We report the functionalization of Si/SiO2 Quantum Dots (QDs) synthesised by laser ablation. Our interest has been to
increase the affinity of the QDs surface for organic substances, in order to obtain QD-immunoglobulin conjugates,
particularly for biolabeling. We have studied the UV-induced graft polymerization of the freestanding nanoparticles.
High resolution transmission electron microscopy and laser granulometry, were used to obtain information on particle
and cluster size distribution, degree of agglomeration, etc. The polymer-dot complexes appeared as relatively well-defined
clusters, QDs being surrounded by a polymer layer with thickness 3-10 nm. The size of the primary clusters was
in the range 60-500 nm. The polymerization and filtration process (0.1 μm pores) involved a diminution of the clusters
size in the range of 18-65 nm, and moreover, by a subsequent dialyses process the cluster size decreased to 5-15 nm.
We report preliminary measurements on the catastrophic damage threshold and also on the maximum fluence/irradiance
for non-damage of a 355 nm high reflectance mirror, by using a new optical arrangement. Our goal was two-fold: to
determine the ability of a new, variable spot size (zoom) optical system (named VariSpot®) to be used in laser-induced
damage measurements, and also to characterize the damage properties of the mirror under test. The classical
measurement scheme maintains a constant spot size on the target by using a fixed-focus optical system, and the laser
fluence/irradiance on the target is varied by appropriately attenuating the laser beam before the focusing optics. In
contrast, our scheme maintains constant the energy/power of the incoming beam before the focusing optics and uses a
zoom-type optical system to continuously change the spot size and correspondingly the fluence/irradiance on the target,
while keeping constant the working distance (from optics to target). A 355 nm beam representing the third harmonic of
an electro-optically Q-switched, unstable cavity Nd:YAG laser was used as incoming beam. Its spatial diagnostics was
done by using a CMOS-type beam profiler and following the definitions and recommendations of the ISO 11146
standard. The VariSpot optical system represents a prototype with a working distance of approximately 100 mm and
delivering a round and adjustable spot size with diameters from 0.085 mm to 4.3 mm at that distance for the specific 355
nm incoming laser beam. The results show the advantages of using the VariSpot system for such type of measurements
and also reveal reasonable good damage properties of the tested mirror. We briefly discuss the major sources of errors in
the obtained results and also suggest several ways to improve the future measurements using similar arrangements.