The Down Facing Camera is incorporated to the backside of the Z-Axis. The camera locates fiducials, checks part orientations and calibrates the feeder positions. I first tried out an ordinary light ring around the camera and afterwards a lighting dome, but I kept getting the same result - the center of the picture was always dark and I couldn't get a reliable fiducial check of my pcb. After some research on this topic the solution was clear to me - I need to build a beam splitter. This is how professional machines do their lighting. I know this might be overkill for some people and they could get their vision pipeline to work with an ordinary lighting setup, but this was the route I went for and I have not regretted it since. A beam splitter or also called two-way-mirror consists of a glass that in my case reflects 50% of the light and lets 50% of the light shine through it. Beam splitters are for example used in teleprompters for tv shows. The light shines at a 45 degree angle at the glass and 50% is reflected onto the pcb and the other 50% shines at the black back wall. The camera looks through the glass at a 45 degree angle at the pcb and the black back wall, which can’t be seen in the final picture because it is black. This results in a perfect lid picture of the pcb, without any dark points at the center of the picture.

First mount the camera to the 3d printed mount and cut the beam splitter glass to size and clamp it in place. The light reflector can be glued in place and the led power wires routed through the traces in the 3d printed mount. Thermal paste is added to the backside of the led and clapped onto the Z-Axis Mounting Plate by screwing in the M5 bolts. The camera and led wires can be zipped tied to the mount at the provided slots.

Outline of the LED: