Aiming and tracking: An adjustable reflector steered by two serially connected stepping motors, guided by a depth camera with RGB and IR sensors, enables real-time targeting of PV receivers.

The depth camera detects receiver position with RGB data and irradiance spots with IR data, allowing precise, rapid beam adjustments for multiple receivers.

Intro: Scientists in Science Tokyo unveil the world’s first automatic and adaptive dual-mode LED-based optical wireless power transmission (OWPT) system that powers multiple IoT devices in both bright and dark indoor environments, enabling AI-powered image recognition to run without interruption.

The reflector features horizontal and vertical rotation controlled by two series-connected motors, delivering precise beam aiming toward photovoltaic receivers.

In experiments, the auto-OWPT system achieved stable and efficient power transmission up to five meters under both bright illumination and dark conditions.

An adaptive double-layer lens, comprising a tunable liquid lens and an imaging lens, maintains optimal beam focus and mitigates distance-related power loss.

The adaptive lens adjusts the beam spot size based on receiver distance and size to minimize power loss over distance.

Multi-receiver capability: The system can sequentially switch focus between multiple PV receivers of varying sizes and distances, delivering uninterrupted power.

PV receivers feature retroreflective edges to reflect IR light from the depth camera, enabling precise shape and position detection and reduced interference; a CNN based on SSD enhances detection accuracy.

A convolutional neural network based on Single Shot MultiBox Detector (SSD) improves receiver detection accuracy and positioning.

The technology offers a safer, cost-effective alternative to laser-based OWPT, with scalable indoor IoT power delivery suitable for smart factories and homes.

Publication: The study was published in Optics Express on October 24, 2025, by Miyamoto, Zhao and colleagues from Science Tokyo, with a conflicts-of-interest statement indicating none.