If you’ve used a diode laser engraver or cutter ... [Makers Mashup] shows in a video how to use an adjustable IR filter to cut out all the light bleed to get a sharp image to make focusing ...

The transmitter is a set of lasers, one is visible red for aiming, and the other is infrared for measuring the vibration of a surface. Point the transmitter at the window of the room you want to ...