To read the data from an HVD, you need to retrieve the light pattern stored in the hologram.
In the HVD read system, the laser projects a light beam onto the hologram -- a light beam that is identical to the reference beam (Read System 1 in the image above). The hologram diffracts this beam according to the specific pattern of light interference it's storing. The resulting light recreates the image of the page data that established the light-interference pattern in the first place. When this beam of light -- the reconstruction beam -- bounces back off the disc (Read System 2), it travels to the CMOS sensor. The CMOS sensor then reproduces the page data.
Now let's take a look at how HVD compares to other next-generation storage media.