Thanks for your response to my article. In answer to your question, I can point you to the Wikipedia article “Double-Slit Experiment” which has a lot more information on these observations. I also copied a section of that article and here it is:

“Which-way” experiments and the principle of complementarity[edit source]

A well-known thought experiment predicts that if particle detectors are positioned at the slits, showing through which slit a photon goes, the interference pattern will disappear.[5] This which-way experiment illustrates the complementarity principle that photons can behave as either particles or waves, but cannot be observed as both at the same time.[35][36][37] Despite the importance of this thought experiment in the history of quantum mechanics (for example, see the discussion on Einstein’s version of this experiment), technically feasible realizations of this experiment were not proposed until the 1970s.[38] (Naive implementations of the textbook gedanken experiment are not possible because photons cannot be detected without absorbing the photon.) Currently, multiple experiments have been performed illustrating various aspects of complementarity.[39]

An experiment performed in 1987[40][41] produced results that demonstrated that information could be obtained regarding which path a particle had taken without destroying the interference altogether. This showed the effect of measurements that disturbed the particles in transit to a lesser degree and thereby influenced the interference pattern only to a comparable extent. In other words, if one does not insist that the method used to determine which slit each photon passes through be completely reliable, one can still detect a (degraded) interference pattern.[42]

The links in this article should also work for you for more detail.

Thanks again for your interest.

John Karpinsky