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Thread: A new Project: Use of laser projector connected to an APP on a phone or a remote.

  1. #11
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    could you not just set it up to have the patterns on a SD card or somthing. then when you press a button or tap your screen it loads whatever pattern you want?

    and what kinda of power / Laser types should i be looking at? not a large distance it needs to project and people need to be able to put their hands around and through the beams.

  2. #12
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    Quote Originally Posted by Dojo View Post
    What i want is to project a laser pattern onto a surface from above.
    No problem. Easy to accomplish. However, there are some things to consider... First, a complex pattern will be difficult to project (it will tend to flicker). This is why it will be very difficult (if not impossible) to do a "color fill". You would need to scan the beam back and fourth in a raster pattern to fill a shape. Lots of scanning (many points) means the frame only gets drawn a few times per second, and that's why it flickers. (The mirrors can only be moved so fast, and if your frame refresh rate drops much below 20 fps the human eye will object to the flicker.)

    Second, the wider you have to scan the beam to draw the pattern, the harder it will be (because the mirrors have to move more, and movement speed is a serious limitation). So if you have room to place the laser projector well above the display table (minimum of 2X the maximum width or length of the pattern, but ideally 4X or further away) that really helps. (Further away = reduced scan angle = less mirror movement to completely "draw" the frame.)

    you should be able to have patters outlining areas of the table starting from the correct coordinates.
    There are a few ways to do this. You *could* build a custom solution yourself using an inexpensive computer and some software that would convert a table of coordinates to a varying analog output voltage and feed that to a conversion amplifier that generated a +/- 5V differential signal before feeding that to a set of scanners. Or you could download some free laser show software (like Laserboy) and use it to create custom wave files that correspond to the shapes from your table of coordinates and then output that to a modified sound card (with a correction amp) to generate the differential signals.

    But I think the easiest way would be to purchase some low cost laser show software and a dedicated laser show controller. Then you can create the frame files in the editor and see the output on the table in real time. In fact, you might also be able to use another piece of software (ILDA S.O.S.) to convert the table of coordinates directly to an ILDA frame file and display that with no editing at all.

    A few important questions before you go any further:

    1) What is your budget for the project?
    2) Is it more important to you that this be a home-build project (educational / training environment), or is off-the-shelf OK?
    3) Will this be used in a business or in the general public, or is this something that will live exclusively in your basement. (Safety & regulatory issues here.)
    4) Do you need/want multiple colors on the laser projector?

    I want to be able to connect this apparatus to either a phone via app or a bluetooth remote for control.
    This is definitely possible. However, if the device will be used in a commercial or public environment, it will open up a huge can of worms with regard to regulatory and safety compliance. (Or, alternately, it will force you to use very low power lasers.)

    Quote Originally Posted by Dojo View Post
    why would audio have anything to do with projecting a laser?
    Laser projectors "draw" images by moving the beam up and down, left and right, using a pair of tiny mirrors that are rotated back and fourth slightly. To draw shapes that are not connected to each other the laser is turned off (lifting the pen from the page, so to speak) and then the mirrors are re-positioned to the next spot before the laser is turned on again to resume drawing. These tiny mirrors are moved by galvometers ("scanners"), and the input signal to the scanners is a varying analog voltage.

    Audio signals also consist of varying analog voltages, and as it happens the bandwidth for audio fits nicely within the limits for laser scanners. So in some cases people have re-purposed audio hardware for use with laser projectors. Because the audio market is so big, you can get high-quality parts for cheap prices. By comparison the laser light show industry is much smaller, yielding much higher prices for gear that generates similar signals.

    Audio is not an exact fit, however. Most re-purposed audio equipment needs to be modified before it can be used to control a laser projector. But even with these modifications it can often still end up cheaper than the cost of a dedicated laser controller.

    Are there lasers that would be able to statically draw my lines on a board or is is just a single ray tracing a pattern very quickly giving the illusion of a solid line faster than a humans 60hz eye capability.
    To create the entire pattern continuously (with no scanning) would require a specialized holographic diffraction grating. This is probably not practical for your application. Scanning the pattern over and over (so that persistence of vision blends the moving spot on the wall into lines and curves that make up the completed frame) is far easier. Also, you can go quite a bit slower than 60 Hz. Most people start to notice the flicker at between 20 and 25 hz. (Lighting conditions and the laser's wavelength also play a role.)

    What are some good Lasers for this purpose?
    There are *many* commercial projectors that can be used for this. Deciding factors would be budget, environment (especially lighting conditions), safety concerns for operators, and durability requirements.

