Can't say I'm happy with current system, I need to look into different approaches.
Not sure what you don't like about, but I have some thoughts.
If it's a visibility thing than increasing the size or brightness of the effect could maybe help. Changing everything to grayscale with the objects in a distinct color (a la "detective vision") would be another alternate choice.
Separately, I also think that binding the effect to a button would be nice because waiting creates this sense of uncertainty to a degree as to whether it's working. However, I would definitely have it be for only a few seconds with some kind of cooldown. The last thing you probably want is for people to just walk around with the effect constantly on. (I've definitely done that in some games)
An alternate method entirely could be something like a "spell" in front of you that you use. It being directional means more work for the player to gain the information but could mean an assumption they didn't miss something if they weren't paying enough attention where they'd scanned. I wouldn't recommend something like this unless you wanted to incorporate it into puzzles in the future somehow.
With any of these, though, they could even be explained with lore as a focus she has used to find important books in her studies. (almost like the Jack Sparrow's compass that points to the thing he wants most)