Harmonic free periodic signal production device

摘要

The appliance has scanning units (T1-T4) with scanning panels (A1,A2) for opto-electronically scanning the measurement divisions, and having a period (2p). The interval between scanning panels deviates from that of the measurement divisions. The scanning units each have one group (A11, A12) each with at least two scanning panels arranged either side of a symmetrical axis (S21). The interval (2a) between the symmetrical axes (S1,S2) of the scanning panels, and the interval (2b) between the symmetrical axes (S11,S12) of groups (A11,A12) of scanning panels differ. Four photo sensors (8) and scanning units (T1 - T4) are arranged in a clover leaf pattern in the four quadrants of a rectangular coordinate system (X,Y). The centre is formed by of the incident light beam (5a) optical axis (S) to the scanning units. Between the scanner units in the first and third quadrants, and those in the second and fourth quadrants, there is a p offset.