RDWorks Learning Lab 46 Copper Mirrors+HQ Lens=20% More Power
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- čas přidán 24. 07. 2024
- If you own a Chinese laser cutter this little series of videos about me learning how to use the free software provided, may solve the problem of trying to learn from a virtually unreadable manual.
I am nothing to do with RD Works, I am not an instructor and I am no expert. This series will document the essential bits of many hours of trial and error - Věda a technologie
Thank you for your efforts, Sir.
I do appreciate sharing your journey with us.
Another great video Russ, thanks for sharing all your knowledge.
This was the best series of video's so far. I feel like I am going on this journey with you and am very happy to have learned about the mirrors and positioning. I also love the new access doors. LOL
Hi Scott
For me this is truly a journey. I can see no end at present as I continue to learn by discovery. It seems like there are still so many dark corners to explore. Quite exciting.
Best wishes
Russ
Hello Russ,
Still following your excellent series which will be an enormous help when I get my machine. Keep up the good work.
Regards
Joe.
+JoePCP
HI Joe
Thanks for the appreciation, I'm sure you will have so much fun when you eventually start your journey and hopefully will steer clear of the mantraps that slowed me down.
Best regards
Russ
You are awesome!!! Like this Channel so much ! Cheers from Germany ;)
Great video. Please mention what meter are you using? where can it be purchased from? Thank you for your videos. :-)
amazing video.
hi Russ.
Great video
and very helpful, have you considered using brass or to gold plated the
mirrors.Thanks
Hi
Brass is 90% copper and yes it is reflective to IR but not as good as pure copper because the zinc content is messing with the crystal structure. At IR frequency, reflectivity is nothing to do with visible light. so colour and shininess have nothing to do with it except that if you get a shiny surface it usually means it is flat which is good for coherent reflection. The only reason they gold coat copper mirrors for industrial use is so that they don't oxidize. Even oxidized copper has high reflectivity but it looses several percent. Also, gold has a slightly lower reflectivity than copper so why compromise the reflectivity? I was warned about oxidation of those mirrors I made and the doom merchants were forecasting repolishing every few weeks. I am pleased to report that after 6 months I have not touched them and everytime I look at them they are as pristine and shiny as the day I fitted them. All thanks to the protective film imparted by the polish I used. I shall be doing a review of my beam alignments and the mirror power transmission in a near future video.
Thanks for you appreciation ans comments
Best regards
Russ
Hi Russ more great info. Regarding the copper mirrors who do you stop them filling over time. if you polish copper pipe to a bright finish with in a few days the colour starts to change as the oxide starts forming on its surface.
+Carbon - G10 - FR4 - CNC Routing - 3D Design & Printing - Online Shop
Hi
The set I swapped out had been in the machine for two weeks and showed no signs of tarnishing. As I mention in the video, the polish I used has left some sort of protective coating that's preventing the air from oxidising the surface. The mirrors do not get hot so that film will not get burnt off. I can't really answer your question at the moment. My machine is in an unheated workshop and it can get quite cold and damp this time of the year here in the UK. I mentioned in the recent Power v Temperature video that I had 100 watts of heating lamps in the body of the machine, I'm hopeful that these will mitigate the dampness that can occur. I'll leave them in and check their progress regularly but it looks possible that I wont have to touch them for at least a couple of months. I have a second set that I will re-polish by the Mk3 method and seal into little ziplock bags until needed. With the aid of my laser pointer and the quick change fixes I done to the mirrors, it takes no more than 10 minutes now to swap out all three mirrors. No longer a fearful task.
The polish I used is
www.amazon.co.uk/Meguiars-NXT-Generation-Metal-Polysh/dp/B0009U7Y14 . Considering that this is a product out of California I thought it would be easy for US users but this is the closest I can find on their website www.meguiars.com/en/automotive/products/mc20406-all-metal-polish/
Thanks for your kind words
Russ
good to see you are getting a lot of use out of the power meter.
