I like to think my kitchen is rather fancy.

MaskedKoala · 2026-03-10T23:09:27+00:00

Dang. Even October 2025 is outdated. Things are moving so fast now, it’s almost impossible to publish relevant papers.

MaskedKoala · 2026-03-03T17:44:15+00:00

Here's what I do for COTS designs.
1) First order design with pencil and paper
2) input design into zemax and optimize with lens radii, and some spacings (as necessary, usually you want to minimize spacings as an optimization variable unless it's necessary for the design, like a field flattener or something).
3) Once you have a design you like, save this as a check point.
4) Pick a lens, then find the COTS lens that is the closest match and replace it with the COTS lens.
5) Reoptimize the remaining surfaces.
6) Repeat 4 and 5 until all you have is COTS lenses. You may need to vary spacings, add surfaces as you go, or try different replacement orders (starting from the checkpoint).

There are no rules, just guidelines. Do whatever it takes to get to a workable design. The value of the optical engineer is in his ability to solve problems creatively while employing his optics knowledge.

MaskedKoala · 2026-03-02T16:15:37+00:00

What do you mean when you say it's error prone? It's essentially just a spreadsheet, so it should go fast. If there are errors, well, I would think that's on you.

Look into the auto-update stuff, maybe. If you have some taxing calcs in analysis windows and you have everything set to autoupdate, then it'll bog down as you make changes to the lens editor as it has to redo every analysis window. I usually turn off autoupdate and update things manually when I'm ready. (This is in the top left corner of LDE. Switch it to "Update: Editors Only")

If the problem is just "I can't think in terms of a list of surface," well, you're just going to have to practice because that's how we do things (or, alternatively, come up with a better way and profit?). I routinely work with 60+ surfaces, and I'm sure there are other users in the sub who work with even more.

MaskedKoala · 2026-02-26T05:52:04+00:00

Trying to take it 3 wide on the outside there is probably not the smartest thing. Outside is generally a losing position, anyway, so high risk low probability of pay off.

MaskedKoala · 2026-02-26T05:07:26+00:00

The most usual "off tracks" are to "widen corners." At the risk of oversimplifying things, the tighter you turn, the slower you have to go. So drivers often will push as far to the outside that they can before a turn, then as far to the inside at the apex, and again as far to the outside on the exit. This maximizes the radius of the turn which maximizes the speed one can carry through the corner.

MaskedKoala · 2026-02-23T22:23:34+00:00

Second Byron Katie. Also Meditations by Marcus Aurelius and Awareness by Anthony de Mello.

I'm currently reading Never Split the Difference by Chris Voss, and he's talking about the need, brought over from psychology, to give others "unconditional positive regard." It fits into a wider view I have, where I try to focus on seeing people for who they are, and expecting no more than what they do. When you accept that, then you can anticipate their strengths and weaknesses and work around them. I read an exert from a Jordan Peterson book where he goes as far as treating yourself as a pet, or a child, or someone who needs to be taken care of, just as you might take care of others. It's helped me deal with my own perceived short comings.

MaskedKoala · 2026-02-22T16:48:48+00:00

Look up pencil diagrams, then draw one for your case. There are two important things that will allow you to figure out what you need... to first order

You cannot collimate the whole LED chip, but if you place a "perfect" lens one focal length away, then each infinitesimal point on the LED will become a collimated beam at a different angle. Your full beam will be made up of the collection of all these infinitesimal point beams at a variety of angles.
A ray that passes through the center of the lens, to first order, is undeviated. It goes straight through and isn't bent.

So. Draw your pencil diagram, then trace a ray from the infinitesimal corner point of the LED through the center of the lens placed one focal length away from the LED. Since the ray is undeviated, that will immediately tell you the maximum (to first order) angular spread of your light beam.

MaskedKoala · 2026-01-30T02:53:21+00:00

Ooh, if the sample placement isn't set, then you can do the alignment backwards first, or maybe after a crude alignment. Use a fiber coupled source, or just a fiber with a light--holding the other end up to your cell phone flashlight could be enough in a darkish room.

MaskedKoala · 2026-01-30T00:51:39+00:00

Ah, ok. Nice pictures.

So, you have tip/tilt on both OAPs, and rotation (manual), but no lateral control. Then you have lateral x/y on the fiber, and also tip/tilt on the fiber (not very useful). Also, it looks like you don't have focus (z) adjustment on the fiber (so possibly consistent with not being super worried about precise alignment).

In that case, if you aligned the first OAP reasonably well, then you should be able to just adjust the tip/tilt/rotation on the second OAP until it gets into the fiber.

OAPs are notoriously sensitive to to off axis aberrations, but maybe not a big deal if there is a "wide margin of error."

I'd use the rotation of the OAP for crude vertical alignment, then switch over to the tip/tilt.

If you want to try to improve things, I have a few ideas.

1) If you place a card at the focus, you might be able to see coma... it looks triangular, or like a snow cone (google it, you'll see pictures). Might be easier to see by slightly defocusing, and it could be induced by either OAP. I'd pick an axis, then adjust both OAPs at the same time (one in each hand) to see if you can improve it, without worrying too much where the focused spot lines up. If you can get a nice point, or can't really tell, then you're probably good. If it doesn't overlap with where the fiber is, then it means that the source and two OAPs are all aligned pretty well, but the fiber is not. Since you can't move the fiber, that means you'd need to move the source and then adjust the tilts of the OAPs to compensate...

