The pursuit of stable performance led to Philips' development of the single-beam swing arm system. Imposing a couterweight (balancing weight) on the side facing the optical lens block enables the system to adjust the weight distribution and move the optical system usigin relatively minimal power. It also facilitated increased structural precision and, perhaps even more importantly, allowed overall movement to be controlled using highly versatile analog servo circuitry.
CDs are irradiated with a 780nm red laser beam from the polycarbonate resin substrate side, and whether the digital data is "0" or "1" is determined by an increase or decrease in the reflection of the laser beam. Thus, extremely accurate optical technology (lens design, lens fabrication, special coatings, and precise assembly) is required for the small optical pickup block.
The last large-scale drive mechanism to follow in the wake of the Philips CDM0 and Philips CDM1 was the Philips CDM1 mk2. This was based on a flat top plate design, with additional intergrated circuitry and a compact base. Of course, the entire unit was made from strong die-cast metal. The Philips CDM1 mk2 was used in the Marantz CD880j, Marantz CD80 and Philips CD880. Period wise, this was around the time that 8-cm "CD-single" was introduced.