Help confirming and diagnosing a light leak issue with the V4 miniscope

[Christopher Fields]

Hi everyone,

We recently bought a pre-assembled V4 miniscope from OpenEphys and I am in the process of getting it up and running. I am noticing a potential light leak issue and would like some assistance confirming.

I am noticing the blue excitation light escaping the body of the miniscope in two places: 1) right next to where the CMOS sensor portion of the PCB is epoxied to the body (image 1) and 2) right next to the excitation module (image 2). This concerns me because it means that ambient light is able to get into the miniscope at the point of contact with the CMOS and potentially contaminate the signal. Also, from what I can tell based on the published diagrams, the excitation light shouldn't be visible near the CMOS sensor as it should be filtered out by that point in the optical path.

To figure out if this is actually an issue, I ran the light leakage test that is detailed on the github wiki, which I believe shows that there is excitation light contaminating the CMOS signal. Here is a screen capture of the DAQ software during that test.

Finally, here is a short video demonstrating that we are able to image cells on coverslipped fixed brain tissue expressing GFP.

I'm wondering if anybody could confirm that my assessment of these issues is correct, and also if anybody has advice to offer on how to remedy this. Thank you!