+2020tesla
Yep, that power meter and my ammeter have been my best friends ever!!! Now that i know I can so easily make copper mirrors, the cost of the meter is already recovered.
Thanks for your help
Another great video Russ!
Thanks for sharing your all great knowledge,
I think I lost a lot of power at my machine's, can you suggest me mirror's to replace, presently I am using mo mirrors
Waiting for you reply
Regards
Hi
I became obsessed with the idea of having 99% efficient mirrors and copper was the best candidate. I spent a lot of time and quite bit of money chasing that dream. It was a fascinating exercise but my conclusion was simple Forget copper mirrors. I finally achieved 98% plus efficiiency and I still have those mirrors in one of my machines today (some 3 years later). BUT for less than $5 per mirror you can have the best type of mirror .....molybdenum!!! Yes you already have the best. They are typically 97% efficiient ie youlose about 10% over your 3 mirrors, It cost me time and effort to gain another 1% per mirror . Never touch a plated mirror because they are plated (usually with gold) for a reason, The material beneath the gold is not reflective and if you clean them a few times the soft gold will wear off and then you WILL lose lots of power. Molybdenum is bullet proof soli through and through. If you mirrors are not clean and shiny then you can go as far as gently restoring the surface with silver or brass polish.. Generally a clean with acetone will restore the finish, but finallywipe it with toilet tissue to remove a film that will always be left.. The should look just like a silver mirror. In reality, unless you have been brutalizing them with abraive paper those mirrors should last for ever.. If you mirrors are clean then your power l;oss is likely to be either because you have a damaged lens or you beam is not passing cleanly through the tubular path within your head.. Then lens is the most damage prone part of your machine(alwys keep a spare). If you allow a film to build up on the underside then you could well burn off the antireflective coating. This will seriously affect its performance.
Best wishes
Russ
Really good video
Brilliant! The hockey puck to attach all three lenses to is a great design. Now if we could get you to try a granite surface plate and a little oil... =-)
I think that you had a very good idea using the Mcguires polish, they usually use an optical grade wax in their products which should work quite well in this application to protect your mirrors!
+mrchew1982
I can't see my wife being happy about me lapping mirrors on her granite worktop
In doing this experiment I tried to consider what others may have easily available to replicate my findings. The great thing about copper is that it's naturally extremely reflective to 10.6micron wavelengths and needed very little surface preparation to promote its reflectance from super to hyper. Now that it's been polished, I think it's going to have to acquire a significant oxide layer before the reflectance drops off significantly (95 to 96%). I don't wish to claim anything about the Mcguires wax, that was an accident of fate. It worked better than the Brasso and interested me because of the molecular protective coating it imparted. I have hopes that it will be two or three months before I have to take the mirrors out for a quick buff up.
Please forgive my ignorance but, as I am neither an astronomer or mirror/lens/telescope maker, what improvements over and above the fantastic results I already have would that final tedious oil lapping give me?
Thanks for your appreciation and great information
Russ
Hello Russ,
I am considering upgrading my (so-called) 50W laser to a 60W item similar to yours. At least, it has the brass head as yours does.
Did you also have to replace the power unit and/or computer to upgrade your machine?
A 50 watt tube will be 1000mm long but I guess yours will be 800mm long 40 watt tube. If your machine is an Ebay purchase then dump the B grade tube and power supply in favour of a proper 60 watt tube and matching power supply. Depends on where in the world you are I may be able to recommend a reliable source apart from China. No new PC required
Best wishes
Russ
Very thorough and informative! Thanks for taking the time to show us. Could you post a link to the HQ lens or was that an Ebay find?
+sabotshell
Thanks for your appreciative comment.
Yes, It was an Ebay item from China
www.ebay.co.uk/itm/330769086309 Cost£26.88 18mm diameter, 1.5" (38mm )focal length
Russ
+sabotshell
Here's the same seller listing in the US:
www.ebay.com/itm/HQ-ZnSe-Focal-Lens-CO2-Laser-Cutting-Diam-18mm-FL-1-1-5-2-2-5-3-4-/331105608153?var=&hash=item7dcd68499a
You have a link to those Hank bushes or whatever you call them? You might search for telescope mirror making about how they polish telescope mirrors. Those mirrors have to be perfectly flat to form the images right. We're talking about mirrors from a couple inches across to several feet.
