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  1. Thread: The 'Pits'

    by Falstaff
    Replies
    3
    Views
    2,536

    The 'Pits'

    Hello,

    Could someone help us out please? Everybody here talks about 'coating pits' as though they are fully familiar with what they are, but when interrogated, I don't think anyone is really sure...
  2. Replies
    6
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    3,009

    Hi vyking, A good book is Angus Macleod's...

    Hi vyking,

    A good book is Angus Macleod's 'Thin-Film Optical Filters'

    You will need a good background in Mathematics and Physics however.

    Best Regards,

    Falstaff
  3. Replies
    2
    Views
    1,938

    Viscosity Measurements

    Hello,

    We are considering making an investment in the equipment necessary to monitor the viscosity of our hardcoating lacquers.

    My question is, will this give us any valuable information that...
  4. Replies
    2
    Views
    2,599

    Many thanks Mauro, That gives us something to...

    Many thanks Mauro,

    That gives us something to work with.

    Falstaff (Quasimodo)
  5. Replies
    4
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    3,582

    Okay, Thanks Mauro. We will try this. Falstaff.

    Okay, Thanks Mauro. We will try this.

    Falstaff.
  6. Replies
    4
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    3,582

    Hi Mauro, Thanks for replying. The haze...

    Hi Mauro,

    Thanks for replying.

    The haze change we get normally on the CR39 lenses is just over 20%. This is normal, according to Colts, on the 6 base lenses which they recommend (21% +/- 4%).
    ...
  7. Replies
    4
    Views
    3,582

    Bayer Test Problems

    Hello,

    We are having some problems with our Bayer Tester. Just wondered whether anyone out there has seen this before.

    Our testing machine is quite old now and showing signs of wear. Instead of...
  8. Replies
    2
    Views
    1,316

    'Slipperiness' of coatings

    Hello,

    We are looking for a test of actual 'slipperiness', rather than just contact angle. We are producing superhydrophobic AR coatings, but realise that the contact angle is only related to...
  9. Replies
    15
    Views
    7,299

    Hi sujeet, We have not encountered this...

    Hi sujeet,

    We have not encountered this particular problem, although we have only just begun to investigate the use of a superhydrophobic pill. It does sound like your superhydrophobic treatment...
  10. Many thanks. There is indeed a typo on my...

    Many thanks. There is indeed a typo on my original post. It should have read n = a + (a^2 - 1)^0.5, which, I think (and hope) is equivalent to the expression given above.

    Perhaps I should have...
  11. Relationship between Light Transmission and Index

    I have come up with an expression (for normal incidence) which relates these parameters, and which takes into account the multiple reflections between the top and bottom surfaces of a substrate:

    T...
  12. Replies
    4
    Views
    2,735

    Fingerprints on AR lenses

    We sometimes see fingerprints on the concave sides of AR lenses where the operators have flipped them over (They always coat the concave side first).

    I am seeing such fingerprints at the moment....
  13. Replies
    15
    Views
    7,299

    It is not actually a blue process, only shifted...

    It is not actually a blue process, only shifted towards the blue. It is still basically a green coating. The decision to make the change happened higher up in the company, and it is not something I...
  14. Replies
    15
    Views
    7,299

    Actually, I have not checked the hydrophobic...

    Actually, I have not checked the hydrophobic coating out with respect to this matter. We do have some problems with hydrophobic coatings on the bottom calotte rows. The hydrophobic properties are...
  15. Replies
    15
    Views
    7,299

    Thank you for the replies. We use Leybold AR...

    Thank you for the replies.

    We use Leybold AR coating machines. The calotte rings are just ordinary metal sizing rings, the same as we have always used. There are no mechanisms to flip the lenses...
  16. Replies
    15
    Views
    7,299

    Outer Zone Redness on AR coatings

    We produce AR coatings with a green reflex colour. Recently, we have changed our colour somewhat and the spectral curve hass moved towards the blue part of the spectrum.

    Sometimes, especially with...
  17. Replies
    5
    Views
    6,428

    Primary Purpose of AR Coating?

    Parameters which are used to indicate the performance of AR coatings often include values for Bayer Ratios, indications of Adhesion, Resistance to Crazing etc.,(important of course). One parameter...
  18. Replies
    12
    Views
    7,190

    Hello, I think you may be right about the...

    Hello,

    I think you may be right about the vacuum. We did a leak tast last night and found the rate to be 1.3 X 10-4mbar l/s. I am currently repeating the test just in case the door seal was to...
  19. Replies
    12
    Views
    7,190

    Hello, Thank you for your help. I have...

    Hello,

    Thank you for your help. I have conducted the tests myself, and there is definitely a problem, but it is not there all of the time. All of the tests are done with identical lenses, all...
  20. Replies
    12
    Views
    7,190

    Thanks for the replies. It is true that we might...

    Thanks for the replies. It is true that we might be attaching too much significance to one or two tests, that maybe do not relate to the real world too well. Perhaps the coatings from this machine...
  21. Replies
    12
    Views
    7,190

    Scratch Resistance/ Hardness

    We have one of our AR coating machines which occasionally fails a scratch resistance test. The Bayer Ratio from lenses coated by it are always a little lower than than that from our other plants. We...
  22. Replies
    3
    Views
    3,248

    AR colour in reflection.

    Just wondered how critical this is to customers in general.

    The AR coating is presumably designed so that the reflected colour appears correct when viewed at normal incidence (90 degrees from...
  23. Replies
    4
    Views
    2,936

    Damage to coatings

    I am interested in how the damage that is sometimes seen on returned lenses evolves. For example, how the different patterns of crazing and scratches might eventually cause delaminated areas.

    In...
  24. Thread: U.V. filter

    by Falstaff
    Replies
    7
    Views
    2,893

    The reason for the yellowing is because a uv...

    The reason for the yellowing is because a uv filter, though efficient at blocking out short wavelengths, has to become gradually less effective upon approaching the visible part of the spectrum. If...
  25. Replies
    13
    Views
    8,270

    Unfortunately, it is more complicated than that....

    Unfortunately, it is more complicated than that. You have to take into account the interference between rays of light reflecting (and multiply reflecting) between all the interfaces of all of the...
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