Self-diffraction for intrinsic optical modulation evolution measurement in photoresists

Two-wave mixing at a holographic grating being recorded in a positive photoresist film is used for simultaneously and independently stabilizing the holographic setup itself and for measuring the real-time optical modulation evolution during recording. The method is more sensitive than directly measuring the diffraction efficiency with a probe beam, being particularly interesting for very low efficiency values. This technique is used here for studying the photoreaction kinetics in a Shipley AZ-1350J positive photoresist, and measurements acree with those made with a well-established spectrophotometric method.