diffraction gratings and does - Breault Research Organization, Inc.

DIFFRACTION GRATINGS AND DOESFundamentals of Diffractive Optical Elements. . . . .3 The substrate areas without photoresist are then etched to a special depthleaving a binary step. The unexposed photoresist remaining on the substrate isimpervious to the etching process.4 The rest of the photoresist is removed and the entire substrate is again coatedwith photoresist.5 The next mask is positioned above the coated substrate and the combination, inturn, is illuminated.6 The exposed photoresist is removed and that portion of the substrate is etchedto a special depth.7 This process is repeated until you have etched the desired number of levels intothe substrate. See Figure 7.ASAP Technical Guide 25