simple icon representing a spectrum

Previous work:

I started my career in 1980. by doing research on CO2 lasers. Later on I did some reserch on Nd:YAG and near IC semiconductor lasers.

 


small picture of a first medical ultrasonic device

For a while I investigated imaging capabilities of medical ultrasound devices, which just started to appear. I got M.Sc. in science for this work. Notice how clumsy and big do those first devices look, compared to modern carriable units with much better performance.


small picture of a spectrograph

After several years I slowly moved to designing CCD-based spectrographs, then a big novelty. The group in which I participated built the first CCD-based spectrograph in this part of Europe. With its capability to take 700 spectra per second in visible to near-IC region, it provided us with some nice resutls. We were able to monitor the burning of pyrotechnical mictures, swiching-on of light bulbs, etc.

 


lab illuminated by a ruby laser light pulse

In 1998. I moved to another research group, and focused more on spectroscopy, especcialy on problems of spectroscopy of laser produced transient plasmas. This is area in which I a few years later made my Ph.D. On the picture you can see the experiment setup illuminated by the deep red light scattered from a 20 ns ruby laser light pulse used to produce plasma inside the experimental chamber.

 


detail of a complex VUV camera

Investigations of laser-produced plasmas requires a lot of very fast XUV imaging and spectroscopy. Thus, a part of my time was devoted to construction and improvements of XUV cameras and spectrographs. Most of this work was done together with my german collegues during my first stay as AvH fellow at Ruhr-University in Bochum (1997.-1998.). On the picture is a detail of a complex VUV camera capable of only 5 ns short exposures that was developped by my german collegues and me.

 


electron microscope picture of deposited debree

For a while I studied possibilities to use laser-produced plasmas for depositing thin films. The main obstacle was (and still is) a lot of droplets in such a deposition process. I managed to reduce their number considerably by using plasmas generated by laser ablation of inner capillary wall. The capilary itself was simply bored through the ablation target. The posibilites of lasers at my disposal were soon inadequate for such an research, so I swiched to other topics. On the left picture is thin film deposited by a usual laser deposition process, at the right film with much lower debree contamination deposited from plasma obtained by laser ablation of a capillary.

 


VUV image of two plasma clouds in collision

Laser-produced capillary plasmas are of considerable interest in the field of X-ray lasers. X-ray lasing can be obtained by colliding two plasmas of appropriate composition and temperature, and one way to produce such plasmas is the laser ablation of solid targets. I tried to generate the required plasmas by simultaneously ablating the wall of a capillary to get the cold plasma, and a solid target placed at some distance behind the capillary to get the hot plasma. Such a geometry has a few advantages: it is simple, only one laser beam is required, and both plasmas collide automatically behind the capillary. But again, the lasers at hand were not powerfull enough for this task, so after showing that required plasmas are produced and coliided as expected, I had to move to another field again without being able to show the lasing in the collision zone. ON the VUV picture above, the collision zone is the brightest object in the midle, and colliding plasmas itself are tvo weak clouds on the left and right side of it.

 


a picture of capillary discharge device!

I did a lot of research on ablative capillary discharges through PVC capillaries and their spectroscopic diagnostics applying time-resolved imaging and spectroscopy in XUV spectral region. I also did some numerical analysis of experimental spectra and line profiles related to my experimental work.


a sketch of capillary discharge principle!

A capillary discharge consists of a capillary placed between two electrodes. The electrodes are connected to low-inductance capacitors charged to high voltage. The discharge is triggered by a HV pulse put onto the trigger electrode. In ablative capillary discharge the capillary is in vacuum so discharge starts as a sliding spark on the capillary wall. High current densities lead to fast evaporation of surface material and plasma formation.


a spectrum of PVC capillary discharge!

Capillaries made of PVC with additives based on tin can produce a very strong EUV band arround 13.5 nm which is of considerable interest for possible applications. Integrated intensity (13-14 nm) of this band is very large 10-50 times larger that concurent sources, red on the graph) and accounts for about 90% of the total EUV output. Other sources like gass-filled capillary discharge produce much less radiation and have a lot radiation outside the spectral band of interest. Laser produced plasmas (LPP) are brighter, but also almoust "white".


a sketch of an all-sky camera!

From time to time a small part of my time was devoted to optical design of astronomical and spectroscopic instruments. Among them are all-sky cameras which are used in meteor astronomy and wide-field correctors for astronomical telescopes which are needed to couple modern CCD cameras with them. The results of this work are exploited at Visnjan Astronomical Observatory which is currently among world top-ten of observatories according to number of discovered asteroids. From time to time I also did some VLF radio observations of naturall VLF activity and its relation to bright meteors.

 


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Last Revised: 23.10.2008.