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Thread: Too noticeable / almost invisible Laser Engravings

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    Too noticeable / almost invisible Laser Engravings

    I have this problem from time to time, and it is super annoying. I never worked with a lens generator that did these laser engravings so I have no reference point on how irritated I should get about this. The thing that annoys me most is that I almost always dispense them first and then have complaints from the wearer - it is hard for me to decide if they will notice or not, but if I'm sitting across the desk from them and I can see the big engravings on either side of the lens - that is too deep.

    Sometimes it seems as if they are so deep that the AR hardcoat pools up inside the engraving and makes them sparkle, usually it is just plain old too visible.

    Trivex seems to be the biggest culprit lately but I have noticed it with other materials as well. So how annoyed should I be about this? Is this something that is hard to calibrate or is it something that once it is set it should not be a problem again without the engraver malfunctioning?

    As much as I hate straining my eyes for 20 minutes trying to dot up lenses, I would take that 10 times out of 10 compared to someone coming back with a state of the art lens complaining about being able to see the engravings.

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    Compulsive Truthteller OptiBoard Gold Supporter Uncle Fester's Avatar
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    Master OptiBoarder OptiBoard Silver Supporter lensmanmd's Avatar
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    Quote Originally Posted by Tallboy View Post
    I have this problem from time to time, and it is super annoying. I never worked with a lens generator that did these laser engravings so I have no reference point on how irritated I should get about this. The thing that annoys me most is that I almost always dispense them first and then have complaints from the wearer - it is hard for me to decide if they will notice or not, but if I'm sitting across the desk from them and I can see the big engravings on either side of the lens - that is too deep.

    Sometimes it seems as if they are so deep that the AR hardcoat pools up inside the engraving and makes them sparkle, usually it is just plain old too visible.

    Trivex seems to be the biggest culprit lately but I have noticed it with other materials as well. So how annoyed should I be about this? Is this something that is hard to calibrate or is it something that once it is set it should not be a problem again without the engraver malfunctioning?

    As much as I hate straining my eyes for 20 minutes trying to dot up lenses, I would take that 10 times out of 10 compared to someone coming back with a state of the art lens complaining about being able to see the engravings.
    laser engravings are material specific and need to be adjusted periodically. Trivex and cr39 are darkest and come out of spec more frequently. We adjust our CO2 engraver monthly. We also engrave prior to polishing so the hardcoat doesn't streak. Next time you get a dark engraving, return them and request a lighter engraving.

    Note: different mfrs require specific darkness on their engravings.

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    Thanks lensmanmd, let me ask you this then:

    How often should I be okay with this happening as a "defect" before I raise hell with the lab. Interesting about the cr39 and Trivex, those are definitely the two that I see it on the most. I'm probably seeing it 1 out of every 40 jobs that comes to me. Its annoying, but if its an unavoidable thing... I guess I will just keep treating it the same as an occasional AR defect.

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    Master OptiBoarder OptiBoard Silver Supporter lensmanmd's Avatar
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    TB

    That would be up to your discretion. If the engravings are easily seen in indirect lighting at arms length, I would hesitate to dispense them.

    1 out of 40 is not all that bad, but I would still reach out to your lab.

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    Optical Thingymajig OptiBoard Gold Supporter PartTimer's Avatar
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    My understanding is that most of this equipment, realistically, is set periodically. If your lab one has one or a few of these engravers, my understanding is that they are set to a uniform setting, and all lenses and materials are thrown through the process at the same setting. That might explain your issue with one material. Otherwise, your lab would have to differentiate by material, which would probably be time consuming. I have heard some of the better engravers are a little smarter about it, but that's my two cents. Used to drive me NUTS with Digital Eye Lab.

    One in forty sounds ok, though.

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    Master OptiBoarder OptiBoard Silver Supporter lensmanmd's Avatar
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    Quote Originally Posted by PartTimer View Post
    My understanding is that most of this equipment, realistically, is set periodically. If your lab one has one or a few of these engravers, my understanding is that they are set to a uniform setting, and all lenses and materials are thrown through the process at the same setting. That might explain your issue with one material. Otherwise, your lab would have to differentiate by material, which would probably be time consuming. I have heard some of the better engravers are a little smarter about it, but that's my two cents. Used to drive me NUTS with Digital Eye Lab.

    One in forty sounds ok, though.
    Our Optotech is adjusted per material just for this reason.

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    sub specie aeternitatis Pete Hanlin's Avatar
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    As indicated earlier, in most labs the laser is going to be set up to provide different levels of power for different materials (in fact, in some labs test engravings on a daily basis to confirm the engraving is within spec). However, it is a process and processes have variables that can be challenging / frustrating.

    Traditional lenses had the same issues (ironically, although we've always called them "engravings," on traditional lenses the engraving is in the mold- so the mark you see on the lens is actually protruding above the lens). Going way back, I remember when the markings on certain Transitions lenses were impossible to see- probably because the extra layer put on front of the lens made the markings less pronounced.

    For sure I would mention your observations to the laboratory- perhaps they can increase their QA testing frequency to keep their equipment to a tighter range. However, I've noticed a certain amount of range from pretty much everyone's laboratories (both independent and manufacturer owned).
    Pete Hanlin, ABOM
    Vice President Professional Services
    Essilor of America

    http://linkedin.com/in/pete-hanlin-72a3a74

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