flood wrote:why 6 lasers?
Well for one I can get the display a lot brighter by using 6 lasers.
Second thing is it improves the color gamut a bit since as you mentioned they are monochromatic and a very narrow bandwidth.
The color range, or "gamut," of a laser projector depends on the spacing of the laser wavelengths. The gamut is represented by the area enclosed by lines drawn between the three laser wavelengths on the chromaticity diagram. As can be seen, the color gamut depends strongly on the choice of green, but the red and blue wavelengths have little impact. Green sources emitting at 520–535 nm usually are considered to give the best gamut.
I know 3 RGB lasers covers almost all colors, but adding 3 more at different wavelengths allows linear combination to cover more of the possible stimulation.
(My 442nm blue is more ultraviolet purple in nature than blue and struggles to do royal "true blue" while my 450nm blue laser does "true blue" with no problem at all.. So it helps the overall color in my opinion to use both.)
The only way more primaries could expand the presentation of an image is if it expands the color gamut.
And although the red and blue wavelength variations have little impact on gamut color when it come to perceived RGB mixed white color temperature, they do with overall brightness.
In the wavelength region of red for instance, luminous efficacy rapidly increases as wavelength shortens.
Current red laser diodes used in the current display engine lase at 642nm. By moving toward a shorter wavelength ,even by a mere 4 nm – the human eye perceives this red light as being much brighter. In this case, at a fixed brightness, red light at 638nm appears about 33% brighter than the same light output at 642nm! Similarly, the blue laser diode being used in the 1st version emitted light at 442nm. By increasing that wavelength to 450nm, perceived brightness would also increase. That is why I have included six of those specific wavelength lasers in the monitor.
Then you have the overall increase of adding another set of RGB lasers to the mix.