RDWorks Learning Lab 245 Lenses and Laser Beams A Marriage Made in Hell SarbarMultimedia 2022-11-24 | Lenses have worked perfectly for thousands of years BUT laser beams have only been around for about 60 years Yes, it's still light waves/rays and will be refracted by lenses in exactly the same manner as always. Normal light is more or less uniform intensity across the surface of a lens whereas the Gaussian profile of a laser beam means it has most of its light INTENSITY at and around the centre of the beam. Light refracts (bends) as it passes through a lens which is designed to direct all light energy to a common point (the focal point). This means the outer edge of a lens must refract the rays more than those at the centre. Our laser machine lenses are manufactured with the age old (and simplest to manufacture) form of lens geometry.....spherical. This shape has imperfect focusing properties called aberration. Thus, light from the outer edge of a lens focuses at different points to that through the center. For uniform light this weakness is hardly noticable, perhaps a bit of blur if you look carefully. However, for a laser beam with its maximum intensity (its max ability to damager material) at the beam axis, this becomes a problem. A lens may have a nominal focal point that would apply to normal light, but pass laser light through it and the maximum intensity at the axis of the beam meets the least refractive axis of the lens. Bad news.Hence the title of this video.......they stay married (with all the imperfections) for the sake of the children and to the outside world all seems well.This video is some background about several months of test work I have conducted using various beam sizes and many lens types to examine the inner workings of this imperfect "marriage".Most will not be interested in the large report of my tests and findings because on the surface, laser machines do aproximately what is expected of them without ever needing to "lift the hood". If you have an interest in the report I produced then please contact me via this private contact form.https://forms.zohopublic.eu/ndeavorlimited/form/K40XtreeemLaserCutterContactRussSadler/formperma/k2Cn0QN5ChpazfTMAUw25lZ-FKpjZa96TQWHjv3ntOg
RDWorks Learning Lab 244 Beam Setting Mk99 Surely the END SarbarMultimedia 2022-09-09 | For 6 years or more I have beem setting beams regularly. I forced myself initially to unset and reset my mirrors because I needed to understand the method the Chinese were claiming to use. I soon realized it was a tedious and error prone procedure. Hence I stsrted to modify my macine to make beam setting simple, logical and perfect. The machine I use in this demonstartion has the main two adjustments that make life so simple. However, the basic method I have decoded and demonstrate on several videos has its faults. The main fault is the "4th Corner Problem". I recently demonstrated how this problem arises and how I fix it.. As I was editing the video, I looked at the exaggerated sketch I used to explain the problem and realized there was a whole new way of tackling beam setting that would be at least 50% quicker and have none of errors that would require secondary correction settings.
RDWorks Learning Lab 243 The Weird Relationship of Lenses and Laser Beams SarbarMultimedia 2022-09-06 | My RF machine seemed to be a waste of time about 18 months ago when I finished building and thorughly testing it. I found none of the "magic" promised by the "big boys" who promote this technology. However, with my practical discoveries of how lenses and laser beam interplay, I noticed the potential for seriously enhancing the performance of this technology. My strategy for turbo charging this technology is contrary to all prevailing theory and practice and many experts have tried to presuade me of its futility.This session is a a summary of what I have discovered so far about the weird relationship that exists between laser beams and lenses. It demonstrates that the accepted practice of increasing beam size, for an RF machine, is great for engraving but bad for cutting. I have already discovered that keeping the beam small dramatically enhances engraving performance and in this session I begin to see the potential I imagined for cutting enhancement.
RDWorks Learning Lab 242 Beam Setting The 4th Corner Problem Revisited SarbarMultimedia 2022-09-04 | The "4th Corner Problem" is an issue that almost everyone will encounter when they set their beam. Very few have fully understood the cause and even less have fixed it by logic . Mitigating the problem with screw twiddling is the normal approach. It took me a long time to decode but like everthing else that's difficult to fathom, a simple exagerated diagram helped keep conflicting intuitive ideas at bay and revealed the simple logical facts creatingh the problem . When you understand the problem the sol ution jumps out at you.
RDWorks Learning Lab 241 EDITED Variable Colour Engraving Bands Decoded SarbarMultimedia 2022-08-27 | I HAVE EDITED THIS VIDEO WITH APOLOGY TO IMAGR FOR INOCENTLY PASSING ON INCORRECT INFORMATION ABOUT THEIR PRODUCT Before creating this video I have run aliasing pattern trials with other PWM frequencies and discovered that I can get an almost aliasing-free image at 9.999kHz .......just 1 Hz short of the theortically perfect 10kHz PWM frequency.. I then demonstrate why this is happening and what happens at other frequencies.. I run a comparative fox image test with the new found settings and see remarkable differences from the previous attempt. I then attempt somethiing that I had been told would be impossible . The Norton White Tile engraving princple at 1000mm/sGlass tube engraving has no PWM to drive aliasing errors. but even so, I discuss how aliasing errors could creep in and cause issues. . Desite careful analysis, there was no obvious mechanism that would result in the banding that others had described. I have known a solution to this banding issue for more than 6 years but never understood the mechanism by which banding occured. In this session, an amazing set of circumstances intersect in a way that forces me to apply 6 years of learning to decoding the issue....eventually.
