Login

Recent searches

No recent searches

Search options

Not available on photog.social.
photog.social is one of the many independent Mastodon servers you can use to participate in the fediverse.
A place for your photos and banter. Photog first is our motto Please refer to the site rules before posting.

Administered by:

Server stats:

292
active users

photog.social: AboutProfiles directoryPrivacy policy

Mastodon: AboutGet the appKeyboard shortcutsView source codev4.3.7

#optics

2 posts2 participants0 posts today
Public
datum (n=1)

hey maths and physics nerds

mathstodon.xyz/@dpiponi/114162 !!!

Unlikely to ever be directly useful in practice, partly because the grating spacing and alignment is so touchy and the light modulator's resolution and speed would need to increase, partly because other methods are so effective.

Still very cool for the nerds!

A graph of a continuous real-valued function that has peaks around prime integers (minus 50) with an overall vaguely Gaussian envelope so peaks around 50 (minus 50) are tallest.
MathstodonDan Piponi (@dpiponi@mathstodon.xyz)Attached: 1 image An optical prime sieve https://arxiv.org/abs/1910.10751
#math#maths#physics
Public
skua

#AssistiveDevice #DIY #Optics #Lenses #Blind

Have a hand-held, near field, low cost camera. See pic below of it upside down.
USB is power supply only. Image out is the red video cable. Audio out yellow

Calling it a #MouseCamera.

How do I go about replacing the lens with one that will focus at ~3 times the current text-lens distance?

Seeking a large field of view on large TV screen.
Which would make whole phrases of text readable. As opposed to several characters from 1 word.

Continued thread
Public
Nonilex

That was the public message. But in response to a lawsuit, the #Trump admin later conceded that ~30% of the Venezuelan migrants sent to #Guantánamo were considered "low-threat illegal aliens," & did not have serious #criminal records.

The WH portrays its crackdown on illegal #immigration as an unqualified success. But critics worry that its high-profile removal flights & arrests…may be prioritizing #optics ahead of results, playing into longstanding misperceptions about immigrants & crime.
#law

Public
Ed Wiebe

Two photos of the same male Anna’s hummingbird. The photos were one second apart. The feathers’ iridescence is structural, not from dyes. It’s caused by layers of tiny granules of melanin in the feather barbules. The melanin is dark brown or black. The structure of the plates results in the nearly speculator reflection of narrow wavelength bands of light and the absorption of other colours. Unedited images.

Here’s the science!

pmc.ncbi.nlm.nih.gov/articles/

A male hummingbird is facing you. His gorget, a hood or cowl surrounding his face is brilliantly red, magenta, orange, and bit purple.
The hummingbird is perched in the same spot but is now turned to face left. His gorged is obvious but it’s a deep brown black colour now.
#birds#hummingbird#optics
Public *
j_bertolotti

#PhysicsJournalClub
"Three-dimensional holographic imaging of incoherent objects through scattering media"
by Y. Baek, H. de Aguiar and @sylvaingigan
arxiv.org/abs/2502.01475
#optics #physics #imaging

As you daily experience anytime you look at anything, light scattering severely impairs your ability to image (mild scattering like mist makes things in a distance fuzzy, strong scattering like your own body makes it completely impossible to see what is happening inside or behind it). On one hand this is good, as it allows us to see where (e.g.) trees are so we don't bump into them. On the other hand there are a LOT of situations where you would really like to see what is going on behind a scattering medium (surely it would save a lot of exploratory surgeries).
The problem of imaging through a scattering medium is largely unsolvable in its most general form, but there are a lot of special cases where you can go surprisingly far, and people (me included) have spent a lot of time checking exactly how far.

In this paper the authors consider a set of small fluorescent objects behind a not-too-thick scattering medium, and look for a way to retrieve their 3D arrangement.
Problem: fluorescent emission means incoherent emission, so the phase information (which encodes a lot of information about position) is lost. Still, we can rely on the assumption that there is a finite (ideally not too large) amount of point emitters. Since each emitter is point-like, if we only measure the light that reaches us through the scattering medium at a single frequency (to be more realistic, a small bandwidth), we will see the incoherent sum of a speckle pattern per fluorescent emitter.
1/2

arXiv.orgThree-dimensional holographic imaging of incoherent objects through scattering mediaThree-dimensional (3D) high-resolution imaging is essential in microscopy, yet light scattering poses significant challenges in achieving it. Here, we present an approach to holographic imaging of spatially incoherent objects through scattering media, utilizing a virtual medium that replicates the scattering effects of the actual medium. This medium is constructed by retrieving mutually incoherent fields from the object, and exploiting the spatial correlations between them. By numerically propagating the incoherent fields through the virtual medium, we non-invasively compensate for scattering, achieving accurate 3D reconstructions of hidden objects. Experimental validation with fluorescent and synthetic incoherent objects confirms the effectiveness of this approach, opening new possibilities for advanced 3D high-resolution microscopy in scattering environments.
Public *
TomKrajci 🇺🇦 🏳️‍🌈 🏳️‍⚧️

How good is my camera lens?

This is a series of images of an artificial star as seen by a camera lens and digital camera. They range from one side of best focus, through focus, and onto the other side of focus.

I see two errors:

1. Collimation/alignment

2. Astigmatism (probably pinched optics...bad optomechanical support)

I will disassemble this lens to investigate further.

skyatnightmagazine.com/advice/

A series of images of a pinpoint light source as captured by a camera lens and a digital camera. The upper left image is rather far on one side of best focus. The lower right image is rather far on the other side of focus. This series shows the lens has at least two optical problems. One is a slight alignment/collimation error. The other is astigmatism. Best focus is not very sharp.
#Optics#Testing#Collimation
SearchLive feeds
About