The answer, in this specific case, is that you need to multiply the output of scipy.ndimage.filters.laplace with a factor of (1/delta_x) ** 2. Where delta_x = np.diff(x_range)[0]
I simply assumed that the filter would take care of that, but in hindsight it is of course not able know the value delta_x.
And since we are differentiating twice, we need to square the inverse of this delta_x.
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