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DLP3000-C300REF: Mirror reset for each modulation of DMD

Prodigy 110 points

Replies: 19

Views: 204

Part Number: DLP3000-C300REF

Hi there, I'm using DMD to modulate the laser pulses, and it is set to HDMI mode. I modulate the binary patterns on the DMD at 100 Hz, and found that whenever the pattern is changed, the DMD would first reset all the mirrors, which give me a lot of trouble. My understanding of how DMD works is as this: whenever the binary pattern changes, the DMD first resets all the mirrors to one direction (or both directions I'm not sure). Then DMD reflects the mirrors to directions as the pattern requests. If my understanding is correct, I have some questions as below:

1. For now, I'm only testing the on state direction. Does this reset also affect the off state direction? If not, I can use the off state direction to avoid this reset.

2. If the reset happens to both sides, can I code the DMD to reset only to one direction?

  • Jiapeng,

    Welcome to the E2E forums and thanks for your interest in our DLP technology.

    The DLP3000 DMD is actually end of life, so we cannot offer support on it. For light control applications light this, you may want to consider the DLP4500 and its associated EVM instead:

    http://www.ti.com/tool/DLPLCR4500EVM

    I apologize for the inconvenience.

    Regards,

    Philippe Dollo

    If a post answers your question, please click the "Verify Answer" button.

  • In reply to Philippe Dollo:

    Hi, we actually have DLP4500 as well but not used in my setup. I think this reset problem happens for all DMDs. If I'm clear whether DLP4500 has the similar problem as DLP3000, I will not able to use it in my setup.

  • In reply to Jiapeng Zhao:

    "If I'm clear whether DLP4500 has the similar problem as DLP3000, I will not able to use it in my setup."

    Can you elaborate on the above? Thanks.

    Regards,

    Philippe Dollo

    If a post answers your question, please click the "Verify Answer" button.

  • In reply to Philippe Dollo:

    Hi Philippe,

    As I described in the original question, when I fast change the patterns on the DMD, the DMD would first reset all the mirrors. I found that whenever the binary pattern changes, the DMD first resets all the mirrors to one direction. For now I only notice the reset goes for the on state direction because I cannot measure the other side. My question is, does the reset only reset all the mirrors to the on state direction? If so, I can just use the other side. If not, can I program the DMD to avoid this reset?

  • In reply to Jiapeng Zhao:

    Jiapeng,

    So you are saying that on the DLP4500, you are seeing all mirrors reset to ON at the start of the pattern. Is that right?

    You mentioned modulating laser pulses? In that case, do you have an external illumination source (the laser) being used with a DLP4500 EVM? Or, do you have a custom designed solution which uses the DLP4500?

    If you can share your illumination setup, as well as your pattern streaming configuration, then we should be able to diagnose your issue.

    Thanks and regards,

    Philippe Dollo

    If a post answers your question, please click the "Verify Answer" button.

  • In reply to Philippe Dollo:

    You got it. Everytime when I switch the pattern, I found that all the mirrors will be reset to ON state for a while. Please see the attached figure. Probe pulse is the fs laser pulse we use. P1 and P2 are polarizers. HWP1 and HWP2 are half-wave plates. SLM is DLP4500. The pattern we add to the DMD is just a binary pattern that sets the mirror either to ON or OFF state. 

  • In reply to Jiapeng Zhao:

    Hi Jiapeng, 

    The DMD reset procedure mandates some wobbling/movement of the mirrors even if the mirrors are being reset to same side as previous state. This is important for reliable  operation of DMD mirrors. 

    Thanks & Regards,

    Hirak

  • In reply to Hirak Biswas:

    Hi Hirak,

    Thanks for your reply. My main question is this: in my operation, I don't want DMD to reset all the mirrors when I switch the patterns. However, I still observe that all mirrors are reset to ON state everytime when I change the pattern. Is that possible to cancel this reset? If not, does the reset only happen for the ON state? That is to say, when DMD resets all the mirrors, does it only change all mirrors to ON state but not OFF state?

    Thanks, 

  • In reply to Jiapeng Zhao:

    Hello Jiapeng,

    On state and all well off sate  will move when reset signal is applied. There is be mirror movement even if a specific mirror stays in same position. It can not be turned off. It design to ensure reliable operation of the device.

    Hope this answers your question.

    regards,

    Vivek

  • In reply to Vivek Thakur:

    Thanks a lot for the answer. Then is that possible to use this reset signal as the trigger to other devices? If so, we can synchronize a shutter to block the beam when the reset signal comes.