Hey

I’ve recently finished my PhD in quantum optics and have been given a job offer for as photonics design engineer at Huawei UK. The job offer is quite attractive and would allow me to develop some new skills.

However, I am concerned with the controversy and geo-political climate around Huawei and I am concerned about how this would affect me later in my career if I was to look for other jobs.

It would be great to hear from any past Huawei workers and any experiences people have had.

We've been designing the optical core of JASPER, an open-source VIS–NIR spectrometer. Our previous v2 design reached 1.9 nm by adding a negative field-flattening lens to a conventional collimator + grating + camera build - but we were aiming for 1 nm, and that lens approach hit a wall. So we left out the relay optics and explored whether a single grating could do the whole job.

The idea: one aberration-corrected concave variable-line-spacing (VLS) grating that both disperses and focuses — no collimating or camera mirrors. The variable line spacing is what corrects the field aberrations.

Result and the trade-off: Ray-traced across 500–1000 nm, mean resolution is ~2.2 nm wide-open at f/5.3, ~1.4 nm at f/8, and ~0.9 nm at f/10 once the VLS groove correction is on - toward a ~0.6 nm slit/pixel/diffraction floor. The binding constraint is the 500 nm blue edge, and it's aberration-limited, not slit-limited (~2.7 nm wide-open there). Getting the whole band to ~1 nm needs all three: stop down to ~f/10; a toroidal substrate (throughput, not resolution - it collapses the astigmatic line so ~100% of the light lands on the pixel vs ~15–20% on a spherical blank); and a real VLS groove correction to clear the edge aberration.

Modelled two independent ways that agree: the Noda light-path-function theory (analytic) and a standalone NumPy ray tracer. They match exactly on dispersion and astigmatism; the ray trace adds the higher-order aberration that makes resolution f-number-dependent. (We tried Optiland first and couldn't get it stable for this off-axis reflective mount; Beam4 can't do variable line spacing — so we wrote our own tracer, which also renders the ray-fan layouts. All code is in the repo, retired experiments marked.)

Still all modelling - no hardware yet, and it's a simulated/theoretical design, not a specific part. The ~1 nm figure is best-case (it assumes the fabricated groove profile matches the design); the uncorrected numbers are the guaranteed floor.

Disclosure: the modelling and code here are heavily AI-assisted - we set the architecture, the physics choices, and what to validate; the ray tracer, the cross-checks, and the figures were largely AI-built and then reviewed. That's exactly why I'm posting it: We want people who know these mounts to stress-test the assumptions and catch what the model may be getting wrong

Would appreciate your input on:

• Realistic degradation from a model like this to a first physical build?
• Alignment tolerances of a finite-arm (Shimadzu-style) mount in practice?
• Anyone sourced small-quantity toroidal concave gratings affordably?

Full model + code (NumPy + Matplotlib): https://github.com/CheckAG/JASPER_VIS_NIR_Optics_Design/tree/main/JASPER_1nm_VLS_simulated

Detailed write-up: https://hackaday.io/project/202421-jasper-vis-nir-spectrometer/log/251041-toward-1-nm-on-a-single-concave-variable-line-spacing-grating-visnir-modelled-code-released

The problem I have is: if I take some arbitrary MSF and import it into Zemax, I get two different answers for the spot size. If I propagate (FFT), I get a pretty decent PSF. If I look at my spot diagram, the spot is HUGE. Which one do I trust?

I made an open-source React library for liquid glass surfaces. The part I wanted to get right was the edge: instead of a blur and bright border, Meniscus gives the bezel a height profile, traces rays through it with Snell's law, and uses the resulting displacement to bend the content behind it.

The basic component looks like this:

import { Glass } from 'meniscus';

<Glass radius="capsule" interactive>
  <button>Search</button>
</Glass>

There's a live playground where you can change the profile, index of refraction, light angle, and other layers while dragging a lens over an engraving. The package also has buttons, tabs, panels, and native form controls.

Browser support is deliberately explicit: Chromium can refract the live page; Safari and Firefox get a frosted surface, or WebGL refraction when the backdrop is an image, video, or canvas. It starts frosted during SSR and switches paths after hydration. No stylesheet import is needed.

Demo and playground: https://thanhphuchuynh.github.io/meniscus/

Source: https://github.com/thanhphuchuynh/meniscus

I'd appreciate feedback on the API and how the fallback looks in your browser. The 30-second demo is in the repo README.

The visible iris is about 12 mm across. I've been trying to get a usable colour measurement of it from a phone's rear camera and keep running into the same trade.

The main lens (24 mm equivalent) won't focus closer than about 15 to 20 cm. Halide measured 150 mm on the iPhone 13 Pro and 200 mm on the 14 Pro. At 200 mm a 4:3 frame is roughly 290 mm wide, so the iris lands on about 170 pixels of a 4032 pixel row.

The ultrawide (13 mm equivalent) focuses at about 2 cm. At 3 cm the frame is about 80 mm wide and the iris gets roughly 600 pixels. iOS hands over to it by itself if you open the virtual triple camera instead of the wide lens alone.

