We now illuminate the microspheres with green light (532nm), to differentiate it from the trapping light (1064nm), which is useful when we introduce feedback. It also looks pretty cool!

These images are of the same thing, a 2.5 micron diameter sphere levitated between aspheric lenses, but have different light levels. The green light is NOT trapping the particle, 1064nm light is not picked up by the camera.