Inherent resolution limit analysis for millimeter-wave indirect holographic imaging

In the classical indirect holographic setup, a wave emitted by the measurement object is superimposed with a reference wave at the aperture of the imaging system. The resulting interference pattern can be recorded with a simple intensity detection. However, the complex object field can be obtained from the plane wave spectrum (PWS) of the interference pattern. Dedicated methods can be used to calculate the field distribution at the object position, which is equivalent to the object properties and to an image of the object, respectively. This paper shows that the resolution of the created image is restricted due to the fact that the bandwidth of the extracted field is limited by the extraction process. A relation between the maximum possible bandwidth and the geometrical dimensions of the imager setup is deduced. Furthermore, a formula for the minimum achievable resolution is derived. Experimental results are presented to illustrate the issue.