i found him in crystal cave u dont fight him there
No you don't...if your darkside then you aid the mercs and take Khoonda, in the process you'll fight Vrook at the end of the battle thereby getting the lens, if your lightside you aid Khoonda and after fending off the merc attack you'll receive it from Vrook...don't worry the pieces will come to you as the story progresses whether you want them to or not....
he is really hard to beat i keep dying
you can also plant mines in the building before the battle.