Evidently I do not understand the details of how whatever was to be achieved will achieve the TS goals.

 

The TS just wants to see the ~10Hz beat frequency of the flashing, not of the differences between the ~333THz light sources.

Agreed, but to get that you need interference from coherence. When you split the coherence into two light sources, each source must maintain wavelength, otherwise the interference from phase shifts as the sources change. LED's will change wavelength as it warms and while being used. So the challenge there is how you can control the two sourecs, or account for their dynamics. Then, even if each "identical" spec LED was staked on wavelength, they will not be the exact same wavelength.

In the single soucre laser example, at least it's a coherent source, so when the wavelength there changes from getting warm you only get slight shift in intereference pattern when the apparatus is fixed, but you can put adjustment into the moveable mirror.

 

@Dr John: it seems that your autocorrect has not been ware of LEDs. AND, only the cheap ones are that cheap.

thank you,
im also dsylsxic, and
my eye sight is also going so my apologies
I hope the meaning made it through though and one does not have to have perfect spelling and punctuation to post here .

 

The meaning was clear from the context. AND I blame the autocorrect because it was a typical autocorrect goof. and the spellcheck would let it pass as well.