| 摘要 |
<p>Readhead for a measuring device, comprising a graduated grating (11), and a light emitter (10) for lighting a graduated scale (2) through said grating (11). The readhead (1) is movable with respect to the scale (2), a distribution of light with a period of modulation in a plane which is at a determined distance with respect of said scale(2) being obtained, after a first interaction between the scale (2) and the grating (11). In said plane, a grating (12) with a period different to but close to the period of modulation is disposed, a new distribution of light with a period of image which corresponds with a image of the scale (2) being obtained as a result of the superposition between said grating (12) and the period of modulation. The readhead (1) comprises also another grating (13) which interacts with said image.</p> |
