| 摘要 |
The determination and optimisation of the optical path length of a thin layer (1, 8, 12, 14) is performed by irradiating the layer (1, 8, 12, 14) by means of measurement radiation (19, 40) of known wavelength lambda . Through a defined structuring of the layer (1, 14) or by applying defined structures (6, 7, 9) to the surfaces of a continuous layer (8, 12) which is transparent to the measurement radiation (19, 40) diffraction rays (210, 211, 212 and 410, 411, 412) are formed whose intensities are detected by receivers (220, 221, 222 or 420, 421, 422). By a comparison of the signal amplitudes of the individual receivers (220, 221, 222 and 420, 421, 422) and by a comparison with the intensity of the measurement radiation (19 or 40), the optical path length of the layer (1, 8, 12 or 14) is calculated. This method is to be applied, in particular, in the production of phase gratings, by regulating the precipitation parameters continuously as a function of the measurement result of the method according to the invention (Figure 5). <IMAGE>
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