Re: Fluorophore excitable with 405nm and 488nm lines

Posted by Craig Brideau on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Fluorophore-excitable-with-405nm-and-488nm-lines-tp6432486p6436624.html

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On Fri, Jun 3, 2011 at 11:59 AM, Barbara Foster <[hidden email]> wrote:

>
> Re: "Use a power meter and measure the power at the objective" and "not as
> practical":
> Take a look a the new XP750 from Lumen Dynamics (formerly EXFO).  This neat
> little power meter was specifically designed to mimic a microscope slide so
> that it sits flat on the stage and measures the intensity right where you
> want it: at the sample plane.  You can use it on an inverted or upright and
> with any type of illuminator (lamp, LED, laser).  For those of you who took
> part in our Illumination Study in 2008, you might have noticed two sneaky
> questions about this device.  The response were huge.. and now it's
> available... for real.
>

I actually got to evaluate this thing.  It was a good product, but EXFO
didn't have a good answer for me when I asked them what the meter does about
the high-angle rays from large NA lenses.  Since the face of the meter is
glass, the higher-angle rays from oil and water immersion lenses will tend
to be reflected and not reach the detecting element of the meter.
 Optimally, you'd want a sealed detector unit that you could put water or
oil on.  That way you could test your oil and water lenses with the power
meter.

Craig

>
> For further information, you can visit their website (
> http://www.ldgi-xcite.com/products-xr2100-xp750.php).  Also, I have an
> article coming out next month (July) in BioPhotonics written around
> interviews from users in three key labs (Jen Waters' NIC at Harvard, the YIP
> lab in Canada, and LBL).  If you want to chat with someone, get in touch
> with their Sr. Apps Scientist, Dr. Kavita Aswant (P:  1 905 812-3342, E:
> [hidden email]).  I know she'd welcome hearing from you.
>
> Caveat: No commercial interest.
>
> Good hunting!
> Barbara Foster, President and Sr. Consultant
>
> M icroscopy/Microscopy Education
> P: [phone]
> W: <http://www.microscopyeducation.com/>www.MicroscopyEducation.com
>
>
>
> At 05:09 PM 6/2/2011, Martin Wessendorf wrote:
>
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>> *****
>>
>> Dear Daniel--
>>
>> On 6/2/2011 1:59 PM, Daniel Gitler wrote:
>>
>>  I am in need of either beads or a fluorophore in solution which is exited
>>> consistently by both the 405nm and 488nm lines of a confocal microscope.
>>> What I really need is that the ratio of excitation should be constant, in
>>> which case two separate dyes are probably not a good choice, unless their
>>> molar ratio can be quite consistent (perhaps in beads?). I also need that
>>> the efficiency of excitation for both lines be quite decent (doesn't have to
>>> be maximal, just decent). Finally (it appears I have a lot of requisites)
>>> the dye/beads should be as insensitive as possible to environmental changes
>>> (i.e., pH etc). The idea is to have a good standard in order to calibrate
>>> the ratio of the power of these two lines when imaging a sample (I do not
>>> need to know the actual number, just a relative measure will do fine).
>>>
>>
>> Based on a quick search, uranium glass looks like a possibility.  The
>> absorbance is perhaps 2x better at 488 than 405.  However, if you're imaging
>> with a confocal, you would probably need to use point-scanning, since
>> uranium has a loooong fluorescence time-constant (e.g. 170 usec in
>> solution).
>>
>> Here are a few (mediocre) references--they might be a starting point:
>>
>> http://pubs.acs.org/doi/abs/10.1021/ac00230a029
>> http://webhost.bridgew.edu/cnoda/research/uranyl/index.html
>> http://onlinelibrary.wiley.com/doi/10.1002/pssa.2211150136/pdf
>>
>> Good luck!
>>
>> Martin
>> --
>> Martin Wessendorf, Ph.D.                   office: [phone]
>> Assoc Prof, Dept Neuroscience                 lab: [phone]
>> University of Minnesota             Preferred FAX: [phone]
>> 6-145 Jackson Hall, 321 Church St. SE    Dept Fax: [phone]
>> Minneapolis, MN  55455                    e-mail: [hidden email]
>>
>