Fiber Laser Learning Lab 20 Photo Engraving on Slate

Lotus Laser (lotuslaser.com) have lent me this MOPA 20 watt fiber laser to “play with”. Although I have a moderate understanding of laser technology and how constant power glass tube systems work, pulsing fibre laser marking machines are shrouded in deeper mystery than the glass tube machines. They have been designed for high speed marking and the technology has been well tried and proven. There are limited “tricks” that the pulsing laser technology can perform. You enter predefined parameters for each marking “trick” you wish the machine to deliver , then stand back in amazement. Most correspondents tell me they have bought their machine direct from China and received a machine and EzeCAD software, preloaded with a few default parameters. No other instructions beyond the EzeCAD manual are forthcoming.
I must stress I am neither a teacher or expert in this field so you join me in my learning adventure with the warning that I have a simple but inquisitive mind and will probably make mistakes on my way to discovering the truth. I WILL oversimplify and maybe distort the scientific detail in my quest to build a simple picture of why and how this technology works. I am not trying to reverse engineer anything , just to break through the seemingly impenetrable “techno cotton wool” that surrounds this amazing piece of science.

[@johnrevill9592]

I do slate on the fiber using the drill mode in EZCAD. This eliminated the issue of pixel overhang as you described at @32:00. In Drill mode, the galvo will move to the point, Stop, Fire the laser for the specified time, them move to the next dot, stop and fire again. All at extremely fast speed. These are 254DPI. Drill speed of 0.05ms Error Diffusion Dithering. 100% power. Pulse Width CW. (Speed is irrelevant in drill mode) drive.google.com/file/d/1AHSImKlatxE-scHnWRNej6CUJqOCMQQr/view drive.google.com/file/d/1mSXdQhbeqpqx3h5tEqy2gISMz1JYkS59/view

[@SarbarMultimedia]

Hi John With lots of experience you have also figured out how drill mode works. I did a bit of searching and found no understandable description of how the drilling mode worked. It told me all about drill time duration and the fact that I could still use the pulse width and frequency to drill holes with different power and that speed was governed by the drill time but nothing about how the drill coordinate was controlled by the fixed DPI. The EZcad manual was almost useless. I eventually found an exact replication of my CO2 slate engraving with a compound lens by using 254dpi ar 850kHz 2ns pulse but 70% power. Depending on the image, the fiber is between 2 and 3 time faster than my CO2 machine. I thought it would have been faster. Thanks for sharing you images. Best wishes Russ

[@NooTwist]

Loos so nice. What is your laser power and lens ?

[@gunscratch]

What a superb video. I'm totally new to the world of lasers and am gradually learning about various aspects. No video that I've seen so far gives as much detail in such an easy to understand manner. It's great seeing your experiments and failing is a huge part of success and hearing your thought process as you work through is brilliant! Thank you so much for taking the time to make this video.

[@japa7221]

I love what you are doing. I'm learning something new with each episode. Thank you very much for the time you spend recording these videos. Greetings from Poland

[@SheaDesign]

That was great! Tnx. With a prepress background, you basically acted out a thought experiment for me. Awesome.

[@robeccs]

Very interesting and educational sir 👍🏼🍻

[@hoocli]

Amazing video as always. You wouldn't happen to have the final settings you use to do the video. I'd love to have that as a starting place if you have it

[@NooTwist]

Thanks for sharing Russ. Did you adjust the drill mode time as 1 ms as seen on Ezcad for 1us real time? About EZcad, I think it is milliseconds, not micro. Because when I adjust the drill mode to 1ms on EZcad for 254 dpi image, it travels about 4 inches in about in1 second, which means about 1000 pixels = 1000 milliseconds. Even If when I adjust drill mode to 10miliseconds, I see how slow the laser moves. Maybe it's firing many pulses on same point?

[@bobreichel]

I prefer the mouse on the right. It may be a bit darker but in your video it had far better definition. I'm taking it that, that image was done on the fiber laser. I had a 30w F/L but the F/L power source went on it. I just received a new power source and upped it from 30w to 50w. I begin the operation to extract the 30w p/s and replace it with the 50w p/s in the next couple of days.

