Will the mirrors used for the laser need to be cleaned/replaced very often?

I had read online that someone heard the mirrors for the glowforge would need to be replaced every 6 months. I thought that in a previous post I had seen @dan say that the only part that will need to be replaced is the tube itself. Not a deal breaker but I am trying to figure out how much maintenance is going to cost me over the long and the short term.

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The mirrors should be sealed behind windows - so the only cleaning you’re likely to need to do is clean those windows - ideally a quick wipe when you’re done for the day.

Thanks for your help. What I read was a post on Reddit. I am beginning to discover that a lot of people are downing a product that they have never used or seen. After reading the post I came back and searched under cleaning and seen that they are sealed. I don’t understand why redditors are so determined to try and cut down glowforge. I can’t foresee ever reading something that would make me cancel my order but I don’t know why they would wish to hurt a company that is in its infancy. The way I believe is that I look for the bet in a company and its people until THEY give me a reason not too. @Dan seems to be a very genuine and honest man. I do not know him personally but I have read a ton of articles on him and am impressed with his dedication to his family. Not to mention his dedication to people who ordered his product.


A lot of what you are seeing were early posts from the edges of the maker world. Everything has to be hackable and completely open source or it is not true to the maker concept. The Glowforge was never intended to be that type of product. None of us really knows whether the production units will meet all of the planned capabilities. We need to have a healthy amount of skepticism. But many forums are like reality TV. The misery of others make some people feel better about themselves.


Spot on.

I always love the commentary by people who have never seen or touched the thing they’re commenting on. It reminds me of the old aphorism - “I am surrounded by people who can’t do what I do but know that I’m doing it wrong”.


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I am far more inclined toward someone who just likes to watch the world burn.

The windows keep you from needing to clean the mirrors often (at all?). And the windows themselves are easily worked with, Dan says they are very easily cleaned.

And of course, replacement is a breeze.

Windows can be replaced with salt

Mirrors can be replaced with old hard drive discs
(if you don’t have a dozen spares, go to any junkyard or university and get a bunch for free)

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And this is yet another reason why the Beta forum is closed to the non-beta testers.
Bad info gets out there and become “fact” so fast these days.


Glad I’m not the only one who feels negatively towards people who try and run down anyone who is offering something new into a stale atmosphere.

“The person who says it is impossible should not interrupt the person doing it.”

I’m sure the windows will be easy to clean, but clean optics is important because if the energy isn’t transmitted it is deposited - so keep 'em clean!

Thanks for the kind words @elsman18 and all. Quite correct, the mirrors are completely enclosed behind laser-transparent windows that are easy to wipe and should last forever. If something does happen to the windows, they can be easily user-replaced, but that should never be necessary if you’re careful with them.


That’s the kind of clever design that will help turn these into consumer machines. Just like when Xerox machines were reinvented by packaging all of the stuff that required a serviceman to fix into a disposable cartridge along with the toner got laser printing out of the copy world and onto desks.

A lot of what we do (3D printing, laser cutting/engraving, Arduino, etc) are doable because most of us are tinkerers. We shouldn’t forget that one reason VCRs (does anyone have one anymore), DVD players, DVRs, etc have self-adjusting clocks is because the average consumer couldn’t figure out how to change them twice a year. (Anyone know friends whose cars still have the wrong time on their clocks?)

Putting the mirrors behind a glass window that is easy to wipe clean is one of those little things that will take this technology to the masses :slightly_smiling:

I think the whole network/cloud based software approach is a similar feature - no more diddling around with different PCs/Macs/etc trying to get the magic combo that makes everything work - put the complexity in the cloud where someone smart can manage it.

I’ll bet there are going to be a lot of these features in the GF that we’ll find make it easy for the average Joe (or Joann) to start their own laser fab lab.


Some of us can subtract one from the clock in the car :wink:

I’m getting too old. I have a brief heart attack before realizing that I’m not an hour late. I’m thinking that might not be good for me long term :smile:

I’m very curious to learn what kind of material is transparent to CO2 lasers. My understanding is that regular glass is not.

Don’t know what the windows will be made of but you are correct that standard glass and polycarbonate is somewhat opaque at those frequencies. I have worked with military infrared sensors and optics for quite a few years and even I had to google it. Found this:
“ZnSe is a preferred material for lenses, windows, output couplers and beam expanders for its low absorptivity at infrared wavelengths and its visible transmission.” (Zinc Selenide)

There are a couple other possibilities including Zinc Sulfide and even Germanium but the ZnSe seems to be in common use.

But now you have me thinking… I don’t know what the optical chain looks like in a standard CO2 laser but you typically adjust the bed to meet the laser focal point. With the Glowforge there is a variable optical path. I wonder if there are more lenses and windows in this path than a typical laser. ZnSe seems to only have a 70% transmisivity for 6.3mm of material. Additional optical boundaries and lens material would decrease the delivered energy. Oh well it’s just a brain worm. We’ll see when the units arrive.

We use a germanium lens to protect an IR sensor. There is some loss of signal.

Thermal cameras lean toward Germanium from what I have seen (about 5 models). ZnSe is what I use for the focusing lens in my laser cutter. Those two both work well as lenses because they have such high indexes of refraction, which allows more “bend” with less total material.

As I posted earlier… rock salt makes a fantastic window. It is moisture soluble, but not to an excessive degree. Amazing transmission, and easily acquired (takes some skill to shape and polish, but not much). There are many other compounds which can work. I am mildly curious what route they took with the GlowForge, as few resources I find comment about scratch resistance of the windows, unless saying it is abysmal.

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Went back to one of Dan’s posts. The claim is that the Pro has “upgraded optics”. Maybe different materials are used for the two different systems?

Gorilla Glass maybe?

I wonder about the optical properties of corundum. physically sapphire is bulletproof in terms of scratches.