Hi Michael
www.pemnet.com/fastening_products/pdf/cldata.pdf
trfastenings.com/industries/sheet-metal/rivet-bushes
There are several companies making similar self clinching nuts. I mentioned Hank even though I often use PEM.
I did research my local area for an amateur astronomer with mirror making skills. Zero. I had lots of advice but my skill level was inadequate to get good results. Polishing was fine but flatness was rubbish. I finally paid to get some disc professionally lapped by a gauge making company. I got tempted by the high efficiency promise of pure copper mirrors. They did eventually deliver 98% and are still running perfectly in my China Blue machine. However it was an expensive saga . Considering you can buy Molybdenum mirrors that will deliver 97% at a fraction of the price , I am glad I experimented but will be buying moly when the copper ones fail.
Best wishes
Russ
Amazing series of videos.Learning so much.Great teacher.Would gold plating make them better? Thanks.
Hi
I had lots of people advise me that copper was unsuitable and all the physics says don't because copper is likely to oxidize whereas gold does not. Also, physics indicates that gold is parts of a percent more reflective than copper. In practice , as you work your way through the videos you will see me experiment with Chinese "gold" plating and also some real genuine 24 carat gold plating. I am still using my copper mirrors today and they have not tarnished. I think the molecular coating applied when I polished them is keeping the oxygen away.
Best regards
Russ
Thanks for your fast reply. I will experiment with my gold plating for mirrors. Respect.
To be fair, you may only need about 10mm of height from each mirror, but you do need all the width you can get - due to the apparently oval shape of it when faced at 45 degrees. Sure, a thin ring of non-flat around the edge shouldn't matter much but still, you'd want to keep it as thin as possible... Anyway, congrats on the improvement, you certainly worked hard for it. :)
Hi
Once I discovered the potential for copper mirrors to be more than 99% efficient I had to follow the project to a conclusion. It took time and money to get there but I did actually reach a conclusion. Copper mirrors are great and in practice will give about 98% transmission efficiency. Here we are 4 years later and those mirrors are still in my machine and working well. I give them a quick re-polish every year or two, so the doom merchants that warned about rapid tarnishing and loss of efficiency were just guessing. Would I do it again or advise others to experiment? No. The simple fact is that for about $15 you can buy three molybdenum mirrors and they will be 97% efficient and bullet proof., so why go through the pain.?
Best wishes
Russ
Great video. I had a look at the price of the Macken probe and it was about $600 Aussie dollars. Just for a bit fun ,I have ordered a brewers temp probe and will modify it with a mild steel block on the tip and blacken the surface. I will try to calibrate it using temperature rinse in water. Maybe it might not work. Let you know how it goes. I will use it as a comparative test mostly. Maybe you might try it also and compare it with the Macken probe.
+Bradley Mohr
I have already been down the "lets be logical and use the laws of physics" calorimeter approach. There are just too many unknowns to be confident of the results. The results will be relatively correct but have no absolute value. Take a short length of bungee rubber and mark it into 12 equal divisions. Are they inch divisions? NO, not until you stretch the bungee against a 12" standard do your divisions become inches. That's the problem with the calorimeter approach, you do not have a standard IR power source to calibrate it with.
I know that this lollipop looks like a simple toy but it has been carefully designed to give constant outputs for constant inputs. Once the reliability of the outputs has been established a calibration against a known IR source is again required to turn it into an absolute secondary measuring tool.
You will see something with your approach but what? I agree that readings will be RELATIVE but look at the work I did in this video and what good would relative results been to me? I knew I was chasing watts of loss and that was achievable. BUT with RELATIVE results two possibilities exist. First perhaps they exaggerate the situation and there were only milliwatt losses that I could never do anything about. Conversely they may hide the true situation by showing I have nothing to worry about.
