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custom coatings for 0.7 XGA DMDs

Ben Lawrie1
Prodigy 40 points
Other Parts Discussed in Thread: DLP9500, DLP7000

I have called all of the DMD resellers that I can find, but as far as I can tell, nobody sells them with anything but Al coated mirrors and a non-AR-coated window.  I've also been told that it is impossible to purchase just the DMD without the development kit due to agreements with TI.  We are currently using three Discovery 4100 starter kits in our lab, but the 0 order throughput is a serious problem for us that custom AR coatings and custom mirror coatings would help to alleviate.  Has anyone found a vendor that offers custom-coated DMDs, or is there any workaround where we could purchase individual DMDs in an attempt to deposit custom coatings ourselves?  I can't afford to pay for new development boards in order to facilitate a thin film deposition onto a DMD, but I could probably afford a few DMDs by themselves so that we could try various coatings.  Thanks.

  • 0
    TI__Intellectual 2175 points

    Hi Ben and welcome to the DLP E2E Forum.

    The DMDs used in the Discovery D4100 kits are now available through TI's Authorized distributors.  Please search for DLP9500 and DLP7000 part numbers.  However, TI does not recommend any attempts to custom coat the mirrors.  This will cause unpredictable operation and likely catastrophic damage to the DMD mirror array.  

    Best regards,

    Eric

  • 0 in reply to ELD
    Prodigy 40 points

    Thanks Eric,

    It's amazing what a part number will do.  Every single company I had spoken with told me that they could not sell the DMDs separately.  We sort of expect catastrophic damage which is why we didn't want to do it ourselves on any of our existing DMDs, but I still haven't been able to find any companies that offer custom coatings.  Do you know of anyone who could offer appropriate coatings on the DLP7000 to improve throughput at 795 nm?  Thanks again,

     

    Ben

  • 0 in reply to Ben Lawrie1
    TI__Genius 9935 points

    Ben,

    Have you checked out this Application Note?  

     Wavelength Transmittance Considerations for DLP® DMD Window http://www.ti.com/litv/pdf/dlpa031b

  • 0 in reply to Pascal DLP
    Prodigy 40 points

    Hi Pascal,

    I have seen that, thank you.  That note outlines the first part of our problem fairly well.  We're losing 8-10% of our incident light just on the window, with another 12-18% on the Al coating.  With appropriate coatings, both of those numbers should be less than 1%.  For quantum optics applications, this is a major impediment.  If we can't find a vendor, we had hoped to deposit dielectric reflective and anti-reflective coatings in order to significantly improve the 0 order throughput.  I hope that we might get away with depositing a reflective coating of several 10s of nanometers by e-beam evaporation without significantly affecting the micromirror operation, but it seems there's only one way to find out.

  • 0 in reply to Ben Lawrie1
    TI__Genius 9935 points

    Ben,

    I hate to be the bearer of bad news, but as Eric said earlier: "TI does not recommend any attempts to custom coat the mirrors. This will cause unpredictable operation and likely catastrophic damage to the DMD mirror array."

    The only thing that I would add to what Eric said is that the result is not, in fact, unpredictable. It is predictable. If you remove the DMD window and attempt a coating deposition the DMD will not function thereafter. I am just trying to save you the expense, effort, and frustration of going down this path.

  • 0 in reply to Pascal DLP
    Prodigy 40 points

    But it sounds like no one knows of any vendors that offer IR-coated DMDs?  When we bought our first starter kit, Digital Light Innovations told us that they could do it, but they don't offer that service anymore.  We're looking at 25k from another vendor for a high throughput liquid crystal SLM, so you can see our motivation in sticking with TI if we can.

  • 0 in reply to Pascal DLP
    TI__Genius 9935 points

    Ben,

    I regret the negative tone of our answers above. I would definitely give you a lead to a solution to your requirement, if I knew of one.

    We indeed understand that you would like a DMD array which is more efficient for your purposes. Even though we don't have a short term solution to your request, it is very helpful for us to know what you do need. It becomes part of the conversation which leads to our future offerings. Anything that you would like to tell us about your requirements would be welcome. If a solution is available, we will surely tell you.