In accordance with the principles of the invention, a lamellar grating interferometer breaks the radiation down into its wavelength components. Further provided is a balloon probe member having a stem portion with an outer screw-thread and a bore freely fitting the external diameter of the balloon tubular sleeve. With the projected vector, it is possible to obtain a more complete reconstructed vector than the measurement vector in terms of incident wave and diffracted wave observation directionspolarizations and the components of which have a better signalnoise ratio than the measurements. According to a method, the inlet air flow guide is installed onto the condensing unit of an ACDX air conditioning unit, wherein a panel of the flow guide has at least a portion spaced from a surface of the condensing unit to define a plenum for cooling air to enter the condensing unit from one side.