抄録
The light pattern method is often useful for the calibration of recorded signal levels of phonograph records, however, it is restricted to the low frequencies because the edges of the pattern become obscure at higher frequencies. It can be theoretically derived and experimentally proved that when a LASER beam is used as the light source in the light pattern method, the pattern changes into a pattern with the bright and dark stripes, and therefore, recorded levels can be calibrated more accurately by analyzing the bright and dark striped pattern instead of the pattern width.
