Beam quality of SHG generated laser source for FLIM

classic Classic list List threaded Threaded
2 messages Options
Heping Yuan Heping Yuan
Reply | Threaded
Open this post in threaded view
|

Beam quality of SHG generated laser source for FLIM

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
Post images on http://www.imgur.com and include the link in your posting.
*****

Hi everyone, our application is FLIM microscopy with a pulsed visible source. Since we have a 100 fs Ti-Sapphire laser, we thought we could generate our pulsed source using a BIBO crystal (10 mm thickness). We end up getting very high SHG conversion for 960 nm -> 480 nm (300 mW average power at 480 nm) but when we try to focus this beam down we cannot get anywhere close to a diffraction limited performance. Does anyone have experience using frequency doubled laser source for imaging? What can we do to 'clean up' this frequency doubled beam and how much power can we expect to lose?

Thanks for any help,
Tim
Craig Brideau Craig Brideau
Reply | Threaded
Open this post in threaded view
|

Re: Beam quality of SHG generated laser source for FLIM

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
Post images on http://www.imgur.com and include the link in your posting.
*****

If your crystal really is 10mm thick, you are using way too thick a
crystal. You are probably getting a great deal of 'walk off' as the phase
matching will be all over the place. Typically for this you want to use 10
to 100 um (micro!) thick crystal and a bit of focusing. You can still get
some spatial chirp and walkoff even with a thin crystal, but I successfully
coupled a doubled Ti:Saph into single mode fiber (without destroying the
fiber) using a setup I detail in my paper:
http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=2195758
You need a freespace solution as fiber coupling can introduce phase noise
into the system, but a simple high energy pinhole should suffice.

Feel free to contact me if you have any questions.

Craig

On Mon, Mar 6, 2017 at 2:33 PM, Tim <[hidden email]> wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> Post images on http://www.imgur.com and include the link in your posting.
> *****
>
> Hi everyone, our application is FLIM microscopy with a pulsed visible
> source. Since we have a 100 fs Ti-Sapphire laser, we thought we could
> generate our pulsed source using a BIBO crystal (10 mm thickness). We end
> up getting very high SHG conversion for 960 nm -> 480 nm (300 mW average
> power at 480 nm) but when we try to focus this beam down we cannot get
> anywhere close to a diffraction limited performance. Does anyone have
> experience using frequency doubled laser source for imaging? What can we do
> to 'clean up' this frequency doubled beam and how much power can we expect
> to lose?
>
> Thanks for any help,
> Tim
>