[@SarbarMultimedia]

Hi If there had been nothing to compare it with you would not realize it was a few shades darker. You are right about the definition and that is all down to the precision and size of the dots that the fiber laser can deliver.. Best wishes Russ

[@LaserEverything]

I love your channel Russ! Let me know if you'd ever like to collaborate on anything or join us on our laser engraving podcast "Laser Source"! Hope to hear from you :D

[@vernaloutback]

Russ, I thought it was this video, but I couldn’t find it as I scanned through it again. What microscope and software are you using to measure your dot size, and how did you generate the program/pattern to ensure the size in Ezcad?

[@SarbarMultimedia]

It was a slightly laborious task in Photoshop I set the resolution to 254 ppi and then used a pencil tool set to 1 pixel to create the pattern 1 pixel at a time.. If you like add another comment and disguise your email address in a sentence or two (otherwise KZbin will reject your comment) l will send you the file and additional oinformation. Create your disguise like this. Use john follwed by a dot and then smith. After an at symbol add g=m* ai&l with a dot and a com. That has beaten their algiryhms so far.. IO wioll delete your comment Best wishes Russ

[@precisionlasersolutions7996]

Hi Russ, have you tried reducing the power even further, possibly 30% on a 20W or even lower, I found that on my 50W Q-switch I had good results on slate with 12% but as I reduced power I increased drill time, I found this lessened the black hole donut effect? frequency effects it.

[@SarbarMultimedia]

Many thanks for your advice. Just after I completed the video, I found that reducing the power to 70% produced and exact replica of my CO2 laser result but in less than half the time. I am pleased with the final outcome especially gaining an exact understanding of how drill mode works Best wishes Russ.

[@damienbriggs1990]

Hi Russ I have built a co2 laser and love your videos and I built my laser purposely for granite as I'm a stone mason and a sculptor. And I tried your dot test for ages but the problem with stone which I found is when doing photo etching is a lower DPI engraves a much higher quality image. And the reason for this is you need the blackness in-between the dots to still be there to create the Grey's

[@damienbriggs1990]

I also brought lightburn with the DSP controller due to your recommendation and good results. My favourite is Jarvis

[@SarbarMultimedia]

@@damienbriggs1990 Hi Damien Granite is a strange material, because it is a mix of minerals,(quartz and feldspar). Both have significantly different damage thresholds (melting points) which makes it a very difficult material on which to get high resolution engravings.. The brain is very good at mixing different density dot patterns into grey scale images but the continuously changing background texture and colour of nearly all granites is very confusing for the eye. I have worktop manufacturer near to me and they import various mineral products from all over the world. I have access to their offcuts and have been lucky enough to test all sorts of minerals,(alabaster, marbles , many different granites and slates from various parts of the world.) The uniform nature of slate allows consistent results but to be honest I have found the cheapest hardest Chinese slate produces the best contrast photo images. and I can comfortably achieve 254dpi images. Lightburn is a fantastic piece of software engineering and I love it's many features. . However I rarely use its graphic features. The Jarvis and Atkins dither algorithms are ok for lower resolution pictures (for reasons too long to explain) But you will note a "pass through" switch at the bottom that allows me to create high resolution images with the Photoshop Floyd Steinberg algorithm and send them unaltered for laser processing after sometimes adding fancy text. Best wishes Russ

[@damienbriggs1990]

@@SarbarMultimedia hi thanks for get back to me. I feel privileged that I am talking to the main man. as I have watched loads of your videos. I wouldn't buy any stone from worktop place as you explained granite can be very inconsistent so I use a monumental quality stone which is called absolute black which we use for headstones but i buy granite chopping boards and granite placemats from dunlem mills at £10 each which come with polished edges. And I sell portraits for £60 and selling really well. If you have Facebook my page is Damien Briggs memorials and you can see how well they come out. I have been selling them under priced for practice reasons incase they come out not perfect. As my main goal is to get good before photo lasering headstones and a sneaky way to advertise with out advertising headstones as no one wants to see that lol. Hopefully one day you could do a granite video with some good quality granite chopping boards as they come very consistent. My settings are 200mps at 22.5% power using a 40 watt co2 laser Thanks once again

[@meangreensvideo9475]

I'm just now finding your channel, and lasers for that matter. This video was single handedly the most NEW knowledge I've ever been presented with, digested, and thoroughly enjoyed. You condensed in one hour what was by all accounts a master class on how heat and time relate to the quality of an image given the constraints of a "low res" image. Your explanation of pixels literally made me sit back and say... Well how about that. Thank you for this video

[@fate2022]

Just out of curiosity since this is an older video, but did you try to change the laser frequency and or the hatch pattern?. I have a hunch changing the laser frequency and or hatch will yield the result you are looking for. changing the laser frequency is like changing the dot resolution, or the number of dot pulses per firing of the laser.

