A derivative technique is developed for measuring the material response of photosensitive films. The method consists of recording a low modulated grating superimposed with different uniform preexposures. The modulation of the resulting shallow gratings recorded on the photosensitive film is measured by diffraction techniques and the derivative response is thus computed. Compared with other diffraction-based methods, this one is not affected by nonlinearities. Qualitative visual monitoring of these diffraction data may be used for optimizing materials and processes in photolithography and optical recording. Some experimental results concerning positive and negative photoresists are presented.
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