u/QuantumOfOptics

Hi all,

I was hoping someone here might have an idea for typical latencies in OADMs (bonus points if anyone has experience with the ones from solid optics)?

Essentially, I'm a scientist using these as spectral filters in an experiment where I'm sensitive to timing disruptions on the sub-nanosecond time scale. I'm finding a null result and one of the causes could be that our OADMs (2 channel, solid optics) are introducing a differential delay of over 3 microseconds. I've never built or seen the inside of an OADM before, but I have a hard time believing that there's over 1km of fiber inside. Especially, to the first drop. If anyone has some more information, it would be greatly appreciated!

Cheers, QoO

Hi all,

I know that you are all probably waiting with baited breath, sitting on the edge of your seat, all while not sleeping until you know what exactly went down with the earliest double slit experiment. /s

Well, I come bearing an update to my previous post https://www.reddit.com/r/Physics/comments/1uak3fz/earliest_double_slit_experiment/ .

After some more digging. I finally found the reference to the double slit experiment by Thomas Young. Its actually buried in the first volume of "A Course of Lectures on Natural Philosophy and the Mechanical Arts" on pages 463-465 (specifically mentioned 464 with a reference to a double slit experiment drawing that appears at the end of the volume). However, interestingly, while he says that the experiment was done, he never describes the experiment and more or less rushes over it. I found it odd (given that its a really important result and, if you read his other papers, he's usually pretty careful to describe his experiments) and it turns out that I'm not the only one. As noted in the book, "The Last Man To Know Everything: Thomas Young, the Anonymous Polymath Who Proved Newton Wrong, Explained How We See, Cured The Sick, and Deciphered the Rosetta Stone, Among Other Feats of Genius," there seems to be a debate over whether this was a thought experiment, something that he did but didnt interpret his results correctly, or that he did the experiment but wanted to focus on his medical practice and wanted to not draw as much criticism (he was heavily criticized for his prior work). So, its relatively inconclusive if he did actually performed the experiment and he never actually published his results in a paper, its just tucked away in this book. 

At this point, I am going to put this to rest. As far as I can tell, the first actually published results on the double slit experiment is from Fraunhofer as I talked about in my previous post. If anyone knows of an earlier work, it would be much appreciated! Throughout this, I found that there are quite a lot of rumors about this subject and a lot that isn't necessarily correct including the Wikipedia articles, which even suffer from incorrect citations.

Best,

QoO

Hi all,

I've found myself interested in the history of light and its measurement again. In this case, about the double slit experiment. Many sources claim that Thomas Young actually did this experiment in, depending on the modern source, his 1801 or 1803 papers. However, as I've read through them (you can too, with the most useful place to find them being a later compendium that Young wrote in 1807--- A Course of Lectures on Natural Philosophy and the Mechanical Arts vol. II, which can be found in full on the biodiversity heritage website https://doi.org/10.5962/bhl.title.22458 note that volume two is found under a drop down on the right hand side, only volume one is open by default), I found that there are two possible claims that could reasonably be taken as discussing something close to a double slit experiment. One being proposition VIII in his paper "On The Theory of Light and Colours" from 1801 (page 624 of the link I shared). This seems to discuss the fact that two sources would "interfere" or rather that you can add/subtract the waves of each source (note: within a few pages, I think are the first calculations of the wavelengths of different colors and they seem to be pretty accurate!). The second being a statement of interest in his 1803 paper "Experiments and Calculations Relative to Physical Optics" where he used a card to act as screen of the light (which we now know is equivalent to single slit diffraction by Babinet's principle this is equivalent) in experiment 1 on page 639 of my source. He goes on to talk about on page 646 about placing several fibers and crossing each other to detect if some artifacts that people were seeing in blood samples under a microscope could be caused by what I'm understanding to be diffraction effects. In either case, the link is tenuous at best with the first option being more promising.

Am I missing a more important source or section from his papers that more clearly describes something like a double slit or where he actually performs the experiment? From everything I've seen it really seems like Young doesn't actually do this experiment, which then begs the question, who was the first? From what I've found, it may have been Joseph Fraunhofer. In his paper, "Neue Modifikation des Lichtes durch gegenseite Einwirkung und Beugung der Strahlen, und Gesetze derselben" from around 1820 to 1821 (you can find it directly again in the BHL from a scanned copy of the journal in volume 8 at https://www.biodiversitylibrary.org/bibliography/10873 starting at the second page 1 that shows up on the left-hand side once in the viewer, a rough english translation can be found in Prismatic and Diffraction Spectra edited by J. S. Ames on the internet arxive, but it lacks some of the important tables in figures and experiments), he very specifically talks about results with single, double, triple, quadruple slits and an elementary diffraction grating. It seems to me, that this is the earliest form of the double slit experiment detailed and performed. But, I was wondering if there are any known earlier examples? It hasn't quite literally kept me up at night, but it might start soon.

In any case, I hope that this might be interesting for discussion and thanks in advance for any resources that you might know about!

Best,

QoO