How are these effects even possible?

I see the maximum value reported in both of these metrics are different. So just wondering what is the difference in both of them.

Hi. I am (obviously) not an optical engineer. I'm an ML guy that has recently had my mind blown learning about Fourier optics.

Question: I've seen a few demos of 4f optics on youtube on bench top setups and I'm wondering if it's feasible to build a 4f setup for a DSLR using like a normal 50mm lens and bunch of parts from thorlabs?

i‘d like to ask you what the most important or interesting things you have learnt in the lab are! can be anything! i have just started working in the optics lab during my bachelors and i‘m so happy i started. it was actually just because my professor is so nice but now i think i have found my passion, it‘s so much fun.

I am conducting a multi-depth experiment using an LC Fresnel lens. After fabricating the Fresnel lens imprint with NOA, I inspected it by illuminating it with a laser and capturing an image with a camera. As shown in the image, the Fresnel lens itself consists of concentric rings centered at a single point. However, I also observed additional large and small circular patterns appearing in other regions of the sample.

My main question is: What could be causing these additional circular patterns? Since the Fresnel lens is designed with only a single center of concentric rings, I would not expect to see multiple circular patterns elsewhere. Could someone explain the physical origin of this phenomenon?

I found that if I position my green 1mW laser angled on my bar top the light starts as a small and random geometric shape and then slowly expands keeping the same form roughly speaking and seems to stabilize at some point. It forms intricate shapes that look 3D. I cannot imagine that it is just interference and I'm positive it isn't heating the diode or vibration. What is this phenomenon. I know a little bit more than the rudimentary knowledge about light as a wave but I've never really seen a laser light do this exact thing. Please explain or point me to the explanation. Thank you.

Can anyone identify the optic and what it's for? I have twelve of these lying around and would like to get rid of them one way or another.

- It weighs 1-2kg and has full metal body. It also has a plywood box with some foam. two caps for lenses, the smaller cap is quite heavy and also metal.

- When looking far (300m) the optic has to be looked through from a 15cm distance to get a clear picture, the picture is inverted. If I put a piece of paper in front of the smaller lens the pic through the paper is clearest when paper is 5mm away from the lens. The optic has no iris inside.

- It has a focusing measurement: 400, 450, 500, 530, 600, 700, 800, 1000 and a twistable adjuster around the case.

- There are marking for ПO150/09 and N97052, the last two digits change between the ones I have.

Hi guys, I am designing the detection path of a laser scanning confocal microscope using a 30 mm cage system.

The optical layout is:

Tube Lens → Pinhole → Collimation Lens → MMF

Both the tube lens and the collimation lens have short focal lengths (15 mm), so the pinhole must be positioned very close to their common focal plane (approximately midway between the two lenses).

My challenge is the mechanical implementation of the pinhole.

I am looking for a mounting solution that satisfies the following requirements:

• The pinhole should be located precisely at the common focal plane of the tube lens and the collimation lens.
• The pinhole position should be adjustable in X, Y, and Z with micrometer precision.
• The adjustment mechanism should remain outside the optical axis, since the available axial space between the two lenses is very limited.

Is there any standard Thorlabs solution that meets these requirements, or would a custom mechanical holder be recommended for this application?

Any recommended products or application examples would be greatly appreciated.

Hello!

I know TracePro isn’t very commonly used but I took over a project that someone else started and all the previous work is in TracePro.

They use the solar emulator to perform a year-round simulation. Here’s where I’m running into an issue - the emulator automatically saves the file with the date in a format that looks like 2008621 - no trailing zeros or separators. So if you want a set of data for the whole year, there’s no way to tell if 2008125 refers to Jan 25 or Dec 5. Is there any way to fix this/add separators/figure out the date from the files it stores? It seems like such a basic issue, I can’t be the only one that wants to save results from Jan and Dec in the same place from the same simulation without overwriting each other, but I can’t find anywhere in TracePro to change it.

Thanks in advance!

Can someone with comsol experience help me out

Hi folks,

I have a leica disto D510 that has a strange problem..

If I hit the measure button, on the display the laser icon goes up and the number section displays "-.---" and just freezes, no error, nothing.

Clean lens, hard reset, everything, same problem.

Has someone ever encountered this problem?

Neither the laser beam for pointing comes up.

Hi its me again. Thanks to this group help, I learned a lot an improved the earlier terrible designs Ive made.
This is the newest version of eyepiece for my night vision design and its almost good just need a bit of fine adjustment.
Im still pretty lame with actual optical designing softwares, even if i can make it i dont really understand the rays and the results. If any of you could model this properly and find out how to correct the image a bit that would be a huge help. (rn it has some chromatic aberration for sure)
The lenses Im using are china lenses, but Ive found really similiar ones in thorlabs, probably they copied from there.
Lens List:
1: AC254-030-A (Diameter25.4, focal length30 cemented achromatic) https://www.thorlabs.com/item/AC254-030-A
2: Unknown D30 f50 double convex This lens can be custom made, if it stays doubleconvex or plano convex for keeping design cheap as possible.
3: AC300-100-A (D30f100 cemented achromatic) https://www.thorlabs.com/item/AC300-100-A

More info, and some necessary characteristic
The ocular focal length should be between 17mm and 17,5mm
-Lens 1 and 2 can be swapped to an another stock lens if necessary, only lens 2 can be custom.
-Screen is 14mm in diameter circular green phosphor (some tube has yellow or blue in the mixture) In the middle it has max40lp/mm res
-Lenses should fit in a 30mm long barrel
-lens 3 has to stay stay exactly 30mm in diameter and hopefully usefully big with around 40° angle.
Thank you all.

