The CD laser has a nano scale beam width and the spiral of physical data on the CD is also nano scale in diameter. In order to keep the laser focused on the data spiral whilst the disc is fluttering there is laser servo feedback system 🔄 and a tiny spring system for the laser that allows the laser to move very easily back and forth as required to stay on the spiral track.
The trouble is there is so much fluttering of the disc and movement caused by external forces (vibration) along with the out-of-round condition of the CD disc the laser servo system can’t keep up with all of the motion. Furthermore, unless you’ve obtained precise level of the CD while spinning the disc will wobble even more. Further exacerbating the situation, very low frequency seismic forces act 🔜 on the tiny spring suspension of the laser, the Fr of which is about 8 Hz, making the laser move unnecessarily. The CD edge beveler from Germany 🇩🇪 was designed to make the CD perfectly round which helped eliminate the flutter problem, but did not go far enough. I stiffen the CD disc and obtain absolute level whilst playing.
The laser light is scattered inside the transport box while the laser reads the data. The entire inside of the transport is lit up like a Christmas tree 🎄 but you would need infrared goggles to see it since it’s invisible light. The scattered laser light gets into the photodetector, which can’t tell the “good light“ from the scattered light. My NEW DARK MATTER scattered light absorber is the only audiophile device specifically designed to prevent invisible AND invisible scattered laser light from entering the photodetector and damaging the sound.