    Likewise, you could build something yourself, although if the ultimate goal is to use it in public or for a business you're probably better of purchasing something off-the-shelf due to the arduous regulatory hurdles involved in certifying a new laser product as being compliant with all government regulations.

    are most able to controlled by a app? or through a cpu through an app.
    Most laser projectors are controlled by custom laser software running on a Windows PC and connected via a dedicated hardware controller. Typically the controller and software is sold as a package. There are a few software options that will run on the Mac, but not many. Also, some software is sold separately from a controller (usually in these cases the software supports multiple controllers).

    Quote Originally Posted by Dojo View Post
    would be possible to do some sort if infil in this case if im willing to accept some flicker (more time to draw more rays).
    If you would be OK with a grid pattern filling the interior of the shapes (think widely-spaced graph paper), then yes, this is doable. But if you want a solid patch of color, that's going to be very difficult, if not impossible.

    Your small-signal bandwidth limit for standard laser scanners is 2500Hz. That means you can move the scanners up and down (or side to side) 2500 times per second. Divide that number by your desired frame rate (say 25 FPS to make the math easy) and you're left with how many "lines" you can have per frame. It's a crude example, but if you can follow it you'll quickly understand just how limiting those moving mirrors really are.

    Then too, remember that "small signal" means a maximum of about 3 degrees of scanning angle. This is quite small! To scan your 6 ft wide table with a scan angle of only 3 degrees the projector would need to be mounted almost 58 feet above the table! It's far more likely that you'll be operating at closer to 30 degrees scan angle - if not greater - which means you're now into the large signal bandwidth limit, and that is far more restrictive. (And, unfortunately, also more difficult to quantify, as there isn't a standardized test pattern for this limit.)

    i assume a higher frequency pattern laser would be more expensive? im trying to keep cost down.
    There are high-performance scanners that can give you up to a 3X speed boost. However, they come with a 10X increase in price.

    Quote Originally Posted by Dojo View Post
    could you not just set it up to have the patterns on a SD card or somthing. then when you press a button or tap your screen it loads whatever pattern you want?
    Yes. If you do not want to have the computer connected to the laser projector all the time, you can purchase a projector that supports automatic playback of frames that are stored on an internal memory card. Create the frames on the computer, load them into the projector's internal memory card, and then run the projector in stand-alone mode. There are several ways to trigger the projector to change the frame it is displaying. (DMX is probably most common.)

    what kinda of power / Laser types should i be looking at? not a large distance it needs to project and people need to be able to put their hands around and through the beams.
    Really need to know more about the whole project to answer this. From a regulatory standpoint, if it's going to be used in public, or if commerce is involved in any way, then absent a bunch of safety hardware and special interlocks the laser must output less than 5 milliwatts. (The problem is when you say you're going to let people put their hands in the beams. That triggers a *bunch* of regulatory issues.)

    Adam
    Last edited by buffo; 12-14-2018 at 06:28. Reason: typo

  3. #13
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    Quote Originally Posted by buffo View Post
    No problem. Easy to accomplish. However, there are some things to consider... First, a complex pattern will be difficult to project (it will tend to flicker). This is why it will be very difficult (if not impossible) to do a "color fill". You would need to scan the beam back and fourth in a raster pattern to fill a shape. Lots of scanning (many points) means the frame only gets drawn a few times per second, and that's why it flickers. (The mirrors can only be moved so fast, and if your frame refresh rate drops much below 20 fps the human eye will object to the flicker.)

    Second, the wider you have to scan the beam to draw the pattern, the harder it will be (because the mirrors have to move more, and movement speed is a serious limitation). So if you have room to place the laser projector well above the display table (minimum of 2X the maximum width or length of the pattern, but ideally 4X or further away) that really helps. (Further away = reduced scan angle = less mirror movement to completely "draw" the frame.)
    Ok, Nix the infill idea its really not important, simpler is better. The Pattern could be as simple as 2 opposing Chevrons ><, or 2 parallel lines at a set distance from edge of table l l (see the picture in my original post and would only need lines to delineate a margin) . and it needn't be very solid, just narrow and enough to know where the line is on the table. Just imagine a visual aid for placing something on the table. wouldn't need to be any stronger than the cheap lasers you can get at the dollar store, though it would need to be more complex to move the laser quickly to create the pattern.

    few important questions before you go any further:

