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Thread: 1.74 backside coating

  1. #1
    OptiWizard
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    1.74 backside coating

    With the recent availability of front side hard coat 1.74, i have been able to process rx in house for ecp's who prefer not to sell w/ar. I know reflectance can be an issue but the topic of this thread is one of applying backside hard coat.

    I am using an ultraoptics mr-iii. Pre coat lenses check great power is dead on. Post coat can see the optics have been affected. Some lenes will change from a .12 to as much as a .25. Obvioulsy the cure and heat is affecting center. I have increased the finish thickness from 1.5 to 1.8 but the goal is to be close to 1.0 with great optics.

    So my question is..any suggested means to adjust coating cycle or methods?

  2. #2
    Master OptiBoarder
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    Is this an issue for all 1.74 lenses or just at your lab? I didn't realize 1.74 only received a backside hard coat? Mind educating us a little while you wait for an answer?

  3. #3
    RETIRED JRS's Avatar
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    If you are attaching the lens directly to the suction cup - when heat is applied, the center is warping. What you then perceive in post coating at the inspection system as a power situation is in fact an aberrated lens
    J. R. Smith


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    Master OptiBoarder LENNY's Avatar
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    Dip Coat might be an answer.....

  5. #5
    OptiWizard
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    Dip coat is the preferred means followed by AR. I'm having to run some high "out of range" rx's that my IDD will not or cannot and insist on AR. I know some warpage is occurring during UV cure I'm looking for any recommended adjusts

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    Master OptiBoarder mshimp's Avatar
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    Try using a carrier lens on top of your 1.74 lens. Use finishing leap pads to adhere to the surface, process as usual. Suction from your unit will be on the carrier lens. Caution: heat from UV cure could cause release from adhesion to carrier lens.

  7. #7
    Master OptiBoarder
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    Spin coating 1.74 is challenging because there are no Index matched coatings available. Most Utra-Opticas HC only go to 1.60 so you are inducing HUGE amounts of birefringence. True 1.74 hardcoats are very unstable, have to be refrigerated throughout shipping and storing, and cost an arm and leg. This is why Essilor brought all 1.74 production back to Texas (and Mexico City). Even using 1.67 HC produced negative results.

    Even 1.67 HC looks terrible on 1.74. Its better to outsource 1.74 surfacing.

  8. #8
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    Quote Originally Posted by JRS View Post
    If you are attaching the lens directly to the suction cup - when heat is applied, the center is warping. What you then perceive in post coating at the inspection system as a power situation is in fact an aberrated lens
    Like JRS said you are experiencing some warping from the curing. Ultra Optics offers a few inexpensive lens carrier products that help with the warping since the suction is not applied directly to the lens itself but to a secondary suction cup or to a secondary lens. Also I would not recommend going lower than a 1.3 CT on your 1.74 this could be adding to the amount of warping you are getting.

    Try these I have had success with them:

    · Lens carrier cup- Part # 65825A5
    · Adapter cup – clear lens w/cup – Part # 1233/U

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