a novel method and apparatus utilizing conventional photo - reactive and reflective layers of a recording medium for optically recording and reading both digital and variable length , analog pulses of data , in an exacting manner to eliminate excess energy absorption by the medium and for reducing latent recording errors due to defects in the recording medium as well as due to the recording process itself . with this precise recording and reading technique , analog variable - length pulse recording , with its inherent wide bandwidth , as well as coded digital pulse recording , with its inherent narrow bandwidth , can be accommodated . the system monitors the optical transmissivity and reflectivity of the recording medium during the recording process in real time to accurately determine initial and terminal inflection points denoting inception and end of a recorded pulse in an exacting manner and to pinpoint and make allowances for recording defects which may yet yield errors on playback . a residual error reduction technique complements the variable pulse recording process by detecting and temporarily storing data and respective address at which data could not be accurately recorded due to chemical or physical anomalies in the recording medium .