GaAs lens part II -

[Kev Williams]

Tried my new ebay GaAs lens last night- First on some stainless, used it to run the outlines on one my big operator panels (header plate)-
I was pleasantly surprised to find the Cermark was noticeably darker than I've been getting--

Thinking all was well, I used it to etch one of the largest black anodized operator panels I build from scratch.

Whoops. All is not well with these lenses-- I actually hope my customer buys this thing. From arms length, I would guess most people would think the engraving is fine. But we who do this for a living certainly won't!

Once the panel was engraved, I found the engraving was, for the most part, barely evident- not enough power. So I added 5%, and eventually found I needed a 7% increase to equal my usual results.

When I finally finished, as usual I took a good look at the engravings overall look and quality. And I'm always amazed at the top-notch engraving I get from the Triumph...

--last night I removed the lens housing to see why it or the the lens was loose. I seriously thought one of them HAD to be loose.

Nope. All tight. And I was now equally amazed that just using a different lens could make such an astounding (< insert favorite radical adjective here) difference in the engraving quality!

So I ran this test this morning just to verify I'm not imagining things...


first pic, top line I ran using a new 'regular' $18 ebay 2" lens, 500mm/s .05 gap, 25% power.
I moved the plate, changed to the GaAs lens, and ran the same job. Not enough power..
Next one down was at 30% power, bottom line at 35%, finally close to the same whiteness..
ga1.jpg
Aside from the extra power needed, the difference in engraving quality is glaringly obvious..
this text measures 3.3mm in height btw...

I turned the piece around and ran a 'controlled' test.
top line is the GaAs lens at 35% power,
bottom line is the normal lens at 23% power (my usual setting for black anodized)
-I actually ran the second line twice since this alum is from a new batch which gets a snick whiter with 25% power,
but the second run blew away about half the alum oxide. The top line removed some itself, just not nearly as much.
But my main concern is the side-by-side engraving quality results...
ga2.jpg
ga3.jpg
ga4.jpg
-even without enlarging these thumbnails the results are obvious... normal lens engraves with crisp lines and corners, radius's are mostly round & smooth... GaAs lens, NOT... And I engraved an entire panel with the 'bad' lettering...

In 15 years of Laser engraving with 4 different machines and the possible variations between them, I've NEVER seen much if any engraving differences between them. I've even tested my cracked and spot-stained lenses against my good-condition lenses and have never noticed a discernible difference even under magnification. But this one lens created a night-n-day difference, which I honestly didn't expect.

One good thing may come from this lens however, it may actually help with my Triumph's Cermark engraving. At least on larger than 3.3mm text -- more experimenting coming...

Dave Sheldrake is always telling us lenses and beam quality matters-- Yes, it does!


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