French physicist Augustin Fresnel signs his preliminary "Note on the Theory of Diffraction" (deposited on the following day). The document ends with what we now call the Fresnel integrals.
The Fresnel integrals have various applications in optics, such as in the calculation of the diffraction pattern produced by a single slit or a circular aperture, as well as in the study of the propagation of light through various optical systems.
After extensively using the #lens#Haskell library for half a year at work I have now played around with the #optics library again. I am amazed by how much more helpful error messages are with #optics. It’s an amazing library and I would recommend it over #lens whenever you have the choice.
@mangoiv Hasn’t been my impression with #optics yet. To me it feels like the type level stuff is "finished". As long as you only define and use existing types of optics you don’t need to worry about it.
Fascinating. It turns out that the secret to the seamless compositing in Mary Poppins was an optical beam splitter just like those used by astronomers today in Sodium laser guide star adaptive optics systems.
I'm more than a little curious about how they could have made a narrowband 589 nm beamsplitter 60 years ago. Having made 3 they then, apparently, found themselves unable to make any more.
If you're in the path of totality on Monday, look around during the eclipse and you might see some optical efects. (Wear strong eye protection if you look up!)
These photos were taken during the 2017 eclipse in a near-totality zone. Trees provided a pinhole effect, casting these 'shadows'.
English polymath Isaac Newton, who was a mathematician, physicist, astronomer, alchemist, and theologian, died #onthisday in 1727.
His pioneering book Philosophiæ Naturalis Principia Mathematica (1687) consolidated many previous results and established classical mechanics [1]. He also made seminal contributions to optics (among many other things), and shares credit with Gottfried Wilhelm Leibniz for developing calculus.
On a whim, I decided to measure the radiation level of this Tokyo Kogaku (Topcon) lens. It is an unusual lens in that it doesnt have an aperture control ring. There is an aperture mechanism, but if is controlled by the camera (like a Topcon Unirex or Topcon IC-1). It is a sharp lens, but given it was the more affordable line (the RE was 50% more expensive), didn't expect Thorium was used for the lens. Then again, it is a 50mm from the 1960s.
Measured at rear element: 5.51uSv/h instant, 5.4 avg. Not background noise. So some front element (there are 6 glass elements in total in this lens) definitely was made with Thorium. It explains the sharpness. Also means I will have to keep it isolated for long term storage, and not on the shelf right next to me... I'll have to check the other Topcon UV lenses...
You'll be surprised to know that the relatively common Fujinon 55mm f2.2 in m42 (fujica st) is also radioactive. I know I was, as that has never been identified before, AFAIK. This is without EBC coating, just regular coating. Front shows 13.64 instant, 13.2 avg. Btw, that is not insignificant.
Apple wouldn't be doing this—at considerable expense—if they didn't consider such attacks to be plausible within the relevant lifetime of currently intercepted and retained messages (ie. not necessarily today, but within the statute of limitations of any crime you might be confessing to in an iMessage).
@cstross Agreed with the general premise, but a part of the justification might also be that they can then use this as a marketing #talkingpoint, that their systems are so much more secure than the competition, ahead of anyone else, and in line with the image they're trying to cultivate that people on iPhones don't get hit by viruses or trojans? #optics being everything these days it seems.
"The UN statement reported allegations that Palestinian women and girls had been arbitrarily executed in Gaza, frequently along with family members, including children."
I’ve got some prisms in the bay window in my kitchen, and the way they’re set up now and the angle of the morning light gets a couple of the spectra that get thrown on the ceiling overlapping, and you can see a pink band to the right of the orange band on the left
Cowardly #SCOTUS Justices Appear Skeptical of Arguments to Kick #Trump Off State Ballots
The #SupremeCourt heard arguments about whether TFG’s attempts to subvert the #2020election#disqualify him from again holding office. Justices across the ideological spectrum questioned several aspects of a ruling from the #Colorado Supreme Court.
#SCOTUS on Thurs seemed prepared to keep #Trump on the #Colorado ballot, expressing deep concerns about the ability of a single state to disqualify a candidate from seeking national office.
Extinction of color in a tourmaline using a computer screen. #mineral#optics
You can see this effect using sunlight and polarized sunglasses but that’s harder to show in a video. 😸
'A George Mason University scientist and team of researchers developed a new camera system that allows ecologists and filmmakers to produce videos that accurately replicate the colors that different animals see in natural settings, according to a report in the open access journal PLOS Biology.'
I designed and 3D printed new mirror clips and an aperture mask for my 6" Newtonian telescope to reduce the uneven diffraction around bright stars and improve overall image sharpness.
The original clips that came with the mirror cell are narrow and protrude a good 7-8 mm into the mirror surface. Making an aperture mask to fully cover those clips would significantly reduce the mirror area.
The new clips are wider but only protrude about 2mm into the mirror surface. The aperture of the mask is not perfectly round to I minimize the amount of mirror area lost while the slight out of roundness will be imperceptible to the eye. The mask also doubles as a link between the clips stiffening the whole assembly.
New version of Optench, my virtual optical bench, is now available (1.2.4)
Just a small bug fix release, operator precedence in aspheric lens expressions was backwards 😅 #optics#education#physics#opensource