  The aim of this work is to develop a simple optical method for the
visualization of the natural convection flow generated in an electronic system
during its normal operation. The presented experimental set-up allows to reveal
local refractive index changes in a phase objects. A fringe pattern is
acquired, through the cooling fluid under analysis, with a digital camera two
times: the first one with the fluid at rest, the second one with the thermal
load due to the electronic device normal operation. By the means of the MATLAB
processing of the acquired images it&#8217;s possible to reveal the shape and
the directions of the thermal flow lines for the cooling fluid. In this way we
can obtain a deeper understanding of the optimal convection working volume or
information for the optimization of the relative spatial positioning of the
several electronic components in a complex electronic system, like a printed
circuit board (PCB). The proposed technique has been tested on two typical heat
extraction situations recurrent in the electronic devices. In this paper are
presented the experimental results of the visualization of the convective flow,
in air, for an heat sink and a power resistor.
