One method would be to put a green filter in front of your laser, then use a cheap digital camera with no IR filter to check for the presence of IR...
I've seen people use a glass of cola as a filter for green, apparently IR passes right through it... If you have a cheap cellphone camera, you should be able to see a dot.
PS: Depending on the power of your laser I'd be much more afraid of green than IR, since IR diverges so much when focused for green. IR dangers are overrated, be afraid of green instead.
Uhh. You don't want to shine any laser directly into a camera lens, that would probably damage the camera.
What I meant by that is shine your laser through a glass of cola, the green will be absorbed by the brown color of the drink, yet the IR will pass through and make a dot on any surface behind the glass. Take a picture of the area behind the glass and if there's leakage of IR you should see a white or purplish dot in your picture.