We present an efficient tool capable of measuring the spectral correlations between photons emerging from a Hong-Ou-Mandel interferometer. We show that for our spectrally factorizable spontaneous downconversion source the Hong-Ou-Mandel interference visibility decreases as the photons frequency spread is increased to a maximum of 165 nm. Unfiltered, we obtained a visibility of $92.0 pm 0.2 %$. The maximum visibility was $97 pm 0.2 %$ after applying filtering. We show that the tool can be useful for the study of spectral correlations that impair high-visibility and high-fidelity multi-source interference applications.
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