Yes it was an expensive investment but it has taught me so much about my machine, including the fact that I never have to buy another mirror and that alone will soon give me payback. The cheaper option is the Mahoney meter which is 1/3 of the price
Good luck in your experiments.
Regards
Russ
here is a question for fellow laser-ites...
best way to line up work of different mediums? example (but applies to different things)
I print off some complex picture and stick it to hardboard, then want to cut it out on laser...
it's easy to set up one corner accurately, but getting it square is a bit of a hassle.... any tricks? I could cut first and then stick but that is time consuming, when I can cut cleanly after stuck, if I could get it lined up...
+Michael Edmond
Hi Michael
I can see several possibilities but which one to suggest will depend on your situation.
Do you have a honeycomb bed?
Is this a once-off occasional job, doing just one picture? a batch job with several pictures to cut? A regular job that you run often?
If there is more than one to cut at a session are they all the same size?
What's your max picture size?
Regards
Russ
+SarbarMultimedia a bit of everything, yes I have a honeycomb bed, but made it so it's easily removable, and there are various possible projects.... mostly one offs or small batches
+Michael Edmond
Along the back of your honeycomb bed (back beyond your zero line and approx parallel to it) I would bolt a reference straight-edge perhaps (6 or 8mm thick MDF )about 2" wide and with a short 1" L sticking forward at the left hand end within a mm or two of X zero. I would now take a sheet of clear acrylic 2mm or 3mm thick, the size of your work area, and push it back and left against the reference bar so that this sheet will reposition accurately every time. With your speed set really low, drive you head to a position with nice round coordinates at the centre of your work area and press the Origin button. Note the coordinates because you will need to set your origin to them every time you want to use this method..
Now go to RDworks and draw a box to represent your work area but 20mm small all round. Now draw a vertical centreline across your box followed by a horizontal centreline.
Within each quadrant draw a box about 50mm away all round from the existing lines. Place these 4 smaller boxes onto a different (red ) layer which you will need to set as a cut through parameters to produce 4 windows. Delete the outer work area box. Set the black cross lines to be cut but at very low power so that they make lines and do not cut through..
MOST IMPORTANT. you must now go to Config, System Settings and change the laser head to the central position. When you OK this you should find the green square on the centre of your black cross. If not move all elements together as a group so that they are. Make sure you mark the top left corner. It may be a good idea to add a 10mm circle at that corner (either layer will do).
You can now cut your target template from it's central origin point.
Now for your picture. When you produce your picture you will need to add 4 short lines outside your picture to mark the centre of each side. Glue it to your backboard .
Back to RDWorks. Draw your cutting frame, the green square should be in the centre of your frame .
Place your picture approx central and place the acrylic template into its back/corner reference position over the picture. Move the picture so that its centrelines coincide with the target centrelines. Remove the target carefully and RUN
Voila!!! Will work for all sizes and shapes of picture from this central origin point. I have been very detailed but you may wish to adapt it to suit your needs.
Regards
Russ
Hello, Russ,
would you be interested to make another small experiment in order to check if by lifting up the entering point of the 3rd mirror( lowering the head) you don't actually cut off the upper part of the laser beam. If it turns out to be the case, that would mean that you actually do that on 1st and 2nd mirror also. The experiment that I suggest is to remove the 3rd mirror and put the calorimeter in front and then behind the mirror mount to see if the result would be the same. Cheers!
If you look at the drawing I did of the head to identify my problem you will see exactly the opposite to your suggestion ie the beam was already clippingthe bottom ofthe mirror and lowering the head was necessary to put the beam onto the centre of the mirror but mor importantly to ensure the reflected beam was passing axially down the lens tube. You must remember that this stuff was fairly early in my learning journey and I am now so much older and wiser about this machine. The Z axis is the most misunderstood part of this technology, the most critical to performance and the most difficult to set up on most machines because the head is not adequately adjustable.
