As Blu-ray and HD DVD media uses much smaller pits than DVDs, the manufacturers have to operate their equipment within much stricter production tolerances. While there are various ways the manufacturers can check for common defects such as layer thickness, bubbles embedded in the disc and so on, the only way to examine the actual pits on the disc is by analysing it using optoelectrical reference drives.

TOPTICA Photonics developed such a reference drive, which is designed to test the quality of both Blu-ray and HD DVD optical media, such as to determine whether the disc presser is wearing out or if there are issues with the moulding process. In order to ensure that each reference drive returns equal results for a given disc, each drive is calibrated against a master reference disc from Sony, Philips or Toshiba during the manufacturing process.

In order to cut the cost of replicating discs, forward error correction algorithms are used in order to allow for a certain amount of errors caused by physical defects present on the disc as well as errors during the pick-up process. So, in order to check for errors before the error correction stages, the reference works directly on the raw optical pick-up data. Finally, to allow the drive to work with both HD DVD and Blu-ray media, it ships a 0.65 numerical aperture lens for HD DVD Media and a 0.85 numerical aperture lens for Blu-ray Media. The production testers for Microsoft’s Xbox360 HD DVD discs will be one of the first to use these reference drives.

TOPTICA Photonics of Germany has developed a reference drive for testing the quality of Blu-ray and HD DVD optical discs. Dubbed HUSKY and said to be the first of its kind, the drive can identify production faults such as a worn disc stamper or poor molding conditions.

Blu-ray and HD DVD disc manufacturers are being forced to operate within much tighter production tolerances thanks to the tiny data structures found on next generation optical discs. While defects such as tilt, sputter variations, layer thickness or bubbles in the disc can be studied by a variety of in-line inspection methods, the disc’s microscopic bit structure can only be analyzed using opto-electrical reference drives.

It seems like this drive essentially does a similar process to LiteOn’s KProbe tool, since it reports low level error information directly from the disc. However, the main difference here is that while each LiteOn DVD writer may produce different results with KProbe for the same disc, these reference drives for testing HD DVD and Blu-ray media are calibrated to all produce the same results for a given disc.