A Spatial Light Modulator-Based Educational Apparatus for Dynamic Pseudo-colour Display

Abstract To advance the undergraduate laboratory experiment associated with the conventional $\theta$-modulation technique, this paper presents the design and technical characterisation of an SLM-based educational apparatus for advanced undergraduate Fourier-optics laboratories. The apparatus features digitally generated coding plates and enables dynamic pseudo-colour visualisation. A digital coding method for the SLM-based system is developed to account for the black-grating effect arising from inactive inter-pixel regions and the discrete pixel structure of the SLM; a corresponding Fourier-plane optical spatial filtering scheme is also proposed. This system simplifies the fabrication of coding plates while providing a programmable, dynamic, and visually intuitive demonstration of pseudo-colour coding. Specifically, it allows students to design, simulate, and test their own digital coding patterns rather than rely solely on prefabricated coding plates. The scheme is therefore intended as an advanced undergraduate Fourier-optics laboratory module that integrates digital pattern design, SLM operation, and pseudo-colour reconstruction, and can be extended to open-ended investigations of SLM-based pseudo-colour coding.