Abstract: In 3D sensing based on gray-code and phase shifting, non-sinusoidal phase-shifting gratings influence the precision markedly. Traditionally the obtained phase value is corrected by applying the object phase transfer function (OPTF) to improve the measurement precision. But the corrected result still has definite errors because of the periodicity assumption of OPTF. It is suggested to get the accurate phase distributing function of the conference plane by studying the phase distributing rule of plane objects combined with system calibration, then reduce the influences of non-sinusoidal gratings, eliminate the error carried from the periodicity assumption of OPTF, assure the measurement precision and the stability of measurement system.

Key words: 3D sensing, Gray code, Non-sinusoidal, Phase shifting