Legal Question in Criminal Law in California

I don't see how you could, assuming your back yard is not readily visible to the public. But the officers who stopped to ogle you might be. I don't think they committed any crimes, but they likely violated their department's rules of conduct. You may want to file a complaint with them, especially if you think they photographed you and/or made a video.

I always forget that law enforment comes with its own "perquisites." This reminds me of an incident when I was in the Navy and the Commanding Officer recorded a video of a topless party on a yacht in the Virgin Islands using the periscope.

I wouldn't file a complaint, as then they can counter with charging you for masturbating in public.

Assuming there is a fence around your backyard you didn't do anything wrong, and if anybody deserves to go to jail it is those creepy officers who mis-spent your tax dollars on expensive helicopter fuel.

But do this again and you might go blind ;)