| 摘要 |
<p>An apparatus and method for determining at least one characteristic parameter (quality defining characteristic) of print material (1) consisting of a periodic array of dots. The apparatus comprising a light source (2) for providing a spatially coherent light beam (3) to illuminate and be diffracted by the print material (1); detecting means (4) arranged to detect the Fourier transform distribution of the print material from the diffracted light beam and processing means (5) for processing data from the detecting means to calculate the characteristic parameters from the Fourier transform distribution of the print material.</p> |
