Van Dien filed divorce docs in L.A. earlier this week, citing irreconcilable differences. He and Oxenberg have two daughters ... 14-year-old Amanda and 11-year-old Celeste, and he's asking for joint physical and legal custody.
The "Starship Troopers" star also doesn't want to pay spousal support to Catherine ... who famously starred on "Dynasty" back in the '80s. Casper isn't asking for spousal support either -- so, he's hoping for a clean break. This is the 2nd divorce for both of them.
Oxenberg is real life royalty, sorta. Her mother is Princess Elizabeth of Yugoslavia ... which doesn't exist anymore.