the solvent at a temperature of 65 u00b0 c either for 15 minutes in an oven or for 2 minutes on a hot plate in this way the coated plate according to fig5 is obtained in fig5 it is possible to see that the substrate 21 constituted by the silicon plate is covered with a first resin layer 23 having a relatively large thickness 2 u03bcm and also a second layer 25 of the photosensitive film according to the invention in order to form a mask on certain zones of the substrate 21 the assembly undergoes irradiation by radiation hv with a wavelength of 436 nm as shown by the arrows using a masking device 27 placed between the radiation source and the coated silicon plate so that only zones 25a of the photosensitive film layer 25 are irradiated for carrying out this irradiation use is made of a photo repeater and a total irradiation dose of 80 mj cm 2 following irradiation the silicon containing polymer of zones 25a of the layer of photosensitive film 25 is converted by reaction with the brunsted acid produced by photolysis of the triphenyl sulphonium hexafluoroarsenate in the presence of perylene in a polyvinyl phenol of formula ii this modification of zones 25a is revealed by infrared spectrometry of the substrate coated with the.