Page 1 of 3 123 LastLast
Results 1 to 10 of 21

Thread: Gain Medium

  1. #1
    Join Date
    Apr 2018
    Location
    New York City, NY, USA
    Posts
    5

    Default Gain Medium

    My apologies if this is an "asked and answered" question, but I didn't see anything directly on point while searching this forum.

    Regarding neodymium-based lasers: is the gain medium consumed as the laser is used, or is the rod a fixed "permanent" component of the laser assembly?

  2. #2
    Join Date
    Jul 2009
    Location
    Orlando, FL
    Posts
    373

    Default

    In an ideal world, the rod/crystal/chunk-o-gain medium is a "permanent" component- it doesn't get "used up". In practice, they can develop fractures or burns/imperfections on the optical surfaces that require them to be replaced.

  3. #3
    Join Date
    Jan 2006
    Location
    Charleston, SC
    Posts
    2,147,489,446

    Default

    To expand on David's post:

    In a typical application where the rod is not being pushed hard (that is, the laser is not designed for very high power output), the rod itself will last forever and so will the mirrors - unless there is a physical mishap that damages the rod mechanically.

    But in higher power applications, then yes the optical coatings can degrade over time and repeated use.

    To get at the heart of your question though: the lasing action is a function of the electrons in those neodymium atoms being excited to high energy levels and then falling back to the ground state. This action does not change or degrade the material at all.

    HOWEVER, the process of exciting those electrons is not 100% efficient. That is, not all of the pumping energy goes into changing the energy state of those electronics. A great deal of that pumping energy is lost as heat. And if that heat isn't properly controlled, then the rod can be damaged (or even destroyed).

    It's also good to note that most of the rod is actually made of glass. The Neodymium is added in small amounts, and it's only those atoms that participate in the lasing action. (Likewise, in a ruby laser, it's the chromium atoms that do the lasing, which are in the minority in the crystal... Most of a ruby's structure is aluminum and oxygen, but that little bit of chromium gives it the red color and also allows it to lase.)

    Adam

  4. #4
    mixedgas's Avatar
    mixedgas is offline Creaky Old Award Winning Bastard Technologist
    Infinitus Excellentia Ion Laser Dominatus
    Join Date
    May 2007
    Location
    A lab with some dripping water on the floor.
    Posts
    9,890

    Default

    All rods do degrade very slowly, and in extreme high power apps or apps that are water cooled with direct cooling of the rod, the outside certainly degrades very slowly. . With lamp pumping the outer part of the rod can get bleached or become adsorbent. ND:YAG is long lived while For example ND:YLF rods in water cooled systems last about three or four years before the outer surface of the rod in contact with cooling water dissolves so bad as to reduce power by 30-40%.
    ~
    For most modern apps, at modest pump powers, other parts of the laser will die first. For example the mirrors might degrade because of the very high electric fields that can be created by the intracavity light. KTP and LBO crystals have a finite lifetime, as well.
    ~
    ND:YAG usually gets repolished and re-used if the ends are damaged, can suffer from ion migration, end coating damage, or thermal cycling causing cracks, etc.
    But in general, in a sealed cavity CW or Q-Switched laser, it is extremely rare to replace a rod unless the cooling system corrodes or freezes. . For a very high power laser running in "Giant Pulse, Sub-Nanosecond, Amplifier, or Mode Locking services", replacing a rod may not be so rare..
    ~
    Clean cooling water of the proper pH is important here in the case of wet rods. With good cooling water a rod may only degrade 1-2% in terms of power in 10-20 years. I've seen quite a few 20 year old rods in service.
    ~
    Usually you can assume 5-7 years minimum for Nd:YAG, less for ND:GLASS, etc. Modern crystal growing techniques are amazingly good, and post grind inspection will easily catch 99% of possible defects.
    ~
    I have one ND:YLF diode pumped rod that has defects in it at the pump diode focal points, but other then that, I rarely see defects. The user simply moved the rod over to get around the defects a few times.
    ~
    small slices or wedges of rod in Green pointers are where I see the most gain medium defects or death. They are often very thin and grossly overdriven.

