mechalloy, you will probably find the ball falling rather straight, you problem will most likely be the point of departure at the top.
Are you going to spin the ball across a horizontal axis at the drop point, then you apply a force in the liquid and will have some sideways movement, that could stuff up your whole experiment in any case?
I'm sure you used to get laser that wasn't just a straight line propagation, back in the day, but now I'm not sure, maybe someone will help us out. Or maybe it was another light spectrum. Diffused/ion something or other, damn this alzheimers-light.
Sorry can't help any more.