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Semi-OT: Any experts on solid state lasers?

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  • #16
    Diode lasers especially blue light and others related are extremely hazardous to your eyesight. Damage occurs so fast the blink can not help prevent damage. Do the research before you need the white cane.
    Retired - Journeyman Refrigeration Pipefitter - Master Electrician - Fine Line Automation CNC 4x4 Router

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    • #17
      Looking at the title of this thread, we had a resident laser expert, "Macona" but he hasn't posted in a long time. I miss his posts.

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      • #18
        You need to get your hands on a copy of ANSI Z136.1. This is all the basics of laser safety. Read it carefully.
        Last edited by IkeHarris; 02-26-2020, 12:42 PM.

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        • #19
          Sorry I'm getting to this late, but did you figure out if your laser just appears dim because of a low duty cycle, or does it completely shut off? Can you play with the laser on its own to see if it just appears dim because it's only on a tiny percentage of the time (at 60 revolutions per second it would only be .06%)? It's also possible that your laser doesn't like to run at short pulses, so getting a laser designed to be pulsed might work better.

          How many sides does your mirror have? If it turns out that a low duty cycle is causing it to be dim than you can increase the number of sides on it.

          Solid state lasers generally have an additional step required to get them to shine. Original ruby lasers basically had the flash from a camera, but there are other ways to do it now. I doubt that they will work better than diode lasers at the speeds you are looking for, but maybe. You can also just go buy higher powered diode lasers, although I can't speak to the safety of any of it.

          Edit: Take the pulsed laser bit with a grain of salt. The only ones I found were IR lasers.
          Last edited by AssertiveWall; 03-09-2020, 09:22 PM.

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          • #20
            The other thing to look at is your MOSFET and gate driver. Not all MOSFETs are created equal in respect to how fast they can turn on. You also need a good stiff gate drive to turn it on fast. If you have access to an oscilloscope, look at the output pulse to see how fast it is actually turning on.

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            • #21
              This thread makes wonder how my little Laser Sndway 150 meter distance measurement unit works. $63 oneBay, here: https://www.ebay.com/itm/SNDWAY-150M...4AAOSwE~pdAK9A

              I've checked it against my 200 foot survey tape and it was within 0.01 feet. It does not like bright sunlight on a target, unless it is reflective tape. Standard 635nm Class II laser, powered by 2 AAA batteries. I do not have stock in this Chinese company, but I am actually quite impressed with it. I've taken hundreds of 'shots' with it around my home. I made a bracket for it to mount on my Wild T16 where normally a D14 Distomat would have mounted 40 years ago. So, gathering horizontal and vertical angles along with the line of sight distance allowed me to tie landscaping, structures, and infrastructure all together in CAD.

              What I'm curious about is the source laser. If I locked down movements on the T16, blocked off the laser output and used a handheld separate laser dot at the same 635nm, would it actually read the distance?
              I should try it out in my shop.

              Dan
              Salem, Oregon

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              • #22
                Originally posted by Danl View Post
                What I'm curious about is the source laser. If I locked down movements on the T16, blocked off the laser output and used a handheld separate laser dot at the same 635nm, would it actually read the distance?
                I've set up something similar to how those range finders work. The common explanation is that they send out light, then measure how long it takes for a signal to return. What that meant for us in practice is that we sent out a waveform (varying light intensity), and then measured the offset between the waveforms. If you were sending out a separate laser, you would have to match the waveform to the one that the device is using in order for it to read as anything.

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                • #23
                  That's what I thought. So you are saying that the proper frequency would not be enough, and that they are internally synchronized?

                  Salem, Oregon

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                  • #24
                    Yes, the received signal is measured against the sent signal.

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                    • #25
                      Think about a laser assy. for a laser printer. Solid state shutter, laser stays on all the time, spinning mirrors to scan the laser across the page. Should be lots of info on the web. I've been away too long to remember much.
                      M.Barry

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                      • #26
                        Originally posted by mattthegamer463 View Post

                        That would work but I am looking at speeds in the low microseconds, so a mechanical or electromechanical shutter won't be able to open and close in time. It seems to me the electrical method is necessary. Syncing two mechanical mechanisms would also prove tricky as I need firing time control.
                        Referring to post #5, do an internet search with the term "optical chopper".

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