RDWorks Learning Lab 240 Aliasing Bands in Dithered Images SarbarMultimedia 2022-08-24 | I am using my RF laser to investigate how aliasing can causes "banding" in dithered images . I know that many people with glass tube constant current machines have experienced this banding problem, although in the many years I have been doing fine engraving it's never been a problem In the last session I demonstrated that despite failing a couple of years ago when I first tried photo replication on this machine,. However through different techniques I have acquired basic mastery of photo replication on this RF machine , but there are small oddities in certain parts of the image. I make a cruude attemptt at fixinbg the issues and have some success when I reduce the PWM frequency to 9.7kHz. instead of the theoretically correct 10kHz.. To try and understand what the optimum PWM frequency should be , I develop a special test program to aid reverse scanning offset precision and to help track down that magic PM setting to minimise aliasing.
RDWorks Learning Lab 239 RF laser CAN do high speed photo REPLICATION SarbarMultimedia 2022-08-07 | After a break for other projects I am back investigating the poperties of a super high intensity small diameter 30 watt RF CO2 beam A long time ago i had established that setting my cheap Chinese 5030 RF machine to run at 1400 mm/s was a waste of time because the 30 watts of power was anable to support normal engraving at more than 500mm/s and photo replication was near impossible, even at 200mm/s. By removing the commercial X2 beam expander and replacing it with my on beam "conditioner", allowed me to project the 3mm beam exiting the tube tube through to the middle of the work tabe My intial experiments with lenses showed an unexpected inability of lenses to focus this small high intensity beam to make it a CUTTING monster. However, the geometry of very short focal length lenses showed hints of focussing abilityPutting the CUTTING dream aside I have done some more experiments with various compound lens configurations to see if I can exploit this high intensity beam in a different way .....for high speed photo replication.
RDWorks Learning Lab 238 The ULTIMATE A to Z tutorial of beam setting SarbarMultimedia 2022-07-27 | I recall the uncertainty I felt the first time I removed a mirror 7 years ago. Would the machine ever work correctly again?. Over an 18 month period I kept purposly upsetting my beam alignment in an attempt to understand the logic behind setting the beam perfectly and soon discovered that Chinese machine designers either didn't understand the process or purposly made it difficult for "non-professionals". I suspect my first assumption is correct and naive machine design is responsible for the MANY different beam alignment strategies people have proposed to overcome the mess Chinese designers have created.This session deconstructs beam alignment and machine design. I have modified my machines to make beam setting simple with a series of logical and progressive actions that guarantee setting perfection. I have tackled this subject several times over the years but never in such all -encompassing detail. As a young design engineer I was taught that "you must understand the problem before trying to design a solution". It seems that very few people really understand what they are trying to achieve with beam alignment beyond making sure the beam passes through the nozzle.
K40 Xtreeem mechanical upgrade kit SarbarMultimedia 2022-06-28 | My promise to send a set of mechanical upgrade parts to Cloudray has now been done. I cannot indicate IF, WHEN or at what COST, that kit will be available . In the meantime I have manufactured a batch of 17 kits that are now available for those keen to modify their machines. The dxf files for this kit are already available at the laseruser.com website and this video shows the manufacturing process for those parts. My goal was to modify an existing very basic K40 and transform it to a small format "big" machine. I am extremely pleased with the outcome and it has genuinely been accepted as an equal member of my ever increasing laser machine harem. If you visit the laseruser.com website you may be able to learn more about a separate venture that has been inspired by my K40 Xtreeem project. but it is not something I am personally involved with.For the spring specification go to the springmasters .com website and search for part C6607010
K40 remodeling Preview SarbarMultimedia 2022-05-15 | I have been working on a project that I admit did not get my full mental commitment initially. WOW!!! How , things changed. Here is a preview of what I achieved . I see furthere expansion of this project to include rotary in the future.
RDWorks Learning Lab 237 Black Marking Stainless Steel SarbarMultimedia 2022-05-14 | It must be 5 years since i looked at this subject the first time. During that time there have been just one new marking ink and Cermark and Thermark are now integrated to one product. All these products are expensive (and good) but the cheaper alternative has always been spray-on Molybdenum Disulfide.. Some claim it is far inferior and it is possible that the perimeter range for these alternative products may be narrower. This session investigates the chemistry underpinning this technology and tests novel products that posses the suspected chemistry for success. To make things fair and comparative I use the same lens, power and speed settings throughout.
RDWorks Learning Lab 236 Powder Coating with your Laser SarbarMultimedia 2022-04-18 | I have been sent video links of people using plastic powder coating materials to coloiur fill deep cut wood engravings. Hmmm . Their results look OK from a distance and yes the idea is perfectly logical. Add heat to plastic and it melts (provided you are not too enthusiastic). Having been a user of the powder coating process for many years, I understand how it is designed to work.....and wood is not on that list of suitable materials. This is an investigation to see if the process is really viable and what parameters, if any, should we be using. Could it be extended to other materials?
