For the 3d polarized glasses when i exposed it to the light. i can see that the lense on the
left eye become darker compare with the right eye.

The polarized filter also works similar with the glasses can become darker depends on the degree your turn.

my question is to place the filter on the projector have to be both filter darker or just one of the filter
darker?if only one which one the top or the bottom of the projector supposed to be darker?

Second how many inches the best distant between the projector and the filter, cause my filter is not
the glass one so i scared it melt?

thanks in advanced.

I'm not too sure i got the question right but: Have you tried to clean the polarizers? If they're dirty it not only shows dirt, it also interferes a bit with polarization (slight ghosting increase). Otherwise it can only be the filters that aren't identical (either glasses or the filters).

The things that happens if you burn a polarizer (yes, i've done it. ) is that they don't physically burn. They just stops polarizing the light. At the beginning i used simple camerapolarizers for my rig but they soon checked out.

Align the filters as far away from the lense as possible but at the same time keeping the beam within the filter. Having bigger filters will help. I had 2500 lumen from the projectors and fried the filters but i think having a distance of maybe 7-10 cm's from the beamerlens could make a great difference (i had 0.5 cm's from the lenses).