    Steve
    Last edited by mixedgas; 04-19-2018 at 12:41.
    Qui habet Christos, habet Vitam!
    I should have rented the space under my name for advertising.
    When I still could have...

  5. #5
    Join Date
    Apr 2018
    Location
    New York City, NY, USA
    Posts
    5

    Default

    Thank you all for your replies - very helpful! I suspected that medium degradation was something along the lines of "entropy plus epsilon" at lower energies.

    It now occurs to me that, rather than pursuing various hypotheticals, it might be more practical to describe the application I have in mind and ask for input.

    With the advent of consumer-accessible DIY tools - 3d printing being the big one, of course - I'm converting part of my apartment into a fabrication lab: my own personal "maker space". I also want a degree of portability in my tools, along the lines of "break the equipment down, load the parts into Pelican cases, re-assemble on-site" for both actual engineering work and eventually (once I understand the tech well enough myself) educational demonstrations for schools, other makers, and so on.

    One tool I'd like is a CNC cutting laser. I'm not adverse to building something myself - my engineering experience is up to the task of building the mechanical, power, and control systems for such a machine - and I actually want to do a cutting-laser build to teach myself (with appropriate safety precautions, of course; body protection, interlocks, and a high-density backstop at the end of the beam path). I was seriously considering something from the "Wicked Lasers" product line, but then I came across gain-medium lasers.

    My knowledge is limited mostly to solid-state diode lasers with no gain medium, and I'm accustomed to thinking purely in terms of mW and wavelength, but I'm intrigued by the possibilities of gain-medium lasers. From what I've read, a Nd:YAG laser outputs in the infrared range; it does reasonably well as a working tool but is not open-air visible. I'd like to achieve open-air beam visibility (educational demos are LOT more effective if "it looks cool") while also retaining practical utility as a fabrication machine.

    So, here's what I'm looking for:
    1. Open-air visible beam (definitely under indoor-lighting conditions; bonus if I can get open-air visibility in outdoors daylight though I presently assume that that's not possible).
    2. Precision cutting for parts fabrication (plastic and aluminum at least, bonus if it can etch denser metals).
    3. "Breakdownable" portability (US standard 120v@60Hz AC input, bonus if I can power it with a rechargeable DC battery bank built into the Pelican).

    Given that use-case, and that I want to build it myself, what sort of laser would fit best?

    Thanks again.

  6. #6
    Join Date
    Apr 2018
    Location
    New York City, NY, USA
    Posts
    5

    Default

    PS: I live in New York City and, from what I've read, I may need to obtain permits and/or licenses to legally own and operate certain types of lasers. This is a big part of why I'm switching this thread from "this specific question about a specific type of laser" to "here's what I want to do, what are my options?"

    Not looking to solicit a legal opinion here; I would just like to get some advice as to which technologies would fit my use-case so I can RTFM and so I can be specific when I ask the local government what I can and can't do.

  7. #7
    Join Date
    Jan 2006
    Location
    Charleston, SC
    Posts
    2,147,489,446

    Smile

    Quote Originally Posted by GSTR View Post
    I actually want to do a cutting-laser build to teach myself (with appropriate safety precautions, of course; body protection, interlocks, and a high-density backstop at the end of the beam path).
    This sounds like a fun project, and indeed several members here have built their own laser cutters. It sounds like your design will need to be very small, however, since you want it to be portable. That will probably limit the types of lasers you can use. (In particular, I'm thinking this may rule out the use of a CO2 laser, unless you can make do with a lower power unit.)

    My knowledge is limited mostly to solid-state diode lasers with no gain medium
    So, you've got a bit of a conceptual error here. Not trying to be pedantic, but all lasers have a gain medium. In the case of a direct-injection diode, the gain medium is the P/N junction area of the laser diode. As electrons pass from the N material and into the junction, they fall into "holes" in the P material. Really what this means is that a free-flowing electron is captured by an atom, but it's important to realize that when that electron is captured, it is in an excited energy state. Thus the current flowing through the junction provides the pumping energy.