RDWorks Learning Lab 235 Small Beam and Long Focus Lens Incompatable SarbarMultimedia 2022-04-11 | I started off this project trying to create a small high intensity raw beam onto my work area. For 80% of the work area I succeeded but then discovered an unexpected problem. Lenses could not focus this small intense beam. So this project has now developed into one of investigating just what it is that prevents lenses from amplifying my very small unusual beam of energy.
RDWortks Learning Lab 234 Small Beam Glimmer of Hope SarbarMultimedia 2022-04-03 | Despite advice to the contrary. I am not yet giving up on my quest to make my 30 watt RF laser perform the same cutting tasks as my 70 watt glass tube machine. At this point, I appear to be proving the skeptics right but this session is one where I take stock of the data I already have and examine some of the "interesting" observations. This leads me to a investigate a totally illogical set of new conditions that shows promising results.
RDWorks Learning Lab 233 More Small Beam Experiments SarbarMultimedia 2022-03-22 | I freely admit to being a mechanical engineer that has no right to be dabbling in the well researched 3000 year old science of lenses. I keep being told by those well versed in this subject that the smallest focal diameter will be achieved when I use the maximum diameter of lens available. In my case that means expanding a naked 3 mm 30 watt output beam by at least a factor of 4. I can fully understand how and why this works just fine for creating a concentrated focal spot for engraving but my experimental work and vandalism of lenses indicates that an engraving focus is not a cutting focus. Thus I am fascinated by the very small very high intensity beam I have managed to project into the central area of my worktable. Previous quick exploratory tests indicate that there is a very weird relationship between this very small beam and lenses. In this session I try to examine that relationship in more detail with several comparative experiments.
RDWorks Learning Lab 232 Beam Expansion Means Degraded Cutting SarbarMultimedia 2022-03-10 | Demonstration trumps any theoretical argument. I have long been fascinated by the supposed "magic" of RF laser technology. The prohibitive cost of those masterpieces of engineering can only be justified by industry or a small business. About a year ago I decided to build my own budget version by modifying a cheap Chinese glass tube machine with a 30 watt RF laser source. It did not take long to find that there was no "magic" to this complex technology after all. I tested and experimented for a few months before consigning the machine to a corner of the workshop where it remained unused for almost a year. With just 30 watts it was very poor at cutting and although the machine was capable of engraving at 1500mm/s, the 30 watt power limit meant that 500mm/s was the real ceiling. In the meantime, research with lenses and my glass tube machines allowed me to discover the importance of light INTENSITY for cutting. Purists will claim light is something you see and energy density is a more correct term....sorry, not for me. I gravitated back to the RF laser source when I realized it possessed an incredibly high INTENSITY small diameter beam. However an RF laser beam diverges at about 7mm/m and as the beam diameter grows its intensity decreases. To make the beam diameter uniform across the whole work area and optical device called a beam expander does exactly what it says . It takes the diverging small high intensity beam, and increases it to a larger diameter that can be optically tuned to virtually parallel. Sadly, this increase (as mentioned previously) is at the expense of light INTENSITY. Less intensity is still fine for engraving but crucifies cutting potential.Once that INTENSITY has gone it cannot be recovered. Putting the remaining intensity through a lens will amplify it BUT you cannot amplify what's not there. Thus any RF source with a beam expander (and that means all those expensive machines!!) will be very inefficient at CUTTING. The fix is easy.......... throw more watts at the problem ( if you have LOTS more $)
RDWorks Learning Lab 231 Search for a Beam Conditioner part 4 SarbarMultimedia 2022-02-22 | Although I have managed to condition the output laser beam so that its original diameter and intensity are projected into the work area, the amazing cutting potential have not been realized. I accidentally discovered that it does fantastic things for engraving provided i use a compound lens but that was not my objective. This session is all about trying to decode why that super high intensity is not being amplified as it passes through a lens.
RDWorks Learning Lab 230 Beam Conditioning Part 3 SarbarMultimedia 2022-02-19 | My quest is to find ways to improve the cutting performance of this 30 watt RF machine Now that I have finalized the beam profiling I imagine will work, testing lenses can begin to see how they react to the ultra small beam I have produced. Optical theorists tell me that my approach will not produce the rewards I dream of. Right or wrong. I must pursue the research I have started to find out for myself if theory has nailed everything down. Are there treasures to be found?
RDWorks Learning Lab 229 Search for a Beam Collimator Part 2 SarbarMultimedia 2022-02-11 | I am attempting to upgrade my 30watt RF machine into a 60 watt cutting machine without spending any money. A Coherent 60 watt equivalent would cost about £6000 . My knowledge of laser beams and how they work has allowed me to look at this 30 watt RF unit with a fresh pair of eyes. I have a 70 watt glass tube machine that has a beam diameter of about 8mm and it is a super all-purpose machine with great cutting ability. When I look at this RF unit the beam exits the source as a 4mm beam,. which means the beam has an incredibly high light INTENSITY. Intensity =rate of material damage. The greater the intensity the faster material damage will occur. The beam intensity of this 30 watt tube is greater than my 70 watt tube purely because of the beam diameter. It therefore has the potential to cut better than my 70 wat tube IF I can find a way to keep the beam at 3mm diameter thoughout the work area without losing that INTENSITY. Experts tell me that failure is a certainty.