    1) What is your budget for the project?
    2) Is it more important to you that this be a home-build project (educational / training environment), or is off-the-shelf OK?
    3) Will this be used in a business or in the general public, or is this something that will live exclusively in your basement. (Safety & regulatory issues here.)
    4) Do you need/want multiple colors on the laser projector?
    1: Budget for myself is one thing, i would be happy spending a couple hundred bucks to get what i want. i had considered perhaps making a sale able package to people who are interested which makes me think that just buying a controller and projector package would not make sense to sell even if i create the patterns.
    2/3: I think i could build it myself and pair the laser i build to a software package. Ideally this would be able to be used in both environments, but like i said wont need a strong laser the 5mw ones would be more than enough given that i dont anticipate being able to place it more than 6 feet above . I realize you mentioned about the angle playing a role in draw speed, but i think with how solid i want it to look shouldn't be an issue to be closer. just need enough to know its there.
    4: Multiple colors would be nice but not required. Would 2 color be better (2 seperate lasers = Half work done per laser). but honestly lines just need to be visible for placing objects against in relation to the table space.

    There are *many* commercial projectors that can be used for this. Deciding factors would be budget, environment (especially lighting conditions), safety concerns for operators, and durability requirements.
    Likewise, you could build something yourself, although if the ultimate goal is to use it in public or for a business you're probably better of purchasing something off-the-shelf due to the arduous regulatory hurdles involved in certifying a new laser product as being compliant with all government regulations.
    at the start its fine cuz ill be using it privately at the start, but given that the power will already be within Canadian safety guidelines eventually i might try to do something with it perhaps in a business setting.

    If you would be OK with a grid pattern filling the interior of the shapes (think widely-spaced graph paper), then yes, this is doable. But if you want a solid patch of color, that's going to be very difficult, if not impossible.
    yea death to the infill idea.

    Yes. If you do not want to have the computer connected to the laser projector all the time, you can purchase a projector that supports automatic playback of frames that are stored on an internal memory card. Create the frames on the computer, load them into the projector's internal memory card, and then run the projector in stand-alone mode. There are several ways to trigger the projector to change the frame it is displaying. (DMX is probably most common.)
    im thinking of this kinda situation. only need teh laser to draw the red lines in the photo.
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    Really need to know more about the whole project to answer this. From a regulatory standpoint, if it's going to be used in public, or if commerce is involved in any way, then absent a bunch of safety hardware and special interlocks the laser must output less than 5 milliwatts. (The problem is when you say you're going to let people put their hands in the beams. That triggers a *bunch* of regulatory issues.)
    yea doesnt need to be powerful, just needs to be obvious and also needs to able to draw a few lines on a table.

  4. #14
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    A laser projector has one set of scanners that move the beam in X and Y.

    There are three lasers inside of an RGB color projector. The 3 colors are mixed into a single beam that go into the scanners.

    Different colors are made by turning on individual lasers or combinations of lasers. Some systems can only turn the lasers on or off (TTL modulation). Some can blend colors in varying amonts of each RGB (analog modulation).

    You can get an inexpensive "party laser" projector that has RGB lasers that are TTL modulated that can read an SD card. You only get 7 unique colors of red, green, blue, yellow, cyan, magenta and white. Typically these units come with lower quality scanners and the optics table is literally glued together. The alignment of the three lasers (R G B) is usually not very good and there isn't a whole lot you can do about it.

    But, it might be a place to start.
    Creator of LaserBoy!
    LaserBoy is free and runs in Windows, MacOS and Linux (including Raspberry Pi!).
    Download LaserBoy!
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    All software has a learning curve usually proportional to its capabilities and unique features. Pointing with a mouse is in no way easier than tapping a key.

  5. #15
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    Quote Originally Posted by james View Post
    A laser projector has one set of scanners that move the beam in X and Y.

    There are three lasers inside of an RGB color projector. The 3 colors are mixed into a single beam that go into the scanners.

    Different colors are made by turning on individual lasers or combinations of lasers. Some systems can only turn the lasers on or off (TTL modulation). Some can blend colors in varying amonts of each RGB (analog modulation).

    You can get an inexpensive "party laser" projector that has RGB lasers that are TTL modulated that can read an SD card. You only get 7 unique colors of red, green, blue, yellow, cyan, magenta and white. Typically these units come with lower quality scanners and the optics table is literally glued together. The alignment of the three lasers (R G B) is usually not very good and there isn't a whole lot you can do about it.

    But, it might be a place to start.
    Might legit only need red and a set of galvometers. should simplify things a bit.

  6. #16
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    Then all you need is a red laser module that can be turned on or off with a control voltage, a pair of scanners, a hunk of Aluminium plate to bolt everything together with some stability and a DB25 (printer port style) connector to hook it all up.

