SCHLIEREN IMAGING METHOD AND ITS APPLICATION FOR VISUALIZING OF
SOME PHYSICAL PROCESSES V. Ohanesjan, R. Popeski-Dimovski, and S.
Topuzoski
Slide 2
Schlieren imaging as technique for visualization of
nonhomogeneous regions. Word Schlieren origins from old German,
meaning bits or pieces. We present here a theoretical explanation
of the schlieren imaging, and a simple experimental procedure.
21.09.2012 IX Conference of the Society of Physicists of Macedonia
20-23 September 2012, Ohrid, R Macedonia Shimmering mirages on a
hot road or optical distortions caused by the hot air from jet
engine are everyday life examples of schlieren effect. Introduction
Fig. 1 Fig. 2Fig. 3 During the time, many different apparatus for
Schlieren imaging have been developed (two mirrors, one mirror, two
lenses (Toepler), one mirror). Our schlieren system is with two
lenses. convergent
Slide 3
First observations on schlieren effect were reported by Hooke
and Huygens in XVII century. 21.09.2012 IX Conference of the
Society of Physicists of Macedonia 20-23 September 2012, Ohrid, R
Macedonia Historical facts August Topler (1836-1912) Gave a name to
this technique (Schlieren); First basic apparatus for flow
visualization by using a knife edge; Classics of Exact Science ; In
present time, the most significant names in this field of physics
are Leonard M. Weinstein and Gary S. Settles. Fig. 4 Hubert
Schardin was recognized as a modern pioneer of the color schlieren
technique. Fig. 5
Slide 4
Human eyes and CCD detectors are only color and intensity
sensitive. 21.09.2012 IX Conference of the Society of Physicists of
Macedonia 20-23 September 2012, Ohrid, R Macedonia The light wave
changes its phase during propagation in a transparent medium with
refractiv index gradient. Using the schlieren optical method the
phase variation is transformed into intensity variation, allowing
us to detect refractive index gradient. Gary S. Settles has made a
lot of outdoor observations on different phenomena. Application of
the method to liquid membranes, sonar pulses, optically transparent
polymers and polymeric foils. Schlieren method and application Fig.
6 Fig. 7 M. Weinstein had transformed an telescope into schlieren
apparatus.
Slide 5
Two convergent plano convex lenses with 9 cm diameter and 50 cm
focal length. 21.09.2012 IX Conference of the Society of Physicists
of Macedonia 20-23 September 2012, Ohrid, R Macedonia Optical fiber
from Oceans Optics Spectrometer as a point light source. Micrometer
diaphragm as a knife edge. Nikon d 5000 with AF-S Nikkor lens
55-200mm. Computer software: Camera Control Pro 2 and Capture NX 2
Experimental setup Fig. 8 Fig. 9
Slide 6
21.09.2012 IX Conference of the Society of Physicists of
Macedonia 20-23 September 2012, Ohrid, R Macedonia The light rays
propagating in medium with refractive index gradient bend
fractionally to the regions of greater index due to the change of
the speed of the light. Theoretical explanation
Slide 7
21.09.2012 IX Conference of the Society of Physicists of
Macedonia 20-23 September 2012, Ohrid, R Macedonia Fig. 10
Slide 8
21.09.2012 IX Conference of the Society of Physicists of
Macedonia 20-23 September 2012, Ohrid, R Macedonia where Fig.
11
Slide 9
21.09.2012 IX Conference of the Society of Physicists of
Macedonia 20-23 September 2012, Ohrid, R Macedonia Experimental
results Knife - edge orientation Fig. 12 : Horizontal temperature
gradient due to the lighted match, and horizontally orientated
knife edge. Fig. 14: Turbulent air flow. Here in this case is no
preferred axis, because of that knife edge orientation does not
influence significantly. Fig. 13 : Horizontal temperature gradient,
and vertically orientated knife edge.
Slide 10
21.09.2012 IX Conference of the Society of Physicists of
Macedonia 20-23 September 2012, Ohrid, R Macedonia Image digital
processing Fig. 15: Just captured image. Fig. 16: Post processed
image with Capture NX2
Slide 11
21.09.2012 IX Conference of the Society of Physicists of
Macedonia 20-23 September 2012, Ohrid, R Macedonia Electrostatic
discharge Other examples Fig. 17: Human breathing. Fig. 18:
Electrostatic discharge between the electrodes of the high voltage
supply.
Slide 12
21.09.2012 IX Conference of the Society of Physicists of
Macedonia 20-23 September 2012, Ohrid, R Macedonia Conclusion We
succeeded to set up a schlieren system with the optical elements we
have in our laboratory and tested its sensitivity. We have observed
and recorded by camera: laminar and turbulent gas flow, an electric
discharge in air, temperature gradient, breathing and heat flow
from palm. These experiments are also valuable from the educational
point of view, because they serve as an introduction in optical
design and alignment for undergraduate students. Some of the
experimental processes visualized by this method can help in
studying the corresponding physical phenomena. Part of this paper
was presented on the student competition Primatijada 2012, and was
awarded as a best student project in physics.
Slide 13
21.09.2012 IX Conference of the Society of Physicists of
Macedonia 20-23 September 2012, Ohrid, R Macedonia Thank you for
your attention !