RDWorks Learning Lab 228 Search for a Beam Collimator Part 1 SarbarMultimedia 2022-02-06 | With advice from a guy commenting on my recent failed attempt to create my own X1 beam expander/collimator, I have been persuaded to revisit the X2 beam combiner I currently use on the RF Tangerine Tiger machine. He provided suggestions that had been successful for him, on how I may be able to improve the performance of that X2 device.Followers of my journey will know of my mistrust of lens theory when it comes to mixing laser beams and lenses. This is yet another exsmple of how lens theroy may work perfectly for imaging but does not work for damaging. This is an exercise in lens juggling and disdain for conventional optics. However, in parallel with this personal effort, I have challanged several global optics companies selling beam expanders, with this problem. Much as expected the silence has been deafening.
RDWorks Learning Lab 227 Cutting 40mm Polyethylene Foam SarbarMultimedia 2022-01-31 | About 3 years ago I used DOT mode to cut shapes in polyethylene foam packing material. It was not entirely successful because the bottom of the cut opend up witth a significant taper. My previous attempts were based on the traditional approach of experimenting with parameters to try and find values that minimised the taper. During that intervening period I have come to understand fully the relationship between the laser beam, the lens and the way light interacts with materials. I no longer randomly hunt for successful cutting parameters but start off by trying to understand the properties of the material. From there I try to zoom in on lens and beam configurations that are sympathetic to the needs of the material.This is a fairly quick revisit to cutting PE, to see if my new knowlegede can help decode the cutting mechanism that causes PE to cut in such an uncontrolled manner.
RDWorks Learning Lab 226 Can my Beam Collimator Work SarbarMultimedia 2022-01-14 | After some crude experiments with lenses in the previous session, I settled on a promising configuration that seemed to allow me to control beam divergence. The main goal for me was to try and control the 7 mrad beam divergence on my RF machine. With a claimed beam diameter of 2mm and 30 watts of power, this machine could turn into a CUTTING monster if only I could keep that 2mm beam parallel and retain its Gaussian intensity profile.over the table area.I modified a redundant X3 beam expander to perform proper evaluation of my test configuration.My acquired knowledge of how laser beams have no respect for lens theory meant I was entering uncharted territory. Pre-testing established it was possible to control beam divergence but could I retain Gaussian intensity?
RDWorks Learning Lab 225 Is a Beam Expander useful SarbarMultimedia 2022-01-03 | All laser beams have divergent properties and that causes the peak INTENSITY of the beam to degrade with distance. INTENSITY is a vital requirement for efficient cutting. Thus a diverging beam reduces its ability to cut the more it diverges. If you can optically correct the divergence then you have a beam with constant cutting properties.. Sadly, lens theory tells us that you have to EXPAND the beam diameter to control its parallelism. That increased (blunter) beam is fine for engraving but degrades cutting ability. In this session, my optical engineering naivety allows me to ignore the theory and see if there is a practical way to collimate the beam with no loss of cutting ability.
RDWorks Learning Lab 224 Blue Dream Begins its Test work SarbarMultimedia 2021-12-13 | Although my Russ Spec machine arrived several weeks ago, updates and modifications have prevented my from using the machine in anger to see how it compared with the original China blue that it was emulating. In reality it is a better quality machine but the anticipated performance needed to be verified. Only a few key tests were required to assess performance, so this is a mixed bag of testing and using the machine to explore the properties of Borax as an engraving enhancer. At the same time it was an opportunity to test my new design of engraving air assist.Canon and Variation by Twin Musicom is licensed under a Creative Commons Attribution 4.0 license. creativecommons.org/licenses/by/4.0Artist: http://www.twinmusicom.org
RDWorks Learning Lab 223 Air Assist Why, How and When SarbarMultimedia 2021-12-10 | There are many myths and misunderstandings associated with air assist. .Does more air pressure mean a deeper, faster or cleaner cut? Efficient cutting requires a "sharp" laser beam intensity profile. A "blunt" beam will still cut but much slower and with more collateral damage such as scorched top corners and dark/burnt edges. I cannot test for those conditions because I have sharp beams on my machines. Because of my advantage, it is possible that I will not see the gains that others claim from more powerful compressors. This was supposed to be more of a demonstration session to share my experience but as I was demonstrating I saw new possibilities for improving the engraving air assist.. Oh dear, I feel another design project awaits.
