EXTENSIONS TO SPECTROMETER EXPERIMENTS BASED ON THE CRITICAL ANGLE OF TOTAL INTERNAL REFLECTION

The spectrometer experiment is a classical fundamental optics experiment in science and engineering education. In traditional teaching, the minimum-deviation method is commonly used to measure the refractive index of a prism. However, in actual operation, improper prism placement or incident-angle adjustment may cause the internal incidence angle at the second interface to exceed the critical angle for total internal reflection, making the refracted light disappear and leaving students unable to locate the refracted image. This paper systematically analyzes the global dependence of the deviation angle on the incident angle and refractive index in a triangular prism, and clarifies the physical constraints and modulation effects of total internal reflection on deviation angle and spectral dispersion. Based on this analysis, an AI-assisted virtual experiment interface is developed to intuitively demonstrate the dynamic processes of total internal reflection and dispersion. In addition, a new experimental scheme for measuring the refractive index of a medium based on the critical condition for total internal reflection is proposed. By introducing photoelectric detection technology, this scheme is expected to extend the experiment from qualitative observation to high-precision quantitative analysis. This work deepens students' understanding of optical boundary conditions and provides an innovative approach for modernizing and extending spectrometer experiments.