"HoloLens" - PR speak for LASER.
To create Project HoloLens’ images, light particles bounce around millions of times in the so-called light engine of the device. Then the photons enter the goggles’ two lenses, where they ricochet between layers of blue, green and red glass before they reach the back of your eye. “When you get the light to be at the exact angle,” Kipman tells me, “that’s where all the magic comes in.”
First part is clearly a LASER because that's how they work. Second part is? Prism? LCD panel? DLP thing?
It sounds interesting enough on it's own without having to fluff the language so badly. At first it sounded like it could be a hologram due to it using a LASER (coherent light) but it just sounds like a projected screen; common sense tells us that there's not enough processing power to render volumetrically at the required resolution to start with.
My guess is that they were worried that the public might be scared of the makers of Windows and the XBOX 360 RROD disaster making hardware that shines a LASER directly into their retina?
But yeah "light engine", FFS.