RDWorks Learning Lab 222 Beam combiners A new approach SarbarMultimedia 2021-12-07 | I looked at the performance of beam combiners more than 4 years ago and decided then that it was impossible to set them with any precision. I have managed for 6 years without one and at the last review, I power tested before and after to find a 5% power loss. I thought this was a heavy premium to pay for an unpredictable indication of where the beam would hit your work. Cloudray are most insistent that a beam combiner is the only way to provide a "red dot" for the lightweight head on the Russ Spec machine they have produced. I found myself with a dilemma......... agree to shipping a high spec high quality machine with a piece of known substandard kit or design a replacement that would do the job properly. I accepted the latter challenge and this video is an an analysis of the task to be performed and then testing the design that I created.
RDWorks Learning Lab 220 The Cloudray Russ Spec Prototype SarbarMultimedia 2021-11-29 | After many months of waiting, despite Covid 19 slowing things to zero at times, Cloudray have delivered on their wish to manufacture a small format, well specified laser cutting and engraving machine. With just a couple of videos and some sample parts I sent them to upgrade a basic machine, the team at Cloudray have succeeded in replicating my much-modified China blue machine. As you will see from the video they succeeded.......plus some. This is a pre production prototype that was sent for me to critique, so, as you would expect from me, this is an honest review of their success so far.
Stoneage Upgrade for a Keyless Chuck SarbarMultimedia 2021-10-09 | Portable power tools are an essential part of modern life. However I think the invention of the keyless chuck for portable drills should be competing with the square wheel and chocolate fireguard for most useless design. There is zero choice these days because ALL portable drills have keyless chucks. When I want to do any serious drill work I still rely on my mains powered KEYED chuck. Having now run out of patience I looked for an alternative solution. After minimal research I found that I could make a retrograde step and fit my semi useless portable drill with with an upgrade to make it 100% reliable.
RDWorks Learning Lab 219 Lenses and Laser Beams Laugh at Lens Theory SarbarMultimedia 2021-09-21 | This is the final session of my mission to understand how laser beams and lenses act together to circumnavigate the well established rules of lens theory. It was obvious 3 years ago that something illogical was occurring because so many of my tests and experiments were unexplainable by the disciples of lens theory. With only two grey cells, a cheap Chinese laser machine and a plethora of optical ignorance, I was obviously well qualified to solve a problem that everyone else seemed to be ignoring for the past 60 years. I could clearly demonstrate that there was some sort of secret love affair between lenses and laser beams that was allowing them flout the norms of conventional geometric optics.One of my early engineering mentors taught me that ignorance and intelligence are vital problem solving tools and that reverse engineering a problem can often lead you slowly back to the source. After 3 years of nibbling away at the problem, my perseverance has now been rewarded by a recent lightbulb moment that enabled me to visualize the mechanism by which the unique properties of a laser beam allow it to have its own secret relationship with lenses. This video attempts to share that secret by piecing together a series of demonstrable concepts that build to help YOU visualize the final mechanism. No laws of physics are broken but the optics industry seems to have ignored these weird properties that are beyond the scope of conventional lens design.
RDWorks Learning Lab 218 Old Light Through New Windows SarbarMultimedia 2021-09-20 | This is a short video to introduce a new condensed series of videos for newcomers to the laser community. The videos are not machine or software specific but are aimed at teaching the science basics, the machine basics and the fundamental priciples behind the many processes that are possible with this technology. I am sure there will be material in here for experts as well as beginners.
RDWorks Learning Lab 217 Do Laser Lenses Meet Specification SarbarMultimedia 2021-09-02 | My recent understanding of the mechanism by which laser beams cut, has had knock on effects that help solve other issues that I have been struggling with. In particular I have never been able to get even close to the spot sizes claimed for various focal length lenses. I have known for many years that the idea of a fixed focal point for our laser machine lenses was a myth but never understood why. It is easily proven that changing speed or power can affect the "focal point", thus proving it must be something other than a light ray focal point which is fixed when the lens is designed. With my new found knowledge of the cutting mechanism, I now understand why the spot size and other claimed lens properties are so exaggerated and impossible to achieve. A normal light beam carrying image information can be manipulated and tamed by one or more lenses, however, although a laser beam obeys the same laws of physics, the peculiar non-uniform INTENSITY within the beam exploits weaknesses inherent within the spherical lens design.
RDWorks Learning Lab 216 The FOCUS Fallacy (Ooops, sorry about incorrect numbering) SarbarMultimedia 2021-08-26 | When you buy a lens you have to believe the manufacturer when he defines its focal length. We can only buy two lens material types for our machines. Zinc selenide and gallium arsenide. It is possible to crudely verify the focal length of a ZnSe lens because you can see through it. However it will only be in the ball park with normal light because the real focal length is different at at our invisible laser wavelength and that will be how the lens was designed. No that is not the fallacy. There are many videos on Youtube showing you ways to find the focus . Very few people realise that they are not finding the lens's fixed focal point but something else. This session proves that the manufacturer's focal point is nothing more than an imaginary value as far as our technology is concerned because we can change parameters and influence its position.
