In the physical optics course, a learning-centered teaching innovation is proposed, and a three-tiered progressive teaching design of “problem-oriented interactive classroom, immersive exploratory teaching, research-oriented project design”, and a five-ring constructive teaching method of “phenomenon-problem-theory-method-capability” is developed. As a common data storage medium in daily life, the optical disc is also a reflective diffraction grating, exhibiting obvious grating diffraction phenomena that are easy to observe. The paper takes the project-based design experiment on measuring the operating laser wavelength and the track spacing of optical discs using diffraction gratings, as an example, to explore the teaching reform practice of research-oriented project design in the physical optics course. The proposed experimental method is straightforwardly designed with strong repeatability, combining the grating diffraction theory with actual diffraction phenomena organically, which is helpful for deepening the understanding of the Fraunhofer diffraction effect.