Worf: "Captain, they are now locking lasers on us."
Worf: "Yes, sir."
Picard: "Lasers can't even penetrate our navigation shields. Don't they know that?"
Riker: "Regulations do call for yellow alert."
Picard: "Hmm, a very old regulation. Well, make it so Number One. And, reduce speed . . . drop main shields, as well."
Riker: "May I ask why, sir?"
Picard: "In case we decide to surrender to them, Number One."
Picard: "They could fire 'till their lasers ran dry; they wouldn't hurt the Enterprise."
Alas, some take the above statements from "The Outrageous Okona"[TNG2] to imply that no simple electromagnetic beam weapon can ever affect the Enterprise, because the navigational deflectors would somehow always protect the ship. However, there are logical and canonical limits. There is just no way the Enterprise can effortlessly ward off blasts of near-infinite energy just because that energy is electromagnetic in nature. Further, we have seen highly powerful electromagnetic fields affect the ship's technology in other episodes, so a more focused version of that with sufficient power shouldn't be so easily ignored.
On the other hand, an important note in reference to lasers is that they are effective because they produce overwhelming energy intensity. An ant, for example, can survive the amount of sunlight that would fall on its tiny back, but when a small child with a magnifying glass focuses a larger amount of sunlight on the same area, the intensity increase will result in the rapid cooking of the ant.
So, if the navigational deflectors operate against lasers by somehow causing a blooming/scattering/incoherence in the beam, this might explain their effectiveness against weak laser weapons. Indeed, it might even be possible that the navigational deflectors are effective against relatively-powerful laser weapons, but that whatever effect is used would not be operable against incoherent, wider-spectrum, or broader/less-focused discharges over the entire ship's area. Even if that hypothesis is accurate, though, it still does not allow for infinite resistance to laser weapons.
And, of course, the "Okona" quote is of questionable utility anyway. Many various theories of what the 'lasers' and 'turbolasers' of the Empire actually are have been fielded, and many contradict.
The pro-Wars faction originally spent a great deal of time trying to prove that the bolts fired by Imperial weapons are not lasers, owing to the fact that we can see them from the side, the bolts don't move anywhere near lightspeed, et cetera. They claimed instead that turbolasers operate by firing some sort of plasma, contained somehow . . . perhaps by magnetic fields or something.
The explanation does have the benefit of explaining the "flak burst" effect often seen in the films and referred to in the novelisations, where a bolt will seem to harmlessly explode in midflight, buffeting the target. (However, it's odd they'd use such a technique if they had the targeting capability to shoot at something directly, since it seems to be a pretty useless use of a plasma weapon . . . or any weapon, for that matter.)
In recent times, however, the pro-Wars debaters have changed their tune. The E2ICS suggests that there is an invisible laser (presumably in a higher spectrum than we can see) fired by the lasers and turbolasers first, with the green bolts merely being a visible, tracer-like expulsion of waste gases from the gun:
Pg. 3 : "Energy weapons fire invisible energy beams at lightspeed. The visible "bolt" is a glowing pulse that travels along the beam at less than lightspeed [...] The light given off by visible bolts depletes the overall energy content of a beam, limiting its range. Turbolasers gain a longer range by spinning the energy beam, which reduces waste glow."
Most would consider the above concept rather unusual, and with good reason. However, that was the rationalization the EU author employed to allow for speedier weapons than what is seen in the canon.
Often cited in favor of that view is a screen shot of Luke's hand being struck by a blaster bolt in Return of the Jedi. They claim that the skin melts away a frame or two before the bolt hits. Unfortunately, the skin is already missing from that spot. Further, the shot does not hit the area of missing skin . . . it hits the sleeve:
Had there been a beam that managed to melt away
Luke's hand, where is the evidence of this? Obviously, the film shows
none. And further, how in the world would Luke and other Jedi be
able to swipe away blaster bolts with their lightsabres? It would be like
swatting at a laser beam with a mirror . . . you'll reflect part of it for a
moment, but the rest would still hit you.
So, which idea on all these turbolaser and blaster bolts is true?
It's hard to say. I would argue that they certainly aren't lasers, invisible or otherwise. We didn't see any invisible lasers damaging the ground when the Geonosian fighters were using flak bursts against the LAAT flying gunships in AoTC, and the "evidence" for invisible lasers is tenuous at best. Further, if Star Wars weapons use an invisible laser component, it would seriously reduce the firepower figures they would have available for use, owing to the increase in dwell time.
