Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 28

Thread: Seeking Casio's without diode block

  1. #11
    Join Date
    Sep 2007
    Location
    Denmark
    Posts
    48

    Default

    Thank you all, for the inputs.

    Hopefully there is a couple of projectors on the way soon. Thanks!

    Jan
    Last edited by FutureDesign; 05-01-2013 at 05:19.

  2. #12
    Join Date
    Feb 2011
    Location
    New Hampshire
    Posts
    3,513

    Default

    Jan,

    What are you doing if I might ask? Any chance you are looking @ DLP scanning of collimnated (not focal plane) lasers?

  3. #13
    Join Date
    Sep 2007
    Location
    Denmark
    Posts
    48

    Default

    Quote Originally Posted by planters View Post
    What are you doing if I might ask? Any chance you are looking @ DLP scanning of collimnated (not focal plane) lasers?
    I'm afraid that I will have to disappoint you. My use for them is not that exotic.
    Actually, it's been years since I did solid experiments with lasers.

    I will be using the Casio for several experiments.
    One being 3D scanning by the means of structured light. (Initial test done, however my camera is terrible, so the output was noisy)
    Another being a 3D printer. (Mechanics have been designed and are being fabricated in a professional workshop as of writing).
    And lastly (red only) OpenGl cluster (distributed) rendering. (I have one node working)
    Maybe you will see a post in the Lounge when I'm done with the experiments.
    Until then I'll be watching your amazing experiments closely :-)
    Best regards
    Jan Thogersen

  4. #14
    Join Date
    Dec 2006
    Location
    Essex, UK
    Posts
    8,648

    Default

    ive got a casio a140 without the diodes in your interested?
    Eat Sleep Lase Repeat

  5. #15
    Join Date
    Oct 2012
    Location
    Germany
    Posts
    1,478

    Default

    ... I'm 3D-scanning with David Laserscanner and a 'only red'-modified Casio and a 'colour'-Casio with only 6 remaining blue LD's ... and have modified two other for 'lampless' and using them for tests with UV-LED's, UV-LD's for UV-curing and a pulsing high-power UV-laser for material processing.

    After some initial successfull experiments I switched to SLS and DMLS with IR-lasers, but will coninue with the UV-beamers too ...

    A friend is UV-printing with an UV-modified Casio with reducing lens and resolutions down to 10 microns without problems ;-)

    Viktor

  6. #16
    Join Date
    Sep 2007
    Location
    Denmark
    Posts
    48

    Default

    Quote Originally Posted by planters View Post
    Any chance you are looking @ DLP scanning of collimnated (not focal plane) lasers?
    I'm hijacking the thread!
    planters, I guess that you are interested in the subject? I have for a long time been interested in MEMS as moving mirror. Have you or anyone else in the forum done any experiments with such?
    I ones worked for a company (Martin Processional) as an engineer and there we had a MEMS prototype sent for evaluation. At that time it was pretty impressive, however far to expensive and rotation angle to small. But I guess that much has changed during the past 8 years :-D
    When I meet a week with two weekends, then I will start digging into the MEMS again. Could be interesting if the galvos could be avoided. Projectors would then be fast, damn small and probably less subject to mechanical failures.
    Best regards
    Jan Thogersen

  7. #17
    swamidog's Avatar
    swamidog is online now Jr. Woodchuckington Janitor III, Esq.
    Join Date
    Nov 2006
    Location
    santa fe, nm
    Posts
    1,545,752

    Default

    historically, the big problems with mems is the damage threshold.

    Quote Originally Posted by FutureDesign View Post
    I'm hijacking the thread!
    planters, I guess that you are interested in the subject? I have for a long time been interested in MEMS as moving mirror. Have you or anyone else in the forum done any experiments with such?
    I ones worked for a company (Martin Processional) as an engineer and there we had a MEMS prototype sent for evaluation. At that time it was pretty impressive, however far to expensive and rotation angle to small. But I guess that much has changed during the past 8 years :-D
    When I meet a week with two weekends, then I will start digging into the MEMS again. Could be interesting if the galvos could be avoided. Projectors would then be fast, damn small and probably less subject to mechanical failures.
    suppose you're thinkin' about a plate o' shrimp. Suddenly someone'll say, like, plate, or shrimp, or plate o' shrimp out of the blue, no explanation. No point in lookin' for one, either. It's all part of a cosmic unconciousness.

