Beam is used to combine the two.
Two piece available.
Polarized Beam Splitter Cube
Ideal for red and blue laser.
yield: 100/90
Dimensions 10 mm * 10 mm
wavelength: 400nm to 660nm
new product
http://www.youtube.com/watch?v=-onCVd5EmaQ
A PBS cube can be used to combine 2 lasers based on...