    Laser diode materials are selected so that the upper energy states contain at least one metastable energy level. This allows you time to develop a population inversion. The other requirement is the existence of a low energy state in the material that electrons will tend to fall to once they leave the metastable level, and this is key: the energy difference between these two states corresponds to the desired output wavelength.

    Comparing the lasing process in a direct injection diode with other types of lasers, we see that the primary difference is in how the electrons in the gain medium are excited. Also, not all lasers excite the electrons to the point where they are free flowing and no longer bound to an atom; most simply raise the energy level while keeping the electrons bound to their host atom. (Although admittedly most visible wavelength gas lasers do ionize a portion of the gain medium, and in some of those lasers the pumping/capture/decay/lasing process is quite similar to what is happening at the P/N junction of a laser diode.)

    From what I've read, a Nd:YAG laser outputs in the infrared range; it does reasonably well as a working tool but is not open-air visible.
    Correct. The output is 1064 nm, which is completely invisible to the human eye. However, this IR wavelength can be frequency-doubled to green light (532 nm) using a non-linear crystal optic, typically Potassium-Tyanyl-Phosphate (KTP). And you can still cut/etch/burn objects with 532 nm light, although interestingly there are many materials that perform better when cut with IR. It all depends on the material you are cutting.

    Several commercially-available laser cutting machines offer a variety of wavelengths with which the machine can use to cut or etch with. My wife used to operate one that used a CO2 laser for long wavelength (10,640 nm) IR, an ND:YAG for short wavelength (1064 nm) IR, and a KTP doubling stage coupled to the ND:YAG for optical wavelegth (532 nm) cutting applications.

    Also, members here on PL have used higher-power Blu-ray diodes (405 nm, so near UV output) to cut and etch materials with their home-made laser cutting units, and some of the results they've achieved are remarkable. So you may want to spend some time thinking about the types of materials you will need to process before selecting the laser(s) you'll use. For example, you mentioned aluminum and plastic, but you didn't state how thick the material will be, how big the total cut will be, or how long you're willing to wait for the cut to finish. Also, will you need/want to cut other materials? (Leather looks amazing, as does paper...)

    I'll defer to other members who have actual experience building and operating their own laser cutters as to which laser would be best if you had to choose just a single wavelength. But as a general rule, commercial suppliers recommend long wavelength IR for things like wood, plastic, paper, and leather, while shorter wavelegth IR is usually recommended for metals.

    Then I would suggest you look at the work that member VDX has done with his *scanning* laser cutter, and compare that with the work that member Swamidog has done with his X/Y-table-based laser cutter. Lots of good information to be found in those threads.

    As for the regulatory issue, you should be OK for the moment as you are not introducing anything into commerce when you are designing/building the unit. But if you plan to take the finished product out into public for demonstrations (especially if you're being paid for that, such as a guest-speaker spot at a local high school), then you'll need to get legal first. In particular, the Department of Labor for the state of New York imposes significant additional requirements (including a "mobile laser operator" certification) that must be met should you ever find yourself under their jurisdiction. (Note that this is above and beyond the federal requirements from the CDRH.)

    I'm not certified for New York, but I think we have a few LSOs here who are. Ideally you'd want to discuss this project in depth with one of them long before you planned any public use of the cutter. As for the CDRH compliance, that's a bit easier, although it is still going to be a good bit of paperwork for you and it also will need to be completed before you introduce the cutter into commerce.

    Adam

    PS: Welcome to the forums!

  8. #8
    Join Date
    Apr 2018
    Location
    New York City, NY, USA
    Posts
    5

    Default

    Wow... Just... Wow! Thank you, buffo! I've done a few read-throughs of your reply and it's becoming clear to me how much I have to learn before I attempt this build.

    No worries about being pedantic. As a result of being an engineer by profession, a scientist by both disposition (in the 'Dilbert' definition, I have "the knack" ) and tradition (I come from a long line of scientists; something I'm very proud of), and the influence of my parents (prior to retirement, Mom was a teacher and Dad was an engineer), I'm well up on the importance of precise nomenclature. I found your correction both polite and enlightening (aaaaand I just made my first bad laser pun; didn't notice it until I went back to proofread this post). I was under the impression that the term "gain medium" implied something you pass a beam through after the output of the diode, which I now know is incorrect (I thought that "post-diode gain media" like Nd:YAG rods applied some sort of polarization or collimation, not excitation). I now know more than I knew yesterday.

