In this study, the issue of potential photosensitive absorption interference induced by conventional red-light sources in the optical detection of photopolymer dark reactions is investigated. To address this issue, infrared light is employed as the coherent light source for holographic monitoring of dark reactions, significantly reducing the extraneous photosensitive absorption interference generated by the light source during the detection process. Utilizing Irgacure 785/PMMA photopolymer as the material under investigation, absorption spectral analysis along with comparative experiments on refractive index variations under green light (sensitizing light), red light, and infrared light are conducted. Results indicate that infrared light elicits minimal refractive index changes in the material, making it more suitable as a detection light source. Infrared digital holographic technique is applied to detect refractive index changes during the dark reaction of the photopolymer material, yielding visualized grating phase distributions and temporal curves of grating peak refractive index variations. The findings demonstrate that the application of infrared light sources can effectively mitigate extraneous photoreaction interference triggered by detection light sources during dark reaction holographic measurements, thereby enhancing the accuracy of refractive index change detection in photopolymer materials.