RDWorks Learning Lab 215. AT LAST!!! I understand how lenses cut. SarbarMultimedia 2021-07-25 | I have struggled for 2 years to understand why conventional lens theory does not match the observable experimental laser cutting data. This session uses my new set of gallium arsenide lenses to create data sets from a mix of new and old experiments. Reverse engineering the ray paths and integrating my knowledge of how and why mode burns produce their erosion shapes, has allowed me to create scale CAD drawings for each of my 4 lens focal lengths. The end result is that my theory about projecting focal points below the normal focal point proved to be correct ......BUT is only a contributing and limiting factor for the cutting action that we observe. Damage to materials with light energy is totally dependent upon light INTENSITY ( some call it energy density) which my new model includes. However, the conventional lens theory models that you will encounter make no mention of this fact as you will see in the links that follow.Here are links to credible sources that try explain how and why to use different focal length lenses but all are basing their messaging on standard white light visible optics lens theory (ray tracing). American Photonics youtube.com/watch?v=ykZScC5cuHA&t=26s Trotec youtube.com/watch?v=K_dKUsY05jYUniversal youtube.com/watch?v=ykZScC5cuHA&t=26s Epilog http://support.epiloglaser.com/article/8205/42831/focus-lens-101
RDWorks Learning Lab 214 Setting Z to a New Zero Position SarbarMultimedia 2021-07-06 | With the luxury of a stepper controlled Z axis, I have always wanted to be able to quickly set the table to a different position and to set that position as Z=0 . There are a few ways to achieve this on a standard macine but all are rather tedious. . In this seession I show how to modify your machine to make setting Z=0 instant and at any table level.
RDWorks Learning Lab 213 How Lenses Cut More experiments SarbarMultimedia 2021-07-06 | The facts so far in this saga point to one or more focal points below the nominal focal point. This appears to be the reason that lenses can cut material. However, there are some obvious facts that indicate that my interpretation of the evidence is either incorrect or maybe only part of the total picture. This video analyses the experimental data is a detailed way that casts a wider light on this subject of how lenses cut.
RDWorks Learning Lab 212 Understanding Black Etching Ceramics Part 2 SarbarMultimedia 2021-06-27 | In the previous session I discovered how white titanium dioxide powder becomes black solid. In this session I attempt to discover if it is possible to make precision black dots from this process. If you understand the fundamental principles of photo replication with a laser engraver, then crisp black dots on white ceramics promises the possibility of a new era of precision in CO2 glass tube laser engraving. It may also mean no special photo preparation software will be needed.
RDWorks Learning Lab 211 Understanding Black Etching Ceramics Pt1 SarbarMultimedia 2021-06-22 | The popularity of the 450nm blue diode laser has created a lot of interest in etching images onto ceramic tiles.There may be similarities between the physics/chemistry of this new technique and the LaserTiles that I tested about 3 years ago, but I was never able to decode the vital facts that underpinned the Laser Tile magic. With several failed emulation attempts in my history book , I lost interest about a year ago. However, my new enthusiasm for this subject has been prompted by people wanting to add a CO2 laser machine to their hobby inventory after starting small with a blue diode laser. I keep being questioned about whether the CO2 laser can perform this same black etching onto ceramics. The 450nm wavelength light has significantly different capabilities to the 10,600nm CO2 wavelength, so there is no simple yes/no answer I can give. I have already demonstrated failure, but now there are a few more clues that I can examine from the successful diode laser method. Anyone familiar with my learning journey will realize that I will not be interested in a tedious hunt for parameters that may or may not be there. I need to understand the mechanism that allows the blue diode to be successful at this task. Only when I possess that knowledge will I be able to answer the question.
RDWorks Learning Lab 210 Lets Focus on Focus AGAIN SarbarMultimedia 2021-05-30 | The dictionary describes a focal point as that place where parallel rays of light passing through a lens are refracted to converge on a single point. That may apply to visible light for cameras and telescopes where light sources are uniform and lenses are high precision and usually multiples, but in the world of Chinese lasers things are a long way from that dictionary definition. The use of a single lens and then a choice of just two forms, plano convex and meniscus, is the first disadvantage. The simple spherical geometry of these lens forms will never achieve that dictionary perfection. The longer the focal length of the lens, the greater the imperfection. The single feature that ALL lasers beams posses is a non-uniform intensity profile. The perfect laser beam will conform to a Gaussian intensity distribution. ( a bell shape graph) where the central light intensity is many times greater than the outer regions of the beam. Combine the focussing weakness of spherical lens geometry with the non uniform intensity within the laser beam and we no longer have that idealized model of focus that we are all taught.We set the focal point for a lens to that distance where we create the smallest burn spot or the thinnest drawn line. This is not setting the LIGHT focal point but that point where the the light INTENSITY is sufficient to damage the material we are marking/cutting . I clearly demonstrate that the traditional model of focus is of very limited value in our weird world of lasers.