    On 'NCIS: New Orleans', Scott Bakula (one of my favorite actors, and my initial inspiration: I'm a huge fan of 'Quantum Leap', I've coveted a replica of the "gummi-bear handlink" prop since it first appeared on the show, and the idea that I could theoreticaly *make* one was what got me into DIY fabrication) often says "let's learn things". I absolutely love that phrase and the approach and the attitude it implies; the main purpose of all my meshugas here is to do exactly that. So, while I understand various things, I'm conscious of the likelyhood that I'm not using the right terms and am aware of why that's not a good thing (see also: the "dy/dx" part of "He Fixes Radios by Thinking!" from 'Surely You're Joking, Mr. Feynman!'). In that spirit - and barring any obvious "RTFM and GTFO, stupid" - I welcome all "pardon me, but that word doesn't mean what you seem to think it means" that you or any other members of this forum might take the time and effort to provide.

    Bottom line: feel free to get as pedantic as you want - barring any obvious "GTFO until you RTFM", I take it as an earnest attempt to educate and advise.

    I'm familiar with the concept of using a salvaged laser diode from an optical-disc drive - I remember when people first started doing that with CD-R lasers, and of course the "Blu-Ray Star Trek Phaser" videos on YouTube - but my knowledge on such conversions is easily a decade out of date. I will certainly reference the more current works you mention.

    Warm-fuzzies aside, let's get down to the science. I do still need to really deep-dive on the information from your last post, but I do have a few avenues of thought that having validated as possible or invalidated as a dead-end would save me a LOT of work.

    1. I've come across some theoretical material on enhancing excitation. I imagine that both of these have massive safety concerns (I'm reminded of the "unlicenced nuclear accelerator" scene from 'Ghostbusters') but - as I suspect the answer is "no" and a "no" would shut down the question entirely - would integrating either a klystron or a magnetron result in (if you'll pardon me going "Tim Taylor" for a moment) "more power"?

    2. I'm also curious as to how fiber optics might apply. Let's take a stock Wicked Lasers Arctic (3.5W, 445nm): what would happen a) to the cable itself and b) at either end of the cable, if one end of a fiber-optic cable was placed on the device's "emitter"?

    3. To answer your question about materials: I'd be looking to cut aluminum, acrylic, and 3d-printed objects (I'm still debating which type of source plastic I want to use). Let's select a soda can - more accurately, a flat piece of typical soda-can metal - as our baseline for thickness and composition. I would also like to cut plastic; let's go with acrylic (the material the handlink was made of) at 0.125 inches thick. For the 3d-print material, let's go with "it'll cut your soda can, it'll cut your little bits of Ziggy, so you can probably assume that it'll cut 3d-print objects" and not worry about that usage just yet. As to the operational expectations, let's use "successfully cut a 1x1 inch square from the defined material" as the baseline. Mass-production of objects is neither needed nor desired; we can assume that the primary use-case is fabricating prototype components on a scale best measured in inches / centimeters. In terms of portability, let's go with Pelican's HTC Vive case (https://www.amazon.com/HTC-Vive-Peli.../dp/B01MFAIXA8) as a starting point. With these givens, how to the various types of cutting laser rate in terms of a) providing the cleanest-cut edges, b) completing the cut in the shortest amount of time, c) consuming the least amount of electricity, and d) take up the least amount of space in an equipment-case with batteries included?

    OK, this thread has clearly gotten away from me. I apologize for all the tangled threads; I didn't set out to be a "Usenet kitten", but this stuff is just so **** interesting and I'm all excited about having access to minds who know the subject!

