Abstract: A device manufacturing method is disclosed in which the aberration of the projection system of a lithographic projection apparatus is obtained in terms of the Zernike expansion. The field distribution of displacement error and focal plane distortion of the projected image are calculated on the basis of the Zernike aberration and sensitivity coefficients which quantify the relationship between Zernike aberration components and the error in the image. A calculation is then performed to determine the compensation to apply to the apparatus in order to minimize the error in the image. The compensation is then applied to the apparatus. The compensation may comprise increasing one component of aberration of the apparatus in order to decrease the effect of another aberration, such that, on balance, the image quality as a whole is improved.

Abstract: A reading apparatus for reading information recorded on a first longitudinal recording medium in the form of helical scanned information tracks, according to a first format in which the tracks have been recorded on the medium at a first track pitch and have a first track width, the information being read by the apparatus at a given tape velocity, the information being read from the first medium at a first bit rate, immediately adjacent tracks exhibiting alternately a first and a second azimuth angle, pilot tones being recorded in information tracks, the frequency of the recorded tones cycling through at least two different frequencies (f1, f2); and a second longitudinal recording medium recorded in the form of helical scanned information tracks, in accordance with a second, new, format in which the information track pitch is substantially twice the first track pitch, the information track width is greater than the first track width, the information being read from the second medium at substantially half the f