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 Philips CDM2, with a resin top plate, was developed with the aim of reducing cost and weight while maintaining the quality of the zinc die-cast in the Philips CDM1. The Philips CDM2 however did not last long and was only installed in less expensive machines, such as the Marantz CD-25, Marantz CD-45, Marantz CD-65 and Marantz CD-75.