In order to critical with the Eldar Pulsar Lance, do you have to a) hit with it all 3 times or b) score any one of the hits with 3+ degrees of success. And if the answer is (b) then can you score 3 critical hits in the same turn with this component?

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Personally I think it'd be you can crit for each of the 3 attacks (assuming you succeeded the BS on each one of them) since it is technically 3 separate attacks in the same round with the same component (since you have to roll BS 3 separate times). It wouldn't be that bad in the hands of an NPC (since its hard for them to get that many successes) so its not that big a problem, but its not that hard to get all 3 of the lance attacks to hit.

to lasey to dig out books and look but if it realy 3 sepreate rolls it whould be 3 possible crits unless there was a specific rule to say otherwise

I would agree, up to 1 crit per roll to hit with the pulsar. Eldar are rather nasty after all.