slide 56

Lower coherence in an interferogram can affect the clarity of patterns. Regions with higher coherence show clear patterns, while regions with lower coherence result in a messy and noisy interferogram. This is caused by residuals of random components. Good coherence is important for a clear interferogram. Here is an illustration of the impact of lower coherence on the unwrapped interferogram. We can see left regions have higher coherence, so the interferogram can show the obvious patterns. However, the coherence in the right regions are low. We can see the corresponding region in the wrapped interferogram is messy and noisy. The noisy pattern is caused by the residuals of the random components. Through this illustration, we can know good coherence is key to a good interferogram.