r/Optics

What is the minimum number of physical properties of an unknown glass sample that must be known to theoretically determine its refractive index—without using ray tracing? Are there cases where this theoretical method yields a refractive index different from the actual one (as determined by ray tracing)?

I’m working on an optical design where I have some freedom to choose between different freeform/aspheric surface shapes that give similar optical performance.

At this stage, I’d like to include manufacturability as part of the optimization, rather than designing the best-performing surface first and only later discovering that it is difficult or expensive to manufacture.

What parameters do you actually use in industry to estimate how difficult a freeform/aspheric lens will be to manufacture?

For example, I’ve been looking at things like:

• Maximum aspheric/freeform departure from a best-fit sphere
• Maximum surface slope
• Maximum slope departure from the best-fit sphere
• Curvature / minimum local radius of curvature
• Rate of change of curvature

But I’m not sure which of these are genuinely useful predictors of manufacturing difficulty.

Is there a commonly used figure of merit or set of rules of thumb for manufacturability?

I’d also be very interested in hearing how optical fabricators look at a surface when deciding whether it is “easy,” “difficult,” or “very expensive” to make.

I'm considering URochester for Masters in Optics. I am currently a 4th year ECE student (Not in the US/ non US citizen). I am primarily interested in photonics, but im open to working in other domains. I have experience working with photonics and I have a publication in FIO+LS as well. I wanted to know what the placements are like? And are there any sites or resources to look at placement statistics for colleges in general?

https://preview.redd.it/rvmpx5c4j8kh1.png?width=757&format=png&auto=webp&s=e803401b797b5306465fb8882da0d78715700553

Rough diagram without polarization

This is a birdbath AR optics setup with a 0.23in OLED micro display, a linear polarizer, a polarized beamsplitter, a QWP, and a concave mirror. The light from the display becomes P-polarized relative to the PBS after passing through the LP so it passes through the PBS without reflecting. Then after the image is magnified and passed through the QWP twice so the magnified light is now S-polarized, it reflects off the PBS into the users eye.

The issue I have with the setup is that since the display produces a diverging light source, the diverging light that doesn't hit the PBS coating at a AOI of 45deg is then reflected through the front side of the setup. Only when viewing through the front of the PBS (the part where no light should be seen) with your eye at around 45deg from the PBS coating, the light then disappears because the polarization state was properly filtered. When viewing from any other angle you can see the unmagnfied light.

I have tried using plano convex lens and aspheric lens to collimate the light before it reaches the linear polarizer so that all light would be 45deg AIO to the coating but none solution seem to work. I have a aspheric lens with a 3mm FL and when placed 3mm from the display the same behavior occurs.

Am I wrong about why the PBS only works properly when viewed at a certain angle? What are my options to figure out a solution?

Hi all, I am a last year undergrad who is working in photonics, mostly in the fabrication part. As my seniors, I wanted to get some advice from you guys. Right now, I am in my last year, and working for a professor who seems to be nice so far. Previously, I had some experiences which people may call as toxic environment. One of them being 4 month and another a year and a half.

So far, in this new group I have been working for more than 2 months now, and the professor gave me an opportunity to work on fabrication more, whereas in the previous one I couldn't do that no matter how much I tried to show that I was willing to. Anyways, in this group I got a support I needed. For instance, I wasn't sent to the clean room with no idea, at least I was told in every stage some of the rough things I need to do or I was accompanied, if it was my first time doing that task or if I had some problems earlier. I kinda have a PTSD from my previous experiences hence try not to get too happy if things are working in my way.

Due to some reasons, I cannot directly start as a PhD in this group and I will need to spend a year as a research assistant. During this 2 years, what would you recommend me observe and in your opinion how I shall improve better in my research?

Hello! I'm a Senior in high school with a massive interest in studying Optical Engineering in college once I graduate from school. I'm currently trying to finalize my list of college's I'm applying to for my commonapp application and I just wanted to post here to see what other Optical Engineering programs are out there in the US and to also get some more info on the well established ones.
I already have the University of Arizona & University of Rochester on my list, along with Rose-Hulman and UCF. I also encountered OE programs (ABET Accredited) being hosted at Norfolk State University and Bridgewater State University (In-state for me) but I haven't seen much info on those programs so I'm a bit skeptical on applying to them.

My main plan was to attend Rose-Hulman for their program, but I'm having serious doubts about the student life on-campus and the student demographics. as of right now I'm a bit of coin-toss between UR and UA, with my choice mainly being the distance from home and opportunities.

If anyone has any experience in any of the OE programs (or any engineering program in general!) from the school's I mentioned I'd love to hear your experiences there and any recommendations you have. I'll also keep an eye out for any other OE programs you guys want to give a shout to.

Thanks!

Metamaterials are already capable of hiding specific wavelengths of light, however full spectrum invisibility requires complex active cloaking machinery and engineering to be possible. How long do you roughly project it is going to take before invisibility across the entire visible spectrum is on the market?

Hi i am CS grad and very new to this stuff. I was exploring photonic memory, that's when i thought why not use refractive index of an material to encode the data. Recently when I was reading about refraction of light i came across how the refractive index is affected by the electrons distribution in the material. So why not say for an single bit you use a small material like few ~nm in range and the material has an shaded region representing 0 and an photo detector as such on the other region representing 1 and the material is enclosed by an material that referact the light. You now apply voltage to the material, an specific voltage changes the electron distribution of the material making the passing light through referact and hit the shaded region or photo detector. This photodetctor then drives an small electric switch which turns on an another light beam that's powered seperately that's used to route the light to the readers photo detector. Say if you have a number of such forming an 8-bit an byte.

I need help finding a library that allows me to connect an AvaSpec-ULS2048CL-EVO spectrometer from Avantes to a python script to get live readings from it.

So far I found avaread which allows me to read files from the Avasoft 8 software. But that would require me to save a file each time I need to make a measurement and then run the code which would be inefficient because I need to make a lot of measurements just to get one result.

Is there any other way to connect the spectrometer to my code? or has anyone tried anything similar?

Everyone seems to agree that the line between the centers of curvature of a single lens element is the optical axis. Because it is the line between two spherical surfaces, it is normal to the surfaces so a light ray along the optical axis is not deviated but exits the lens coaxial with how it enters. Does anyone see a reason not to adopt the same definition for an assembly of lenses such as a camera lens or Cooke triplet? To the best of my knowledge I do not know of anyone who has discussed this question. I know several people who claim there is no optical axis to an assembly of lenses, but I don't believe they were thinking in terms of my definition.

So I obviously just spent a pretty penny on the rifle. I know a good scope is important. Are there any scopes out there that you would reccomend? It’s a 12.5 inch barrel and I plan to use primarily for home defense and recreational shooting. Trying to avoid breaking the bank again but realize I can’t put a bumper sticker on my new Ferrari. Thanks!

Hi, Ive been struggling with a very weak flourecence signal having low contrast. Its not clear where the low contrast is coming from, but I believe it may be from excitation leakage through the filters.

If I stack several dielectric longpass filters do the ODs actually add up linearly? Should I stack away until contrast improves or the signal diminishes? Whats the theory behind these decisions?

Thanks all