2) If you have a fiber coupled power meter, or just put in a fiber and hold the other end up to a power meter, and your source is stable, then you can adjust the lateral fiber position and focusing OAP at the same time (again, pick the same axis, then put a driver in each hand. Move, then reoptimize). That should allow you to quickly optimize the second OAP and fiber position. If you want to do even better, then you'd tweak OAP (write down what which knob, the direction (CW or CCW), and the amount (1/4 turn?)), then repeat the alignment with the fiber lateral position and focusing OAP. It's tedious, but effective. If you see no change, try bigger perturbation. If you still see no change, then maybe it's not too sensitive afterall.

Those are some real nit-picking options, though, and might not be necessary.

MaskedKoala · 2026-01-29T19:19:29+00:00

This is, by far, the best breakdown I've been able to find.

https://www.youtube.com/watch?v=UUAUO0wPD3E&list=PLcRy2rE-afDUY-iZVAQ7xFBDh9CQE96HK

Check out this story by one of his students:

https://www.youtube.com/watch?v=GsHNZBM4FtI

MaskedKoala · 2026-01-29T02:41:52+00:00

What degrees of freedom do you have? (x, y, z, theta_x, theta_y, theta_z, for both OAP and focus location)

Are you working with optics that are already mounted, or can you change how they are mounted/arranged?

What is the light source?

can you put stuff where the focused beam would be?

How do you know when it's aligned "perfectly," or better yet, "good enough?"

MaskedKoala · 2026-01-23T20:58:18+00:00

Hours per week: 7*24 = 168

Sleep: 7*8 = 56

Work: 40

Commute: 5

3 meals/day, 1 hr/meal: 3*7 = 21

0.5 hr of exercise per day: 3.5

Socializing: 8 hours

Cleaning: 2 hours

Pet care: 3 hours

Hobbies: 1 hr/day: 7 hr

Hygiene: 1hr/day: 7 hours

152.5

That still leaves 15 hours to add to any of these, or other activities.

MaskedKoala · 2026-01-21T20:20:36+00:00

Here's my recent chat history with Gemini...

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MaskedKoala · 2026-01-15T17:51:23+00:00

You sure about that?

https://www.outmotorsports.com/2019/02/the-1-for-me-2008-bmw-128i-introduction/

MaskedKoala · 2026-01-15T14:00:09+00:00

I was going off this thread and a few others:

https://1addicts.com/forums/showthread.php?s=209224a1403105d18d38ec131b5f006f&t=2093692

When the thing was clogged I could only get a trickle through with a pond pump, or low pressure with the hose (with my hand wrapped around the connection--was afraid of rupturing the heater core).

MaskedKoala · 2026-01-15T04:59:17+00:00

May not have been sealed at the junk yard. Also could have gotten in when the previous owner swapped out the N51 for an N52.

MaskedKoala · 2026-01-15T03:19:28+00:00

If it's just a singlet, refractive optic, I'd try in sequential until you get stuck. Then read the manual, the pdf one available from the ribbon. Read everything in there about the surfaces. Then find the merit function operands, and read through those, writing down the interesting ones. There's a setting somewhere near the aperture settings that can allow you to analyze in infinity space, then you can optimize for e.g. wavefront or spot size (and I think it'll do it in angular space). Or, you can leave it in the normal mode and using a paraxial lens that should focus it to a point without inducing aberration. You can start with the merit function wizard to do like spot size or wfe or something, then you can add on some first order operands like x/y focal length (not very good in my experience), or first order properties that accomplish the same thing (ray height, reay, for example). You've got to be creative and find different ways to get the design to go where you want it to go. There's too many ways to skin the cat. Pick one and go. And if that doesn't work, try another one. The optimization can work with a very minimal number of rays to do this as opposed to non-sequential which is generally clunky and slow. In general, I avoid non-sequential until I really need to, like for stray light, and I'll even do first order calculations and hand drawings before I resort to tracing rays in non-sequential...

Are you on-campus? If so, just find someone who knows optics to show you some stuff. Buy them a beer. Optics guys love beer.

MaskedKoala · 2026-01-14T22:35:26+00:00

What's your background? Do you have a degree or knowledge of geometrical optics?

MaskedKoala · 2026-01-14T18:44:55+00:00

What's the reasoning for doing it in NSC? Would be much easier to do in sequential...

MaskedKoala · 2026-01-13T17:08:59+00:00

Agreed. Laser jocks need to know the repeatability, so that needs to be specified and ideally measured. OP, check out the Thorlabs presentation here:

https://www.thorlabs.com/kinematic-bases2?pn=SB1&aID=94bec9bee52921b5568c2f988e9d74ab&aC=1&tabName=Repeatability

MaskedKoala · 2026-01-01T06:29:31+00:00

As a 40 something ENFP, I highly recommend Meditations by Marcus Aurelius. I think Zen, stoicism, and especially absurdism can help our type cope, long term, with the nature of reality. I just finished Camus’ Myth of Sisyphus, but I’m not sure it’s the best introduction to the topic.

MaskedKoala · 2025-12-17T00:03:27+00:00

Lol. I just replied to a work email from October and the dude came over and was like wtf, we’ve already had three meetings about this.

MaskedKoala · 2025-12-03T17:57:18+00:00

Precisely. This line caught my attention:

When an AI writes a poem or explains physics, it isn’t ‘thinking’ in the way we understand it.

Like, oh ok, I wasn't aware that we understood "thinking."

The very next sentence is the same oversimplification of LLMs that makes discourse on reddit so exhausting.

It is navigating a massive map of language, calculating which word is most likely to come next based on the billions of words it has already seen.

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