  9. #9
    Join Date
    Jan 2006
    Location
    Charleston, SC
    Posts
    2,147,489,446

    Smile

    Quote Originally Posted by GSTR View Post
    it's becoming clear to me how much I have to learn before I attempt this build.
    Don't be so hard on yourself. Truthfully you do not need to understand any of the theory that makes the laser work to build your own laser cutter. However, it's clear that you're interested in the WHY as well as the HOW. And that's cool, because that mindset is common among many of the members here, including me. As a general rule, most folks here are more than happy to discuss both the theoretical side and the practical side of the tech. But don't beat yourself up too badly about the theoretical side. The actual task of constructing a laser cutter isn't terribly challenging (I would estimate that it's on par with building a laser projector), and it's much easier when you've got experienced people who can help you out if you get in a bind.

    Then too, you mentioned that you're an engineer, with a strong family background in science and tech. My guess is that you probably already have most of the mechanical and electrical skills needed to complete the project. It would be prudent to spend some time reading about general laser safety topics, however, as that knowledge is going to be important both during the build process and when you're operating the machine. And as lame as it sounds, literally googling "Laser Safety" is a great place to start, as the common references (Wiki, OSHA) are quite informative. Also, if you haven't already discovered it, "Sam's Laser FAQ" is a goldmine of information for all things laser.

    With regard to general theoretical knowledge, I have a book that is literally from my childhood that I often recommend to people: "The Story of the Laser", by John Carroll. It's out of print now, so you'll probably only find used copies of it, but if you can snag one, I would say it's worth it. I first read this book in 7th grade, and it is largely responsible for jump-starting my passion for lasers. Also, I should warn you that it's an old book (Published in 1964), so many of the newer technologies are not covered because they hadn't been invented yet. Still, if you can follow the theoretical discussion in this book, you'll have the fundamentals down and can apply that to any new laser design.

    Thanks for the Feynman reference. I've watched several of the taped living room chat sessions that were recorded before his death, but I haven't read "Surely You Must be Joking". So that's on the Amazon list now! The man really did know how to tell a good story while still getting his point across.

    I'm familiar with the concept of using a salvaged laser diode from an optical-disc drive
    These days it's easier to purchase the bare diode. Harvesting diodes is tricky work; diodes are extremely sensitive to static shocks and it's easy to kill them during the salvaging process. Plus the bare diodes can be purchased for very reasonable prices these days. (15-20 years ago this was not the case, which is why so many people started harvesting the optical sleds of these drives to get cheap laser diodes.)

    I've come across some theoretical material on enhancing excitation.
    When it comes to diode lasers, excitation is a direct function of current. More current = more output, at least until the gain medium saturates. Also note that some diodes will fail before the gain medium saturates because the optical power density at the emitter face becomes so high that it causes catastrophic damage to the crystal. (The early low-power single-mode red diodes that lased at 660 nm were notorious for this failure mode. If you reflected the output beam back to the emitter it would destroy the output face. Search the forums here for "back reflection" and you'll read plenty of horror stories from the 2005-2010 years.) Another common failure mode is over-temperature, which basically cooks the diode until it cracks and/or the electrical connections at the ends of the diode separate from the crystal.

    A magnetron or klystron will generate high power RF - usually in the microwave region of the spectrum. That would definitely not be good for a diode laser! (Think about how RF can induce currents in electronics, now consider how diodes fail under high current.) However, there are some gas lasers that still use RF excitation, the most common of which is probably the sealed-tube CO2 laser. (Which just happens to also be a commonly-used laser for cutting applications.)

    That being said, increasing the RF excitation in a gas laser can cause some of the same problems as increasing the current in a diode laser. (Excessive heat, gain medium saturation, and output mirror damage.) So the short answer is, no, you probably won't be able to *significantly* increase the output power of a given laser beyond it's baseline capacity, pretty much no matter what you do. (Admittedly some lasers are de-rated before they're sold, and those can be "over-clocked", if you will, by running higher current. In those cases you might get 50-80% more power, with the trade-off a greater chance of sudden failure.)

    If you need/want more power, the better option is to either purchase a larger laser to start with, or add a second laser and either stack the beams together using a knife-edge mirror or combine the beams (assuming they are polarized) using a polarizing beam-splitting cube in reverse.

