I put that fancy Maple in my Airy disc file where power was defined as you show it and nothing seemed to happen.
Did you see this in the Maple file in the subject Unapply post?
powerfunction := unapply(power, theta)
I found it in Introduction to Maple, Third Edition by Andre Heck page 208. His book is based on Maple 8.
Would you please look at the A Real Life Test post. All you have to do is look at his graph down near the bottom of the post or his BitWise article and to me it just doesn't seem to answer the question. The width of the spacial pulse could be 35% or 42%.
On the other hand, don't bother. The only thing that matters is that there is a very nasty integral that Mathematica will evaluate numerically and Maple will not.