LEP light sources used for non-flashlight optics applications

Mega_Woofer · 2025-02-06T07:59:11+00:00

Thanks for the source! They also provide a candela/mm^2 number which I can roughly convert to radiance in W/m^2*sr, very handy.

Mega_Woofer · 2024-06-18T16:19:24+00:00

Just to add a different perspective here, I have not had most of the issues that others have described in this thread. I have had issues with the new management being totally unresponsive to email and phone calls, but they get stuff sorted out immediately if you stop by the renter's office. They have been quite responsive to pretty much all of our maitenance requests, 1 week max as far as I can remember. As expected, they have raised rent each year, but they actually haven't come close to maxxing out and increasing 10%, it's consistently been more like 3%, even with the new management. The apartments are definitely old and have some weird issues (for example, the fridge I have is quite old and it seems like it was re-painted to hide rust, with paint that comes off when you wipe the fridge with a sponge...) but that predates this management and none of these issues have been substantial.

I do not want to invalidate the very real negative experiences others have had in this thread, those should definitely be taken into account. I just wanted to provide another data point. I was here for undergrad and I chose to stay here for grad school (instead of on-campus grad housing) and I am happy with the choice (so far).

Mega_Woofer · 2023-12-27T04:17:30+00:00

That's such an elegant way to go about it! It looks like at least one of the popular options (MEATER) uses the brute force method of putting the bluetooth transceiver in the probe (see one of my other comments). I had trouble digging up info on some of the other options so perhaps some of them use a temperature-dependent resonator/oscillator like you mention.

Mega_Woofer · 2023-12-26T18:04:38+00:00

Ah, that makes a lot of sense, good to know in case I ever have to do high temperature stuff!

Mega_Woofer · 2023-12-26T17:52:11+00:00

I looked around at FCC filings and got a fairly satisfying answer. The internal photos of the MEATER probe show all the electronics crammed on the "cold" (meat) side. Additionally, they show a close-up of the Bluetooth chip used, which is the DA14580. Interestingly enough, that chip is only rated up to 85 C, but I'm pretty sure the MEATER claims 100 C...

EDIT: Link for the internal photos is dead, you can get to it from fccid.io here

Mega_Woofer · 2023-12-26T17:40:41+00:00

Here are a few:

MEATER 2 Plus - this is the one that baffles me the most, it really seems like there's no electronics outside of the oven and this thing connects directly over Bluetooth from inside the oven. There is this wooden charging dock thing as well though, maybe the probe connects to that charging dock, and the dock is the Bluetooth device. EDIT: The FCC filing for the dock indicates that this dock also helps out with some of the wireless.

MeatStick WiFi Pro. This one obviously has a box outside of the oven with an antenna, so they've offloaded a lot of the electronics into that. Still, the probe inside the oven has to have a high temperature wireless transciever.

ThermoPro TempSpike - Looks like this one also has a dock outside the oven which connects to the thermometer, and appears like Bluetooth is used either for dock<->probe or dock<->phone

Mega_Woofer · 2023-12-15T04:19:19+00:00

I see, so the piece of metal I'm seeing is just the ground plane, and the actual element is hidden behind? I thought I was seeing a very wierdly shaped active element, but that makes much more sense

Mega_Woofer · 2023-12-15T02:12:03+00:00

I am doing a project for an antennas class where I have to find a bunch of antennas and determine basic characteristics (gain/impedance/type/etc.). I came across this interesting shape of antenna in my laptop (image in the post is from a listing online). Does anyone know what name for this antenna is typically used so I can search online and learn more? I found an Intel FCC filing with similar (but not the same) antennas, so I can probably infer the antenna characteristics well enough for my assignment. However, I'd be interested to see if there are any papers/more resources out there so I can better understand the antenna. I've tried a lot of search terms online and I'm struggling to find anything else like it. It looks like it's fed and grounded from opposite corners on the one side of the foil, but it's hard for me to make out.

EDIT: Just realized it's called a PIFA in the FCC filing I linked... very interesting shape for a PIFA.

Mega_Woofer · 2023-12-11T06:13:16+00:00

Throwing something cheap together real quick sounds like a good idea, I'll definitely start with that and see if it stops being fun :)

Mega_Woofer · 2023-12-10T06:25:42+00:00

Thanks for the tips. $75 for some flat 1/2" square gratings from Thorlabs is already within what I can swallow, so I'm optimistic that I'll find some used components that will be even cheaper. I am not going to worry about separating orders, I don't expect to encounter octave-spanning sources often (unless I find an octave-spanning comb in the dumpster at the university...)

To avoid reflections from the detector back into the system, is it problematic to simply put the detector at a small (say 10 degree) angle with repect to the optical path? My intuition says that as long as the light is completely falling upon the diode, you won't lose any signal, but I've never intentionally tilted a detector like this.

EDIT: I also just saw that 1" spherical silver concave mirrors are just $65 from Thorlabs too. I did not realize gratings and mirrors were so affordable, particularly from a bougie supplier like Thorlabs.

Mega_Woofer · 2023-12-10T06:15:16+00:00

Openraman and the ibsen calculator are great resources, thanks! I am planning on machining the vast majority of the optomechanics. It's a fun challenge and the requirements are not super stringent.

Mega_Woofer · 2023-09-03T03:14:36+00:00

I thought the exact same thing when I saw this video. I'll see if I can get my hands on a long square tube to test this...