Watch one of my later videos where the setting the Z axis is clearly explained and demonstrated
czcams.com/video/jVGByifge_Q/video.html
Best wishes
Russ
Hi russ. What about oxidation of copper? It run very fast usually in normal condition. What about yours? Thank you
Hi Andrea
Many people have warned of the oxidation issue. My copper mirrors have been sitting in the machine without attention since February. I have inspected them and cleaned them once with isopropyl alcohol. but not repolished them. They still show no signs of oxidation. I guess that is because of the atomic protective layer imparted by the polish I used. I also believe that some oxidation will have little effect because it is not the shininess of the surface but the crystal structure that is reflective to IR at this wavelength.
Best wishes
Russ
SarbarMultimedia thank you for answer Russ. This sound pretty magic to me be.. everything i have in copper go by oxidation very quickly, but is also true that they are objects that are often keep in hands
Hi Russ, as a smoking Pipemaker with a lots of experiments on finishing techniques at silver, brass wood etc i would probably can go on a higher polishing level on copper and have much more shining duration. Can i send you an email explaining?, i also have some other questions too. I ve just bought a laser engraver and your work here is amazing, not just for info about Lasers but opens our minds about general info too! Thank you so much
As you work further through my learning journey you will find I became a bit obsessed with the promise of copper mirror efficiency. Although I have now arrived at a conclusion and still have the final professionally machine lapped copper mirrors in the machine today. See czcams.com/video/55T_rDsj2go/video.html That was 9 months and they are still in the machine today without any re-polishing.
I don't encourage sending email addresses to an open forum like this but if you would like to use the You Tube private messaging system to send your email I will respond
All best wishes
Russ
What is the device you are using to check the laser?
This is a piece of equipment from Macken Instruments (a USA company. www.macken.com/collections/analog-power-probes/products/p100c
It is very expensive for the very few times thattypical hobbyists will use it. Hence I designed my own version at 10th of the price
see czcams.com/video/lO9rWlobLZU/video.html
Best wishes
Russ
superb!
I noticed on my machine I don't have the mirror channels on mirror 1 and 2, but I do on 3, I shall have to check how good the alignment is... also, where do you find these meters? (laser power meters)
+Michael Edmond
Hi Michael
I checked out the design of mirrors 1 and 2 for my Line of Sight calibration video and they were dimensionally correct. So I never dreamt that mirror 3 would carry a design error
The cheap Mahoney meter, which looks a lot like my meter, seems to have disappeared from sale. I'm in the UK and had great trouble trying to find one. A fellow machine user in the USA was kind enough to buy a Maloney meter from an Amazon.com seller. Maybe it was old stock because when delivered it was unusable . He got a full refund. I found a more expensive alternative in California.
www.macken.com/price-list.shtml mine is the P100C model. Although they purported to have a UK agent I could not track them down. My fellow US machine user bought one on my behalf and for his kindness, I suggested he use it himself to calibrate/profile his own 60 watt machine, before shipping to me. Without this inter-country collaboration I would still be in the dark because I don't think Macken ship outside the US......but obviously worth an email if you are serious.
Best regards
Russ
+SarbarMultimedia
I checked with a supplier, and it looks like I can get them for $95 + tax and shipping to UK...
+Michael Edmond that's a mahony 100 watts 100cy
+Michael Edmond
I'll be interested in your feedback if you get the cheap meter. Does it come with a calibration certificate?
+SarbarMultimedia I asked exactly that and how much shipping is...
it's from Seattle USA
What would happen if the mirrors were removed and replaced with flexible fiber optic?
Hi
I thought I had answered your question but it appears to have gone into outer space. Thanks CZcams!!
My basic answer was nice idea but not possible with this 10.6 micron wavelength of light. Well I say light (which technically it is ) but as far as we can tell, its heat radiation the same as comes from a radiator, a hot cup of coffee or a hairdrier. You can do a great job of engraving glass with it because glass is 100% absorber of the energy. Thus you can deduce that if you fired the beam at a glass optical fibre bunch, it would damage the polished input surface and not transmit. Fibre optic lasers are possible but at a completely different wavelength in the sub micron UV range.
