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Kate,

what type of scanner is this Odyssey? If it's a point-scanning device,
then 3 mW per point is a lot (nice for FRET or FRAP). So you would have to
consider the amount of scanned pixels in your comparison, maybe 1024 times
1024... times 3 mW.

Michael


> Search the CONFOCAL archive at
> http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
> Thanks for all your helpful suggestions. I thought the following might be
> interesting:
>
> I used my laser power meter to check the power density for different
> lenses
> and light sources that we have.
>
> At 740 nm (Chroma SP-106 excitation filter is 740±35)
>
> No lens - 43 mW with Hg and 58 mW with Halogen (3200K)
> 20x/0.45 Achroplan Ph2  - 79%T
> 40x/1.2 W C Apochromat - 81%T
> 63x/1.4 oil PlanApo - 67%T
>
> At 774 nm (peak absorption for IRDye 800)
>
> No lens - 40 mW with Hg and 50 mW with Halogen (3200K)
> 20x/0.45 Achroplan Ph2  - 50%T
> 40x/1.2 W C Apochromat - 60%T
> 63x/1.4 oil PlanApo - 42%T
>
> There is a lot more light out there with the Hg than you might think even
> though the Halogen is better. The %Ts at 740 nm are pretty similar to the
> "typical" curves for these lenses found on the Zeiss website. The drop off
> when going up to 774 nm was quite a bit more than expected.
>
> Licor tech support does not have information on the power density of the
> laser in the Odyssey but they thought it was pretty low. We put the power
> meter in the Odyssey and never recorded more than 3 mW during the scan.
>
> So compared to the Odyssey we have plenty of light.
>
> Kate