Hello all, I have been reading about quantum entanglement on this webpage. It builds up to the quantum eraser where two entangled photons are produced using a BBO crystal, that have opposite polarity, with one going through a double slit to a detector and the other going to another detector linked - to correlate detections. This setup produces an interference pattern. Then special crystals (that don't destroy entanglement) are placed in front of the slits to impart rotational polarisation either clockwise or anticlockwise depending on if the incident polarisation is horizontal or vertical. The polarisation is measured at both detectors - if its horizontal at one and clockwise at the other you can tell which slit it went through. This destroys the interference pattern. The finale is the placement of a polarising plate on the photon on the none slit pathway so that the polarisation's horizontal and vertical components become a mix and the original polarisation cannot be determined.. the interference pattern reappears. Well that's my following of it, the question I have though is isn't the last polarising plate simply acting as a filter so that counts are only made when the photons have a certain range of polarities that would produce a pattern i.e surely the plate blocks some photons with an exact opposite polarity of the plate and if these counts were added back to the pattern then it would just become a blob?