I regularly (several trips thru security per week) carry external hard drives, multiple laptops, Cisco equipment and other things that would raise an eyebrow to the uneducated without incident. If they (TSA) ask what it is, I start going down the extremely technical explanation and start to explain the finer points of 1's and 0's before getting told to go on my way.

You shouldn't have any issues. If asked, it's your portable storage device for your digital photos.