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DLP3000: Maximum incident power of monochromatic 450 nm laser

Ethan Simmons
Prodigy 110 points

Part Number: DLP3000

The datasheet for the DLP3000 does all of its example calculations using the light engine of the DLP Lightcrafter EVM, but I removed the light engine and need to know how to properly calculate the maximum laser power at 450 nm on the DMD so that I stay within limits of what the DMD can handle. Thanks in advance! 

  • 0
    TI__Mastermind 30600 points
    Hi Ethan,

    If you are concerned about how much power the DMD can handle without optics, then the main parameter you care about is the power density on the DMD, calculated in W/cm^2. This value is given in table 6.4 of the DLP3000 datasheet. In this case, the value is "thermally limited" meaning that you'll need to refer to section 6.5 and 7.6 for calculating the temperature rise in your given scenario and understanding the impact of temperature on lifetime.

    I hope that makes sense,
    Paul
  • 0 in reply to Paul Goedeke
    Prodigy 110 points
    I tried calculating this, but the datasheet gives the values of constants using nominal values of the LED light engine, which I am not using. In particular, CL2W assumes many things that are not necessarily true of my laser.
  • 0 in reply to Ethan Simmons
    TI__Mastermind 30600 points
    Yes, of course. Can you tell me more about your laser? DMD overfill, average power, etc?

    -Paul
  • 0 in reply to Paul Goedeke
    Prodigy 110 points
    The laser has variable intensity via a current controller, and we have a variety of lenses that we can use to shape the beam. Average power is anywhere between 1 mW and several W depending on the current. The laser is also single-mode. I'm not sure what you mean by DMD overfill. If this refers to the cross-sectional area of the beam, we can adjust it using lenses. Thanks so much for your help!
  • 0 in reply to Ethan Simmons
    TI__Mastermind 30600 points

    Overfill refers to how much of the light/laser energy falls outside of the mirrors on the DMD. As an example, 10% overfill would be that 90% of the laser cross-sectional area is on the mirrors and 10% is off.

    To adjust the calculation found in Section 7.6, what I would do is take the average power of the laser and the percentage of the laser that is hitting the DMD mirrors and substitute CL2W as the product of those two values.

    For example, if your laser is 1W and 10% overfill, then CL2W = 1 * 0.9 = 0.9W. That will give you a good upper bound on power on the DMD and allow you to calculate the worst case temperature rise. If all the laser energy is hitting the mirrors (laser area is less than the mirror area) then simply use the laser power as your CL2W.

    -Paul

  • 0 in reply to Paul Goedeke
    Prodigy 110 points
    So a worst-case scenario would be 0% overfill, corresponding to CL2W = Laser power (with appropriate units), right? Also, I'm using a delta T of 5 C (less than the recommended 10 C max) to solve for maximum power, which gives me 850 mW of laser power. Does this seems reasonable?
  • 0 in reply to Ethan Simmons
    TI__Mastermind 30600 points
    That does seem reasonable to me.

    -Paul