With some Hybec and Crompton tubes I have, you can see the cathode with the tube on since the phosphor is thin.

The phosphor is quite thick in the tube pictured here, even shining a torch through it's hard to make out. As you can see the laser pen paints a very clear image!

I can confirm this works with the cat toy laser pointer I have here too - they'll have to consider it confiscated!

I have a laser but it's a bit dangerous lol. Like glasses needed as even reflections can cause damage!

A red laser might be better, the green is a bit bright & I don't think this one is quite legal lol!

Yes, the laser works much better than a torch.

Dads got one of these kicking around. I was winding the kids up in the street with it a few weeks back shining it from the upstairs Window and on the road lol they were all chasing it confused and wondering what was going on getting all frustrated. Wondering where the heck it was coming from lol so much fun. My friends little 4 year old was trying to do a proper investigation into where it was coming from.

You could get the same effect with any small bright light source and a blank card with pinhole in it...