  8. #18
    Join Date
    Sep 2007
    Location
    Denmark
    Posts
    48

    Default

    Quote Originally Posted by swamidog View Post
    historically, the big problems with mems is the damage threshold.
    Cinema DLP projectors are taking in the hundreds of optical watts. Of cause the target area is bigger, however the mirror on single mirror MEMS has grown and reflection ratio improved. So I guess the technology is there for doing at least 10 optical watt from a collimnated source.
    Best regards
    Jan Thogersen

  9. #19
    Join Date
    Feb 2011
    Location
    New Hampshire
    Posts
    3,513

    Default

    Future,

    You are right re the power. A few months ago I contacted TI and talked with their engineers about this as well as two MORE SIGNIFICANT limitations. They sell development packages for OEMs that would allow an individual to work with the DLP directly from the control computer @ approx $2,500. However, I think a gutted Cas would be a less expensive route. One limitation is the quantized nature of the movement. It is +12, 0, and -12 degrees and that's it. There is no input (at least at the user level) to allow steering of the beams. For them this works as they project vs dump a particular pixel. This is an arbitrary limitation based on the control electronics because if you know how they work (a Si cantilever attracted by a capacitive force) they are a flexure device and should be capable of continuous rotation. The second limitation is phasing. If a macroscopic (mm dia.) beam is tipped by an array of 1,000 x1,000 mirrors of um dimensions then the divergence will increase a lot due to the diffraction effects from each of these um scale mirrors. Phasing is impossible because for any given wavelength the mirror to mirror step distance varies with the projected angle.

    For those less familiar with the optical issues, the reason they work and produce high resolution on a projection screen is that here they operate @ the focal plane. They are re-imaged onto the projection screen, greatly magnified by the large high quality projection lens. If you could somehow tip them in this scenario, the projection would move only by the inverse ratio of the magnification; less than 1%.

  10. #20
    Join Date
    Sep 2007
    Location
    Denmark
    Posts
    48

    Default

    Quote Originally Posted by planters View Post
    One limitation is the quantized nature of the movement. It is +12, 0, and -12 degrees and that's it. There is no input (at least at the user level) to allow steering of the beams. For them this works as they project vs dump a particular pixel.
    Quote Originally Posted by planters View Post
    For those less familiar with the optical issues, the reason they work and produce high resolution on a projection screen is that here they operate @ the focal plane. They are re-imaged onto the projection screen, greatly magnified by the large high quality projection lens. If you could somehow tip them in this scenario, the projection would move only by the inverse ratio of the magnification; less than 1%.
    Exactly because of what you are saying here it is a mystery for me how the DLP can ever be used for projecting laser, as the beams will only be "nice" at the focal plane.
    I did think a bit about it after you asked about the Casios. I just can't imagine that DLP's can be useful for laserists other than for holographic films.

    As said before, one day I will try go get in contact with manufactures of single mirror mems. Most pico video projectors are based on them, so the price must be affordable. As far as I know there are two different versions of them. One working in resonant mode and the other running free open loop.
    The resonant mode is easily controlled, as it only requires two high voltage clock pulses. One for each axis. It's like a swing. You push the mirror at a constant frequency and the mirror will by itself rotate in a sinusoidal motion.
    For a laserist this mode is not so attractive as the mirror will travel using same principle as an old CRT monitor. The beam will sweep through all pixels regardless if it will be used or not. This means that source power is divided into all available pixels even if only one pixel is used.
    The other open loop mode is similar to driving a GM20. You have no way of knowing exactly what the mirror is doing as there is no feedback. Three things can be considered:
    1) Living with the nature of the mirror and its resonances.
    2) Put a DSP in front of the mirror and apply an inverse transfer function that compensates for all the bad manors the mirror has.
    3) Try to implement some kind of external feedback. This way it can be driven like closed loop galvos.

    When I get involved with the mems, I will try to make an external feedback. I'm thinking 2 laser beams. One at one attack angle for projecting and another at a different angle (45 degrees) and wavelength for feedback. With different angle and wavelength they should not interact with each other. Four PD's in two Wheatstone bridge could be the answer to the missing feedback problem.

    I did quick sketch of the idea: Click image for larger version. 

Name:	mems_feedback.png 
Views:	11 
Size:	1.05 MB 
ID:	38087

    Anyway, that was a completely different talk.
    Last edited by FutureDesign; 05-10-2013 at 05:55. Reason: spelling and stuff
    Best regards
    Jan Thogersen

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •