Pinhole aperture and then wavelength filter. The wavelength filter is causing spatially coherent wave packets to return to coherent waves (plane waves).
Yes, two forms of decoherence in a particles path causes it to return to coherent waves (plane waves). The quantum which way experiment displays the same effect.
When you use laser light for a quantum experiment which includes a decoherence event ..the process must be starting over.
Is incoherent light intersecting coherent waves that are immune to decoherence from other light waves? Does the chaos of its phase cause matter waves to decohere? Does a pinhole aperture cause them to be wave packets (decohere) and to be orderly?