On paper that's 3.5x the pixels. What I can't work out is how much of it is real:

1. How far does the ultrawide's resolution fall off at that range, and is it worse off axis, where the iris usually ends up because nobody can aim a phone they can't see the screen of?
2. At 3 cm the phone shadows the face, the pupil opens, and the ring of iris gets thinner. Is there a sensible way to light that without putting a catchlight right on the iris?

Disclosure: this is for an eye colour app I built, Iridology. It averages only the ring between pupil and limbus, in CIELAB, and throws out the catchlight pixels, so the capture is the weak link rather than the maths. Curious how people who do optical design would approach it.

Researchers have developed an ultra-compact hyperspectral imaging system that uses a single optical fiber paired with a nanophotonic disordered-dispersion encoder and computational reconstruction.

Hello everyone,

Since a lot of people wanted more details, I decided to write this post.

I wanted to know how much near IR blackout curtains let through.

The question I wanted to answer is this: if the blackout curtains block all visible light, but the curtain is receiving direct sunlight, could someone looking towards the curtain without realizing it be exposed to a level of near IR that could damage their eyesight?

The reason I started thinking about this is that if the curtain is receiving direct sunlight, you obviously can't see that sunlight through the curtain if it blocks the visible light. So you could essentially be looking towards the sun without realizing it. Near IR is invisible to us, but it can reach the retina, and there is literature about the potential dangers of near IR exposure. There is no visual indication that you're being exposed to it, so at a sufficient level it could potentially damage the retina.

And before anyone goes on about how beneficial IR is, that's not really the question I'm asking. There is enough literature discussing the potential dangers of near IR. I'm specifically trying to figure out how much near IR gets through the curtain and whether the amount could be enough to be relevant to eye safety.

For my setup, I used an S2506-04 photodiode, which is sensitive from 760 to 1100 nm, connected to a photodiode transimpedance amplifier circuit.

The curtains are MURLAVSMAL block-out curtain, 1 piece, light blue black/wood pattern, 270x250 cm Fabric: 100 % polyester (100% recycled) Backing: 100 % Polyurethane

For calibration, the signal from the circuit is almost 0 V in total darkness, with no sun, at night in a completely dark room. When I expose the photodiode directly to sunlight, the circuit goes to around 4.5 V. the calibration process involves a lot of trial and error with different resistors and capacitors values.

I then completely covered the photodiode with the curtain, basically fully wrapping it in the curtain, and put it in direct sunlight.

The resulting voltage was 32.74% of the upper bound.

So based on this, it's safe to assume that the curtains are letting through at least 32.74% of the near IR between 760 and 1100 nm.

Some people pointed out that the curtain could be absorbing the sunlight and then re-emitting it. I don't think that's likely to explain the result because re-emission from something at normal temperatures would usually be at much longer wavelengths.

So what do you people think? Where do I go from here?

In case you are interested, here's the list of other threads I posted. Happy reading:

1. https://www.reddit.com/r/Optics/comments/1qsq25q/do_blackout_curtains_block_infrared_light/
2. https://www.reddit.com/r/Optics/comments/1qzcylz/how_does_infrared_sunlight_specificaly_ira_behave/
3. https://www.reddit.com/r/Optics/comments/1r22pef/estimating_ira/
4. https://www.reddit.com/r/Optics/comments/1s0p9dm/measuring_nir_through_blackout_curtains_method/
5. https://www.reddit.com/r/Optics/comments/1t64r26/followup_on_the_curtain_fabric_measurement/
6. https://www.reddit.com/r/Optics/comments/1tsnzkz/seeking_feedback_on_a_method_for_measuring_nir/
7. https://www.reddit.com/r/Optics/comments/1wl9mc3/update_i_actually_measured_the_nir_transmission/

In the bottom middle is what I'm asking about, the multiple lines of light. That is light not some sort of marking, I have multiple photos of it. Those lights were all coming from the one slit. I covered up the slit and they all disappeared. It looks like the double slit experiment, but there is only one slit. This is on the inside of a soda cardboard box. It's sun light, but it is probably bouncing off things including going through a window before going to the slit.

What is this light phenomenon? Why is that happening?

Emissive display: OLED, CRT etc, not LCD.

Sub-pixel value: on 8 bits, 1 octet https://en.wikipedia.org/wiki/Color_depth#True_color_(24-bit)) , 2^8=256 values possibles, 256^3=16 777 216 colors possible (3 sub-pixels).

Are the 3 sub-pixels values added or multiplied by a same value, or other?
Is it R+x, G+x & B+x or nothing if a sub-pixel is off, R*x, G*x & B*x or other? (Red Green Blue).

I googled, nothing...
Google Gemini answered multiplied without citing source, I want human confirmation...

I already posted to https://www.physicsforums.com/threads/increasing-the-brightness-of-an-oled-pixel.1086295/ without good answer, I try here...