    I'm also curious as to how fiber optics might apply.
    Fiber optics allow the laser to be hard-mounted in one place while the output is moved around by simply moving the end of the fiber. So in the case of a laser cutter you have to have some means of X and Y movement. You can mount the laser in the center (like the spindle of a milling machine) and just move the table that the workpiece sits on. Or you can have the table be fixed in place and mount the laser on a movable head that traverses left and right, and forward and back, using a pair of gantry arms in the shape of a cross (or alternately, a single gantry that spans front to back and moves left-right on tracks).

    But what if you want to use a high powered diode laser that needs a big heavy heat sink and large fans to cool it? Or worse, what if you want to use a large, high power CO2 laser, but the laser head is 30 inches long? It's going to be difficult to move all that hardware around on this complicated gantry of stepper motors, tracks, pulleys, and so fourth, right?

    However, if you couple the beam from the laser into a bit of fiber, now you can run the lightweight fiber up onto your gantry. So the mass that is moving in the X and Y direction is fairly small, because the big, heavy laser head is mounted elsewhere in the machine. All you have at the end of the fiber is the coupling device and the final focusing lens. That's the advantage of fiber.

    There is a third option, and this is to use mirrors to reflect the beam up to the gantry assembly and then down to the work piece. This makes for a complicated optical path as you'll need several bounce mirrors that move with the gantry arms, and getting everything aligned correctly might take some time (especially if you're using an invisible wavelength laser), but this is an arrangement that is used in some commercial laser cutters when fiber isn't an option, either due to beam quality (can't couple it to the fiber efficiently enough) or power density (can't put 10 KW down a fiber without burning it).

    With regard to your specific example of the 3 watt 445 nm output of the Wicked Lasers Arctic laser pointer - that beam could be coupled to a fiber optic cable and used to cut things. However, the Arctic hand-held would not be the best laser to purchase. You would be better off purchasing a stand-alone 445 nm laser module, attaching it to a baseplate, and mounting the fiber launch on the same plate so you can accurately position the fiber in front of the output of the module. You could take this even further if you wanted to and purchase the bare 445 nm diode, a laser diode driver, and a machined brass diode mount with output lens and construct everything yourself. But the Arctic is going to be difficult to mount, difficult to control, and nearly impossible to keep cool for long duration, continuous operation.

    I'd be looking to cut aluminum, acrylic, and 3d-printed objects (I'm still debating which type of source plastic I want to use).
    There are lots of different plastics available for 3D printing. I'll defer to others here as to which wavelength will be best, but I suspect that either CO2 or YAG will work well enough. And given the added complexity that using CO2 brings, it's probably smarter to just use YAG.

    Let's select a soda can - more accurately, a flat piece of typical soda-can metal - as our baseline for thickness and composition.
    Hmmm... OK, that's quite a bit thinner than I was expecting. This is well within the abilities of a bunch of different lasers. In fact, VDX has been cutting metal at thicknesses similar to this using his Blu-Ray cutter.

    I would also like to cut plastic; let's go with acrylic (the material the handlink was made of) at 0.125 inches thick. For the 3d-print material, let's go with "it'll cut your soda can, it'll cut your little bits of Ziggy, so you can probably assume that it'll cut 3d-print objects" and not worry about that usage just yet.
    Fair enough. So, yeah, right now everything you want to do can be done with either Blu-Ray or 1064 nm IR from a YAG or Vanadate (YVO4) laser. And given that you wanted a visible beam, I'm leaning towards the 405 nm Blu-Ray diode, even though that limits your maximum power output...

    successfully cut a 1x1 inch square from the defined material
    Oh wow - 1x1 inch is trivial! The smallest cutter I've ever seen was 12" x 8", and that was a small unit...

