diffraction - monochromatic aberrations shown as different color on screen?

Below a picture of an 8mm ball bearing taken with a blue LED back light (447.5nm). I assume what we see here is a diffraction pattern, and the blue/yellow banding is due to chromatic aberration.

I didn't expect to see these blue/yellowish fringes because the LED is monochromatic.

Is this normal? I notice a lot of red pixel noise in the picture, maybe it's more a software thing? Would a blue filter in front of the camera lens help?

Fyi, this question is related to this question

Thanks,

Answer

If the light is monochromatic, there are no yellow fringes. Likewise, there is no red light. So a filter would not help.

I would look to your camera. If the blue light is too bright, does it respond by showing yellow?

I presume you are getting a numeric measure of intensity as well as a visual display. You might calibrate your camera with a uniform blue light. Then you can get correct values for the intensity of the diffraction pattern. This should help you find the location of the edge as discussed in the link.