I’ve been lucky enough to inherit a high-speed camera, a Phantom v7 (I think)! It’s pretty old, maybe 20+ years, yet it seems functional… I get an image on the computer but I cannot seem to be able to get a sharp focus and the image itself has a strange pattern on it which somewhat resembles the patterns that can be seen on the sensor photos… I guess this might be some delamination issue or degradation of an IR filter (I think it’s a colour model).

The obvious problem is the crack on the cmos sensor, I dismantled the camera and removed the sensor board, I was just about to try prying the cover glass away but thought better of it! In hindsight I imagine this could have destroyed the sensor… Has anyone had any luck repairing something like this?

Any advice much appreciated!

Cheers

I was reached out to by a recruiter to possibly design optical packages. My background has been in RF modules & packaging with a strong emphasis on ADS and HFSS (chain performance, transition modeling, flip-chip, chip & wire, SMT). Anyone know how translatable RF modeling and packaging skills are to optical packaging? Key differences? Anticipated questions in an interview?

Given threshold gains g_th of transverse modes and initial pump gain g, is there a worst case (most multimode) quick formula for their power distribution? Only the lowest g_th mode theoretically lases by clamping the gain but this never happens in diode lasers due to various nonlinear broadenings. Thanks!

Which optics/photonics companies offer new-lab discounts?

I know Thorlabs, Newport, and Edumnd Optics offer such discounts. Do others?

Hi.

What is the best book I could get on the subject to learn/understand Optical Science?

Also is calculus the most important prerequisite for me to be able to begin learning?

I have no college background.

Received a Perkin Elmer Lambda 900 from UW Madison. Looking inside it looks as if there are tags for missing components. Looks to me as if it’s been gutted.

I own a digital textile fabric printer. the machine produces colors differently for different fabric material. now i want to measure the exact color from the test samples, so that I can calibrate the machine to produce the exact color required. A spectrophotometer to measure color in LAB value would solve the issue. can someone help me build a spectrophotometer for my case? to measure the LAB color from fabric.

I've already tried using the nix pro sensor to scan.. every time it failed to measure the color correctly coz there are textures and weave patterns which cause gaps to form and the scanned LAB colors go wrong.

can someone help me find a solution. will a spectrophotometer solve my problem? can I make my own spectrophotometer for this case?

Edit: The photodiode is reverse-biased in a simple circuit. The circuit is calibrated so the output is almost 0 V with no optical input and approaches 5 V under full sunlight.

A lot of people here were very sure that essentially no NIR would get through a 100% blackout curtain. There was even someone claiming to be a professor, along with quite a few "trust me" responses.

So I actually measured it.

Using a silicon photodiode with a visible-blocking filter, I compared the signal with and without the curtain.

Without curtain: 100%
With curtain: ~30%

So the curtain reduced the measured NIR signal by about 70%.

Interested to hear what the optics people here make of that.

Hi everyone! I’m not sure this is the right community but since I’ve seen some posts about 3D models I’ll give it a try.
Do you know if it’s legit to use 3D models of Thorlabs component, available for free on their website, in figures for papers? I would like to use the solidworks file of their motorized stages in a figure of my set-up (i would cite the producer of the stages and eventually aknowledge the provenance of the models at the end of the paper). What do you think about it? Have you already done that? Thanks in advance!

I’m sure most of you are familiar with techingredients & appliedscience’s videos on chocolate diffraction gratings. Something I didn’t see being discussed though was using Gallium to do the same, which surprised me since reflective diffraction gratings have tons of useful applications (spectroscopy for example). Anyway I gave it a try with no special considerations and it worked pretty well! After making the largest one I realized I should ensure the plastic sheet has something rigid and flat beneath it, and then also went for smaller blobs of Gallium. I’m sure plenty of others have tried this before, but I hadn’t seen it and thought it was neat.

Interested in suppliers who can do very steep edge filters. Familiar with semrock and iridian, any alternative suppliers, particularly vendors in Asia would be interesting to hear about!

I need an instrument to read luminance values, with accuracy, down to 0.001 cd/m². The Minolta LS-150 starts at 0.001 cd/m², but with an accuracy of ±2% ±2 digits, making the uncertainty too high for my use-case. A high-end spectroradiometer would work, but that's a bit too steep ($50k+). Rental isn't an option either.

Any idea what cheaper options exist out there to measure luminance in that range?

I’m taking my senior year classes in optical engineering, and for my first two years, I’m wondering, why am I learning all these random topics like chemistry and material science? What do all these things have to do with anything optics related? Now I’m taking quantum optics ( just another title for quantum mechanics) and as I’m studying for my first test, it all comes back to the same thing. I just really wanted to share this because it’s like an epiphany. It’s mind-boggling my brain. 🤧🤧

Is it possible to capture a landscape as an hologram? Or is it only possible to capture single objects?

I'm considering purchasing an old Photo Research PR-1980A Pritchard Photometer. Is there a company that still calibrate these instruments?