Does a Rotating Laser Beam Drill Better Than a Non-Rotating Laser Beam?

[Spacescifi]

Just curious... if you take two lasers, both hot enough to melt steel, only one  laser has a rapidly rotating beam while striking the steel and the other laser does not... any advantage whatsoever other than some scifi character being able to brag that they have a RBD (Rotating Beam of Death)?

[darthgently]

I'm not a physicist but I'm going to give a hard nope.  Maybe a laser with tunable frequency and a target penetration feedback mechanism that dynamically tunes the laser freq to the most effective for penetration moment to moment would be a good uber sci fi flex?

The feedback could be based on minimizing reflected laser frequency energy, or maximizing target point temperature readings

Edited November 14, 2023 by darthgently

[monophonic]

Maybe, if the rotating beam covers only a portion of the hole at a time. For a precision drill you want to outright vaporize rather than melt the material anyway. Then you need to get the vaporized material out of the hole. The only route out is the one the laser beam is entering, so the material disrupts the beam and thus your drilling efficiency. A partial cross section beam would leave space for the material to exit, but you would need to rotate or otherwise move it to keep creating the open space as the hole deepens. This is not entirely unlike how a CNC router creates a hole bigger than the bit in use.

[darthgently]

3 hours ago, monophonic said:

Maybe, if the rotating beam covers only a portion of the hole at a time. For a precision drill you want to outright vaporize rather than melt the material anyway. Then you need to get the vaporized material out of the hole. The only route out is the one the laser beam is entering, so the material disrupts the beam and thus your drilling efficiency. A partial cross section beam would leave space for the material to exit, but you would need to rotate or otherwise move it to keep creating the open space as the hole deepens. This is not entirely unlike how a CNC router creates a hole bigger than the bit in use.

I assumed he meant rotating the beam around its own axis.  Yes rotating the aim point around a point on the target is an entirely different matter and makes sense for all the reasons you bring up

But would be limited by distance, beam  decoherence, and heating being spread by the circular path radius

[NFUN]

no

[Nuke]

not sure that would do anything. pulsed lasers can do more damage for creating shockwaves on the surface of anything it hits, making it more suitable for weaponry than continuous beams. 

[kerbiloid]

What's "rotating", compared to the light speed?

[darthgently]

29 minutes ago, kerbiloid said:

What's "rotating", compared to the light speed?

Precisely 

[NFUN]

what's "rotating" compared to a symmetrical gaussian beam? the only difference a rotation makes is polarization and you are already free to set up the polarization to whatever is convenient (and it probably either doesn't matter or if it does, just make it circularly polarized )

Edited November 14, 2023 by NFUN

[kerbiloid]

46 minutes ago, NFUN said:

polarization

Spoiler

If the laser failed, you can always apply the axe.

 

[magnemoe]

3 hours ago, Nuke said:

not sure that would do anything. pulsed lasers can do more damage for creating shockwaves on the surface of anything it hits, making it more suitable for weaponry than continuous beams. 

Agree, also like the drilling an hole you want the boil of to get away before the next pulse. And the laser gatling in the fallout games makes some sense.  I assume it was to cool the lasers between pulses but you want more than 100 pulses a second. 

[mikegarrison]

Folks, you know that laser drilling is a thing in real life, right? Used in industry all the time. No need to be guessing about this.

https://en.wikipedia.org/wiki/Laser_drilling

Edited November 14, 2023 by mikegarrison

[mikegarrison]

One characteristic of laser drilling is that it has a tendency to make conical holes rather than cylindrical ones, and we used to use that to our advantage with combustors. We would drill the cooling holes from the inside of the combustor, thus making each hole slightly diffusing, which helped keep the cooling air at the wall of the combustor where it was needed.

[Nuke]

like i said, pulsed lasers. 

been wanting to get a laser cutter/engraver for the shop. they got that $600 k40 machine made in china, but i have my doubts that the laser tube would arrive in tact. been looking for a model that uses a solid state laser for under a thousand but that might just be wishful thinking. i mean there are kits, but the lasers these things use are kind of dangerous to your vision so alignment procedures tend to require more care than i usually give my projects. also hear horror stories about the kits coming with the wrong safety glasses that dont block the ir. where they use an array of ir modules to pump a yag crystal. this changes the frequency to visible spectrum light, but enough ir makes it through to be dangerous, so your glasses need to be able to block both components. i also worry about my kitties because they cant seem to go 2 minutes of me being in a different room. and will preemptively sneak in and hide if they think im going that way.

Edited November 15, 2023 by Nuke

[monophonic]

19 hours ago, darthgently said:

I assumed he meant rotating the beam around its own axis.  Yes rotating the aim point around a point on the target is an entirely different matter and makes sense for all the reasons you bring up

But would be limited by distance, beam  decoherence, and heating being spread by the circular path radius

I'm certain he meant exactly that, but as has been mentioned it makes no difference. So I jumped forward to what might actually do something. Actually I originally though about a semicircular beam that rotates around its center, but that might be overly complex to get set up right. Reading the newer posts it does seem other effects like those you mention dominate anyway.

[kerbiloid]

Spoiler

 

[Shpaget]

Here's a real world example from personal experience with a 60W fiber laser that can cut through metal.

If I want to cut through a 1 mm plate (which is a very deep cut compared to the size of the laser dot, and near the limit of the machine I have) I get better results if I wobble the laser beam; meaning a straight line is actually a spiral (think tiny circular motion combined with linear movement). This makes the kerf (width of cut) significantly wider than the size of the laser dot which makes evacuation of ablated material much more efficient. Otherwise the evaporated / molten and exploding material just deposits  back on the previously cut side walls and the cut partially closes again. Wider channel prevents this depositing and recutting since the material can be thrown out.

[jimmymcgoochie]

Multi barrel guns and cannons exist and for a few good reasons, many of which would also apply to a laser system- each laser only fires for a short pulse and then has time to cool before being fired again, the spinning improves airflow and by extension cooling, etc.- and the failure of one laser wouldn’t break the whole drill, merely slow it down a bit. (pun mostly intended)

[darthgently]

58 minutes ago, jimmymcgoochie said:

Multi barrel guns and cannons exist and for a few good reasons, many of which would also apply to a laser system- each laser only fires for a short pulse and then has time to cool before being fired again, the spinning improves airflow and by extension cooling, etc.- and the failure of one laser wouldn’t break the whole drill, merely slow it down a bit. (pun mostly intended)

Also, the  "Gatling" mechanism is a design pattern that is seen all over, not just in weaponry.  In general manufacturing it works to increase the rate of any process where recovery/feed/settling time of each element is longer than the desired rate of production

[kerbiloid]

https://en.wikipedia.org/wiki/Aniara

The phototurbs are powerful.