172 174 and 176 in fig7 as a result of not including this lens the observed pattern for a diffracting object 900 u03bcm wide 3 u03bb at distance of 66 cm from the array falls into the fresnel regime and not the fraunhofer a consequence of not using the fourier lens is that the diffraction pattern does not represent a simple convolution operation with the signal spectrum however despite this fact it is still possible to correlate the narrow band impulse response coefficients for the filter state to the observed average intensity profile by using a least means square error u201c lmse u201d fit specifically if h m corresponds to the complex amplitude of the m 39 th tap that is the value corresponding to the m 39 th impulse response coefficient then the resulting intensity profile for a monochromatic input of wavelength u03bb at a distance z from the array would be proportional to i ue8a0 x u03bb u221d uf603 u2211 m 0 3 ue89e h m ue89e exp ue8a0 j ue89e ue89e 2 ue89e u03c0 u03bb ue8a0 c ue89e ue89e t 2 x ue89e ue89e u03bb z ue89e m ue89e exp ue8a0 j ue89e ue89e u03c0 u03bb ue89e ue89e z ue8a0 m ue89e ue89e u03bb 2 uf604 2 where.