A simple, inexpensive, real‐time interferometric cure monitoring system for optically cured polymers

Abstract

Optically cured polymers play a crucial role in many commercial applications, ranging from UV-cured inks, coatings, and dental fillings to the optical fabrication of three-dimensional prototypes by means of stereolithography. However, our understanding of the detailed processes that occur in the curing of these materials is often limited by the practical difficulty of observing the cure process in real time, under ''real-world'' conditions. This article reports the simple implementation of a free-space Mach-Zehnder interferometer that can be constructed inexpensively from readily available components, and demonstrates its utility in monitoring the UV curing of a typical acrylate photopolymer system in real time. In particular, it is shown that this system can sensitively track the induction period, the light-induced photopolymerization reaction, and the subsequent dark reaction that continues after the irradiation has been halted. This Interferometric Cure Monitor, or ''ICM,'' thus provides a valuable addition to other analytical methods, both for improving the quality control of existing commercial processes and for aiding the development of improved photopolymer formulations.

Review of quantitative and qualitative methods for monitoring photopolymerization reactions

“…Therefore, the wavelength of the beam needs to be altered (compensated) to incorporate any changes in these parameters. 252–256…”

“…Therefore, the wavelength of the beam needs to be altered (compensated) to incorporate any changes in these parameters. [252][253][254][255][256] The advantages of interferometry include the inherent sensitivity and accuracy of interferometric measurements offered by an instrument that does not need to be calibrated because…”

“…Therefore, the wavelength of the beam needs to be altered (compensated) to incorporate any changes in these parameters. [252][253][254][255][256] The advantages of interferometry include the inherent sensitivity and accuracy of interferometric measurements offered by an instrument that does not need to be calibrated because 251 Polymer Chemistry Review the wavelength of the laser light source provides a precisely known wavelength. In addition, the ability to collect data at high speed allows for the real-time characterization of rapid photopolymerization reactions, among others.…”

Real-time interferometric monitoring and measuring of photopolymerization based stereolithographic additive manufacturing process: sensor model and algorithm

“…The interferograms intensity signal is about 0.6 Hz, which is obviously the lowest non-zero frequency component f in table 2. Since the refractive index of resin n l is 1.4723 [29]…”