• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 28 subscribers
  • Views 1591 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DLP4500: Replacing the LED light engine with a fiber coupled laser input

Mike A.
Prodigy 20 points
Part Number: DLP4500

Hi All,

What would one need to do to a stock LightCrafter 4500 in order to modify it for use with fiber coupled laser sources? Something similar to what EKB has done with their "Fiber E4500MKII" offering: 

Normally, I'd just buy one of these to save time. However, the research group I'm currently working with has already purchased a 4500, and doesn't have the spare funds for another.

Basically, the application will be in projecting random dithered structured light patterns, and requires a relatively high radiant flux (>=10W). Wavelength doesn't matter (can be anywhere between 400nm and 800nm). It would be awfully convenient to have the source fiber-coupled for apparatus design and safety reasons.

Thanks,


Michael

  • 0
    TI__Mastermind 30600 points
    Hi Michael,

    Thanks for your question and welcome to the DLP forums.

    This is not something that TI has done, so I won't be able to comment on the details of your question. Broadly speaking, this is not a simple undertaking. Right now, the construction of the EVM is such that the DMD is incorporated into the optics engine.

    The first steps would be to remove the optics engine, disassemble it so that you can remove the DMD and flex cable, and then incorporate those components into your laser system. From that point, once you have the DMD and flex connection, it will be up to you to design or rig up a system to use laser illumination.

    Hope that's enough to get you started,
    Paul
  • 0 in reply to Paul Goedeke
    Prodigy 20 points
    Hi Paul,

    Understandable as far as the details go. Thanks for the great starting advice!

    From the optical side of things, I wasn't able to find much advice here on the forums with regards to what components would be required in an optical chain to make a "normal" image with a LD source (same as you'd see with a single color of LED), free of the effects of diffraction. I glanced through the resource everyone was linking to, the TI white paper on the subject, but I wasn't able to really make the connection from the presented theory to execution in real world hardware.

    For example, if we were to just de-focus a laser diode's beam such that it illuminated the entire DMD, what kind of projected patterns would we see? Would one see a superposition of images, superimposed over one another with the spatial and intensity distribution of a 2-D diffraction, or something else?

    Is there perhaps a way to use an optical component to make a laser's beam incoherent, to very simply get around this problem?

    Otherwise, would I have to find some way to only collect the most intense order refracted off of the DMD?

    Thanks Again,

    Michael
  • 0 in reply to Mike A.
    TI__Mastermind 43215 points

    Hello Michael,

    Paul asked me to help with this inquiry. 

    My first question is are you planning to re-image the surface of the DMD at some distance away (i.e. sweet spot of your structured light system) or do you plan to work in collimated space at the 3D target?

    First, regarding the illumination, defocusing the laser diode will help some.  What is important is what extent (etendue) will each pixel "see" at the DMD surface.  A beam expander would probably give a better result.

    It is important to understand that if you plan to re-image the surface of the DMD then the lens will converge the image at the focal plane as normal. 

    Imagine a non-coherent illumination with a lens that re-images at some focal plane.  Now imagine a baffle with regularly spaced holes placed just in front of the lens (or better yet split the lens in half, i.e. two plano convex lenses, and place the baffle right between the two).  The image will still form although you will have thrown away a bunch of light.  But this is just the same situation as the diffraction orders.  Ideally you will want slow enough optics to give you a good depth of field.

    I hope this helps.

    Fixiz