Combination of jRGECO1a and ChR2

[ivo.sonntag]

Hi,
we would like to combine jRGeco1a recordings with ChR2 excitation and are currently looking for appropriate filter sets from Chroma. Based on a previous discussion (http://miniscope.org/board/index.php?topic=393.0) on this board we picked three potential candidates with the following emission/excitations specs:

Set 49306
https://drive.google.com/file/d/0B9suQzQan1hqN3BNLVU4Vm9RbkE/view?usp=sharing

Set 49008
https://drive.google.com/file/d/0B9suQzQan1hqT3RVM0wzSGRFVGs/view?usp=sharing

Set 49017
https://drive.google.com/file/d/0B9suQzQan1hqZll3SHJJZ2dwZUU/view?usp=sharing

Now these are all very similar, however there are two points that we are currently still trying to sort out.
The first is that we would obviously like to avoid exciting the ChR2 along with the jRGECO1a. ChR2 excitation drops to its minimum at 550nm which means that if it is necessary to block all ChR2 excitation by the green LED, only set #49306 is an option. Does anyone here have any experience on how easily ChR2 will be unintentionally excited at the 'edges' of its spectrum?

Secondly, depending on the set of filters, different LEDs will have to be used. Luxeon currently has 4 colors that seem to have appropriate spectra.

Green (maximum at 530nm)
https://www.digikey.de/product-detail/de/lumileds/LXML-PM01-0100/1416-1036-1-ND/3961141

Lime (maximum at 568nm)
https://www.digikey.de/product-detail/de/lumileds/LXML-PX02-0000/1416-1185-6-ND/4626446

Amber (maximum at 590nm)
https://www.digikey.de/product-detail/de/lumileds/LXML-PL01-0050/1416-1033-6-ND/3961197

PC-Amber (maximum at 591nm)
https://www.digikey.de/product-detail/de/lumileds/LXM2-PL01-0000/1416-1027-6-ND/3961191


Here are also two images from the Lumiled Datasheet (https://www.lumileds.com/uploads/265/DS68-pdf):
https://drive.google.com/file/d/0B9suQzQan1hqN0VpZ044NG1tSmM/view?usp=sharing
https://drive.google.com/file/d/0B9suQzQan1hqUVdIYUlyVEdSN3c/view?usp=sharing

Based on the spectra drawn in the datasheet and the three filter sets we picked, Green is probably not going to work. Lime, Amber and PC-Amber should work, however depending on the filter set some will probably require higher LED power than others to get the similar results, depending on the filter sets used.

@Daniel: Does that make any sense so far or are we overthinking here?

@anyone else: Any input to this is highly appreciated. As soon as we can provide more informartion on the technicalities we'll post them.

cheers,
Ivo

[Daniel Aharoni]

Hi Ivo,
In my opinion the most important consideration here is to minimize the excitation of ChR2 when exciting jRCeco1a. For this reason I think 49306 is the best fit.

As for picking an LED. You ideally want to pick the one that excited jRCeco1a the most when passing through your filter. This means you have to take into account both the filter band as well as the excitation spectra. I think the amber or PC-amber would work just fine.

[ivo.sonntag]

Hi Daniel,
thanks for the input!

cheers,
Ivo