Best regards
Russ
SarbarMultimedia
Ahhh. Well, lets not forget that having an open system like this that if there is even the tiniest bit of smoke it will reduce the output as well so having the stock evacuation system that the K40 has is bad bad. So, smoke between the mirrors and smoke between the last mirror and the object being burned I wonder what the final output would be like that?
Hi Russ. May we have an update. Are you still using your copper mirrors and if so have to checked the power levels recently. Be interesting to see the results
Hi
I'm currently away on holiday but back soon. Last time I checked about a month ago they were as shiny and bright as the day I installed them 4 months ago and I have not detected any power loss or cutting inefficiency. I initially was checking them weekly because the doom merchants warned me that tarnishing would soon set in and reduce their efficiency. Personally I didn't believe this for two reasons. Firstly I had proved in my reflectance tests that even a non shiny copper surface is capable of reflecting about 96% which is almost as good as the moly mirrors I was supplied with. The reflectance is more to do with the crystal structure of the copper than the visible light surface reflection. Secondly, although it was an accidental choice, the McGuires polish I used turns out to be what a lot of amateur astronomers use to make their optics. The molecular coating it imparts seals the surface from oxidation. I can attest to this. When I return I will do some figures for you but I'm very confident they are still pristine. In your situation of heavy daily use you have nothing to lose. If they need a quick buff up every 6 months (my expectation,.... but it could be a year) then this is way more cost effective than new mirrors. I have a spare set prepared ...just in case.
Best regards
Russ
So roughly 6 months after installing and they are still good?
I must admit I too was concerned about oxidisation. Didn't like the idea of pulling the mirrors out to polish them every few months which is apparently the normal length of time, without treatment, in which copper oxidises.
I plan to rip them out for checking in a near future video (maybe a 1 year review) and check their performance after 6 months. I have no signs that I am getting power loss so in general if it's not broken I don't fix it
I think the polish I used is doing a fab job of sealing the surface against oxidation
www.amazon.com/Meguiars-G13005-Nxt-Metal-Polysh/dp/B0009U7Y14/ref=sr_1_1?ie=UTF8&qid=1471075547&sr=8-1&keywords=nxt+generation+all+metal+polish
I'm also a bit puzzled as to why people are concerned about any slight oxidation. These are not visible light reflectors but IR heat reflectors that reflect because of the crystal structure of the material rather than its
surface shininess. (demonstrated in my video about reflectivity)
Best regards
Russ
+SarbarMultimedia great job. I don't think we are concerned more interested in the results as you have proved that it is easy to make your own mirrors. we are all learning
+3K Carbon - G10 - FR4 - Supplies & CNC Routing - 3D CAD Design & 3D Printing - Online Shop
I have a cnc router and I am thinking if I can make a jig and you it to Polish the mirrors. I feel a video coming on
Brilliant and extremely clear to understand (I think) lol Thanks
+paul w
Hi Paul
After 3 months the mirrors are still pristine despite warnings about tarnishing. That polish is certainly doing a superb job.
Best regards
Russ
+SarbarMultimedia Thanks for all your videos after many months of research I have taken the plunge and am awaiting delivery. It seems from everything I have read that buying the larger machine is the better option as it is far more reliable and better at what it does. Do you have any thoughts or regrets.
+paul w
HI Paul
I knew before I bought my machine that any problems would be MY problems as there was no backup support or service team to jump in with help. Fate dealt me a bit of a crappy hand with this machine but let's look at the positives...if I had received a perfect machine I would not have been forced into researching the technology to such depths and there would be precious little video for you to watch!!!
No, I have zero regrets. After 9 months, I am a lot wiser about dealing with the Chinese and now that I have fixed all the problems, I feel that my little Chinese Dragon is now "house trained" and obedient. I now embark upon a quest to see what tricks it can do.