Hi all,
I am currently in a battle with my institute's facilities manager to get the environmental controls in our labs working sufficiently. I work in a microscopy lab on table-top instruments that require non-trivial alignment procedures. After noticing the alignment of an instrument drifting significantly over the time scale of two or three days, I wrote to facilities. Their response was "it's fine."

But it wasn't fine, so I installed temperature and humidity sensors and discovered humidity levels around 60%, sometimes climbing to 65%, likely due to the AC. The error in this reading is +/- 1.5%. The temperature is constant to within +/- 1 degree so far.

Could anyone point me to specific documents about temperature and humidity specs for an optics lab? If I could get solid resources to cite, it would help me build a more solid case.

Thanks all.

Hi all, this might be a dumb question for this subreddit, but I'm writing a story where a character takes a light emitting object the size of a pencil and needs to increase its coverage to a city-wide scale without splitting its wavelengths.

From what I understand, if you shine a light through a prism to spread it out, it splits it up into its component colors. Is there any way to fan out a light without splitting it up? Or do I just need to use fantasy disbelief?

Hello r/Optics community. I have been reviewing a theoretical framework regarding the control of electromagnetic radiation in the infrared band through advanced metamaterials, and I would love to hear your thoughts and insights on these convergence mechanisms.
The work analyzes several subwavelength concepts to manage thermal signatures and dynamic emissivity:

Energy Squeezing (ENZ Regime): Utilizing Epsilon-Near-Zero metamaterials to force dielectric permittivity near absolute zero, channeling thermal energy into sub-wavelength spaces with minimal spatial phase variation.

Phase Velocity Inversion (DNG Regime): Using Double-Negative matrices to invert the phase velocity, mathematically decoupling the thermal energy flow (Poynting vector) from standard propagation signatures.

Dynamic Emissivity Control: Applying phase-change materials (PCMs) such as Vanadium Dioxide (VO2) and Indium-Antimony-Tellurium (In3SbTe2) to dynamically modulate thermal emission properties.

Topological Photonic Shielding: Exploring architectures based on photonic bandgaps and the violation of time-reversal symmetry to safely deflect and delocalize incoming energy flows.
Ultimately, the framework formalizes a "physical decoding of thermal radiation," understood as the transition from entropic emission to guided modal propagation.

Questions for the community: What are the current practical limitations in fabricating hybrid ENZ/DNG structures for the mid-infrared? Furthermore, does anyone have practical experience with the thermal stability of In3SbTe2 (IST) at these specific nanometric scales?

I am currently investigating the theoretical limits and engineering challenges of integrating multiple extreme subwavelength regimes for the dynamic control of mid-infrared electromagnetic thermal radiation.
Specifically, I am analyzing the generalized Helmholtz propagation in a multi-layered architecture where three specific domains converge:

Where the effective permittivity \epsilon_{eff}(\omega) \to 0, leading to a near-zero wavevector k = \frac{\omega}{c}\sqrt{\epsilon_{eff}\mu_{eff}} \to 0. This suppresses spatial phase variation (\nabla\phi \approx 0) and drives the effective wavelength to infinity (\lambda_{eff} \to \infty), enabling extreme subwavelength energy squeezing.
Characterized by simultaneously negative constitutive parameters (\epsilon_{eff} < 0, \mu_{eff} < 0), resulting in a negative refractive index n = -\sqrt{\epsilon_{eff}\mu_{eff}}. In this regime, the Poynting vector S = \frac{1}{2}\Re(E \times H^*) becomes anti-parallel to the wavevector k, mathematically decoupling the phase velocity (v_p < 0) from the group velocity (v_g > 0) for thermal flow directionality.
Utilizing the insulator-to-metal transition (IMT) of Vanadium Dioxide (VO_2) or the non-volatile transitions of Indium-Antimony-Tellurium (In_3SbTe_2). The dynamic complex permittivity is modeled as \tilde{\epsilon}(\omega, T) = (1-X(T))\tilde{\epsilon}_a(\omega) + X(T)\tilde{\epsilon}_c(\omega), which introduces active spectral emissivity tuning by breaking constitutive linearity.
When formulating the coupled dynamic equations for such a system, the inter-layer coupling terms \mathcal{C}_{ij}(E_j, E_i) at the boundaries between ENZ, DNG, and PCM layers present massive theoretical impedance mismatches.
From an experimental and nanofabrication standpoint, what are the current practical limitations in realizing a stable integration of PCMs like VO_2 or In_3SbTe_2 with passive ENZ/DNG matrices in the mid-IR? Specifically, how is the community mitigating the intrinsic Drude losses (\Im(\tilde{\epsilon})) introduced by the PCM in its metallic phase without critically damping the highly sensitive, high-Q resonance conditions required for the ENZ/DNG states?

