Active thermal marker using thermal images of heated areas with visible semiconductor laser

In situations where the object being captured or the camera itself is in motion, object tracking using conventional attached markers or detailed textures is useful to keep capture the object with high accuracy; however, tracking accuracy has been degraded in situations where texture features are scarce or where it is difficult to attach markers. Therefore, in this study, the temperature rise corresponding to the laser irradiation time to the object is detected by a thermal camera, and the points where the temperature reaches or exceeds a threshold value after the laser irradiation ends are used as markers. After the temperature drops, laser irradiation is performed again to repeatedly generate markers. Furthermore, by controlling the irradiation point with a 2-axis galvanometer mirror, a marker that can code arbitrary shapes and information can be generated on a 2-dimensional plane. In our experiments, we irradiated a red semiconductor laser onto black paper, and found that an irradiation time of 10 ms was the most efficient in terms of heat dissipation time, enabling the simultaneous generation of up to 33 markers. As a result, it was found that it is possible to draw distinguishable characters and graphics such as lines and circles by continuous drawing. Future plans include application to non-paper based on additional physical property investigations and actual tracking applications.