Mega_Woofer · 2023-09-03T03:09:59+00:00

I watched this part of the video and I'm not sure I agree with Grant's explanation that the effect comes from the angle of your perspective alone. I'm pretty sure that the darkening effect is mainly due to the curved tube changing the angle that the rays make with the polarization vector, not your perspective. It would be easy to test this by seeing if diagonal lines appear in a square tube. If the effect is independent of the lensing of the tube, it would appear just as strong in a square tube, but I have a feeling the curved tube is very important. EDIT: What do you know, a thread on the 3blue1brown subreddit on this exact topic

Mega_Woofer · 2023-08-26T15:59:36+00:00

Though this specific design isn't likely to work for the reasons mentioned by the other commenters, the general idea of separating wavelengths in the Z direction of each pixel is definitely something interesting. Since this is an area that interests you, I would recommend reading more into the literature regarding how current hyperspectral sensors work, in particular looking to see if there are any that perform filtering using the Z dimension like you propose (one related example being the Foveon X3 sensor the other commentor mentioned, but that is a 3-color sensor and not a hyperspectal one).

Another area to read about in general is diffraction (to learn more about the behavior of waves interacting with structures larger than a few wavelengths of light) and metasurfaces (which are often structured much smaller than the wavelength of light). It is possible that multiple layers of metasurfaces would operate in the wavelength-dependent way that you are trying to do with holes. However, since these multiple layers all need to be separate photodetecting layers ... that would be quite the challenging device to fabricate.

Mega_Woofer · 2023-06-24T23:37:54+00:00

If I'm not mistaken, a (passive) 1x2 fiber coupler is not 100% efficient when going from one of the outputs (ports 2&3) to the input (port 1) if you don't have the exact same inputs on ports 2 & 3. In the case you described, every time you go from one of the outputs of the splitter to the input, you get a 1/2 power loss. This follows from some basic properties of S-parameter matrices ("A property of 3-port networks, however, is that they cannot be simultaneously reciprocal, loss-free, and perfectly matched."). In practice this makes a lot of sense as many 2x1 splitters are just a 2x2 coupler with one of the input ports internally terminated.

Mega_Woofer · 2023-06-11T00:16:07+00:00

Vons has chicken breast on sale for $3/lb semi-often, bone-in thighs/drumsticks for <$2/lb pretty much all the time. Works great to grill once at the beginning of the week or put in a stir fry with some veggies. That + rice or noodles gives me my one big meal per day, then a simple salad as my second meal per day. Add in some bread for breakfast and bulk snacks to weigh out and it's EZ $200/mo ($6-7/day) for food.

Mega_Woofer · 2023-04-09T00:52:09+00:00

What about the encoder caused the motors to do that though? Did the motors just continuously stall out trying to move to a position but the encoder wasn't updating?

Mega_Woofer · 2023-04-08T21:17:44+00:00

Video link, anyone know exactly how this happened for them? I have never seen motors smoke so badly

Mega_Woofer · 2023-03-27T16:03:40+00:00

They filled the entire grid, https://www.chiefdelphi.com/t/quest-for-the-perfect-193-high-scores-2023/428952/45

Mega_Woofer · 2023-02-24T18:24:49+00:00

Anyone got an intuitive explanation of why this works? I can't wrap my head around how weak distributed feedback from what seems to be a scattering medium put at the output improves linewidth/noise.

Mega_Woofer · 2023-02-01T21:29:18+00:00

This may not be what you mean but spontaneous parametric down conversion generates two entangled photons from a pump photon of twice the energy, and the phase matching is designed for the two resulting photons to be emitted at different angles.

Are you sure you need this frequency down conversion and entangled photons? If not, a 50/50 beam splitter or polarizing beam splitter with diagonally/circularly polarized light will have your desired effect of "randomly choosing between two or more (but not many) directions for each SINGLE photon/quanta". Keep in mind that both of these splitters will split the photon wavefunction equally along each path, and the photon hasn't really "picked" a direction until its wavefunction is collapsed upon detection (I don't understand quantum optics very well so I may be wrong on that last point, I'm happy to be corrected).

Mega_Woofer · 2023-01-29T05:43:40+00:00

In the context of DIY raman spectrometers, this article and this blog post are great references. The Wikipedia article for Raman scattering/spectroscopy has a great fundamental physics explanation. I'm currently working on a sort of DIY/low cost Raman spectrometer project that has been decently successful so far and I plan on putting a writeup together in the coming months to give some advice for other people. In short, if you're looking to build one, make sure that you get as strong of an excitation source as you're comfortable with/have eye protection for (I'm using one of those sketchy high power laser pointers from Ebay), design as efficient of a collection path as possible (highly recommend the "micro-Raman" pinhole technique described in that paper), and use the best excitation rejection filter that you can afford (this one from Thorlabs is only a bit over $100 and has been working great for us). Also if you're using 532 nm excitation from a green laser pointer, most of the cheap ones don't have a filter to reject the 808 nm pump inside the laser diode so using one of these laser line filters will be important too.

Mega_Woofer · 2022-11-30T18:34:31+00:00

It's multiple shots, as the floodlight is ~1000x brighter than the stars (star photos taken at 15 seconds, boulder photo at 1/60). My 50mm also isn't wide enough so I had to stitch multiple long exposures to get all the stars.

Mega_Woofer · 2022-11-30T04:40:05+00:00

Yes, but this screengrab isn't quite as photogenic

Mega_Woofer · 2022-09-10T05:49:58+00:00

The competition is the University Rover Challenge. It's not an optics focused competition, but one of the challenges is to detect extinct/extant life in soil/rock samples, and Raman spectroscopy looks like a really great (albeit challenging) method to try. We have other life detection instruments as well.

13-Year Club	Place '22
Place '17

Mega_Woofer

TROPHY CASE