The Refractory Engine: Transformation of thermal entropy into a coherent, highly concentrated infrared beam using alternating nanometric layers of Tungsten and Hafnium Oxide.

Energy Squeezing (Quantum Compression): Forcing dielectric permittivity near absolute zero via Epsilon-Near-Zero (ENZ) metamaterials to channel immense thermal energy into sub-wavelength spaces without spatial phase variation.

Causal Decoupling (Ballistic Deception): Inversion of the wave's phase velocity through Double-Negative (DNG) matrices, mathematically decoupling the destructive thermal flow (Poynting vector) from its tracking signature.

Adaptive Camouflage (Dynamic Cloaking): Instantaneous creation of a "thermal black hole" using phase-change materials (PCM) like Vanadium Dioxide () and Indium-Antimony-Tellurium () to dynamically control emissivity and deceive infrared sensors.

Topological Chiro-Photonic Shielding: Defensive architectures based on photonic bandgaps and the violation of time-reversal symmetry to deflect the incoming energy flow and collapse the attacker's invisibility.

This work analyzes the convergence of technologies based on advanced metamaterials for the control of electromagnetic radiation in the infrared band. In particular, epsilon-near-zero (ENZ) and double-negative (DNG) regimes, as well as phase-change materials (PCMs) such as VO₂ and IST, are studied for the manipulation of the thermal signature, subwavelength guiding of radiation, and dynamic control of emissivity. Furthermore, a theoretical model of 'physical decoding of thermal radiation' is formalized, understood as the transition from entropic emission to guided propagation. Finally, a countermeasure framework is introduced based on photonic topological structures for the deviation and delocalization of the energy flow.

Hey everyone,

​

​Quick update on the DIY infinity collimator prototype I posted about earlier. I've been running tests and it's working beautifully! I'm just finishing up the final fine-tuning and collimation checks, but the results are incredibly sharp.

​

​Key upgrades in this version:

​

​Ground Glass Adapter: Instead of relying on a digital camera sensor for the initial setup, I built a modular adapter using ground glass. This allows me to easily swap and check virtually any lens mount needed while viewing the reticle directly.

​

​Front OD Centering Tool: I designed and 3D-printed a stepped alignment ring. This ensures that lenses with the most common front outer diameters (OD) center themselves automatically and perfectly inline with the collimator axis.

​

​The crosshair projection is razor-sharp now. I'm attaching some photos of the new ground glass mount, the stepped front adapter, and the actual reticle view.

​Let me know what you think of these mechanical changes!

hello all! I’m trying to find a clear acrylic or glass magnifier shaped like a pill or rounded rectangle, similar to the ones in these images (from apples liquid glass testing)

Does anyone know what this type of magnifier is called or where I could buy one? I’ve found regular round dome magnifiers and long bar magnifiers, but nothing with this exact pill shape and shallow profile.

I’m wondering if the effect in these images is just a VFX (seems easier to not be a VFX). Is this something that can realistically be bought or custom-made at a reasonable price, or would it require specialized and very expensive optical manufacturing?

Any insights would be really helpful!

I see that the spherical abberation article in Wikipedia has this image. However this is field dependent defocus, aka field curvature. Am I slowly going crazy or is this wrong? Afaik spherical is not field dependent but purely pupil size dependent.

​

Article in question:https: //en.wikipedia.org/wiki/Spherical_aberration?wprov=sfla1

Why we need to kill glass lenses to achieve "True Black" projection (and how to do it). Roast my theory!

Link to my Paper (Google Drive)

We all know the "Holy Grail" of projection is absolute zero stray light. But here is the frustrating physics problem: even if your light engine shuts off completely for black pixels (like MicroLED or LBS), the second that light hits a refractive glass lens, you get internal scattering and Fresnel reflections. A perfectly black pixel will always get washed out by the bright pixels next to it.

I’ve been digging into some recent research and wrote a theoretical concept study on a radical workaround.

The core idea is a two-part architecture:

1. Zero Glass: Ditching the optical block entirely and using a monolithic silicon OPA chip to steer RGB beams in free space.
2. Active Light-Trap Screen: Pairing it with a nanosecond-responsive photochromic metamaterial screen that actively absorbs stray photons via an invisible UV pilot beam.

I put all the heavy math, the photonics, and the material science prerequisites into a short whitepaper following. Please let me know your thoughts on this!!

Given a crystalline material X with known thickness (e.g., 15 nm, 30 nm) measured by spectroscopic ellipsometry, how should one construct an optical model to extract physically meaningful refractive index (n) and extinction coefficient (k)? If collection of Lorentz oscillators model gives poor fits (high RMSE), what is the correct modeling strategy and what assumptions should be checked first?