Buying Your First Laser Machine SarbarMultimedia 2021-05-18 | This is not a machine comparison video thats helps you choose the best machine. No, this honestly discusses the key points to look for in your new purchase and all the dishonest marketing and sub standard products that are being sold. At the budget end of the market , any machine you buy from "flea bay " will be built from many B grade components. The machine will work "in some way" but as a naive newcomer to the technology it is likely that you will be blaming your lack of technical prowess for the poor results you achieve. You have nothing to compare it with and it is the fascination of owning a super high tech LASER machine that is being exploited by the Chinese as they sell you a sub standard version of your dream. Don't assume this is a total scam because if you choose the right basic mechanics, despite the substandard main components, you are getting a basic CNC machine at a bargain price. Add about 25% of the purchase price for a new tube and spend some time setting the machine properly and you will finish up with a reliable piece of kit for a fraction of the price you will pay for a "supported " plug and play machine imported via a third party local company.Here, the facts about the industry are laid bare and I hope this will help you negotiate the purchasing minefield you are just about to enter. It is really a matter of choosing the least worst.I have had 6 years of amazing fun from this technology even though I admit to being one of those naive dreamers when I bought my first mahine.
RDWorks Learning Lab 209 Cutting with a Projected Focus Final Proof SarbarMultimedia 2021-05-15 | During the past few sessions I have been trying to prove that there is something other than the traditional focal point that is responsible for the the cutting behaviour that all lenses exhibit.The commonly held view to date that the increased focal range that happens as the focal length increases is somehow responsible for that cutting depth increase. This is transparently illogical when you see me cutting 26mm deep hardwood with a 2.5" lens. That lens has a focal depth of less than 2mm!!!!. I have developed a theory based on observation and reverse engineering that explains what ACTUALLY happens as the laser beam pases through a lens and after several sessions of experiments and tests I have demonstrated the credibility of that theory. This session finally demonstrates that removing the central axis of a lens has no impact on its engraving properties. I also prove that removing those engraving properties still leaves a lense with cutting ability and that cutting ability comes from a second thin axial beam that focuses at some point beyond the normal focal point. It is this "leakage" path that allows a thin focused beam of intense light to damage material BELOW the focal point.
RDWorks Learning Lab 208 Can I Remove the Focal Point SarbarMultimedia 2021-05-06 | The Russ theory of how lenses work for our laser machines took a major step forward a couple of sessions ago when I proved I could remove a lens's cutting capability by drilling a hole through the central axis where I theorized there was a high light intensity secondary focussing" leak" path projecting beyond the nominal focal point. I postulated that this projecting focal "spike" was the REAL reason why we can cut with a lens. I also demonstrated that the same degraded lens was still able to engrave perfectly. In this session I try to prove the opposite by removing the engraving capability yet leaving the cutting capability . I know it sounds totally bonkers but there is no other way to prove to doubters that there is something in my theory that requires serious consideration. Lenses have been around for more than 4000 years, thus statistically this must have been investigated before. .... but then again they didn't have lasers and YouTube in ancient Egypt.
RDWorks Learning Lab 207 The Importance of Beam Intensity SarbarMultimedia 2021-04-25 | As I begin to understand how lenses really work in our laser machines many other puzzling issues seem to be resolving.This understanding of lenses has highlighted just how vital it is to have almost perfect Gaussian beam intensity for successful cutting.It is an accepted "fact" that more watts= deeper and /or faster cutting. I now find this incorrect on both counts. Deeper cutting is a factor associated with lens choice and faster cutting is dependent upon light INTENSITY. More watts= more light intensity but the efficiency of that energy transfer depends on the QUALITY of beam your tube can generate, The best beam quality you can ever achieve is a Gaussian intensity distribution. How good is yours????A rarely considered factor that affects ALL machines is beam DIVERGENCE. The bigger your machine the more this factor will impact your cutting performance. I am sure machine builders don't even understand this when they sell you a big machine. Users will be shocked when they see this video and test their own machines.
RDWorks Learning Lab 206 Experiments to Test the Lens Cutting Theory SarbarMultimedia 2021-04-12 | Having told the world how I theorize lenses cut, based on a collection of observations and tests that did not accord with traditionally accepted "facts", it now becomes my task to push beyond theory. Without the aid of any scientific equipment, I am forced devise PRACTICAL methods to prove the implausible may in fact be reality. If I can take a lens that cuts and engraves and modify it in such a way that it only engraves, then I deduce that cutting must be embodied in that modification.My methods are very unorthodox and crude but they demonstrate some surprising facts about lenses and eventually only support rather than discredit my theory. .
