Media and drive quality testers are named differently depending on the technology type, for instance cleaner, inspector or certifier for tapes, tester, verifier, analyser or checker for optical discs. However the purpose is to control the quality of media and drives.

Most of the testers available on the market were once laboratory instruments for R&D or quality monitoring tools for process manufacturing and static testing. They control and report a full analysis of some media and drive (pick-up heads) characteristics or technical properties (the change of the optical properties, the reflectance for phasechange media, polarization-rotation for magneto-optical media), and check whether or not they are compliant with the industry specifications.

Optical Disc Testers

At the output of an optical disk readout channel, there are several major types of noise: thermal, shot, laser, media, and writing. Among these noise sources, the thermal and laser noises can be controlled and minimized, leaving the media noise as the dominant source. The interaction of the incident light with the media yields not only a readout signal but also the undesirable media noise. Various fluctuations in the optical properties of the medium, which scatter the light, contribute to the observed media noise. These include the surface roughness as well as the bulk inhomogeneity and birefringence of the substrate and the non-uniformity, graininess, and segregation in the materials of the various layers as determined by the physical properties of materials as well as the deposition process.

HDD production testers

Since hard disk drives are hermetically sealed, most of the HDD testers are used for quality control in production. They perform tests such as:

• start-stop test on the disk landing zone,
• start-stop test with periodic head seeking,
• continuous-seeking test,
• continuous-dwell-flying test,
• park-stiction test,
• fly-stiction test,
• dynamic load-unload test,
• load-unload tests at different disk speeds,
• combination of the load-unload and seeking test,
• simultaneous measurement of the dynamic gram-load,friction force and magnetic signal degradation during start-stop test.

Magnetic tape tester

Most magnetic tape testers perform one or more of the following operations:

• Retensioning
• Cleaning
• Optical inspection
• Magnetic scanning