The “corpuscular theory” is an early viewpoint in classical optics, proposing that light consists of tiny, indivisible particles propagating in straight lines. Newton, as one of its principal advocate, suggested that the motion and interactions of light particles could explain fundamental optical phenomena such as reflection and refraction. This paper examines how the “corpuscular theory” accounts for interference, diffraction, and polarization—phenomena typically associated with wave optics—and reveals the wave-like ideas it implicitly contains. Newton introduced the concept of “fits” to explain interference from the perspective of particle motion, while Malus and Biot further proposed laws governing the motion of light particles under forces, theoretically unifying phenomena such as total reflection, interference, and polarization, thereby elevating the corpuscular theory to new heights. Although the theory regarded light as composed of particles, its explanations of polarization and interference already incorporated periodic features characteristic of waves, albeit unconsciously. These early studies not only laid a solid experimental and theoretical foundation for the rise of the wave theory, but also vividly demonstrate the internal logic of scientific development—the opposition and unity of contradictions. Incorporating this historical perspective into teaching can help students better appreciate the complexity of scientific progress, cultivate critical thinking and creativity, and inspire a strong interest in scientific inquiry.

Laser-based light sources are highly desirable for display applications due to their narrow emission linewidth and exceptional brightness. However, the coherence inherent in lasers often leads to the formation of unwanted speckles, which can significantly degrade display quality. Thus, there is a critical need for light sources that retain the narrow emission and high brightness of lasers while minimizing spatial coherence to reduce speckle formation. Random lasing has emerged as a promising strategy to address this issue, though its random emission directions can lead to energy losses. To overcome this challenge, we propose a novel approach in which CdSe nanoplatelets, known for their efficient optical gain properties, are self-assembled into supraparticles (SPs), serving as both scattering centers and gain media. This configuration enables random lasing, and by coupling the random gain medium to a Fabry–Pérot (FP) cavity, we successfully direct the typically omnidirectional random lasing into a controlled, low-coherence emission. Our experimental results, comparing conventional lasers (e.g., He:Ne lasers) with our SP-based laser for a projector, demonstrate effective suppression of speckle formation, reducing speckle contrast from 0.5 to 0.05. These findings offer a promising solution for improving the performance and quality of laser-based displays.