I'm sure you will get endless hours of fun (and a few of frustration) when your new machine arrives. I suspect it will not be fitted with an ammeter so make that a priority to order a cheap Chinese 30mA ammeter from ebay, it will be your best friend ever.
Best regards
Russ
+SarbarMultimedia Thanks Russ . Your knowledge sharing has helped many I am sure .. keep up the good work. I look forward to tinkering with the machine
Do you know why these machines are designed with the extra be3nd at the first mirror? This mirror is losing 0.8-0.9W and seems to serve no purpose. Surely the laser tube should be on the left facing forward into what is now lens 2 rather than on the back facing left into lens 1. Do you understand why they include the first lens with the consequent loss of power when it seems to me to be unnecessary?
Hi Paul
You maybe lucky enough to have a workshop where you could hang 1200 to 1800mm of tube out of the back of your machine, with all the risk and mechanical stability issues that would accompany such a design. Mirror 1 allows the tube to be mounted safely, securely and space efficiently withing the footprint of the machine. Typical moly mirrors are about 98% efficient, so that's about a watt on a 50 watt machine. Change the mirrors to copper or gold and that efficiency will be above 99% and the loss less than 0.5 watts. Although I completely agree with your sentiment to reduce the losses by removing a mirror, it is not a practical solution. Pragmatism advises improving the mirror transmission efficiency instead.
Best regards
Russ
OK, I hadn't considered that.
Thanks.
Maybe you need to adjustment for mode make sure the mode is sharp like a cone
The question is, if copper make good lens, why they don't use it on laser cutter 🤔
Hi
Just to clarify. Lenses allow I R light to pass THROUGH and mirrors reflect the light.
Copper has a very high natural reflectance at 10.6 micron wavelength, about 98 to 99%. That is a key factor why they ARE used as mirrors in industrial lasers. Plus the fact that copper is one of the best conductors of heat, means that the fairly easy machining of copper allows cooling water to run through the mirrors on machines that are using beams carrying 6 to 30. kw of power.
Generally the copper reflecting surface has a VERY thin gold coating because gold does not tarnish. Despite dire warnings that my copper mirrors would quickly degrade because I had not coated them, the polish that I used had a protective molecular formulation that has done perfect anti oxidation job . In 3 years I only recall two brief repolishes.
Best wishes
Russ
I apologize for not answering your question properly. As I have proved with my very expensive quest into copper mirrors there is a VERY small 1 or 2% gain of efficiency over a cheap bullet proof molybdenum mirrors . The only time you need power is during CUTTING. So what extra speed can you gain with 2 or 3 extra watts? And at 5 times the cost, a gold coated copper mirror is just not cost effective. That's the main reason why they are not used.
Best wishes
Russ
the metal stand this guy is using to hold the power meter on last mirror is acting like a heatsink and throwing off the power readings
When you use one of these meters you will know that it takes 20 to 30 seconds for the reading to finally settle The stainless steel stem is at room temperature and the metal vee block is at room temperature also. The temperature of the anodized block rises by about 20C for a 30 watt test.and whatever is inside the stainless tube is not a heat conducting fluid because the tube remains at room temperature throughout the test.You can only heatsink something if there is a temperature difference and even then the efficiency of that heat sinking depends on two things. Firstly the contact area, so if there was to be any heat transfer it would be VERY inefficient along two metal to metal contact LINES and secondly the amount of heat transfer would be time dependent. Did you notice that as soon as the test was completed I picked the meter from the vee block ........with my warm hand!!
In the test that i did just prior to your observation did you not notice the OPPOSITE. I hold the meter by its stem with LOTS of contact area in my warm fingers. I would have thought that more worthy of comment. BUT to remove doubt I can confirm that holding the meter by its stem for 1 minute with warm fingers has no effect on the reading.
Please don' regard the above as a criticism of your comment because I regard any comment (positive or negative) as a useful vehicle for gaining a better understanding about the science of this technology.
Thanks again
Best regards
Russ