1. A test device for characterizing point flaws of an optical filter under test including pinholes and point defects, the test device comprising: a passband illumination source configured to illuminate the optical filter under test with passband illumination whose spectral range at least overlaps a passband of the optical filter under test; a stopband illumination source configured to illuminate the optical filter under test with stopband illumination whose spectral range lies entirely outside of the passband of the optical filter under test; and a two-dimensional array of photodetectors arranged to detect the passband illumination after passing through the optical filter under test and to detect the stopband illumination after passing through the optical filter under test.