10-09-2021, 02:41 PM | #1 |
Join Date: Jun 2020
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Ultra-short duration pulse lasers
So, I've been investigating how GURPS treats pulse lasers and it has been enlightening, but sad. For one, there is no way to simulate pulse lasers at the micro to pico-second duration range and another has me finding out that it is spread over the overall output and not per-pulse. The only rules for pulse lasers are that if RoF is greater than or equal to 4 does the damage double and a change of damage type. Energy requirements stay the same, no additional modifiers, that sort of thing.
This is at odds with the pulse lasers that I've been planning to use in my future-history setting where they're triple-digit microsecond pulses, meaning that a 1GJ/pulse laser (the smallest anti-ship laser in one faction's arsenal) requires 4TW of electricity to function. So how would I stat such lasers in this regard? |
10-09-2021, 03:00 PM | #2 | |
Join Date: Jul 2008
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Re: Ultra-short duration pulse lasers
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You should also look at the rule on Ultratech p118-119. However, the way you're describing it seems rather weird. A pulse laser isn't necessarily (or likely, I should think) emitting a pulse train with no breaks! There are some sources (well, at least one) for probably more realistic treatments of lasers than GURPS standard, but I'm not sure realistic is what you're looking for here... EDIT: Though you would need to back-convert from material effects to GURPS damage.
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I don't know any 3e, so there is no chance that I am talking about 3e rules by accident. Last edited by Ulzgoroth; 10-09-2021 at 03:15 PM. |
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10-09-2021, 03:28 PM | #3 | ||
Join Date: Jun 2020
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Re: Ultra-short duration pulse lasers
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The pulse lasers I'm usually used to in their descriptions have been output per pulse, not overall output. Add to that the descriptions having 'cycles' -i.e. how many times a laser goes on and off- as well, and thus wanting to port this over. So far I've been thinking of using a 'per cycle' damage (so, a 1GJ/pulse laser that has a 16-pulse per cycle would thus have an output of 16GJ) instead of the usual damage figures. |
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10-09-2021, 04:00 PM | #4 | |
Join Date: Feb 2005
Location: Berkeley, CA
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Re: Ultra-short duration pulse lasers
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10-09-2021, 04:05 PM | #5 | |
Join Date: Jun 2005
Location: Lawrence, KS
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Re: Ultra-short duration pulse lasers
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Bill Stoddard I don't think we're in Oz any more. |
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10-09-2021, 04:13 PM | #6 | |
Join Date: Jun 2020
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Re: Ultra-short duration pulse lasers
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Especially when a joule per 500ns (nanoseconds) is 2MW... and just having a laser in the microsecond range has something on the order of 1-joule per 500m microseconds being 2kW... Given that damage only increases when RoF of a pulse laser is 4 or more (ignoring the effects of ultra-short duration pulse lasers that the scientific community has been putting out)... |
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10-09-2021, 04:55 PM | #7 |
Join Date: Jun 2020
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Re: Ultra-short duration pulse lasers
From what I can tell, that isn't exactly the case. Especially as you get to ultra-short durations.
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10-09-2021, 05:57 PM | #8 |
Join Date: Aug 2004
Location: United Kingdom of Great Britain and some other bits.
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Re: Ultra-short duration pulse lasers
What's the purpose of an ultra-short duration laser pulse for a weaponised laser? I was under the impression that the main purpose of pulsing a high-energy laser weapon was to allow the debris (plasma, hot gas, vapour, molten droplets, fragments) generated by blasting the surface of the target to clear out of the way, so that the next pulse would hit the bottom of the crater created by the previous one and so eventually drill deeper than just using the same energy as a steady beam. But that seems to requite micro-second pulses rather than pico-second ones, which would surely be too quick to actually let the stuff move far enough (although I suppose at very high energy densities, stuff moves quicker, so really big lasers might want to pulse faster).
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My blog. |
10-09-2021, 06:01 PM | #9 |
Join Date: Jun 2005
Location: Lawrence, KS
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Re: Ultra-short duration pulse lasers
It sounds like the math is wrong, but I would need to see the actual calculation.
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Bill Stoddard I don't think we're in Oz any more. |
10-09-2021, 06:40 PM | #10 | |
Join Date: Jul 2008
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Re: Ultra-short duration pulse lasers
FYI, it's generally recommended to flag when your topic is 3e. Otherwise people will usually assume that we're working with the current edition instead.
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A pulse laser has a pulse power, which is pulse energy/pulse duration, and an output power. Output power will always be less than pulse power, because it's not a pulse laser if it's emitting 100% of the time. It can be much less. A laser that shoots a picosecond pulse could perfectly well shoot only one such pulse per second.
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I don't know any 3e, so there is no chance that I am talking about 3e rules by accident. |
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Tags |
game mechanics, gurps 3e, lasers, pulse lasers |
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