Diode Laser---Under the hood 05
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- čas přidán 29. 03. 2024
- It is important to understandf that POWER is not the parameter that causes material damage. A relatively large ELECTRICAL input power is required to drive a laser creating source that in turn creates a much lower OPTICAL output power in the form of light photons . It is the INTENSiTY of those photons arriving at the material surface that detrmines the RATE of material damage. Thus, the performance of your system is dependent upon the choice of lens made by the designer (let's hope he chose well) and your ability to set the best focal point. Focal point?? there is an OPTICAL focal point and an INTENSITY focal point. I wonder which one your focus setting piece uses?
Every diode head is sold with a claimed SPOT size. I am puzzled as to how this can be possible when changing the exposure time changes the SPOT size "burnt" into your material. When doing research for this series I inquired of many "brands" as to the exact meaning of spot size. The response rate was zero. That seems to indicate this is a marketing feature and not something that is real. As this series progresses and I test more units the answer to this question will clarify. - Věda a technologie
Excellent investigation dissecting the focal effect of the lens and the intensity of the power deposition all the way down to the beam waist. Much like you I got a CO2 laser in 2017 after retirement for intellectual stimulation and found your videos at that point. Now I also have a diode laser, so thank you for the journey of exploration and the derived education!
It's most likely a clear lens with an AR coating for the 445 nm wavelength. The reflection off of the coating makes it look like a different color lens. They wouldn't use an exotic lens material for a low cost laser head, I would be surprised if they did. It's probably just plain ol' bk7 glass.
Hey, Russ, this is Rick and I was wondering if you could give me a suggestion on a fiber laser, cost is a factor, around 70 watts. I haven't watch too much of late as too much going on but hope to view some of your workshops soon.
thanks so much,
Rick
oh boy i cant wait for you to come up an adapter and a system for diode laser add-on for ruida co2 machines
Hi
The modification I have done to the orange machine is already running with a Ruida RDC6442 controller and also RDWorks or Lightburn (the normal CO2 version). It has to be setup in the vendor settings as an RF machine without preignition.. The RF machine uses PWM to control th laser so even if you have an glass tube machine all you have to do is unplug ther HV power supply and and add a suitable 12vdc or 24vdc power supply to drive the diode head. Everything can be left "as is" so you can easily swap back to a glass tube if required.
Thank you for your videos, you have the best explanation of that actually happens when the laser cuts out there. I have a question, would you consider doing some scientific tests on the effect of air assist during cutting. I.e how psi effects the cut and how the air may change the laser cutting profile? I know you have focused much on the lens and optics but i do wonder if there is a curve related to air assist. Keep up the great content
Hi
I am really just scratching the surface of this diode laser journey I am making. I have gained a lot of prior knowledge with my many years of reserching CO2 laser technology. Much of that is transferrable to this particular wavelength but there are many peculiarities that are suprising and fascinating to me. I know that the intensity profile of the beam and the way in which the lens deals with the beam is vitally important to performance, hence my concentration on this aspect. I was planning to quicklt pass on from 5 watts but I am finding things that pique my curiosity and require understanding before I contaminate the results with multi diode problems.
To your question about air assist for a diode machine.
Air assist is not a problem at the moment because the airgap between the 5 watt head and the work is large (about 25mm). The way the 5watt beam is focused lends itself to engraving but I believe it will be crap at cutting from the few wood tests I have already done. The subject of air assist is very misunderstood and I have tried to dispell many of the myths in 2 videos I did for the CO2 laser. You need to watch these videos because they will allow you to decide for yourself just how much you REALLY need air assist. See this one first
czcams.com/video/79VZjMdfBmI/video.html
and then this one
czcams.com/video/QwOkOLBp1pE/video.html
Sorry, one other thing. Your sunglasses with an OD of (whatever) Is *NOT* sufficient protection from reflected light, the fact you aren't getting spots isn't proof it is safe. Think about it. You have ~4W in a (whatever) um spot that will be imaged on your retina. IF your sunglasses are reducing ~30% that is still a lot of light that can be imaged from a high flux point source. The other thing no one talks about is the high energy blue photons having a photochemical (bleaching) effect on the retina. There are also cataracts issues with lower wavelengths. Do not take laser reflection issues lightly. I have seen eye damage from direct and indirect exposure to laser light. Get some good laser glasses designed for the wavelength. In a pinch, welding glasses will be better than sunglasses. All of these Class 4 blue cutting lasers are super dangerous (optically) and people don't take them seriously enough. You only get two eyeballs.
The old guard is simply built different
Hi
I like Patrick's comment but I am no different to most others when it comes to eyes and personal concen for them. Coherent laser light is indeed dangerous if it enters your eye which is why laser pointers are strictly regulated to very low power outputs. However blue light is not dangerous otherwise we would all be affected by the non-coherent and random nature of blue photons in white light. There are three possibilities for visible blue LASER light when it hits a material surface. First it passes right through (as in the case of glass of clear acrylic). Second, if the surface is metal, a varying but significant percentage (70 to99%) will be reflected as coherent laser light. This is VERY dangerous and why you never fire the laser at an angled metal surface. Third, the target material interacts with the light and the photon energy is converted to harmless kinetic energy which manifests itself as heat. At that point the laser light no longer exists. However, the concentrated pool of energy at the material surface will be stimulating chemical reactions at the molecular level . This in turn may or may not add to the heat with exothermic reactions. The fumes from that reaction zone will then be stimulated by the incoming coherent blue laser photons. Those blue photons will interact with the atoms in the fumes causing some of the electrons to be forced to new orbits for a few nano seconds. When those fume electrons RANDOMLY drop back to their original orbits, they release the enegy in the form of a different wavelength of light depending on the element that was stimulated. The concentated zone of these reactions means INTENSE light will be emitted. It is important to understand that this will NOT be laser light. Instead it will be random normal light with multiple wavelengths . Thus specific wavelength protection glasses are of limited use. Laser safety glasses are designed with open laser souces in mind because in research laboratories the risk of COHERENT light reflection is ever present.. In our case, unless the beam is relected off an incident surface, all the SINGLE wavelength energy is absorbed into a heating effect as it hits the material. Laser light is to be understood and respected, not feared. The fact that some of those emiitted light waves are UVB and UVC (as emitted by our sun) along with the damaging high intensity is the real reason we need to protect your eyes.
Clear industrial safety glasses are usually made with polycarbonate lenses. At 10,640 nm (CO2 laser) these provide 100% protection and below 400 nm (the realms of UVB and UVC) they do likewise. However, being clear , they offer no intensty attenuation Sadly, at 450nm polycarbonate absorption is only 20% , Thus laser safety glasses use specific dyes embedded into the polycarbonate to absorb specific wavelength energies.
You may be interested to look at this on the Thor Labs website. www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=762
By the way, I greatly appreciated your comment because it has allowed me to add so much more on the subject than the video permitted,