[@SarbarMultimedia]

The glass tube CO2 laser has particular characteristics that enables it to produce a real DOT by balancing the HV power supply rise time response time against linear speed. The fiber laser is all electronic and has instant switching on and off. That causes a serious problem when trying replicating what the glass tube laser can do. Lets say for example that the beam width of the fiber laser is 0.1mm and the image is 254ppi. That means each pixel is 0.1mm square. If I have a line of pixels that run black.white.black white for instance then as soon as the program detects the black EDGE of a pixel it will turn the beam on INSTANTLY . At this point there will be half a beam hanging out the side of the pixel in the previous white pixel. The beam will scan across the 0.1mm black pixel until it sees the white edge, whereupon it will turn off. However at this point the beam is already half a beam into the white pixel. Thus no matter what frequency / power / speed you try to run at you will always get a 2 pixel burn for a single black pixel. This may sound inconsequential but you will be amazed at how disruptive this will be to the dithered image. Thus the soulution, for slate at leas,t is to use drill mode because that places a single dot for EVERY black pixel regardless of whether is is a single or part of a multi pixel line. Out of interest, this exact problem is a feature of an RF tube and is why you will never be able to do proper quality photo engraving with these VERY expensive machines They use their own versions of software for photo engraving to supposedly make it easy fro the user but in reality it is using all sorts of tricks to hide this issue. Best wishes Russ

[@fate2022]

@@SarbarMultimedia Russ, thank you for the reply and does make sense, but you can do some really decent photo engraving with a fiber or C02, I suppose it's really going to do with the software being used and the adjustments you make to the photo and laser settings to start with. I was trying but youtube doesn't allow to post a photo I was going to show some really nice laser engravings of actual photos. You have to also take into account the galvo head on the fiber laser which can change focal length and beam dispersion,and then finally of course the material you are trying to engrave on, for instance a paper or a wood material you're going to get edge burn which will cause image distortion depending on the type of image, with a stone material, as you showed, you can get a burn through hole, also causing an image distortion or lower quality resolution.

[@SarbarMultimedia]

@@fate2022 Hi . Don.t misunderstand me when I say that you can.t do proper photo engraving with a fiber laser. We were only limiting the scope to slate. Photo replication with dithering is a hijacked process from black ink printing onto white paper. . It is a process of fooling your eyes into building a false picture in your brain, Dither a grayscale image and if the dots are small enough you will never be able to see it is just a black and white image because your brain is building a false grayscale image. To REPLICATE a dithered image the rule is very simple 1 pixel=1 dot. If one dot =2 pixels as I mentioned earlier that is not photo replication. You can create very passable photo engravings on various materials that fool the brain into believing they are good copies. The key issue is what is the smallest consistent DOT that your machine can achieve if the answer is 0.2mm than I'm afraid the best REPLICATION you can achieve is 127ppi (a 0.2mm pixel) This will produce a very acceptable A3 size picture if you view it from about 10 feet away.........and there is the problem. Judging the aesthetic qualities of a finished image is very subjective. Bill boards are done at 20 to 20 ppi whereas glossy magazine photos are usually only about 300ppi.. The point I am trying to make is that if you can REPLICATE a black and white dithered image with a consistent colour and size "burnt " dot then you do not need to do lots of brightness/contrast/sharpening. Sadly with a fiber laser you cannot burn wood or card because of the 1micon light wavelength but I have done a really nice looking i100mmx70mm mage at 1016ppi on black anodized aluminium. In a way this is a cheat because you cannot overburn it

[@imajeenyus42]

Hi Russ, I'm curious about the special mode you're describing when the pulse width is set to 1ns. I'm now the happy owner of a 30W and 60W fiber engraver, but I've never come across a CW mode for these things. Is it something unique to the manufacturer of your machine? Bitmaps are something I'm wanting to investigate as well - I think I've managed to nail flat all the intricacies of vector marking!

