**The required spectral width and image distortion**

A larger input image (*xsMax*, *ysMax*) or smaller focal length *fs* require a larger spectral width Δλ*BM* to reconstruct the whole image. Generally the required spectral width depends on both directions *xsMax* and *ysMax*, but if the signal, reference, and probe beams lie in the same plane (α*<sup>p</sup>* = 0°), it becomes independent of *ysMax*. Furthermore, the condition α*<sup>p</sup>* = 0° minimizes the image distortion, where the image is magnified by the wavelength ratio μ*0* in the *yd*direction, but is unchanged in the *xd*-direction.
