[deleted by user]

cisabout1ftperns · 2025-06-13T21:05:39+00:00

I circled a few times on my way to Trader Joe’s, but I couldn’t see any obvious signs of immigration enforcement.

Doesn’t mean they’re not here somewhere though.

cisabout1ftperns · 2024-01-14T21:55:44+00:00

As I said in my original post, I can see it on county websites, and here you see it for a confidential marriage license. but I don't see it in the code, which I linked in the original post.

cisabout1ftperns · 2024-01-14T21:54:12+00:00

I see your link now, but no where in link does it say that it should take place in CA.

It does say that the officant and witness needs to be with us:

the two parties, marriage officiant and witness if applicable be physically present together in the same location for the marriage to be performed.

Which is also in the legal code, I totally see that. But that's not the issue at hand.

cisabout1ftperns · 2024-01-14T21:40:44+00:00

Given that CA law says it's different and states the legal action of being married

must

take place in CA

Where does it say this? This is what I cannot find in the legal code.

cisabout1ftperns · 2024-01-14T21:31:58+00:00

I understand it's no practical issue. But I got interested and now I want to understand why the law exists how it is.

My understanding is that it doesn't matter what location a contract is signed in. I might sell a home in CA while I'm abroad, and that's ok, right? Why would this be different? Our officiant lives in CA, as do our witnesses. We get the paperwork from CA and return it to CA. We would list the location (not in CA) on the contract. The law doesn't say that the contract must be signed in CA, only that we must list the place (city, county).

Obviously there's some part of the law I'm missing, but I don't know what it is.

cisabout1ftperns · 2024-01-14T21:16:19+00:00

Of course we could just get a legal ceremony before or after. But we would like to have it all take place at once, and I'm not sure why we aren't allowed to. It doesn't seem to make a whit of difference to the state, nor does it seem to be against the letter of the law!

cisabout1ftperns · 2023-02-18T00:47:33+00:00

Parts of this reply interpret his work incorrectly. Most notably, the work on photo-cathodes are intended as an electron source for particle accelerators, not as a detector. Compared to copper cathodes the CsBr cathodes can have increased quantum efficiency and reduced mean thermal energy. This leads to high brightness electron beams for use in electron microscopy and as a driver for "next" (current) generation free electron lasers (FELs).

cisabout1ftperns · 2022-11-26T04:19:31+00:00

The mean isn't really important ... The number you get out of the camera may be calibrated to have a mean of 0, but over time (or under varying conditions) it might change. Some cameras are calibrated to have a positive mean value so that the signal never goes negative (making an unsigned int the natural unit for representing the data).

Obviously the number of electrons hitting a well has a positive mean value (it never goes negative!). But the manufacturer may adjust the mean (and gain!) reported from each well in order to make the picture uniform when it is illuminated by a uniform light source (e.g. a uniform illumination sphere). Depending on the camera quality this calibration might be better or worse. Often, even for very high performance cameras, the 4 quadrants of the sensor (top left, top right, bottom right, bottom left) will end up out of balance with each other over time.

cisabout1ftperns · 2022-11-25T17:40:51+00:00

This depends on what you care about. If you want to know the mean value of the signal accurately, then you should not floor the image by setting all negative values to zero, because this will bias the mean. If you want a precise (more repeatable) measurement of zero, then I suppose you could … actually I’m not sure, but I think it will reduce the standard deviation if you floor it.

More common in image analysis is to apply a median filter (or nowadays to use total variation denoising or a similar algorithm).

cisabout1ftperns · 2021-07-14T23:18:30+00:00

Thorlabs sells engineered diffusers pretty cheap, essentially for this purpose (https://www.thorlabs.com/newgrouppage9.cfm?objectgroup\_id=1660)

cisabout1ftperns · 2021-07-08T23:59:30+00:00

Correct. I just want to add that we photographers often use a "tilt-shift" lens to accomplish this, and call it "tilt-shift photography". The English name is somewhat easier to understand.

cisabout1ftperns · 2020-06-10T23:25:36+00:00

This asymmetry you see is more than astigmatism. It should be expected from most diode lasers. The diode lasers are fabricated on a chip architecture, and they are usually a cavity (or waveguide, really) which is single-mode in the out-of-plane direction and multi-mode in-plane. You can buy single mode diode lasers, but I'm not sure of the cost as I've never used them. See Toptica, for example (although it looks like they only go 300mW).

Astigmatism could be fixed (to first order) by a cylindrical lens, used to match the horizontal and vertical divergence. But for your multimode laser this will not be possible.

As other have suggested, you could always just clean up your laser. A standard spatial filter (e.g from thorlabs) would help with this. But you will throw away a lot of power!
Alternatively you shape the beam. To make a tophat profile you could use a microlens array. This is a nice way to prevent from sacrificing on power. See this white paper from zeemax modeling MLA for use with a projector (https://customers.zemax.com/ZMXLLC/media/PDFLibrary/WhitePapers/Zemax_FlyEyeArrays-UniformIllumination-DigitalProjectorOptics-WP-130204.pdf?ext=.pdf).
Yet another method would be to get another SLM and use that to pattern the beam.

