overlaying beams by one replacing the other where they intersect rather than superimposing?

[wosoka]

Need to overlay beams by having one replacing the other where they intersect rather than have the beams be superimposed.

this is what I want: https://i.imgur.com/F6HIYBl.png

this is what I do not want: https://i.imgur.com/ylhMeEa.png

This kind of beam combining can be either achieved by the "combiner" OR later in the setup by the "projection screen". Or in other words, having the original beam not reaching the projection surface is not the only solution as somehow not displaying the original beam on the projection surface even if it has reached it will also work.

The colors of the beams are for illustration purposes, so are their positions. Position of the smaller beam can change.

Is there any way at all to achieve this. Brightness not an issue so things such as polarizers can be used.

Any ideas?

Edited March 31, 2018 by wosoka

[Frank]

lcd panel to block out the "red" beam as needed?

 

[wosoka]

That will not solve it, as the red beam will be overlayed on the blue beam on the projection surface and produce a violet spot, rather than red.

If LCD was instead used on the blue beams path to block where the red beam goes that could work, but the method ofacquiring the correct pixels to block on the blue would be complicated and not very accurate with an LCD matrix.