Point and Line to You

Gray Area Showcase, July 2018

Laser galvanometer, OpenFrameworks application

This is a laser, drawing a person’s face in real time.

Point and Line to You is an art installation which sketches line drawings of an observer’s face using an RGB laser and two precise mirror galvanometers.

The observer’s facial keypoints are detected with a camera, which in turn feeds them to a microcontroller, which converts them to coordinates that the galvanometer drivers can understand.

Below you can see the internals of the laser control system. The Arduino (blue board in the lower right half of the image) processes a Serial buffer coming from a computer which is running an OpenFrameworks/OpenCV application and detecting a person’s facial keypoints.

The Arduino then converts these 2D keypoint locations into the laser’s coordinate system, and sends location data to the mirror galvo drivers (red boards in the lower right corner) via some digital-to-analog op-amp circuits (the breadboard) which control the width and sizing of the laser image.

The Arduino also determines the laser’s on/off state and color by sending commands to the laser driver (green board on the left side of the image), which in turn controls the RGB laser, which is actually three different collimated lasers (one red, one green, and one blue - you can see the laser diode module in the lower left corner).

The lasers are joined via one-way mirrors into a single beam. This beam is precisely pointed at one of the galvo mirrors, which in turn reflects off of the other galvo mirror. One galvo controls the laser’s X position, while the other controls the laser’s Y. The lower, darker image shows the laser hitting the galvo mirrors.

The single, moving laser dot is what draws the face - the galvos are just moving fast enough that your eyes (or a camera’s sensors, given the right shutter speed) perceive the laser’s output as a continuous image.

Many, many thanks to Instructable’s user DeltaFlo, and the amazing laser galvo tutorial they wrote!