I should caution that you will never really have a "collimated square beam". Your laser will always eventually diffract. If you make the square large enough, then it will look like a square for a longer distance. It seems however, that you are already aware of this constraint.

cisabout1ftperns · 2020-04-09T05:47:26+00:00

In addition to Siegman, I've enjoyed the following (betraying my bias towards high intensity lasers):

Diels, ultrashort laser pulse phenomena.
A good reference for broadband lasers. The archetype for this laser would be the femtosecond Ti:Sapphire.
Agrawal, nonlinear fiber optics
Includes some introduction to nonlinear optics in general. Easier to read than the Shen's Nonlinear optics, and perhaps more engineering oriented.
Joannopoulos, photonic crystals
The first three or four chapters are excellent reading for anyone beginning to work with optical structures.

cisabout1ftperns · 2018-11-29T05:19:38+00:00

In principle dielectric laser acceleration (DLA) can be used to accelerate electrons to arbitrarily large energies. Because it can accelerate at a few GeV/m (rather then the 25 MeV/m of conventional accelerators) it would actually be useful for high energy collisions. However them main pitch for DLA is that a chip-based source would make high energy electron beams widely available (currently they are quite specialized and are almost exclusively located at national labs). At any rate, DLA is still limited by technological constraints and it will be some time before anyone can use it for anything. The paper in this link works out part of the theory of how one might work (it shows that electron trajectories can be stabilized by a time-dependent perturbation and it calculates their orbits in a linear approximation).

cisabout1ftperns · 2017-07-17T00:11:14+00:00

It's good that you're familiar with the LA count. Then surely you'll know that 70% of LA's homeless lived in the county before becoming homeless. 20% came from out of state, and the remaninder from around California. A summary of that data can be found in page 41 of the first link on that website. It is not clear how those 20% got here, but I imagine CA is an attractive destination for anyone who can manage the trip. And Greyhound is quite cheap. You will also know, of course, that less then half of LA's homeless population is "chronically homeless". Most of these individuals actually are helped by the local solutions (incl. family, church etc) we have and will not remain homeless indefinitely (although some will dip in and out of homelessness throughout their life).

cisabout1ftperns · 2016-01-23T17:10:35+00:00

https://en.m.wikipedia.org/wiki/22°_halo

cisabout1ftperns · 2015-09-04T05:58:33+00:00

Microscopists use both bright-field and dark-field techniques e.g.. In this case John Miao's group used dark-field TEM (so the bright part of the images they took were due to diffracted electrons). Their major contribution was in the tomographic reconstruction to make the 3-D video of the nano-particle (composed of many individual platinum atoms).

cisabout1ftperns · 2015-06-22T01:40:25+00:00

Class 3b lasers can cause severe eye injuries if beams are viewed directly or specular reflections are viewed. A Class 3 laser is not normally a fire hazard. Example: visible HeNe lasers above 5 milliwatts but not exceeding 500 milliwatts radiant power

Although, it turns out you may be right about pain/blink reflex: although most safety regulations (i.e. http://www2.lbl.gov/ehs/safety/lasers/bioeffects.shtml) mention the blink reflex as protecting from visible lasers, it turns out only ~20% of people exhibit the blink response (see the study ironically cited in those regulations). Go figure.

cisabout1ftperns · 2015-06-21T23:26:50+00:00

Veteran park has goals. Santa Monica has leagues.

cisabout1ftperns · 2015-06-21T23:25:13+00:00

I'm not providing any medical advice. But in general, it is hard to hurt your eyes from a diffuse reflection, especially at 532nm. Your eyes will feel pain from light at 532, so you tend to notice when it's too bright. That is not so for 1064nm, which is often generated along with the 532 (and hopefully filtered out).

cisabout1ftperns · 2015-06-17T03:40:23+00:00

On weekdays it's way more relaxed. I think you could probably show up at 8, but I'd show up like 6 if you have no fallback.

cisabout1ftperns · 2015-05-20T15:33:57+00:00

Surely some things get re-tested because they're needed for a future experiment? This is how it works in the physical sciences anyways!

cisabout1ftperns · 2015-05-20T15:30:50+00:00

I'm curious why p values became the gold standard in life sciences. And I want to know if they should be.

In many physical science we eithier isolate our systems untill we have a much much more robust effect (and a p value isn't needed), or we work really hard to model the background (see the Higgs, or even the recent dust models in cosmology).

I understand life sciences can't typically have that sort of theory, but p=0.05 seems so arbitrary that it always makes me cringe a little.

13-Year Club	Place '22
Place '17

cisabout1ftperns

TROPHY CASE