RAAArtyGunnerYes 1/4 inch is probably the max for good quality.
The laser passes throught several lenses which get focused to the top of the material
And yes your understanding the gap gets wider at the bottom.
you dont notice it upto about 3mm but as it gets thicker it cabn be noticed more.
With regards to cleaning you dont get must dust but the filtration system takes any away.
You do get a build up of the burnt glue and resin from the wood on the cutting bars which i just sit in bucket overnight once they get messy wipe off in the morning and off it goes.
You also need to clean the lense once a week with special flued that eats off and build ups.
With the exstraction on machines like this you have got two options 1 being internal filtration like i have
downside being the set of 4 replacement filters is around £800 and can be as often a every 6 months.
or you can have exstract to atmosfear down side being chimney vent has to be above roof hight and in some casses requires planing consent.