    OK - time to reconsider things for a moment here. Up until now I've been thinking about a traditional cutter with a moving head that shuttles in the X and Y planes. But now I'm starting to think that VDX's design (which uses scanners - galvos - like you see in a laser projector) might be the better solution. Especially since you want it to be small and portable, I think this arrangement will be more compact. Even so, I'm unsure if you'll be able to make it fit in the pellican case you linked to. Although maybe if you are willing to go with one that is slightly taller...

    how to the various types of cutting laser rate in terms of a) providing the cleanest-cut edges, b) completing the cut in the shortest amount of time, c) consuming the least amount of electricity, and d) take up the least amount of space in an equipment-case with batteries included?
    You've done a great job of defining the scope of this project. One thing regarding power - you don't have to operate off batteries unless you really want to. A small switching power supply can provide all the DC power you'll need to run the unit. Just bring an extension cord with you. However, if battery operation is a desired feature, then power consumption of the components becomes a lot more crucial.

    I should also say that at this point you should probably solicit other people's advice as well, especially if you can speak with people who have already built their own unit. As I do not have hands-on experience with the process of designing and building one of these, I'm sure there are gaps in my knowledge. Plus it's never a good idea to only listen to a single person's ideas (no matter the topic). Living in the bubble, and all that...

    That being said, with the parameters you provided above, in my opinion:

    Blu-ray should give you the best cut edge, but will be limited on power so cut time will be longer on thick material. It will be the smallest diode package (not much cooling needed) and only needs a few watts of electrical power. I'm really leaning towards this being the optimal solution for you at this point, and I'm also thinking that you might want to use scanners instead of X/Y movement. (Need to speak to VDX about this!)

    Diode pumped IR (YAG/Vanatate, etc) can be scaled up to 5-10 watts easily enough, making for faster cuts. 1-2 watt units still small enough to operate with passive cooling. Edge quality may suffer at high cutting speeds. Should be ideal for metals though. Electrical power will probably be less than 120 watts. (Less than 60 watts at lower powers).

    CO2 laser would be bulky, but you can get 20 watts or more. Probably overkill for this application. Not likely to be portable. But it would cut fast! Power requirements north of 600 watts.

    445 nm direct injection diode is sort of between the Blu-ray and the YAG IR options. Beam quality is relatively poor (so cut edge quality will suffer), but you can get 7 to 9 watts of output from a single diode the size of the eraser tip on a pencil. That power level will make for fast cuts. May need larger heatsinking though. Fiber coupling performance will be poor, so you'd probably mount the laser on the gantry. Electrical power requirements are 40-50 watts. Biggest advantage over the IR design is that the beam is visible, which you said you wanted.

    Adam

  10. #10
    Join Date
    Jan 2006
    Location
    Charleston, SC
    Posts
    2,147,489,446

    Smile

    Sorry for the double-post, but I thought it would be helpful to look up some of the previous threads that dealt with laser cutting/engraving so give you some more perspective. The search engine here on the forum isn't the best, but using Google with the "Site:PhotonLexicon.com" modifier actually works pretty well.

    So here are some threads that you might find interesting: (beware the rabbit hole! many of these threads link to other sites with lots more information)

    https://www.photonlexicon.com/forums...-of-Grey-445nm
    https://www.photonlexicon.com/forums...ng-and-marking
    https://www.photonlexicon.com/forums...utting-project
    https://www.photonlexicon.com/forums...abrics-cutting
    https://www.photonlexicon.com/forums...a-2-watt-laser
    https://www.photonlexicon.com/forums...ngraver-cutter
    https://www.photonlexicon.com/forums...ree-foam-board
    https://www.photonlexicon.com/forums...-with-2W-445nm
    https://www.photonlexicon.com/forums...-optical-fiber

    Also, it's probably a good idea to start a new thread at some point with a different title and an opening that explains what you want to build. That way more people with laser cutting experience will be inclined to jump in to share their thoughts.

    Adam

    PS: When you get a chance, please update your profile to show your location. We often host "Laser Enthusiast's Meetings" in various areas, and if one is reasonably close to you it would be very helpful if you could attend. Also, many members are willing to drive a short distance to meet up with new folks and help them out if they can. Seeing your location in the profile will often trigger this sort of cooperation. And if you're ever going to be in the southeastern US, I know several folks (including me!) who'd welcome the chance to meet you in person and chat about things. But we do also have members in the NY area who may be close enough to meet up with you too.
    Last edited by buffo; 04-21-2018 at 04:39.

Posting Permissions

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