Let's find out how they put 3D images into glass objects. Known as a 'Bubblegram', vitrography or sub-surface laser engraving, this technology has been around for a very long time but remains quite niche in its applications.
Resources I used in research this video:https://en.wikipedia.org/wiki/Bubblegramhttps://en.wikipedia.org/wiki/Laser_e..
thom1218 adds (re 4:03): The lasers in these machines HAVE to be pulsed, using a method called Q-switching to obtain high peak-power pulses that can couple their energy into otherwise transparent material. These pulses, incidentally, are in the megawatt range and over a very short time span, usually a number of nano seconds. These lasers use several IR diode lasers to "pump" a Nd:YAG laser crystal, which is frequency doubled from 1024nm to 532nm (green) in order to be able to pass into the glass target object. Interestingly, this laser technique is used in tattoo removal machines to penetrate skin and oblate sub dermal ink . CO2 lasers can do a continuous etch on glass because glass is opaque to the near IR long wavelength of CO2 lasers, and therefore they can only etch the surface. Also, because glass is opaque to CO2, more energy is transferred directly to the glass, rather than passing through it, which allows the CO2 laser to remain in CW operation (continuous wave, i.e. not Q-switched). So, the operators of these bubblegram machines do not have the option to do a "continuous blast". However, using fewer dots/bubblegram will shorten processing time and wear on the laser components. So in that sense you're right about fewer dots being more economical.