This paper used digital photoelasticity to evaluate the temporal variations of the stress field in an epoxy-metal embedded actuator. Stress variations were generated with magnetic induction heating-cooling cycles and they were analyzed with frames of a color digital video acquired with a circular polariscope. A phase wavelength stepping algorithm and an unwrapped standard algorithm were applied to obtained unwrapped map. The modification of the fields of bi-material stresses opens the opportunity to generate photoelastic actuators, in consequence they can be used as phase modulators. In consequence, digital photoelasticity is an excellent technique to characterize this effect in bimaterials.