of the fisheye lens in combination with a camera body. This can be achieved through lens calibration. The first part of the article explains in detail the calibration method for fisheye lenses which are used to assess the solar radiation in forest ecology research. In the second part the results of calibration for fisheye lens Sigma 8 mm, f/4 (MF, N) are presented. The lens was used on a Nikon F50 camera body

[en] The know-how in the field of solar radiation distribution in forests is important for basic ecological investigations and silvicultural practice. Three methods of solar radiation assessment based on hemispherical canopy photography are compared in the present article: a hemispherical photography by means of a fish-eye lens, a horizontoscope and the ALI-2000 Plant Canopy Analyzer. Experiences, improved methods and a drawing of a horizontoscope stand which was elaborated at the Chair of Silviculture are presented. Fairly good results with some limitations can be achieved with the improved stable horizontoscope in silvicultural work. Hemispherical photography is appropriate for the assessment of light conditions in all stand types and can thus be used in research work. The method has recently been undergoing intensive development. Digitalization of the entire system will speed up standardization. The ALI-2000 instrument is highly suitable for regeneration research in conditions of abundant plant vegetation, in reach sites and modified stands

[en] This paper presents a synthesis of the results of our original research in the area of laser-material interaction and pulsed laser material processing with a special emphasis on the dynamic aspects of laser beam-surface interaction, which include the links between the laser material removal and the resulting material motion. In view of laser material processing, a laser beam is not only considered as a tool but also as a generator of information about the material transformation. The information is retained and conveyed by different kinds of optically induced mechanical waves. Several generation/detection schemes have been developed to extract this information, especially in the field of non-destructive material evaluation. Blast and acoustic waves, which propagate in the air surrounding the work-piece, have been studied using microphone detection as well as various setups of the laser beam deflection probe. Stress waves propagating through the work-piece have been studied using piezoelectric transducers and laser interferometers.

[en] Full text: The selective laser trabeculoplasty (SLT) is a pulse-laser treatment for the reduction of intraocular pressure in eyes with open angle glaucoma and ocular hypertension. It was introduced by Latina and Park, who demonstrated the possibility of selective targeting of the pigmented trabecular meshwork cells by using a Q-switched frequency-doubled Nd:YAG laser with low fluences. This enables treatment without producing collateral damage to the adjacent non-pigmented eye cells and tissues. Moreover, in comparison with an older technique, called argon laser trabeculoplasty, the SLT method does not cause coagulation of the trabecular tissue. Instead, the selective absorption in melanin stimulates and facilitates draining of aqueous humour. The trabecular meshwork cells contain melanin granules, which absorb visible light. This absorption in the pigment turns the absorbed laser-pulse energy in a local rise of the tissue temperature. In such a way, the fluid is vaporized on the surface of melanin granules and therefore micro-meter (transient intracellular) cavitation bubbles are formed around the laser-irradiated cells containing the pigment. By increasing the laser-pulse energy the radius of these bubbles grows to the dimensions, when they become visible by ophthalmoscopy. The cavitation bubbles induced by selective absorption of the laser pulse represent a kind of microscopic underwater explosions leading to cavitation damage. The cavitation damage is confined to the scale of single cells containing the pigment only when pulse energy is low enough to produce bubbles that are only few micro-meters in size. Consequently, proper setting of the laser energy is essential for ensuring that the target cells are successfully and selectively treated without creating excess damage to the tissue. To ensure this, the operation protocol of SLT is as follows. The spot size is fixed during the entire treatment (typically 400 μm), while laser pulses have wavelength of 532 nm and are shorter than 5 ns. The treatment starts with low energy (typically 0.8 mJ) and it is increased or decreased by an increment of 0.1 mJ until the threshold energy is achieved. The threshold energy is defined as the energy, where the ophthalmologist visually recognizes the formation of cavitation bubbles by ophthalmoscopy. When bubbles are visually detected, the operating surgeon lowers the laser energy just below the threshold for bubbles’ formation. In such a way the ophthalmologist subjectively regulates the laser energy during the operation. Since an automatic method to monitor the bubbles’ formation can make the SLT process more reliable and less time consuming, we have developed an automatic detection of cavitation bubbles formation on the patient’s eye. In this contribution we will present ex-vivo and in-vivo experiments, the optical system for image acquisition and the solution for image processing that enable us to develop the automatic adjustment of the laser-pulse energy during the treatment. This allows the execution of the procedure closer to the threshold for the cavitation bubble’s formation, thereby making the entire procedure more reproducible and effective. (author)