Adjustable Aperture Based on the Phase Modulation of Spatial Light Modulator

In this paper, we propose an adjustable aperture based on the phase modulation of a spatial light modulator (SLM). Two polarized beam splitters (PBSs) are used to control the polarized light and one SLM is used to modulate the phase of the polarized light. A specific grayscale is produced, where the middle grayscale is with phase of 0 and the other is with phase of π. When the light passes through the first PBS and the SLM, the polarized state of p-light is changed to s-light by the grayscale with phase of π, so only middle light can pass through the second PBS and is detected by the camera. By controlling the size of the middle grayscale with phase of 0, the device can realize the function of adjustable aperture. Our experiment shows that the aperture can be tuned between 0 and full size, meaning that it can reach the fully open and closed state. The results verify its feasibility. The adjustable aperture has wide applications in imaging system, fiber-optic communication, and photonic signal processing.