r/Optics

A couple years back a colleague told me that lens design optimization is essentially AI.  At the time, I thought that was a strange comment.  But as I’m beginning to educate myself on deep neural networks, I think I see what he meant.  DNNs have weights, lens design has variables.  They have a loss function; we have a merit function.  They’re using gradient descent and finding minima; we’re using damped least squared and finding minima.  In some ways they’re analogous.

Our computers are already cranking away with 100% of our hardware resources doing similar math to what’s done with DNNs.  For the last 50 years we’ve been attacking lens design with everything our computers can give us.  To some extent, we’ve already been doing the type of thing DNNs are doing.

Furthermore, lens design optimization is only going to be successful if you get the merit function right.  Every merit function is customized specifically to the present design.  One bad or missing operand will render the optimization run useless.  I don’t know how you’d train a DNN on merit functions because they’re all unique.  Even if they weren’t, I don’t know where you’d find the merit functions to do the training.  Also, merit functions evolve over time.  At least mine do.  They start out rather coarse to get in the ballpark quickly and then expand to refine the design.  That only adds to the difficulty of training.

So, I tend to think that AI isn’t going to have the impact on lens design that it is in other places.  That isn’t to say there aren’t applications where we’ll use AI.  It’s being used to generate starting designs from trained data sets.  It’s being applied in niches where DLS might not work that well (e.g., freeform optics).  And of course, it’s being used to make the non-design part of our jobs more efficient.  But as a tool to get better lenses out of a conventional lens design effort, I’m not seeing it.  We aren’t going to give Snell’s law to an unsupervised DNN and have it pop out great new lenses a la AlphaZero.

There’s much more, but this post is already long enough.  What do you all think?  How is AI going to change lens design?

I'm driving a 2017 VW Beetle that I really love but am getting concerned about safety and wondering if gluing a Fresnel lens over the amber blind spot warning might enhance visibility - thus safety. Any thoughts about a 30mm (or so) lens type and source would be appreciated.

Here's the mirror:

https://preview.redd.it/9q0gpfwuu52h1.png?width=300&format=png&auto=webp&s=7ecf734009b1f5a6eb51d611dd5b3faf75acaea7

Thanks.

I have a setup with a OLED display with a linear polarizer that is directed at a PBS with a quarter wave plate inbetween. A concave mirror at the bottom reflects light back up to the PBS. Everything works okay except the image produced back at the PBS has ghosting and I see a second slightly dimmer and offset image. Could this be because I bought a relatively cheap PBS off aliexpress that does not have a AR coating? All these components are mounted on a 3d printed sliding structure which may cause minor inconsistencies with alignment. If the AR coating is the issue, is there a way to add it as a separate component?

I’m using an eospace phase modulator EOM at 1012 nm to modulate the input light at 2Ghz. Vpi modulation is 10 dbm higher than the specs at 2Ghz. At low frequencies, 400Mhz, vpi is 5dbm higher than the specs suggest. I have verified that the input polarization is linear and stable. The internal resistance of the EOM is 45 ohms - roughly as expected (50 ohm is spec). I’ve tried this experiment with another EOM across the lab, with same instruments, and it worked. That eom is rated at 960nm and I ran it at 1012.

Any ideas?

I’m currently building a compact Raman spectroscopy setup for biological/organic samples and looking for recommendations for a stable CW laser source around 785 nm, ideally somewhere in the 80–120 mW range with single-longitudinal-mode (SLM) operation.

Main priorities are: narrow linewidth / stable spectral profile with minimal mode hopping during longer acquisitions, low intensity noise and a compact footprint since the system is intended to be integrated rather than purely bench-top

At first I was leaning toward more traditional larger Raman laser heads, but I’m starting to wonder whether modern compact OEM-style modules have reached the point where they’re stable enough for demanding spectroscopy work without sacrificing spectral quality.

I’ve looked into ECDLs, volume holographic grating stabilized diodes, and compact DPSS systems, but I’m still trying to understand what people are actually using successfully in real-world Raman setups nowadays.

For those working in Raman, hyperspectral imaging, or biomedical spectroscopy:

what architecture ended up being the most reliable long-term?

Would appreciate any recommendations and lessons learned 😃

Hello optics enthusiasts,

I am a grad student working in a physical chemistry group. I am in charge of the maintenance of the optical lab space. I have specific instructions regarding the maintenance of our optical systems, but I am looking for advice concerning the maintenance of the lab space.

The lab is fairly dusty and I would like it to not be the case for obvious reasons. What can you recommend to reduce dust? Do you have any resources you'd recommend to help me out?

