I have an 80 milliwatt green laser and ran a test with various colors of theatrical gel filters. The red filter completely consumed the green beam! When the laser source is viewed from the other side of the filter (pilot's perspective) there is no evidence the laser is even switched on (dark aperture hole). Perhaps a sheet can adhere to the cockpit window statically, or a roll could be used, as stated above, as a pull-down shade.
This is the data sheet associated with the filter material and color that I used:
Rosco US : Filters : Roscolux
