Optical position measuring device

The invention deals with a with a scanning unit (2) optical position measuring device, the scan unit contains a light source (4), a projection plane (9) and one for the projective plane (9) produces a periodic grating ruler (10) projection lens Optics (8). According to invention the lens optical institutions (8) by a has grid cells cycle or adjacent lens (81, and 82) mutual spacing of cyclical lens Group column (80) composed, which AG (r) representative lens Group column of grid cells cycle; t (r) representative cyclical ruler grating (10) of cycle; | beta (r) | representative has lens Group column (80) of projection proportion beta of absolute; ψ representative has a can advance provides of phase moved; r representative has grating component of RADIUS, which for linear grating r= ∞, and AG , For constant t and beta; i,k and n represents the natural number, including zero.