Black v Gray Cermark, whuuuUUTT?

[Kev Williams]

Now, according to their website, seems I don't want plano-convex:

"Plano-convex lenses, the most economical transmissive focusing elements available, are ideally suited for laser heat treating, welding, cutting, and infrared radiation collection where spot size or image quality is not critical."

--I'm kinda thinking for my needs, spot size and image quality IS critical! Their description of meniscus's...
"Meniscus lenses are designed to minimize spherical aberration producing a minimum focal spot size for incoming collimated light."

Virtually all laser engraver lenses for sale on ebay are meniscus lenses-- and of all the plano convex lenses for sale on ebay, almost all were clear not yellow, and for totally different machines and/or purposes...

I did buy 3 ii-vi lenses off ebay yesterday, two 2"ers and a 2.5"er, so I'll be reporting back with results when they get here...

[Gary Hair]

Hopefully you didn't order meniscus - they are not what any laser we (the "royal we") use.

https://www.quora.com/Whats-the-diff...d-biconvex-one

Now, according to their website, seems I don't want plano-convex:

"Plano-convex lenses, the most economical transmissive focusing elements available, are ideally suited for laser heat treating, welding, cutting, and infrared radiation collection where spot size or image quality is not critical."

--I'm kinda thinking for my needs, spot size and image quality IS critical! Their description of meniscus's...
"Meniscus lenses are designed to minimize spherical aberration producing a minimum focal spot size for incoming collimated light."

Virtually all laser engraver lenses for sale on ebay are meniscus lenses-- and of all the plano convex lenses for sale on ebay, almost all were clear not yellow, and for totally different machines and/or purposes...

I did buy 3 ii-vi lenses off ebay yesterday, two 2"ers and a 2.5"er, so I'll be reporting back with results when they get here...

[Kev Williams]

https://www.ebay.com/sch/i.html?_fro...+lens&_sacat=0
^^^ this here is a link to what comes up when searching ebay for plano convex laser engraver lenses-- any that actually look like it would fit 'our' machines, is a meniscus

https://www.ebay.com/sch/i.html?_fro...+engraver+lens
^^^ and these are the meniscus offerings...

What am I missing?

[Scott Shepherd]

What am I missing?

A phone call to people who know more about lenses than all of us combined?

Ebay isn't my first choice for trained professional advice.

Plus, on that ebay link you listed as the first one, it says 0 results for what you searched so it's just showing you a search with some of those items missing.

For the record, I believe Gary is right. Here is the description of the lens that I ordered 5 years ago :

The fact that it says PO/CX leads me to believe it's a Plano/Convex lens.

ZNSE PO/CX LENS 0.75''DIA 2.0''FL AR/AR 1 ET=.080''

[Kev Williams]

Not trying to be argumentative, honest, but why is it every laser optics mfr's website I've found describes plano-convex and meniscus lenses exactly as ii-vi described them (as I posted above)? These descriptions lean toward high power cutting machines, but that shouldn't change the generalities...

Now, I've bought many a lens from China since I got the Triumph almost 5 years ago, and while many of them are described in the ads as meniscus, they are in fact plano-convex, as the bottoms are flat as a pancake. All the lenses in my 'good' machines are definitely plano convex too. But I DO have two actual meniscus lenses, they're a pair of GaAs 2" lenses I got a couple of years ago, the bottoms of these are most definitely curved. And, they're true focal length is closer to 1-3/4" than 2". They work nicely, but I've never done any actual spot-size experiments to compare them to my other lenses. I've used 3" and 1-1/2" Chinese lenses in my LS900 once or twice and they worked great, but I've never tried any of them on stainless. Haven't tried one of the GaAs lens in a good machine yet either. Could be one of these cheapies will make my LS100 do stainless better than its current lens. But of course, I can't just swap them because the stock lenses measure 18.8mm dia, and a 19.08 lens won't fit. The GCC lens may be 18.8 too but haven't measured it, I just know that it's smaller...

SO, I'll bet a buck the 'meniscus' lenses I ordered will likely be plano's.

That all said, since every lens I own 'cept the 2 GaAs lenses are plano's, I'd still like to know what's going on with the LS100 lens that it won't turn Cermark black?

[Scott Shepherd]

I'm just giving you a hard time Kev, because you keep asking questions and I keep saying that you can call them as ask them. I don't know the difference or why one works better than another. But I do know they were quite helpful and knowledgable.

Might be worth a call just to get educated. Just in case the rep doesn't know, I suspect they'll get you in touch with someone else who can.

[Kev Williams]

My tinnitus is getting so bad 9 out of 10 phone calls is mostly me saying 'sorry, what was that?'... And I can't understand ANYone who's on an iphone. They've got all the high tech stuff working well, maybe they can actually make the talk quality better than a soup can on a string?
( rant off )

The simple reality is, I want/need a lens for the LS100 and Triumph that will make Cermark black!

[Gary Hair]

Did you look at this link Kev? Our lenses are flat on one side and curved on the other, right? Now which one is like that in the picture from this link.
https://www.quora.com/Whats-the-diff...d-biconvex-one

https://www.ebay.com/sch/i.html?_fro...+lens&_sacat=0
^^^ this here is a link to what comes up when searching ebay for plano convex laser engraver lenses-- any that actually look like it would fit 'our' machines, is a meniscus

https://www.ebay.com/sch/i.html?_fro...+engraver+lens
^^^ and these are the meniscus offerings...

What am I missing?

[Kev Williams]

So I decided to check my lens arsenal just to see...

Turns out my two 3"ers, and my two 4"ers are plano. And most of my 2"ers are actually meni's, even the one with 3 cracks. I have 2 new spares I got the same time as I got the GaAs lenses, they're both meni's.

My favorite lens at the moment in the Triumph is a 2-1/2", and it's a meni. So when I get some time I need to locate all the plano's and do some side by side. Because until I just now checked, I thought only my GaAs lenses were meni's. The concave on those is quite obvious, the others not so much.

Meniscus, notice the daylight-
meniscus.jpg

Plano, flat--
plano.jpg