All of our optics work deals with femtosecond lasers systems. Currently, other than a weekly vacuuming and sticky mats at the entrance, nothing is being done to reduce dust.

https://preview.redd.it/j8zmdxa3uz1h1.png?width=1806&format=png&auto=webp&s=1eeae25da546c89f93dc07551fc8dc494c3e009d

I am trying to replicate the optics setup in the image above. Everything is similar except I have a OLED display with a linear polarizer as the light source and my reflective surface is a concave mirror. Everything works okay without the QWP and light is visible through the PBS but when the QWP is added at 45deg of the fast axis, the image through the PBS is blurry, "smothered out", and unfocused? Why could this be happening if all optical components are for broadband visible light waves?

Pretty much the title. Satellites contain highly aligned optical components. Just to get them to their working environment you essentially have to put them through a crazy earthquake (launch) and then you’re not able to service them after that. How df do optical and optomechanical engineers achieve this?

Shock mounts? Flexures? God?

I've started work on a personal project in which I intend to use an analog micromirror array. I saw a cool kit from Fraunhofer which offered a 256*256 AMD which seemed nice, but it did not specify if it was a 2-axis. Since I'm kind of new in this field (most of what I did so far was in pure mechanics), I wanted to ask in here if this is even a realistic thing or if devices in that category (size of array, analog, two axis) will require me to sell my underwear? If not, are there any other recommended manufacturers or models? Edit: apparently they cost as much as a car in that size range, and only Fraunhofer makes them.

I’m finishing a physics master’s focused on optical metrology, interferometry, precision measurement systems, and industrial sensing.

I’ve been thinking seriously about long-term career direction.

I’m trying to understand the realistic entrepreneurial paths that can come out of it later

Some questions for people already in industry:

• Which career paths in metrology/opening systems/semiconductor tooling actually lead to business opportunities later?
• What kinds of companies do former engineers realistically start?
• Is the most common path consulting/integration/services?
• Are there realistic software/tooling opportunities around measurement systems?
• How capital-intensive are the realistic entrepreneurial paths in this field?
• Which roles give the best exposure to valuable industrial problems/customers?

I currently have a rare opportunity where I can still pivot relatively freely into different roles/industries before committing deeply to one path. I also do not come from capital, so realistic startup costs and entrepreneurial accessibility matter a lot to me.

Titles of roles that could lead to entrepnueral paths are appreciated.

Would appreciate honest answers from people actually working in the industry.

Any coaches? I will pay money for solid advice and someone who takes a deep look at my case and situation.

Hi everyone. I found a loupe at a thrift store. I haven’t bought it yet and forgot to take a photo, but it looked high quality. I’d like to know whether it has a lens suitable for gemstone observation. Is there any quick test or simple hack I can do on the spot to check if it’s a triplet, achromatic–aplanatic lens? Any tips to identify this without special tools would be really helpful.

Hello optical professionals, I have a question for those who know better than me in regard to a specific request my work has received.

Context:
I work at a lapidary/jeweler shop, and got a request for custom .925 hand fabricated frames, with Smokey quartz lenses. These sunglasses are cosmetic. The lenses have been made in house using a faceting machine. Obviously, since we are a rock shop we don’t have the specialized equipment to make real lenses, these are for fun. We did disclose that we don’t recommend wearing just plain Smokey quartz glasses outdoors because they will not protect your retina, and potentially harm it.

In lieu of settling for that, right now we want to figure out if there is any way to treat the lenses we’ve already made with a UV protective coating similar to optical lenses, for our customers protection and our peace of mind lol.

I’ve found some stores near us with in house labs, but it’s the weekend so gotta wait to ask them. So out of curiosity, is this something that’s possible to do? Or are there other solutions that come to mind? Thank you so much!

Hi..

For thoose familiar with tinkering in freecad, there exits a new optics addon.

https://github.com/Pernils74/OBA_OpticsWorkbench/tree/main

Dear optics wizards,

I am facing a problem with surfaces on some calibration artefacts for calibration laser triangulation. For getting exact measurements in calibration we need a perfectly flat surface with a nice diffuse reflection. Mirror finish/specular reflection does not work for standard sensors. Glass bead blasting or trovalizing the surface does introduce more laser speckle.

What I know was tried so far:
Sputtering: does work but does not change the surface roughness and makes the laser "bloom" a bit. Was tried on aluminum and glass.

Paint: nice diffuse reflection but does introduce variance in coating thickness, especially on corners (roundover)

Ceramic: ceramic gauge block was more on the shiny side and also showed blooming

Any ideas what combination of base material and coating could work for this application?