RDWorks Learning Lab 205 The Russ Theory of how Laser Lenses cut .Part 2 SarbarMultimedia 2021-04-08 | We all know that laser machines CUT materials and we complain about edge striations, off-square cuts and non-flat edges but no one seems to ask why and how does that cut happen in the first place? Despite digging through many academic and industry research documents, the cutting mechanism seems unexplained. I find this so improbable that I blame myself for inadequate diligence.....somebody knows. However, in parallel with this search for someone else's answer, I have continued with my own experiments and observations. My recent failure to find a long compound lens combination that could improve the cutting performance of single lens was yet another strange puzzle in this Alice in Wonderland world of lenses. It forced me to examine all the lenses in my collection in a totally different way to see if I could obtain objective test data that characterized each lens rather than one crude "cutting speed" parameter. The results were full of interesting data , the most significant being that cutting ability increases with the focal length. On its own, this is just another interesting observation but to me this was a lightbulb moment that connected all the disparate and puzzling observations I had made over the past two and a half years. Originally I was convinced that amplifying the intensity to the focal point would in effect create a mega (very thin) mode burn. However, a normal mode burn requires PARALLEL rays and lense theory predicts DIVERGING rays below the focal point which will not support that idea. This is a landmark video for me, trying convey the many images (and their complex interrelationships) that reside in my brain. It has been no easy ride , so get a cup of strong coffee and let's see if I can explain a fact that everyone else accepts without question. IMPORTANT NOTE: Even though what happens is fact, this explanation is still a theory that links my many experiments and observations
RDWorks Learning Lab 204 Laser Beam Safety SarbarMultimedia 2021-03-28 | Perhaps the pandemic is forcing people to seek new revenue streams ? I am just guessing but for some reason in the past few months I have had comments (but mainly emails) from many newcomers to this technology. They are all asking similar questions about the dangers of laser machines and in particular eye safety. They usually point to the fact that I run my machines with the cover open and I don't wear any protective safety glasses. I think it will be easier to reference this video than spend time writing an explanation Be warned this is not the normal finger wagging type of safety video.
RDWorks Learning Lab 203 The Russ Theory of Laser Lenses Part1 SarbarMultimedia 2021-03-25 | For about 2 years I have been wrestling with two major "truths" about lenses and laser beams that do not stand up to practical tests. The first was focal length/spot size/energy density. It is well documented that you need more watts to use a 4" lens because its energy density is low due to its larger spot size. That implies that shorter focal lengths with smaller spot sizes cut better with the same power. It was when I discovered this "truth" to be incorrect, that I began my quest to understand how lenses work. At the same time I noted that lens theory takes us as far as the focal point and then dumps us without explaining how it is possible to get a parallel cut BELOW the focal point ( and for very long distances) . After the focal point the beam is diverging and losing it damage capability so how is such material damage possible? It seems to be something that is taken for granted and never been researched. My search for a long compound lens may have ended in failure but some of the data I collected during that search has accidently unlocked the answer to both the questions above.
RDWorks Learning Lab 202 More Laser Cutting Investigations SarbarMultimedia 2021-03-19 | Despite trawling through many research papers. I have found no explanation as to why and how a laser beam cuts materials. We all know it does so because of the FOCUSSING power of a lens. We have all used a magnifying glass to focus sunlight onto a piece of paper and found that it burns a hole (or fries ants!!!!) BUT it ONLY works at one FOCAL POINT. Drop the paper away by a few mm and the effect is zero. This in itself poses a logical question. When we focus a laser beam onto the SURFACE of the material we get what we expect , a burnt dot, but below that focal point according to all lens theory ( and the magnifying glass proof) the beam is losing its burning power .......how therefore can it cut a parallel kerf many millimeters deep????? The problem has been around for ever and, despite my failure to find research on the subject, I feel sure that I am trying to reinvent the wheel....or am I?In this session I push through methods of trying to "see" the beam in an effort to find an objective way to asses beam/lens performance in less crude manner than just cutting material..By the end of this session, I honestly believe I have opened a new exciting door to the future.
RDWorks LearningLab 201 The Science Behind Laser Cutting SarbarMultimedia 2021-03-11 | The search for a long compound lens combination has revaled some issues that I had not envisaged. The results, although showing some promise, did not fully support my theory on how I would achieve a longer/more efficient cut. I thought I had gained a fairly comprehensive understanding the laser cutting mechanism but the strangely uniform compound lens cutting speeds indicated that I was still missing some pieces of the jigsaw. This session explains all the principles that go into the laser cutting process because in the past I have found that explaining to others helps to simulate my own thought processes.
RDWorks Learning Lab 200 Compound lens Conclusion SarbarMultimedia 2021-03-04 | This was an interesting session taking place over several days. My initial random experiments following the light bench "suggestions" showed zero correlation and in fact proved to be misleading.After finding certain combinations had "lens destroying" powers, it forced me to target a limited range of combinations. The results and discoveries are fascinating and although delivering some positive results, finished up begging for more understanding of the cutting mechanism to explain the results obtained. I am sure that the amazing consistency of cutting performance, regardless of lens combinations, is telling me something about a limiting light intensity characteristic at the focal point...... another Pandora's box!!!!
RDWorks Learning Lab 199 Long Compound lens Part 3 SarbarMultimedia 2021-02-18 | I have made a start on exploring the various "reasonable" lens combinations that looked promising for a long depth of high intensity light beyond the focal point. However, the human eye is no good as a light intensity sensor beyond the point where it gets saturated so only these physical tests will define that intensity with cutting performance on standard test materials. There is much experimenting to do but this session demonstrates the methods I plan to use.
