I snapped some pictures of the experiment apparatus that is being used in the lab yesterday, so here goes my best attempt in explaining how this thing works. The metal frame allows us to easily manipulate the furnace (the white cylinder) and other components of the apparatus without touching the furnace itself. A pulley system allows us to lift the furnace and easily place the substance being tested inside. For the work being done now, that is salt compounds made in another part of the department. The furnace heats the substances to temperatures up to 600 degrees Celsius, melting the salts. These molten salts are the fluids that can be used in solar thermal power plants as heat transfer fluids. The salts are placed in a large cuvette that is placed inside the furnace.
An smaller cuvette is then placed in the metal holder that can be seen here above the furnace. This holder can be precisely lowered into the cuvette inside the furnace by a computer. By changing the position of the inner cuvette, the thickness of fluid can be changed.
Seen next to the outer cuvette holder in this picture is the output for a xenon laser (its the black speck thats connected to the wire). This laser is aimed inside of the inner cuvette and passes through the chosen thickness of the fluid being tested. Thanks to the Beer Lambert Law the absorbance of the fluid can be found by changing the thickness of the fluid that the light from the laser has to pass through. A collector below the apparatus collects the light that is not absorbed by the substance at each different wavelength that the xenon laser outputs. The absorbance of the substance affects how it absorbs light, converting that light energy into heat.
