LED Ring diffuser with very glossy PCBs

[sebastian]

We are using PCBs from https://oshpark.com/ - they are purple and very glossy.

Two layers of diffusion on the down-looking camera still create a significant reflection:

diffusion-camera.jpg (300.13 KiB) Viewed 3868 times

Is there a way to manually lower the brightness (exposure time, gain or aperture) of the camera some way?
Has anybody else had a similar issue and found a solution?

[JuKu]

Very glossy indeed!

> Is there a way to manually lower the brightness (exposure time, gain or aperture) of the camera some way?

Not that I know of.

Suggestions:
- lower the light intensity a lot (which creates issues elsewhere)
- add diffusers and play with their distances from the light
- try it anyway: The software looks the PCB only for fiducials. Although the image is far form ideal, maybe there are image processing parameters that still work. Standard fiducial is a non-pasted round pad with a solder-mask free area around that. Hopefully you have these! The solder mask free surrounding should help.
- If you do have this glossy solder mask over fiducials, maybe you can remove that (if one board only) or put some matte tape over that to reduce gloss. Ok, sounds like a hack and likely reduces accuracy somewhat, but you might give that a try.

[sebastian]

Thanks, I will try, test and report back.

[sebastian]

First tests of optical fiducial recognition show that "try it anyway" seems to work in most cases

[johnswenson1]

I have an Andonstar camera and don't use any light on the LitePlacer at all for the down facing camera. My lab has a white ceiling and multiple fluorescent fixtures which give a decent brightness very uniform light on the table. The camera is plenty sensitive to see the any of the features on the board and works great with the OSH Park boards.

The upwards facing camera is a different story of course, IT needs a light source.

John S.

[Covert]

I just put adjustable regulators on the 3 lights I run (third is a second light for the down camera 20mm away from the camera horizontally towards the front of the machine)

I have found it allows me to tune the vision system better for light conditions.

I use some of these and run them right of the 24V PSU.

Been about a week and getting good results. I got some Red LED's in the mail today. I'll be trying those as well.

http://www.ebay.com.au/itm/4-5V-28V-MP1 ... SwzaJX4gTf