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<div><strong style="text-align:justify;font-family:'times new
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style="font-size:14pt;font-family:'century gothic' ,
sans-serif;color:#993300" lang="EN-GB">utorak, 16.
svibnja 2023., u 11:00 sati</span></b></strong><br>
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<div style="text-indent:0px;background-color:rgb( 255
, 255 , 255 );text-align:justify"><font face="Times
New Roman, serif" color="#55913c"><span
style="font-size:21.3333px"><b>Holography and
coherent optics</b></span></font><span
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serif;font-size:21.3333px"> </span></div>
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style="font-size:14pt;font-family:'century
gothic' , sans-serif" lang="EN-GB">Dr.
sc. </span></b></b></span></span><font
face="century gothic, sans-serif"><span
style="font-size:18.6667px"><b>Hrvoje
Skenderović</b></span></font></div>
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style="font-size:14.6667px"><b>Institute of
Physics</b></span></font><b style="color:rgb(
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<p style="text-align:justify;margin:0px"><span
style="text-align:left"><span
style="font-size:14px">The topic of the
talk is research in the field of Digital
Holography and connected themes.
Especially, implementation of holographic
measurements with scanning single photon
avalanche detector (SPAD), as well as
time-averaged digital holography (TADH) is
presented. In TADH measurements, holograms
of a vibrating object are recorded,
usually in such a way that the exposure
period of the camera recording the
hologram is many times greater than the
period of vibrations. We examined the
error in the reconstruction if the
exposure time is only a few times greater
than the oscillation period and if it is a
non-integer ratio of the two times. In the
following, we have shown that it is
possible to obtain an accurate hologram
even when the exposure is only half the
oscillation period with a known phase.
Finally, we have given a procedure for
determining the unknown oscillation period
and phase with several short exposures.
All these numerical calculations were
confirmed by experimental measurements
with real objects. </span><br>
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<p style="margin:0px;text-align:justify"><span
style="font-size:14px">We also investigated
the differences in sampling and
nonlinearities in holography using a SPAD
detector and a camera. We have shown how it
is possible to determine the optimal
sampling using a scanning detector. Also,
the standard camera mainly works with an
8-bit image, that is, it has 256 gray
levels, which easily leads to saturation in
the recording, or to the appearance of
non-linear members in the reconstruction of
the hologram. In contrast, SPAD as a
detector has an infinite dynamic range.</span></p>
<p style="text-align:justify;margin:0px"><span
style="text-align:left;font-size:14px"></span></p>
<p style="margin:0px;text-align:justify"><span
style="font-size:14px">An experiment dealing
with application of quantum light in
holography is also discussed. The objective
is to use individual photons in a classic
holographic setup and see if they can be
used to obtain a hologram and if visibility
improves compared to classic source of the
same (very low) intensity. Since holography
is based on the interference of two light
beams, and in the case of individual photons
we a photon can not be split at the BS, the
possibility of interference is not clear a
priori. Also, there is a problem with the
phase, which is indeterminate for individual
photons. It is shown that a hologram can be
recorded, amplitude and phase reconstruction
can be obtained, and the SNR is better
compared to classical light of the same
intensity.</span></p>
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<div>Predsjednik Znanstvenog vijeća Instituta
za fiziku</div>
<div>dr. sc. Damir Starešinić<br>
<br>
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<div><a
href="https://us06web.zoom.us/j/89856158536?pwd=b2l4bG5reDQ5Tk1wMU1MTG1MeExBdz09"
class="moz-txt-link-freetext">https://us06web.zoom.us/j/89856158536?pwd=b2l4bG5reDQ5Tk1wMU1MTG1MeExBdz09</a></div>
<div>Meeting ID: 898 5615 8536</div>
<div>Passcode: 332504</div>
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