The theory that best fits the facts would be the plasma viewpoint . . . but even that isn't perfect, given the odd bolt reflections we've seen from time to time (such as the Greedo shot against a wall, a TPM bolt that reflected off of grass, and so on). But, I would certainly hesitate before ascribing to the view that the Empire's weapon systems are based on the same plasma weapon technology that became obsolete in Enterprise's first episode.
For now, we simply don't know if the weapons are plasma based, but they
are at least something besides basic laser weapons.
The scripts and novels are dead-set on the idea that the weapons are lasers (though, paradoxically, they also mention flak bursts all the time, albeit without a direct connection between the two). The script for ANH refers to the Death Star's turbolasers with the following peculiar statements:
"Alarm sirens scream as soldiers scramble to large turbo-powered laser gun emplacements. Electronic drivers rotate the huge guns into position as crew adjust their targeting devices."
"Smoke belches from the giant laser guns as they wind up their turbine generators to create sufficient power. The crew rushes about preparing for another blast. Even the troopers head gear is not adequate to protect them from the overwhelming noise of the monstrous weapon. One trooper bangs his helmet with his hand in an attempt to stop the ringing."
Evidently, turbolasers are referred to as such due to the manner in which the laser's power is generated. Beyond that, little makes sense . . . what's the smoke from, and what relation would that have to the turbines? Why is such an arcane system employed? We may never know.
One claim by some pro-Wars debaters is that firepower scales directly with turbolaser barrel size. (Entertainingly, they ignore the fact that this should mean that snowspeeders, AT-ATs, and AT-STs should be way more powerful than X-Wings and TIE fighters.)
While the idea that a bigger gun carries more punch should be true to some degree (and you can make your own joke from that), it is a fallacy to assign direct firepower scaling on the basis of the size of turbolaser barrels. (For a very intelligent commentary on the issue of scaling in general, take a look here).
Thus far, the largest shipboard weapons we've seen (not counting the superlaser) have been the four large turrets on each side of the Star Destroyer superstructure (in red below), commonly referred to as "heavy turbolasers" (HTLs) by Vs. debaters. For rough sizing, compare them to the ~30 meter globes atop the bridge tower (in blue below):
A closer look at those weapons appears in the following shot of the Avenger model (from TESB). Note the size of the 32 barrels, which are perhaps 10 meters long:
We may have seen these largest weapons of a Star Destroyer fired in Return of the Jedi:
We do not know what the firepower of these larger bolts would be . . . we haven't observed them hitting anything we know the qualities of. Indeed, if we're talking about the big bolt above (from the only scene in which we see those guns fire), then we've never seen the gun's bolts hit anything.
The only weapon which we have definitely seen hitting something we can estimate the qualities of would be the gun on the portside ISD trench, seen to fire against the main visible asteroid in the famous TESB asteroid-shooting scene. Interestingly, that gun's barrels are about the same size as the main turret weapon barrels. First, a nice clear view of the model's starboard side, with the main turret and the minor brim notch visible:
For some reason, the starboard side does not have a gun in its notch. (The real-world reason is that the right side of the model had less detail added, much like the large TOS Enterprise model. The "real" ISD would probably have a gun there.) However, the port side notch does have one:
In case you can't see it, the next picture is zoomed-in on it. I've also altered the hue of the picture using an image editing program in order to bring out the darker old-computer-mouse-shaped gun and its two left-facing barrels a bit more:
I've taken the liberty of overlaying the port trench on the pic of the starboard trench and the guns, scaled to the trench.
As you can see, the barrels of the trench gun are at least 80% of the length to those on the main turrets, and, judging by the other pictures, the barrels are almost perfectly identical in girth. Either that's an HTL, or else it's a IMBNQHHTL (impressively massive but not quite "heavy-heavy" turbolaser), and this is especially true for those who think firepower scales proportionately to barrel size.
Further, I also haven't seen anyone attempt to figure out the consistency (or lack thereof) in regards to the actual intensity of the bolts, which is no less important than the size. As an example, let's take a turbolaser bolt, and let the energy content (i.e. joules) remain a constant. You can do three things to the bolt, with the following effects:
Double the length, and you halve the
Double the width, and the intensity (i.e. watts/m2) falls off . . . the ant might not cook.
Double the intensity, and you actually have a thinner bolt, but in defiance to the "big bolt = uber" theory, this smaller bolt will be a superior one.
Of course, all of that assumes that turbolaser
bolt intensity, width,
and so on act more or less like laser intensity, width, etc., which one might expect to be the case but may not
be. We still don't quite know what
turbolasers are all about.
Several of the model pictures used above come from shots taken by Larry
Yee. Though their use is covered by Fair Use terms as they've been
published online elsewhere, I did go ahead and try to e-mail him for explicit
permission . . . there was no reply.