Difference in excitation LED intensity

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earthw...@gmail.com

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Sep 3, 2021, 3:51:42 AMSep 3
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Hi,
I am using four miniscope version 4 which all shows good focal points and neural ca2+ activity. However, I found out that three miniscope show darker view when observing same neural populations. When I measured the excitation LED using Thorlab power and energy meter console, I found out that four miniscopes have different LED intensity as following:

1st : 0.99mW
2nd: 0.67mW
3rd: 0.6mW
4th: 0.65mW

Indeed the one with lower LED intensity showed darker view. I wonder whether this is the issue of LED itself (so, if i change the LED, would it change the led intensity?), or something inside the PCB board. Thanks!

Sincerely,
Gaeun Park 

Zeeshan Haqqee

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Sep 3, 2021, 12:05:50 PMSep 3
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I've done some LED intensity testing myself and noticed some miniscopes can indeed differ slightly in their intensity. However, I've noticed most of this related to the LED module of the PCB not being screwed in properly. I'd would inspect your v4 miniscopes to make sure the screws are in place and the LED module isn't sitting on an angle or leaking too much light from the sides. This might explain why some are darker than others. 

Zeeshan 

Daniel Aharoni

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Sep 3, 2021, 4:40:09 PMSep 3
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Hi Gaeun,
Thanks for the post. I agree with Zeeshan. The hardware on the V4 Miniscope should very reliably set the current through the excitation LED (within a few percent) but there might be variability of the placement of the LED on the PCB and the alignment/placement of the LED PCB on the V4 housing. In addition, LEDs have a bit of variation of optical power output vs current.

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