[@SarbarMultimedia]

Hi Lindsay Congrats on your new toys. The fiber laser I had was on loan and now been "unloaned" because Lotus Laser had an urgent sale they needed to fulfill. The machine was a rather expensive niche type of fiber laser called a MOPA (20 watts) see en.jptoe.com/product/m7-20w-30w-mopa-fiber-lasers/ 9 out 10 machines that Lotus Laser sell are Q switch fiber lasers which I presume is the type you have. The Q switch principle has limited flexibility because it has an almost fixed pulse width. Although the power of your machine may be 30 watts for example , because it stores energy between cycles it can generate more powerful PULSES than the 30 watts on the tin. My laser had 16 different pulse widths and shapes that I could select. and one of those was continuous mde (CW) if I selected 1ns. You do not have such a choice with a Q switch.so I think the closest you can get to CW will be 100% power and max frequency. Simple bit maps are just a matter of matching the scanning interval to match the bitmap resolution. When it comes to dithered images you will get best results by matching your speed and frequency to the picture resolution. It's the same problem I encountered with MY RF laser. There is another way thar EZcad allows, and that is DRILL MODE. (set the X and Y to a fixed resoloution to match your image.) and that is demonstarted laterin this video. Best wishes Russ

[@bradouellette6558]

Great video , very insightful

[@thelaughinghyenas8465]

Great lecture!

[@jtcustomknives]

Next episode we will try and get color from the glass bubbles from using different coatings and focus lengths.

[@FSEAirboss]

Thank you for all the work you do, but especially sharing it with the rest of us. Couple of questions. What happens to the image quality if these are clean with a scrub brush, or perhaps a greenie if they are installed in say a kitchen area where they would constantly be wiped down. Would the glass beads be knocked off like when you tapped it with your camera? Could applying an oil or some other substance enhance or degrade the image quality/black center hole?

[@SarbarMultimedia]

The glass damage was on an exaggerated burn where there was lots of ejected molten material. The idea is to keep the glass ( its the micro bubbles in the glass that creates the light grey/white colour) to just a few microns thick as I manage to do with the CO2 laser. The image is very stable and has been tested numerous cycles in the dishwasher. I can remove the image completely with an orbital sander so, yes if you are really agressive the image can be removed. After engraving I usually seal the surface with a beeswax floor polish. This also enhances the contras because the slate goes darker as it absorbs the oils but the glass is impervious and remains white.. Best wishes Russ

[@FSEAirboss]

@@SarbarMultimedia Thank you Russ. I poorly worded my second question. I meant during the engraving process versus finishing afterwords, Similar to what you were doing with metal engraving on the CO2.

[@johnny0110]

Great work Russ, as always!!

[@jcposada]

Very helpful video.

[@jamesofcork]

I am new to lasers and have just purchased a Beamo (which I realise is not in your league) however I wonder if you could tell if it is dangerpous to cut cast epoxy resin with a CO2 laser? Many Thanks

[@SarbarMultimedia]

Hi James I will refer you so what most companies use as their bible. atxhackerspace.org/wiki/Laser_Cutter_Materials Best wishes Russ

[@jamesofcork]

@@SarbarMultimedia Thank you very much

[@kingy550]

Hi Russ, would it be possible for me to contact you regarding a co2 laser I recently bought? It has started acting up, and I'd really appreciate some good advice. Thanks in advance, Richard.

