What is the usage of "of" in this sentence?

What is the usage of the 2nd "of" in this sentence?

the duration of the x-ray pulse can be of picosecond duration

Why is it not be this?

the duration of the x-ray pulse can be picosecond

Is there a difference in the meaning between the two? Thanks in advance

Solution 1:

I believe the difference is the duration.

the x-ray pulse can be of picosecond duration

this means, that the duration can be measured in picoseconds as compared to minutes or hours. It could be 1.0 ps or 0.7 ps, 5.8 ps, 12.9 ps...

the duration of the x-ray pulse can be picosecond

like Philip Wood said, this sentence is not exactly correct. It could either be missing "a" or "-s".

the duration of the x-ray pulse can be a picosecond - it can be exactly 1.0 ps

the duration of the x-ray pulse can be picoseconds - it is measured in picoseconds