Modulator-free light control via computational beam shaping
image: Numerical examples for explaining the basic procedure for computational light control. (a) Single-lens optical imaging system with three distributed apertures. (b) Phase tilt is added to the small apertures and three light spots are recorded on the camera with reduced peak intensity. (c) Explaining the basic procedure for computational beam shaping by using an example of adjusting the beam propagation direction.
Credit: Tengfei Wu et al.
Controlling light with high precision is crucial for advanced imaging in astronomy, biology, and medicine. Traditionally, this requires complex hardware like spatial light modulators or deformable mirrors. Now, researchers have demonstrated a new, simpler approach that replaces physical components with computation.
Published in the journal iOptics, the study outlines a "modulator-free" method for light control. The technique involves precisely measuring a light wave's properties (amplitude and phase), digitally propagating it through a simulated optical path, and applying numerical corrections to steer its direction or make separate beams interfere coherently.
The team validated the concept with an experiment where they computationally adjusted tilted wavefronts from two separate apertures to make their beams merge and interfere on a camera sensor — all without moving any physical part.
"We are shifting part of the control burden from the hardware domain to the information domain," explains corresponding author Xiaopeng Shao, a professor at the Xi'an Institute of Optics and Precision Mechanics, CAS. "By accurately measuring the complex optical field and processing it digitally, we can emulate the function of physical modulators.”
Notably, this approach not only reduces system cost and complexity but also opens the door to more flexible and robust optical designs. “It holds promise for applications that require precise optical path matching or wavefront correction, such as synthetic aperture imaging for astronomy or compensating for tissue scattering in deep bioimaging,” adds Shao.
While currently demonstrated with simple phase tilts and coherent light, the method's principles could be extended to correct more complex distortions.
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Contact the author: Xiaopeng Shao, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences
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