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Thread: Sputtering coatings

  1. #11
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    I was really tired of replacing diode strings in this design, eventually we substituted better diodes. We had the non- magnetron version. As for targets, we used silver, palladium, and platinum for SEM. One of my co-workers cast a lead disk with a propane torch to make his mirrors, because lead sputters very, very fast. Lead front surface mirrors do not last long, however the slightly grey color in the reflection is beautiful.

    Neon sign transformers have a air gap in the core that makes them current limiting. Microwave oven transformers are far more dangerous, but actually are almost the right voltage for this, and are obviously not current limited.

    Ours was air cooled.

    Sputter Coater Operation - YouTube

    Slow, but by modern instrument standards. there is almost nothing in these but a stock vacuum gauge module, an interlock board, a Variac and transformer, and a mechanical timer straight out of a gas clothes dryer, complete with mechanical bell that goes ding at the end. A good quality needle valve is needed.

    These little ones are fun, but slower. I never tried an oxide in the more primitive ones.

    https://youtu.be/mmd1m4Ud-6E

    Targets:

    Kurt J. Lesker Company | Sputtering Targets | Vacuum Science Is Our Business

    Steve
    Last edited by mixedgas; 11-12-2021 at 08:27.
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  2. #12
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    Reviving this talk a bit.
    So I now understand that coatings for output couplers/dichroics are dielectric which means they are non conductive and work by thin film interference.

    I know this cancels out DC related sputtering and means AC related (RF) sputtering because of the lack of conductivity is required.
    I understand now how the plasma beam works and that getting them wide to achieve a even coating is plausible on small optics just fine and how gasses are sometimes mixed for interaction or left out (oxygen) to prevent oxidization or other contaminations (sometimes even you requiring to do another coat run without removing a vacuum to prevent ruining the prior layer).

    The calculator on filmetrics is a means to find out find out your layer thicknesses and materials/targets to get the transmittance/reflectance desired correct?
    I think a thing I miss on the calculator is that there is no real clear example of what the material will do for you other then selecting the material by trial and error and hoping it has the behaviour that you "may want".

    Isn't there really no research paper publications to show what mixtures they used to get their desired transmittance/reflectance? Or even a wavelength selector tool that calculates your ratios and materials? Is it really safe guarded in industries to avoid competition (despite surely there being many facilities in china doing it and educational labs talking about doing it themselves in papers within their own lab enviroment).

    Say for example I want a output coupler that transmits 577 but reflects things in the blue and IR region of the spectrum. Where does one really start?

  3. #13
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    (PDF) Multilayer Dielectric Thin Film Optical Coating Design for Single Wavelength Operation of Inherently Dual Wavelength Copper Vapor Laser (researchgate.net)

    Run that table through the sim on a AL or insulator substrate and it smokes it.

    Books:

    H. Angus Macleod, Thin Film Optical Filters, 4th edition, CRC press

    Optical Coating Technology
    Author(s): Philip W. Baumeister

    Dr. Baumeister was still posting online before Covid in various news groups. Nice guy.

    William Silfvast, Laser Fundamentals, 2nd Edition. (Silfvast invented the metal vapor laser, and the HeCad. )

    Steve
    Last edited by mixedgas; 02-08-2022 at 08:43.
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    Thanks so much!
    Been trying to get pointers and hate to be that person that asks so many questions!
    Will give it a read!

    I see the table btw! very helpfull

  5. #15
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    The day you stop asking good questions, you should either be 1. Dead 2. Getting Married, thus taking a week off, 3. Retiring.
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  6. #16
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    add to the books, William Silfvast, Laser Fundamentals, 2nd Edition. (Silfvast invented the metal vapor laser, and the HeCad. )
    If you do not buy / borrow a copy of Silfvast, you should quit now and switch to marketing.

    His how to select cavity optics chapter is worth having. He walks you through several designs based on single pass gain methods.

    Laser Fundamentals by Silfvast, William T.: Good Paperback (1996) | HPB-Red (abebooks.com)

    That is Helium Selenium on the cover. Which is the revision you want.
    Silfvast also had RGB out of a HeCad, but it had problems with line competition.

    Steve
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  7. #17
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    Evaporation Boats of Tungsten, Molybdenum & Tantalum

    Check out their surplus page too. I have a bag of evap coils from them that was next to nothing in cost.

    Steve
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  8. #18
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    interesting!
    Someone at a lab (not nearby) who does sputtering also told me a quarts crystal (bought or salvaged from a cheap crystal oscillator) can be used also to determine coating thickness (some sputter coating machines have wire break out in the vacuum to attach a crystal to) then 0 a frequency counter and measure relative drift of the crystal.

    So documents who somewhat document thicknesses are useful! off course determining how the thickness correlates to a the quartz frequency is another unknown but it's a start.
    Currently my goals are to make output couplers for 577 and 607.. not as a means of production or anything but as a means of experimentation. It's a lot faster and easier to just buy various uncoated lenses and coat those (1 unit even) to get what you want rather then splashing out companies to do a coating run for you in low volume which costs a fortune and takes a long amount of time (although done perfectly and hands off off course!).

  9. #19
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    There is a company in Germsny that has reasonable prices for one offs.

    When I send you the evap coils I will tuck some QCM data in the box that I can't post here.

    Bare QCM crystals are not that expensive and work for a long time.

    S.
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