    You won't have an SD card reader so you will need a DAC. You would only need three channels from a sound device for X, Y and red.

    BTW there is a perfect match in resolution between a wave that is 16-bit signed integer samples and the standard file format used to store and transport color laser vector art (the ILDA file format). It too uses 16-bit signed integers to store X Y and Z coordinates.

    You should download LaserBoy listed in my signature below. It's free. It comes with a Windows exe. It might enlighten you as to how all of this works.
    Creator of LaserBoy!
    LaserBoy is free and runs in Windows, MacOS and Linux (including Raspberry Pi!).
    Download LaserBoy!
    YouTube Tutorials
    Ask me about my LaserBoy Correction Amp Kit for sale!
    All software has a learning curve usually proportional to its capabilities and unique features. Pointing with a mouse is in no way easier than tapping a key.

  7. #17
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    Quote Originally Posted by Dojo View Post
    imagine a visual aid for placing something on the table. wouldn't need to be any stronger than the cheap lasers you can get at the dollar store, though it would need to be more complex to move the laser quickly to create the pattern
    Got it. This is well within the abilities of even the cheapest laser scanners if you decided to build this yourself. Likely you could also re-purpose an inexpensive commercial projector to do this.

    1: Budget for myself is one thing, i would be happy spending a couple hundred bucks to get what i want. i had considered perhaps making a sale able package to people who are interested which makes me think that just buying a controller and projector package would not make sense to sell even if i create the patterns.
    Really cheap scanner sets start at around $80, and for ~ $250 you can get scanners that will give you the industry standard 30kpps performance level (which is where the 2500Hz small-step bandwidth limit I mentioned above comes from). That's the scanners with the mirrors, the mounting block, the scanner amps, the inter-connect cables, and the AC to dual-voltage DC PSU to power them. Just add a laser module (with it's own power supply) and a signal source and you're in business.

    Alternately you may be able to find an off-the-shelf projector for about the same price that you could then modify to accept external signals from either some home-brew software or some free or low-cost laser show software.

    2/3: I think i could build it myself and pair the laser i build to a software package.
    This is the approach I would recommend, both because it's a great way to learn about the technology and also because it gives you some additional freedom with the design. Since it will only be used in your home, the legal restrictions are largely irrelevant. Safety is always a concern, but if it's your own project then in the end you'll be protecting yourself from, well, yourself! Take proper precautions (basically be an adult) and you'll be fine.

    i dont anticipate being able to place it more than 6 feet above
    This will impose limits on what you can scan. To scan 6 ft wide when the projector is only 6 feet away from the surface requires a scan angle of just over 53 degrees. That is close to the maximum scan angle for many scan systems, and beyond the abilities of some of the really low-end units. It's still doable, but complex images will not be an option unless you want to add an expensive lens that will artificially increase the scan field size. (Not recommended, as it will also increase the beam diameter.) You will still be able to draw the example shapes you posted above, however.

    Multiple colors would be nice but not required. Would 2 color be better (2 seperate lasers = Half work done per laser). but honestly lines just need to be visible for placing objects against in relation to the table space.
    The scanners are doing all the work, because they have to physically move the mirrors back and fourth. The lasers are turned on and off electrically, and this can be done at Mhz speeds. Thus, the lasers will never be the limiting factor. The scanner speed limit is several orders of magnitude slower.

    The point of having extra colors is to give you more options regarding the pattern you draw on the table. (Red line = work piece edge lines up here, while a blue or green line = make your cut along this line, or something similar.) This may or may not be worth the trouble for your application.

    But the limit on the total number of lines remains the same regardless of how many colors you use. (Unless, of course, you also add an additional set of scanners each time you add another laser.)

    given that the power will already be within Canadian safety guidelines eventually i might try to do something with it perhaps in a business setting
    Ah. Location = Canada. Good to know. Legal issues still apply for commercial laser products in Canada, but they are less challenging vs what we have to deal with here in the USA.

    Regarding your image on what the device might look like, it's probably going to be larger than you think. As for the "magic" portion, that will be the scanners, which will move the beam around to draw the pattern. Here is an example of what it might look like when assembled (this is a single-color laser projector).



    Making it battery-powered is possible, but it will add complexity and you may not be happy with the battery life.

    Adam

    PS: Here's another image that shows you what it would look like with the laser operating...
    Attached Thumbnails Attached Thumbnails scanhead.jpeg  


  8. #18
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    Alright, thanks for the help guys, this has certainly help me get my head into the terminology. i got a better idea now.
    seems like i might need to wait for smaller scale tech to do what i want but ill keep looking into it.

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