Monitoring of solidification induced strains in two resins used in photofabrication

In this work, measurements of in situ solidification and post-fabrication strains in two commercial stereolithography photopolymers are presented. The photopolymers examined in the present investigation are a multifunctional acrylate-based resin and an organic–inorganic polymer known as ORMOCER®, which have been used in single and two-photon stereolithography, respectively. The resulted solidification strain build up is monitored via the use of an embedded Fibre Bragg grating (FBG) sensor during photopolymers stepwise exposure to UV-light irradiation. Analysis of the recorded spectra demonstrate the development of high consolidation strains in both UV cured photopolymers as well as a significant increase of their magnitude after post-fabrication thermal treatment at 75 °C. Based on the strain data from the utilized optical sensor, information on the degree of cure for one of the two photopolymers is also provided.