[@SarbarMultimedia]

Hi Richard Just add your disguised email to another comment and I will contact you I will also delete your comment/email Best wishes Russ

[@richardgreen446]

SabarMultimedia thanks for all your thought provoking and interesting videos. I was wondering about pixel addressing. I always thought that a pixel address was at it's centre and not on the corner. Incidentally in your drawing you showed that the Y position of the laser was at the centre of the pixel but the X position was on the left of the pixel. Just a thought :-)

[@SarbarMultimedia]

Hi Richard this was a video I did whilst a little less knowledgeable about pixels and dots. When a scan takes place across a line of black and white pixels. The controller does not perceive t pixels it is just the EDGE changing from white to black that switches the laser ON and similarly the change from black to white that turns the beam OFF. It regards a single black pixel as a short line and any continuous group of black pixels as a longer line. The problem in this scenario is the response time of the HV power supply to switch on enough power quickly enough to burn a SINGLE pixel. That is what limits speed when it comes to photo engraving. At this stage I di think that pixels were individually addressed and maybe individually burnt. No I was wrong....but that was all part of this discovery journey. Best wishes Russ

[@richardgreen446]

@@SarbarMultimedia Hi Russ, what I was thinking is that you had sized the pixel to the maximum resolution of the machine, 0.1mm but not sure if the machine resolution is 0.01mm, in which case, as you say the controller will treat it as a line. However, you found a way to compensate in X axis, does that method also compensate the Y axis. Since you did the video on this machine, have you decided on buying one or one similar? Best wishes to also.

[@SarbarMultimedia]

@@richardgreen446 Hi Richard Don't get confused by pixels that appear on your screen, dots that you burn onto material and the manufacturers misuse of the word resolution A specification can easily claim that a step increment of 0.01mm is a resolution of 2540 dpi. Yes there are 2540 INCREMENTS in !" but dots are things that YOU create with the parameters and lenses at your disposal. A typical 2" focal length lens will burn a dot on wood of about 0.2mm diameter which is 127dpi. Before you can decide on the image resolution of your photo you MUST know the smallest dot you can make on the material you plan to engrave. Im my case it was 0.1mm on slate so I was able to set my photo resolution to 25.4mm/0.1mm=254ppi. The simple rule for photo engraving is 1 pixel = 1 dot. Pixels do not overlap on the screen so you cannot have larger dots that overlap. There is a lot to learn about photo engraving and it took me a long time to decode it. Pixels are square so YOU have to set the increment for Y after every line scan. In my case I chose 0.1mm as my pixel size and I have no control over what the controller does in X it just scans the line and switches the laser on and off according to what it "sees" If I choose to specify a line interval of 0.15mm for instance the controller will see half of one line of pixels and half of another line and be very confused. Your picture will be covered in black or white lines as a result. That is why you must set the Y step increment tp match the image resolution. Best wishes Russ

[@SarbarMultimedia]

Hi Richard I have to admit to not reading the comment in the correct context of the fiber laser. What I was answering above was the general way that an image is interpreted by the controller. The fiber laser does a reasonable job of doing this normal scanning mode but when it comes to slate and other mineral materials, the single dots get elongated/smeared. That is why I used a special mode they call drill mode. This does innfact look at the mapping of pixels in the image and not just at the start and finish of a black line. With drill mode , if there is a black pixel at a coordinate intersect then it will send out a pulse. That pulse is timed so the speed of dotting is no longer controlled by the linear speed but by the pulse and move time (much slower). I hope this clears the confusion. Best wishes Russ

[@richardgreen446]

@@SarbarMultimedia Thanks Russ, now that makes much more sense. I'm well aware of how bitmap images are formed, I'm a photographer and use photoshop everyday. Fiber Lasers are new to me, but I do rotary engraving and vinyl cutting. In rotary engraving my machine controller and software does treat a joined up row of dots as individual points and with regards to one pixel it would always go to the centre of it before making a mark, which really should be the way it works. Anyway, thank you for what you do and as I said before your video's are thought provoking, we all have a lot to learn. :-) Regards and best wishes, Richard

[@vst190]

для лучшего контраста, думаю надо заполнить отверстия краской..

[@adolfousiermarketstars6765]

cool 👏🏻👏🏻🔝

[@Skinny_Buddha13]

How are you able to do that?

[@SarbarMultimedia]

Hi Slate is a mineral material, which when heated, melts and turns to light grey glass. If you get the power to each dot just right then you produce a small pool of molten grey glass that sets and leaves a very durable image Best wishes Russ

[@Skinny_Buddha13]

@@SarbarMultimedia thank you.

[@kingy550]

Hi Russ, would you delete my previous comment showing my email address please. Thanks again, Richard.