Yep. Thought about it as I was typing and was also thinking about the existing 0.5" focus, so just decided it was easier to say 1.5" rather than explain my meaning. I keep getting into the back and forth about minutia with several folks every time I post something. (Not you).
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Yes, the half inch focus will require us to shim thicker material when the tray is removed to get the surface to fall within that parameter.
A larger focal range would be nice in a subsequent iteration.
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There might be some confusion between “focus range” and “focal length,” as evidenced by the use of “focal range,” which doesn’t really mean anything. If anything, it would refer to the range of focal lengths achievable with a zoom lens.
A long focal length lens lets us cut materials with less of the sloping edge we get with short FL lenses. A long focal length lens can have a short focus range.
A long focus range, like that on the Muse, lets us cut/engrave objects of various sizes without having to prop/shim them to fall within the tight focus range found on other machines. Short focal length lenses can have a very large focus range if they are mounted on some sort of translating support structure.
Another way to think of it is that focal length is a property of the lens, whereas focus range is a property of the mechanism that moves the lens.
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A constant feature of my life. 
Thanks for the clarification.
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The window is actually on the left side of the head, where the beam enters. It exits through the lens underneath and that is supposed to be kept clean by a small fan that gives positive air pressure to avoid smoke going up it. That is probably not easy to clean without removing the head but should not need cleaning baring an accident I believe.
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Where is the small fan located? Is the air filtered? I asked Dan where the source of the positive pressure came from, but got no response.
You can see it in one of the pictures @marmak3261 posted of unboxing the head. It must take air from the build chamber.
Eeek! Dirty air?
Edit: despite assurances below that it is clean air, it has been found to be quite dirty:
I don’t know. Hopefully clean air comes in one side and dirty air is sucked out the other so it can pickup clean air.
There isn’t another window on the bottom? If not, I wonder how come.
How about a laser head you can flip upside-down for those nights when you are the DJ? Laser light show !
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Not really. It pulls from behind the gantry. All the air in the unit is slammed into the front door (along with debris etc) and then flows to the fan side and out the back corner. It would be really hard for that fan to be pulling anything that came off the cut
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Well the lens forms a window itself. A window after it would see the partially focused beam so would need to be very transparent to IR to not heat up.
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So there is a secret compartment right below the top plate of the head. The top plate comes off. Yes, you can decapitate that laser head while it’s still attached to the gantry. The lid is a snap fit again with magnets. From here you can access the right angle mirror that converts the beam from the horizontal line along the gantry direction to vertical out the bottom lens.
It’s a pretty cool setup, how that mirror is aligned but easily removable. This isn’t a normal part of the cleaning routine which is documented in the manual, but I was fiddling with the head and discovered this design.
The mirror inside the head was spotless. This was after I had done an hour and a half of engraving Corian.
As @takitus pointed out, the air assist jets the debris at the front garage door. The head stayed pretty dust free during this whole time.
I’m going to do the lens cleaning tonight when I get back. Haven’t done it yet so I’ll report back on what it looks like on both sides.
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The front garage door… is where the pass-through slot will be? I just had a horrible mental image of debris flinging out through the slot. But if that was an issue, someone would have caught it ages ago… right?
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Let’s hope!
Covered by a flap. Probably more for positive ventilation reasons than to worry about debris.
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I remember that there is a flexible flap, but since we have not seen it, I don’t know if the flap is something that also swings out of the way to allow material to pass through, or if it is just flexible (along the lines of silicone) and so deforms to allow material through, or some combination of the two.
If it is a purely deformable function, then either the force of the air will not be enough by itself to force the opening to open… or there will be a new fashion trend among Glowforge Pro owners called the “Watching-My-Engraving-Soot-Streak”.
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Hopefully they’d install a transparent window.
Are you trying to say that a window will not be able to withstand the power of a slightly focused 45 watt laser? The power density would be doubled, at most.
Sorry if I missed it - it comes in from above and behind the head. We’ve designed it so while it uses air from the interior of the machine, it doesn’t contaminate the lens - there’s some careful airflow engineering that goes into it.
Indeed! We included it as a “belt and suspenders” approach - we designed the mirror to not get dirty, but if it did, we designed an easy way to clean it.
Ditto for the lens itself - more on that later.
Like this.
No, but it’s a very good question - the answer is engineering tradeoffs…
- The window would have to be below the lens
- That would mean it is more likely to get dirty then the lens
- It’s not necessarily any easier to clean then the lens
We decided to optimize the lens for minimum cleaning, and make it easy to do if needed.
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