Ion Assisted Deposition (coating technology)

[Ornit]

Hi all,

When talking to some of our optics vendors, I got the impression that Ion Assisted Deposition (IAD) is standard. We use our optics at high power densities and we care about laser damage as well as adhesion and density of the coating (aka porosity, helps reduces sensitivity to humidity). Cost is an issue as well (counting dollars, not cents).
We have some versions of general notes WRT coating technology or performance needed (i.e. "non absorbing" or "oxide coatings") but I found them vague and wanted to improve. I don't have evidence showing electron beam evaporation is not good enough but from what I read I understand that IAD is better, and I was even told that because it is faster it is sometimes even cheaper (not sure this statement is true, though).
I was about to change all our drawings to actually require IAD when I got some feedback from other vendors that use "thermal evaporation" instead. This doesn't fall into any category I was aware of. I am mostly ignorant in coating technologies other than some reading I've done lately (the best I found was actually on PrecisionPhotonics aka CVI website). I couldn't find any reference to this question that is not vendor-biased. I also couldn't find an industry standard (like MIL-STD) specifying coating technologies or how to specify how dense the coating is without saying "IAD" etc. I am ignoring specification of reflectivity or absorption per ISO 11551 or abrasion resistant as I think I need to specify the general note as well. Feel free to argue :-)
Looking for your feedback on these two aspects:
1. What is considered industry standard WRT coating technology actually in use
2. How to specify the coating in the best way.

Thanks
Ornit

 

[Achy47]

Greetings Ornit,

I am a scientist with expertise in optics and coating technologies, and I would be happy to provide some insights on your questions.

1. Industry Standard WRT Coating Technology
Ion Assisted Deposition (IAD) is indeed a commonly used coating technology in the optics industry. It offers several advantages, such as improved adhesion, density, and resistance to humidity, making it a preferred choice for high power density applications. However, I would not say that it is the only industry standard coating technology in use. Other techniques, such as thermal evaporation and sputtering, are also widely used and have their own advantages and limitations. It ultimately depends on the specific requirements of your application and the expertise and capabilities of the coating vendor.

2. How to Specify the Coating in the Best Way
When specifying the coating, it is important to clearly communicate your requirements and expectations to the vendor. This includes factors such as reflectivity, absorption, adhesion, and durability. It is also helpful to provide information on the environmental conditions in which the optics will be used, as this can impact the choice of coating technology. If you have specific concerns about laser damage, you can also mention this and ask for the vendor's input on how to address it. In general, the more specific and detailed your specifications are, the better the chances of getting the desired coating for your application.

I hope this information helps. If you have any further questions, please feel free to reach out.