Galvo mirror
Reflects rays from a static or animated ideal quasistatic mechanical scan angle; high scan rates use a slowed preview.
Open in the canvas →In the real world
A galvanometer scanner ("galvo") is a small mirror mounted on a limited-rotation motor, used to steer a beam electronically instead of by hand — the core building block of laser scanning microscopes, laser marking and cutting systems, LiDAR, and laser light shows. Because reflection doubles an angle change, a small mechanical rotation produces twice as much angular deflection in the reflected beam:
Real galvo systems pair two mirrors on perpendicular axes (X and Y) to raster- or vector-scan a beam over a 2D field, and their achievable speed is limited by the mirror's rotational inertia — large, fast angular steps take longer to settle than small ones.
In OpticalSetup
The galvo reflects rays with the same exact vector law of reflection as a plain mirror, but its surface angle is recomputed every frame from a configurable command: Static holds a fixed mechanical angle; Sine and Triangle continuously sweep it around that center at a set frequency and peak amplitude. In sweep mode the mirror actually rotates and the reflected beam visibly sweeps back and forth on its own — this is the one component in the library that animates continuously in real time, driven by its own clock rather than the pulse-timing playback controls used elsewhere.
The peak mechanical sweep is capped at 10°, and defaults to a modest 1° — enough to demonstrate scanning clearly without the swing dominating a sketch. There's no modeled inertia, bandwidth, or settling time: the mirror follows the commanded sine or triangle wave instantly and perfectly at any frequency, which a real galvo's mechanical response could not do.