Re: SHG

Posted by Eli Rothenberg on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Re-SHG-tp592071.html

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Hi Sarah,

If you double the frequency of your laser
and get a wavelength that is resonant to your fluorophore's absorption then it is a regular one-photon excitation and
you get linear dependence between your doubled laser and
emission intensity.

You have to make sure you carefully filter the remaining of the Ti:Sa laser after doubling, so you won't have 2P events
as well.

If the doubling crystal is your own "home built" addition, you don't place it in the Ti:Sa cavity but rather after it.
I guess you're using a BBO or LBO, in which case a 5mm by 5mm
piece will be enough, coming to it at a tight focus.
Finding the "mismatch" axis and aligning it is a bit tricky and requires 6 degrees of freedom (x-y-z rotational and angular).


Hope this helped- good luck,

Eli


6 degreess  
 

---- Original message ----

>Date: Thu, 8 May 2008 09:34:58 +0800
>From: Peng Xi <[hidden email]>  
>Subject: Re: SHG  
>To: [hidden email]
>
>Search the CONFOCAL archive at
>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
>Hi Sarah,
>    Just like you asked, it will be an one-photon excitation. So,
>although it is possible that you create a femtosecond 400nm laser pulse,
>it is still linear excitation -- one photon process. Thank you!
>    I am very interested in the experiment itself -- have you tried to
>put a SHG crystal inside the Ti:Sa laser cavity and see the 400nm emission?
>
>Best regards,
>Peng Xi
>Associate Professor
>Institute for Laser Medicine and Biophotonics
>Shanghai Jiao Tong University
>800 Dongchuan Rd.
>Shanghai 200240, China
>Tel: [phone]
>http://biophotonics.sjtu.edu.cn/
>
>
>
>Sarah Kefayati wrote:
>> Search the CONFOCAL archive at
>> http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>> Hello all,
>>  
>> I appreciate if you could help me with my question:
>>  
>> I just want to make sure about this fact that by using a non-linear
>> crystal in the path of my Ti-sapphire laser I will have the frequency
>> doubled beam which excites my sample via traditional one-photon
>> excitation.
>> But dose the intensity of the emitted fluorescence depend on
>> excitation power linearly or quadratically?
>>  
>> any information in this regard is highly appreciated.
>>  
>> Thanks
>> Sarah

________________________________
Eli Rothenberg, Ph.D.
Post Doctoral Research Associate,
Howard Hughes Medical Institute,
Department of Physics,
University of Illinois,
Urbana-Champaign. 61801.
Illinois, USA
Tel: [phone];
Fax: [phone];
Email: [hidden email]