Type of research: basic Duration from: 10/07/91. to 10/07/94. Papers on project (total): 17
Papers on project quoted in Current Contents: 2
Institution name: Centar LAIR, Institut "R. Bošković", Zagreb (1032) Department/Institute: Rudjer Boskovic Institute Center of Laser and Atomic R&D Address: Bijenička c. 54 City: 10000 - Zagreb, Croatia
Communication
E-mail: zorc@olimp.irb.hr
E-mail: skala@olimp.irb.hr
E-mail: dsoldo@olimp.irb.hr
Phone: 385 (0)1 424869, 272759
Fax: 385 (0)1 424869
Summary: Research of the optical bistability in thin films
multilayers has been performed. Optical modelling using a personnal
computer has been done. Such systems has been realised in form of thin
films in a resonant cavity. The bistability parameters have been
determined. The analysis of multilayers containing a simple and compound
resonant cavity has been done. It has been shown that multilayers
containing a compound resonant cavity have lower bistability treshold.
Moreover, varying materials and their thicknesses in the resonant cavity,
it is possible to tune bistable properties! Laser pulse interaction with
the metal surface (Pb and Sn) has been performed. Laser induced metal
plasma spectra in the region 400-700 nm have been taken. Laser pulse of
10MW per square centimeter induced excited and single ionized atoms. Due
the equipment insufficience, research of this phenomena has been stopped.
The two-component model of particle size distribution has been improved
and applied to olygotrophic water. Introduction of this model induced
significant improvements comparing to the use of the classical models. The
results show much better forward scattering predictions, when applying the
two-component model of scattering function. First results of the nonlinear
optical behaviour of C60 molecules stimulated the work in this field. So
C60 and higher fullerenes were synthesized and characterized. Using the
mass spectrometry it has been shown that a UV laser pulse is responsible
for the di- and trimerisation of C60 molecules. Possibilities of
caries healing by using a CO2 laser have been studied. A continous CO2
laser with the CW power 1-2W has been used. The temperature increase in
the tooth root during the laser exposition has been measured, and the
damage treshold has been estimated.
Research goals: There were orriginally three goals in the research
of the nonlinear laser pulse interaction; optical bistability, physics of
the laser induced plasma and interaction of a laser pulse with the
scattering medium (like turbid water or biological tissue). Optical
bistability has been studied on the optical multilayers with a simple and
compound resonant cavity. Possibilities of the bistability treshold
decrease have been studied. It had been expected that a compound resonant
cavity offers a lower bistability treshold. Bistable optical component was
orriginally also in function of reshaping of NdYAG laser pulse, as an
active optical component instead of passive laser mirror. A NdYAG
laser pulse has been used in the research of the metal plasma diagnostics
of the laser ablated atoms. A complete plasma diagnostic has been expected
to be done. Only a qualitative plasma composition diagnostic has been
realized. This research has been stopped due the insufficiency of the
diagnostic equipment. The laser pulse transmission in olygotrophic
water and in the biological tissue has been studied. The two-component
model of particle size distribution has been improved. A two-component
model of the scattering function has been developed. The model has been
applied to the laser beam transmission in water. The research of the CO2
laser transmission in a tooth resulted by the determination of the
biological laser damage treshold. The laser powers beyond this treshold
introduces the damage of the tooth tissue. The interesting early
results in the nonlinear behaviour of the C60 molecule triggered the
research in the fullerene physics.The synthesis of C60 and higher
fullerenes has been done. A complete characterization of C60 and higher
fullerenes has been done to confirm a succsessfull synthesis. It has been
shown that a UV NdYAG laser pulse introduces the di- and- trimerization
of C60 molecules.
COOPERATION - INSTITUTIONS
Name of institution
: Stomatološki fakultet, odjel dentalne
patologije Type of institution: Economical/Production City: 10000 - Zagreb, Croatia Other information about the project.